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Archive for November, 2011

New research from last week 47/2011

Posted by Ari Jokimäki on November 28, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news.

Springer free access campaign

Springer once again has a campaign where some journals are free access to everyone until December 31. Included to the campaign are Springer’s climate science journals Climatic Change and Climate Dynamics. Some other interesting journals on related issues are also included.

Climate change also has an effect to California beach boys and girls

Estimating the potential economic impacts of climate change on Southern California beaches – Pendleton et al. (2011) “Climate change could substantially alter the width of beaches in Southern California. Climate-driven sea level rise will have at least two important impacts on beaches: (1) higher sea level will cause all beaches to become more narrow, all things being held constant, and (2) sea level rise may affect patterns of beach erosion and accretion when severe storms combine with higher high tides. To understand the potential economic impacts of these two outcomes, this study examined the physical and economic effects of permanent beach loss caused by inundation due to sea level rise of one meter and of erosion and accretion caused by a single, extremely stormy year (using a model of beach change based on the wave climate conditions of the El Niño year of 1982/1983.) We use a random utility model of beach attendance in Southern California that estimates the impacts of changes on beach width for different types of beach user visiting public beaches in Los Angeles and Orange Counties. The model allows beachgoers to have different preferences for beach width change depending on beach size. We find that the effect of climate-driven beach change differs for users that participate in bike path activities, sand-based activities, and water-based activities. We simulate the effects of climate-related beach loss on attendance patterns at 51 public beaches, beach-related expenditures at those beaches, and the non-market (consumer surplus) value of beach going to those beaches. We estimate that increasing sea level will cause an overall reduction of economic value in beach going, with some beaches experiencing increasing attendance and beach-related earnings while attendance and earnings at other beaches would be lower. We also estimate that the potential annual economic impacts from a single stormy year may be as large as those caused by permanent inundation that would result from a rise in sea level of one meter. The economic impacts of both permanent inundation and storm-related erosion are distributed unevenly across the region. To put the economic impacts of these changes in beach width in perspective, the paper provides simple estimates of the cost of mitigating beach loss by nourishing beaches with sand.” Linwood Pendleton, Philip King, Craig Mohn, D. G. Webster, Ryan Vaughn and Peter N. Adams, Climatic Change, DOI: 10.1007/s10584-011-0309-0.

Sea level rise brings increased coastal flooding to California threatening lot of people and property

Potential impacts of increased coastal flooding in California due to sea-level rise – Heberger et al. (2011) “California is likely to experience increased coastal flooding and erosion caused by sea-level rise over the next century, affecting the state’s population, infrastructure, and environment. As part of a set of studies on climate change impacts to California, this paper analyzes the potential impacts from projected sea-level rise if no actions are taken to protect the coast (a “no-adaptation scenario”), focusing on impacts to the state’s population and infrastructure. Heberger et al. (2009) also covered effects on wetlands, costs of coastal defenses, and social and environmental justice related to sea-level rise. We analyzed the effect of a medium-high greenhouse gas emissions scenario (Special Report on Emissions Scenarios A2 in IPCC 2000) and included updated projections of sea-level rise based on work by Rahmstorf (Science 315(5810): 368, 2007). Under this scenario, sea levels rise by 1.4 m by the year 2100, far exceeding historical observed water level increases. By the end of this century, coastal flooding would, under this scenario, threaten regions that currently are home to approximately 480,000 people and $100 billion worth of property. Among those especially vulnerable are large numbers of low-income people and communities of color. A wide range of critical infrastructure, such as roads, hospitals, schools, emergency facilities, wastewater treatment plants, and power plants will also be at risk. Sea-level rise will inevitably change the character of California’s coast; practices and policies should be put in place to mitigate the potentially costly and life-threatening impacts of sea-level rise.” Matthew Heberger, Heather Cooley, Pablo Herrera, Peter H. Gleick and Eli Moore, Climatic Change, DOI: 10.1007/s10584-011-0308-1.

Precisely dated European climate record 120–60 ka from speleothems

NALPS: a precisely dated European climate record 120–60 ka – Boch et al. (2011) “Accurate and precise chronologies are essential in understanding the rapid and recurrent climate variations of the Last Glacial – known as Dansgaard-Oeschger (D-O) events – found in the Greenland ice cores and other climate archives. The existing chronological uncertainties during the Last Glacial, however, are still large. Radiometric age data and stable isotopic signals from speleothems are promising to improve the absolute chronology. We present a record of several precisely dated stalagmites from caves located at the northern rim of the Alps (NALPS), a region that favours comparison with the climate in Greenland. The record covers most of the interval from 120 to 60 ka at an average temporal resolution of 2 to 22 yr and 2σ-age uncertainties of ca. 200 to 500 yr. The rapid and large oxygen isotope shifts of 1 to 4.5‰ occurred within decades to centuries and strongly mimic the Greenland D-O pattern. Compared to the updated Greenland ice-core timescale (GICC05modelext) the NALPS record confirms the timing of rapid warming and cooling transitions between 118 and 106 ka, but suggests younger ages for D-O events between 106 and 60 ka. As an exception, the timing of the rapid transitions into and out of the stadial following GI 22 is earlier in NALPS than in the Greenland ice-core timescale. In addition, there is a discrepancy in the duration of this stadial between the ice-core and the stalagmite chronology (ca. 2900 vs. 3650 yr). The short-lived D-O events 18 and 18.1 are not recorded in NALPS, provoking questions with regard to the nature and the regional expression of these events. NALPS resolves recurrent short-lived climate changes within the cold Greenland stadial and warm interstadial successions, i.e. abrupt warming events preceding GI 21 and 23 (precursor-type events) and at the end of GI 21 and 25 (rebound-type events), as well as intermittent cooling events during GI 22 and 24. Such superimposed events have not yet been documented outside Greenland.” Boch, R., Cheng, H., Spötl, C., Edwards, R. L., Wang, X., and Häuselmann, Ph., Clim. Past, 7, 1247-1259, doi:10.5194/cp-7-1247-2011, 2011. [Full text]

More accurate forest radiative transfer models by improving pine shoot albedo estimates

A note on upscaling coniferous needle spectra to shoot spectral albedo – Rautiainen et al. (2011) “Mutual shading of needles in coniferous shoots and small-scale variations in needle area density both within and between shoots violate conventional assumptions used in the definition of the elementary volume in radiative transfer models. In this paper, we test the hypothesis if it is possible to scale needle spectral albedo up to shoot spectral albedo using only one structural parameter: the spherically averaged shoot silhouette to total area ratio (STAR). To test the hypothesis, we measured both structural and spectral properties of ten Scots pine (Pinus sylvestris) shoots and their needles. Our results indicate that it is possible to upscale from needle to shoot spectral albedo using STAR. The upscaling model performed best in the VIS and SWIR regions, and for shoots with high STAR values. As STAR is linearly related to photon recollision probability, it is also possible to apply the upscaling model as integral part of radiative transfer models.” Miina Rautiainen, Matti Mõttus, Lucia Yáñez-Rausell, Lucie Homolová, Zbyněk Malenovský, Michael E. Schaepman, Remote Sensing of Environment, doi:10.1016/j.rse.2011.10.019.

North American boreal forests seem to be browning

Browning boreal forests of western North America – Verbyla (2011) Abstract page contains the whole article without abstract – here’s first paragraph: “The GIMMS NDVI dataset has been widely used to document a ‘browning trend’ in North American boreal forests (Goetz et al 2005, Bunn et al 2007, Beck and Goetz 2011). However, there has been speculation (Alcaraz-Segura et al 2010) that this trend may be an artifact due to processing algorithms rather than an actual decline in vegetation activity. This conclusion was based primarily on the fact that GIMMS NDVI did not capture NDVI recovery within most burned areas in boreal Canada, while another dataset consistently showed post-fire increasing NDVI. I believe that the results of Alcaraz-Segura et al (2010) were due simply to different pixel sizes of the two datasets (64 km2 versus 1 km2 pixels). Similar results have been obtained from tundra areas greening in Alaska, with the results simply due to these pixel size differences (Stow et al 2007). Furthermore, recent studies have documented boreal browning trends based on NDVI from other sensors. Beck and Goetz (2011) have shown the boreal browning trend derived from a different sensor (MODIS) to be very similar to the boreal browning trend derived from the GIMMS NDVI dataset for the circumpolar boreal region. Parent and Verbyla (2010) found similar declining NDVI patterns based on NDVI from Landsat sensors and GIMMS NDVI in boreal Alaska. Zhang et al (2008) found a similar ‘browning trend’ in boreal North America based on a production efficiency model using an integrated AVHRR and MODIS dataset.” David Verbyla 2011 Environ. Res. Lett. 6 041003 doi:10.1088/1748-9326/6/4/041003. [Full text]

Most recent warm event of Atlantic water is anomalous

Interannual to decadal variability of Atlantic Water in the Nordic and adjacent seas – Carton et al. (2011) “Warm salty Atlantic Water is the main source water for the Arctic Ocean and thus plays an important role in the mass and heat budget of the Arctic. This study explores interannual to decadal variability of Atlantic Water properties in the Nordic Seas area where Atlantic Water enters the Arctic, based on a reexamination of the historical hydrographic record for the years 1950–2009, obtained by combining multiple data sets. The analysis shows a succession of four multiyear warm events where temperature anomalies at 100 m depth exceed 0.4°C, and three cold events. Three of the four warm events lasted 3–4 years, while the fourth began in 1999 and persists at least through 2009. This most recent warm event is anomalous in other ways as well, being the strongest, having the broadest geographic extent, being surface-intensified, and occurring under exceptional meteorological conditions. Three of the four warm events were accompanied by elevated salinities consistent with enhanced ocean transport into the Nordic Seas, with the exception of the event spanning July 1989–July 1993. Of the three cold events, two lasted for 4 years, while the third lasted for nearly 14 years. Two of the three cold events are associated with reduced salinities, but the cold event of the 1960s had elevated salinities. The relationship of these events to meteorological conditions is examined. The results show that local surface heat flux variations act in some cases to reinforce the anomalies, but are too weak to be the sole cause.” Carton, J. A., G. A. Chepurin, J. Reagan, and S. Häkkinen (2011), J. Geophys. Res., 116, C11035, doi:10.1029/2011JC007102.

Mediterranean brown trout might become almost extinct by 2100

Global warming threatens the persistence of Mediterranean brown trout – Almodóvar et al. (2011) “Current climate change exacerbates the environmental restrictions on temperate species inhabiting low latitude edges of their geographical ranges. We examined how temperature variations due to current and future climate change are likely to affect populations’ persistence of stream-dwelling brown trout Salmo trutta at the vulnerable southern periphery of its range. Analysis of 33 years of air temperature data (1975-2007) by time-series models indicated a significant upward trend and a pronounced shift in air temperature around 1986-1987. This warming is associated with an ongoing population decline of brown trout, most likely caused by a loss of suitable thermal habitat in lower latitudes since the 1980s. Population decrease may not be attributed to physical habitat modification or angler pressure, since carrying capacity remained stable and populations were not overexploited. We developed regional temperature models, which predicted that unsuitable thermal habitat for brown trout increased by 93% when comparing climate conditions between 1975-1986 and 1993-2004. Predictions from climate envelope models showed that current climate change may be rendering unsuitable 12% of suitable thermal habitat each decade, resulting in an overall population decrease in the lower reaches of around 6% per year. Furthermore, brown trout catches markedly decreased 20% per year. Projections of thermal habitat loss under the ecologically friendly B2 SRES scenario showed that brown trout may lose half of their current suitable habitat within the study area by 2040 and become almost extinct by 2100. In parallel to the upstream movement of brown trout thermal habitat, warm water species are increasing their relative abundance in salmonid waters. Empirical evidence was provided of how current climate change threatens some of the most healthy native brown trout populations in Southern Europe and how forthcoming climate change is expected to further decrease the conservation status of the species.” Ana Almodóvar, Graciela G. Nicola, Daniel Ayllón, Benigno Elvira, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02608.x.

Analysis of Argo network

How well can we derive Global Ocean Indicators from Argo data? – von Schuckmann & Le Traon (2011) “Argo deployments began in the year 2000 and by November 2007, the array reached its initial goal of 3000 floats operating worldwide. In this study, Argo temperature and salinity measurements during the period 2005 to 2010 are used to estimate Global Ocean Indicators (GOIs) such as global ocean heat content (GOHC), global ocean freshwater content (GOFC) and global steric sea level (GSSL). We developed a method based on a simple box averaging scheme using a weighted mean. Uncertainties due to data processing methods and choice of climatology are estimated. This method is easy to implement and run and can be used to set up a routine monitoring of the global ocean. Over the six year time period, trends of GOHC and GSSL are 0.54 ± 0.1 W m−2 and 0.75 ± 0.15 mm yr−1, respectively. The trend of GOFC is barely significant. Results show that there is significant interannual variability at global scale, especially for GOFC. Annual mean GOIs from the today’s Argo sampling can be derived with an accuracy of ±0.11 cm for GSSL, ±0.22 × 108 J m−2 for GOHC, and ±700 km3 for GOFC. Long-term trends (15 yr) of GOIs based on the complete Argo sampling for the upper 1500 m depth can be estimated with an accuracy of ±0.04 mm yr−1 for GSSL, ±0.02 W m−2 for GOHC and ±20 km3 yr−1 for GOFC – under the assumption that no systematic errors remain in the observing system.” von Schuckmann, K. and Le Traon, P.-Y.: How well can we derive Global Ocean Indicators from Argo data?, Ocean Sci., 7, 783-791, doi:10.5194/os-7-783-2011, 2011. [Full text]

Melt season is getting longer in Svalbard

Estimation of trends in extreme melt-season duration at Svalbard – Kvamstø et al. (2011) “A time series of monthly mean surface temperatures taken at Svalbard airport, Spitzbergen, for the period 1912–2010 was examined for changes in melt-season length. The annual melt-season length was constructed from daily temperature estimates based on the monthly data using smoothing splines. We argue that the changes in annual melt-season length are linked to variability in regional sea surface temperatures, the mean Northern Hemisphere surface temperature and the North Atlantic Oscillation (NAO) index. A regression model for the melt-season length with these three parameters as predictors, explained about 40% of the observed variance. The annual mean melt season for the period from 1912 to 2010 was estimated to be 108 days, and the linear trend was 0.17 days/year. The risk of having positive extremes in the melt season increased with increasing Northern Hemisphere surface temperature and the regional sea surface temperatures. On the basis of our study of past observations, the 100-year return length of the melt season at Svalbard was predicted to change from the current 95% confidence interval of 131 (108, 138) days to 175 (109, 242) days with 1 °C warming of both regional sea surface temperature and the mean Northern Hemisphere surface temperature.” Nils Gunnar Kvamstø, Dag Johan Steinskog, David B. Stephenson, Dag Bjarne Tjøstheim, International Journal of Climatology, DOI: 10.1002/joc.3395.


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New research from last week 46/2011

Posted by Ari Jokimäki on November 21, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news.

There will still be cold months in warmer climate

Cold months in a warming climate – Räisänen & Ylhäisi (2011) “The frequency of cold months in the 21st century is studied using the CMIP3 ensemble of climate model simulations, using month-, location- and model-specific threshold temperatures derived from the simulated 20th century climate. Unsurprisingly, cold months are projected to become less common, but not non-existent, under continued global warming. As a multi-model mean over the global land area excluding Antarctica and under the SRES A1B scenario, 14% of the months during the years 2011–2050 are simulated to be colder than the 20th century median for the same month, 1.3% colder than the 10th percentile, and 0.1% record cold. The geographic and seasonal variations in the frequency of cold months are strongly modulated by variations in the magnitude of interannual variability. Thus, for example, cold months are most infrequently simulated over the tropical oceans where the variability is smallest, not over the Arctic where the warming is largest.” Räisänen, J. and J. S. Ylhäisi (2011), Geophys. Res. Lett., 38, L22704, doi:10.1029/2011GL049758.

You need at least 17 years of TLT data to detect anthropogenic warming signal

Separating signal and noise in atmospheric temperature changes: The importance of timescale – Santer et al. (2011) “We compare global-scale changes in satellite estimates of the temperature of the lower troposphere (TLT) with model simulations of forced and unforced TLT changes. While previous work has focused on a single period of record, we select analysis timescales ranging from 10 to 32 years, and then compare all possible observed TLT trends on each timescale with corresponding multi-model distributions of forced and unforced trends. We use observed estimates of the signal component of TLT changes and model estimates of climate noise to calculate timescale-dependent signal-to-noise ratios (S/N). These ratios are small (less than 1) on the 10-year timescale, increasing to more than 3.9 for 32-year trends. This large change in S/N is primarily due to a decrease in the amplitude of internally generated variability with increasing trend length. Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming. A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature.” Santer, B. D., et al. (2011), Separating signal and noise in atmospheric temperature changes: The importance of timescale, J. Geophys. Res., 116, D22105, doi:10.1029/2011JD016263. [Full text]

Climate model shows skill in predicting decadal trends in global surface temperature

Skillful predictions of decadal trends in global mean surface temperature – Fyfe et al. (2011) “We compare observed decadal trends in global mean surface temperature with those predicted using a modelling system that encompasses observed initial condition information, externally forced response (due to anthropogenic greenhouse gases and aerosol precursors), and internally generated variability. We consider retrospective decadal forecasts for nine cases, initiated at five year intervals, with the first beginning in 1961 and the last in 2001. Forecast ensembles of size thirty are generated from differing but similar initial conditions. We concentrate on the trends that remain after removing the following natural signals in observations and hindcasts: dynamically induced atmospheric variability, El Nino-Southern Oscillation (ENSO), and the effects of explosive volcanic eruptions. We show that ensemble mean errors in the decadal trend hindcasts are smaller than in a parallel set of uninitialized free running climate simulations. The ENSO signal, which is skillfully predicted out to a year or so, has little impact on our decadal trend predictions, and our modelling system possesses skill, independent of ENSO, in predicting decadal trends in global mean surface temperature.” Fyfe, J. C., W. J. Merryfield, V. Kharin, G. J. Boer, W.-S. Lee, and K. von Salzen (2011), Geophys. Res. Lett., doi:10.1029/2011GL049508, in press.

Global warming might have inreased potato yield in Scotland

Attribution of climate change: a methodology to estimate the potential contribution to increases in potato yield in Scotland since 1960 – Gregory & Marshall (2011) “Maincrop potato yields in Scotland have increased by 30-35 t ha−1 since 1960 as a result of many changes, but has changing climate contributed anything to this? The purpose of this work was to answer this question. Daily weather data for the period 1960 to 2006 were analysed for five locations covering the zones of potato growing on the east coast of Scotland (between 55.213 and 57.646 N) to determine trends in temperature, rainfall and solar radiation. A physiologically-based potato yield model was validated using data obtained from a long-term field trial in eastern Scotland, and then employed to simulate crop development and potential yield at each of the five sites. Over the 47 years, there were significant increases in annual air and 30 cm soil temperatures (0.27 K decade−1 and 0.30 K decade−1 respectively), but no significant changes in annual precipitation or in the timing of the last frost in spring and the first frost of autumn. There was no evidence of any north to south gradient of warming. Simulated emergence and canopy closure became earlier at all five sites over the period with the advance being greater in the north (3.7 and 3.6 days decade−1 respectively) than the south (0.5 and 0.8 days decade−1 respectively). Potential yield increased with time, generally reflecting the increased duration of the green canopy, at average rates of 2.8 t ha−1 decade−1 for chitted seed (sprouted prior to planting) and 2.5 t ha−1 decade−1 for unchitted seed. The measured warming could contribute potential yield increases of up to 13.2 t ha−1 for chitted potato (range 7.1 – 19.3 t ha−1) and 11.5 t ha−1 for unchitted potato (range 7.1 – 15.5 t ha−1) equivalent to 34-39% of the increased potential yield over the period or 23-26% of the increase in actual measured yields.” P J Gregory, B Marshall, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02601.x.

Do tropical plant species experience cold-ward range shifts with global warming?

Distributional migrations, expansions, and contractions of tropical plant species as revealed in dated herbarium records – Feeley (2011) “Species are predicted to respond to global warming through “cold-ward” shifts in their geographic distributions due to encroachment into newly suitable habitats and/or dieback in areas that become climatically unsuitable. I conduct one of the first ever tests of this hypothesis for tropical plant species. I test for changes in the thermal distributions of 239 South American tropical plant species using dated herbarium records for specimens collected between 1970 and 2009. Supporting a priori predictions, many species (59%) exhibit some evidence of significant cold-ward range shifts even after correcting for collection biases. Over 1/3 of species (35%) show significant cold-ward movement in their hot thermal limits (mean rate of change = 0.022°C yr−1). Most of these species (85%; 30% of all study species) show no corresponding shift in their cold thermal limits. These unbalanced changes in the species’ thermal range limits may indicate species that are experiencing dieback due to their intolerance of rising temperatures coupled with an inability to expand into newly climatically-suitable habitats. On the other hand, 25% of species show significant cold-ward shifts in their cold thermal range limits (mean rate of change = 0.003°C yr−1), but 80% of these species (20% of all study species) show no corresponding shift in their hot thermal range limits. In these cases, the unbalanced shifts may indicate species that are able to “benefit” under global warming, at least temporally, by both tolerating rising temperatures and expanding into new suitable habitat. An important ancillary result of this study is that the number of species exhibiting significant range shifts was greatly influenced by shifting collector biases. This highlights the need to account for biases when analyzing natural history records or other long-term records.” Kenneth J. Feeley, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02602.x.

New study says semi-empirical sea level projections are robust

Testing the robustness of semi-empirical sea level projections – Rahmstorf et al. (2011) “We determine the parameters of the semi-empirical link between global temperature and global sea level in a wide variety of ways, using different equations, different data sets for temperature and sea level as well as different statistical techniques. We then compare projections of all these different model versions (over 30) for a moderate global warming scenario for the period 2000–2100. We find the projections are robust and are mostly within ±20% of that obtained with the method of Vermeer and Rahmstorf (Proc Natl Acad Sci USA 106:21527–21532, 2009), namely ~1 m for the given warming of 1.8°C. Lower projections are obtained only if the correction for reservoir storage is ignored and/or the sea level data set of Church and White (Surv Geophys, 2011) is used. However, the latter provides an estimate of the base temperature T 0 that conflicts with the constraints from three other data sets, in particular with proxy data showing stable sea level over the period 1400–1800. Our new best-estimate model, accounting also for groundwater pumping, is very close to the model of Vermeer and Rahmstorf (Proc Natl Acad Sci USA 106:21527–21532, 2009).” Stefan Rahmstorf, Mahé Perrette and Martin Vermeer, Climate Dynamics, DOI: 10.1007/s00382-011-1226-7.

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New research from last week 45/2011

Posted by Ari Jokimäki on November 14, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news.

New analysis of global carbon dioxide fluxes

Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses – Deng & Chen (2011) “The net surface exchange of CO2 for the years 2002–2007 is inferred from 12 181 atmospheric CO2 concentration data with a time-dependent Bayesian synthesis inversion scheme. Monthly CO2 fluxes are optimized for 30 regions of the North America and 20 regions for the rest of the globe. Although there have been many previous multiyear inversion studies, the reliability of atmospheric inversion techniques has not yet been systematically evaluated for quantifying regional interannual variability in the carbon cycle. In this study, the global interannual variability of the CO2 flux is found to be dominated by terrestrial ecosystems, particularly by tropical land, and the variations of regional terrestrial carbon fluxes are closely related to climate variations. These interannual variations are mostly caused by abnormal meteorological conditions in a few months in the year or part of a growing season and cannot be well represented using annual means, suggesting that we should pay attention to finer temporal climate variations in ecosystem modeling. We find that, excluding fossil fuel and biomass burning emissions, terrestrial ecosystems and oceans absorb an average of 3.63 ± 0.49 and 1.94 ± 0.41 Pg C yr−1, respectively. The terrestrial uptake is mainly in northern land while the tropical and southern lands contribute 0.62 ± 0.47, and 0.67 ± 0.34 Pg C yr−1 to the sink, respectively. In North America, terrestrial ecosystems absorb 0.89 ± 0.18 Pg C yr−1 on average with a strong flux density found in the south-east of the continent.” Deng, F. and Chen, J. M., Biogeosciences, 8, 3263-3281, doi:10.5194/bg-8-3263-2011, 2011. [Full text]

Climate change is expected to increase waterborne pathogen concentrations in surface waters globally

Quantifying the impact of climate change on enteric waterborne pathogen concentrations in surface water – Hofstra (2011) “Climate change, among other factors, will impact waterborne pathogen concentrations in surface water worldwide, possibly increasing the risk of diseases caused by these pathogens. So far, the impacts are only determined qualitatively and thorough quantitative estimates of future pathogen concentrations have not yet been made. This review shows how changes in temperature and precipitation influence pathogen concentrations and gives opportunities to quantitatively explore the impact of climate change on pathogen concentrations using examples from ecological and hydrological modelling, already available statistical and process-based pathogen models and climate change scenarios. Such applications could indicate potential increased waterborne pathogen concentrations and guide further research.” Nynke Hofstra, Current Opinion in Environmental Sustainability, doi:10.1016/j.cosust.2011.10.006.

Ocean acidification also affects coral symbiotic algae which might enhance decrease in calcification

Effects of acidified seawater on coral calcification and symbiotic algae on the massive coral Porites australiensis – Iguchi et al. (2011) “We investigated the effect of acidified seawater on calcification and symbiotic algae (zooxanthellae density, chlorophyll content per single algal cell, fluorescence yield (Fv/Fm)) on a massive coral, Porites australiensis, a common species in the Ryukyu Archipelago of Japan. We found that acidified seawater significantly decreased the calcification and fluorescence yield, but did not affect zooxanthellae density and chlorophyll content per single algal cell. This indicates low levels of photoacclimation to acidified seawater in this species, and this is contrary to the findings of previous studies of Acropora species. A significant correlation between calcification and fluorescence yield was observed, indicating the presence of a strong relationship between calcification and algal photosynthesis. Our results indicate that endosymbiont photosynthetic dysfunction may enhance the decrease of coral calcification in future acidified ocean conditions. Calcification and fluorescence yield among colonies clearly differed, showing that the response to acidified seawater is highly variable among colonies in natural coral populations.” Akira Iguchi, Saori Ozaki, Takashi Nakamura, Mayuri Inoue, Yasuaki Tanaka, Atsushi Suzuki, Hodaka Kawahata, Kazuhiko Sakai, Marine Environmental Research, doi:10.1016/j.marenvres.2011.10.008.

Tropical insects living in thermally heterogenous environment tolerate more warming

Climate heterogeneity modulates impact of warming on tropical insects – Bonebrake & Deutsch (2011) “Evolutionary history and physiology mediate species responses to climate change. Tropical species that do not naturally experience high temperature variability have a narrow thermal tolerance compared to similar taxa at temperate latitudes, and could therefore be most vulnerable to warming. However, the thermal adaptation of a species may also be influenced by spatial temperature variations over its geographical range. Spatial climate gradients, especially from topography, may also broaden thermal tolerance and therefore act to buffer warming impacts. Here we show that for low seasonality environments, high spatial heterogeneity in temperature correlates significantly with greater warming tolerance in insects globally. Based on this relationship, we find that climate change projections of direct physiological impacts on insect fitness highlight the vulnerability of tropical lowland areas to future warming. Thus, in addition to seasonality, spatial heterogeneity may play a critical role in thermal adaptation and climate change impacts particularly in the tropics.” Bonebrake, Timothy Carlton, and Curtis A. Deutsch, Ecology, doi:10.1890/11-1187.1.

Global temperature doesn’t correlate significantly with sunspot number or geomagnetic activity

Are secular correlations between sunspots, geomagnetic activity, and global temperature significant? – Love et al. (2011) “Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868–2008, solar cycles 11–23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically-significant correlation between sunspot number and geomagnetic activity, Pearson p < 10−4, but correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction.” Love, J. J., K. Mursula, V. C. Tsai, and D. M. Perkins (2011), Geophys. Res. Lett., 38, L21703, doi:10.1029/2011GL049380. [Full text]

Updated dataset shows that global warming is due to greenhouse gases

Sensitivity of the attribution of near surface temperature warming to the choice of observational dataset – Jones & Stott (2011) “A number of studies have demonstrated that much of the recent warming in global near surface temperatures can be attributed to increases in anthropogenic greenhouse gases. While this conclusion has been shown to be robust in analyses using a variety of climate models there have not been equivalent studies using different available observational datasets. Here we repeat the analyses as reported previously using an updated observational dataset and other independently processed datasets of near surface temperatures. We conclude that the choice of observational dataset has little impact on the attribution of greenhouse gas warming and other anthropogenic cooling contributions to observed warming on a global scale over the 20th century, however this robust conclusion may not hold for other periods or for smaller sub-regions. Our results show that the dominant contributor to global warming over the last 50 years of the 20th century is that due to greenhouse gases.” Jones, G. S. and P. A. Stott (2011), Geophys. Res. Lett., 38, L21702, doi:10.1029/2011GL049324.

Several warmer than today periods in Greenland thousands of years ago but global warming is catching up

High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core – Kobashi et al. (2011) “Greenland recently incurred record high temperatures and ice loss by melting, adding to concerns that anthropogenic warming is impacting the Greenland ice sheet and in turn accelerating global sea-level rise. Yet, it remains imprecisely known for Greenland how much warming is caused by increasing atmospheric greenhouse gases versus natural variability. To address this need, we reconstruct Greenland surface snow temperature variability over the past 4000 years at the GISP2 site (near the Summit of the Greenland ice sheet; hereafter referred to as Greenland temperature) with a new method that utilises argon and nitrogen isotopic ratios from occluded air bubbles. The estimated average Greenland snow temperature over the past 4000 years was −30.7°C with a standard deviation of 1.0°C and exhibited a long-term decrease of roughly 1.5°C, which is consistent with earlier studies. The current decadal average surface temperature (2001–2010) at the GISP2 site is −29.9°C. The record indicates that warmer temperatures were the norm in the earlier part of the past 4000 years, including century-long intervals nearly 1°C warmer than the present decade (2001–2010). Therefore, we conclude that the current decadal mean temperature in Greenland has not exceeded the envelope of natural variability over the past 4000 years, a period that seems to include part of the Holocene Thermal Maximum. Notwithstanding this conclusion, climate models project that if anthropogenic greenhouse gas emissions continue, the Greenland temperature would exceed the natural variability of the past 4000 years sometime before the year 2100.” Kobashi, T., K. Kawamura, J. P. Severinghaus, J.-M. Barnola, T. Nakaegawa, B. M. Vinther, S. J. Johnsen, and J. E. Box (2011), Geophys. Res. Lett., 38, L21501, doi:10.1029/2011GL049444.

Vertical climate forcing & feedback analysis highlights important role of water cycle

The vertical distribution of climate forcings and feedbacks from the surface to top of atmosphere – Previdi & Liepert (2011) “The radiative forcings and feedbacks that determine Earth’s climate sensitivity are typically defined at the top-of-atmosphere (TOA) or tropopause, yet climate sensitivity itself refers to a change in temperature at the surface. In this paper, we describe how TOA radiative perturbations translate into surface temperature changes. It is shown using first principles that radiation changes at the TOA can be equated with the change in energy stored by the oceans and land surface. This ocean and land heat uptake in turn involves an adjustment of the surface radiative and non-radiative energy fluxes, with the latter being comprised of the turbulent exchange of latent and sensible heat between the surface and atmosphere. We employ the radiative kernel technique to decompose TOA radiative feedbacks in the IPCC Fourth Assessment Report climate models into components associated with changes in radiative heating of the atmosphere and of the surface. (We consider the equilibrium response of atmosphere-mixed layer ocean models subjected to an instantaneous doubling of atmospheric CO2). It is shown that most feedbacks, i.e., the temperature, water vapor and cloud feedbacks, (as well as CO2 forcing) affect primarily the turbulent energy exchange at the surface rather than the radiative energy exchange. Specifically, the temperature feedback increases the surface turbulent (radiative) energy loss by 2.87 W m−2 K−1 (0.60 W m−2 K−1) in the multimodel mean; the water vapor feedback decreases the surface turbulent energy loss by 1.07 W m−2 K−1 and increases the surface radiative heating by 0.89 W m−2 K−1; and the cloud feedback decreases both the turbulent energy loss and the radiative heating at the surface by 0.43 and 0.24 W m−2 K−1, respectively. Since changes to the surface turbulent energy exchange are dominated in the global mean sense by changes in surface evaporation, these results serve to highlight the fundamental importance of the global water cycle to Earth’s climate sensitivity.” Michael Previdi and Beate G. Liepert, Climate Dynamics, DOI: 10.1007/s00382-011-1233-8.

Researchers link sea level rise to Earth’s core and suggest consequences for global warming

Geomagnetic South Atlantic Anomaly and global sea level rise: a direct connection? – De Santis et al. (2011) “We highlight the existence of an intriguing and to date unreported relationship between the surface area of the South Atlantic Anomaly (SAA) of the geomagnetic field and the current trend in global sea level rise. These two geophysical variables have been growing coherently during the last three centuries, thus strongly suggesting a causal relationship supported by some statistical tests. The monotonic increase of the SAA surface area since 1600 may have been associated with an increased inflow of radiation energy through the inner Van Allen belt with a consequent warming of the Earth’s atmosphere and finally global sea level rise. An alternative suggestive and original explanation is also offered, in which pressure changes at the core-mantle boundary cause surface deformations and relative sea level variations. Although we cannot establish a clear connection between SAA dynamics and global warming, the strong correlation between the former and global sea level supports the idea that global warming may be at least partly controlled by deep Earth processes triggering geomagnetic phenomena, such as the South Atlantic Anomaly, on a century time scale.” A. De Santis, E. Qamili, G. Spada, P. Gasperini, Journal of Atmospheric and Solar-Terrestrial Physics, doi:10.1016/j.jastp.2011.10.015.

Warming rivers in northwest U.S. are causing stress for salmonid fishes

Climate change effects on stream and river temperatures across the northwest U.S. from 1980–2009 and implications for salmonid fishes – Isaak et al. (2011) “Thermal regimes in rivers and streams are fundamentally important to aquatic ecosystems and are expected to change in response to climate forcing as the Earth’s temperature warms. Description and attribution of stream temperature changes are key to understanding how these ecosystems may be affected by climate change, but difficult given the rarity of long-term monitoring data. We assembled 18 temperature time-series from sites on regulated and unregulated streams in the northwest U.S. to describe historical trends from 1980–2009 and assess thermal consistency between these stream categories. Statistically significant temperature trends were detected across seven sites on unregulated streams during all seasons of the year, with a cooling trend apparent during the spring and warming trends during the summer, fall, and winter. The amount of warming more than compensated for spring cooling to cause a net temperature increase, and rates of warming were highest during the summer (raw trend = 0.17°C/decade; reconstructed trend = 0.22°C/decade). Air temperature was the dominant factor explaining long-term stream temperature trends (82–94% of trends) and inter-annual variability (48–86% of variability), except during the summer when discharge accounted for approximately half (52%) of the inter-annual variation in stream temperatures. Seasonal temperature trends at eleven sites on regulated streams were qualitatively similar to those at unregulated sites if two sites managed to reduce summer and fall temperatures were excluded from the analysis. However, these trends were never statistically significant due to greater variation among sites that resulted from local water management policies and effects of upstream reservoirs. Despite serious deficiencies in the stream temperature monitoring record, our results suggest many streams in the northwest U.S. are exhibiting a regionally coherent response to climate forcing. More extensive monitoring efforts are needed as are techniques for short-term sensitivity analysis and reconstructing historical temperature trends so that spatial and temporal patterns of warming can be better understood. Continuation of warming trends this century will increasingly stress important regional salmon and trout resources and hamper efforts to recover these species, so comprehensive vulnerability assessments are needed to provide strategic frameworks for prioritizing conservation efforts.” D. J. Isaak, S. Wollrab, D. Horan and G. Chandler, Climatic Change, DOI: 10.1007/s10584-011-0326-z. [Full text]

Recent drought in Australia might be worst since the first European settlement

On the long-term context of the 1997–2009 ‘Big Dry’ in South-Eastern Australia: insights from a 206-year multi-proxy rainfall reconstruction – Gergis et al. (2011) “This study presents the first multi-proxy reconstruction of rainfall variability from the mid-latitude region of south-eastern Australia (SEA). A skilful rainfall reconstruction for the 1783–1988 period was possible using twelve annually-resolved palaeoclimate records from the Australasian region. An innovative Monte Carlo calibration and verification technique is introduced to provide the robust uncertainty estimates needed for reliable climate reconstructions. Our ensemble median reconstruction captures 33% of inter-annual and 72% of decadal variations in instrumental SEA rainfall observations. We investigate the stability of regional SEA rainfall with large-scale circulation associated with El Niño–Southern Oscillation (ENSO) and the Inter-decadal Pacific Oscillation (IPO) over the past 206 years. We find evidence for a robust relationship with high SEA rainfall, ENSO and the IPO over the 1840–1988 period. These relationships break down in the late 18th–early 19th century, coinciding with a known period of equatorial Pacific Sea Surface Temperature (SST) cooling during one of the most severe periods of the Little Ice Age. In comparison to a markedly wetter late 18th/early 19th century containing 75% of sustained wet years, 70% of all reconstructed sustained dry years in SEA occur during the 20th century. In the context of the rainfall estimates introduced here, there is a 97.1% probability that the decadal rainfall anomaly recorded during the 1998–2008 ‘Big Dry’ is the worst experienced since the first European settlement of Australia.” Joëlle Gergis, Ailie Jane Eyre Gallant, Karl Braganza, David John Karoly, Kathryn Allen, Louise Cullen, Rosanne D’Arrigo, Ian Goodwin, Pauline Grierson and Shayne McGregor, Climatic Change, DOI: 10.1007/s10584-011-0263-x.

Granger causality analysis attributes recent global warming to greenhouse gases

Atmospheric Science Letters

A contribution to attribution of recent global warming by out-of-sample Granger causality analysis – Attanasio et al. (2011) “The topic of attribution of recent global warming is usually faced by studies performed through global climate models (GCMs). Even simpler econometric models have been applied to this problem, but they led to contrasting results. In this article, we show that a genuine predictive approach of Granger analysis leads to overcome problems shown by these models and to obtain a clear signal of linear Granger causality from greenhouse gases (GHGs) to the global temperature of the second half of the 20th century. In contrast, Granger causality is not evident using time series of natural forcing.” Alessandro Attanasio, Antonello Pasini, Umberto Triacca, Atmospheric Science Letters, DOI: 10.1002/asl.365.

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Papers on bird and bat mortality caused by wind power

Posted by Ari Jokimäki on November 9, 2011

This is a list of papers on bird and bat mortality caused by wind power. Also studies on wind power effects to other animals can be included. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

Weak relationship between risk assessment studies and recorded mortality in wind farms – Ferrer et al. (2011) “Wind farms generate little or no pollution. However, one of their main adverse impacts is bird mortality through collisions with turbine rotors. Environmental impact assessment (EIA) studies have been based on observations of birds before the construction of wind farms. We analysed data from 53 EIAs in relation to the actual recorded bird mortalities at 20 fully installed wind farms to determine whether this method is accurate in predicting the risk of new wind farm installations. Bird data from EIAs were compared with bird collisions per turbine and year at functional post-constructed wind farms to identify any relationship between pre- and post-construction studies. Significant differences in birds recorded flying among the 53 proposed wind farms were found by the EIAs. Similar results were obtained when only griffon vultures Gyps fulvus and other raptors were considered. There were significant differences in indexes, including the relative index of breeding birds close to proposed locations, among the 53 proposed wind farm sites. The collision rate of birds with turbines was one of the highest ever recorded for raptors, and the griffon vulture was the most frequently killed species. Bird mortality varied among the 20 constructed wind farms. No relationship between variables predicting risk from EIAs and actual recorded mortality was found. A weak relationship was found between griffon vulture and kestrel Falco sp. mortality and the numbers of these two species crossing the area. Synthesis and applications. There was no clear relationship between predicted risk and the actual recorded bird mortality at wind farms. Risk assessment studies incorrectly assumed a linear relationship between frequency of observed birds and fatalities. Nevertheless, it is known that bird mortality in wind farms is related to physical characteristics around individual wind turbines. However, EIAs are usually conducted at the scale of the entire wind farm. The correlation between predicted mortality and actual mortality must be improved in future risk assessment studies by changing the scale of these studies to focus on the locations of proposed individual wind turbine sites and working on a species specific level.” Miguel Ferrer, Manuela de Lucas, Guyonne F. E. Janss, Eva Casado, Antonio R. Muñoz, Marc J. Bechard, Cecilia P. Calabuig, Journal of Applied Ecology, DOI: 10.1111/j.1365-2664.2011.02054.x. [Full text]

Novel Scavenger Removal Trials Increase Wind Turbine—Caused Avian Fatality Estimates – Smallwood et al. (2010) “For comparing impacts of bird and bat collisions with wind turbines, investigators estimate fatalities/megawatt (MW) of rated capacity/year, based on periodic carcass searches and trials used to estimate carcasses not found due to scavenger removal and searcher error. However, scavenger trials typically place ≥10 carcasses at once within small areas already supplying scavengers with carcasses deposited by wind turbines, so scavengers may be unable to process and remove all placed carcasses. To avoid scavenger swamping, which might bias fatality estimates low, we placed only 1–5 bird carcasses at a time amongst 52 wind turbines in our 249.7-ha study area, each carcass monitored by a motion-activated camera. Scavengers removed 50 of 63 carcasses, averaging 4.45 days to the first scavenging event. By 15 days, which corresponded with most of our search intervals, scavengers removed 0% and 67% of large-bodied raptors placed in winter and summer, respectively, and 15% and 71% of small birds placed in winter and summer, respectively. By 15 days, scavengers removed 42% of large raptors as compared to 15% removed in conventional trials, and scavengers removed 62% of small birds as compared to 52% removed in conventional trials. Based on our methodology, we estimated mean annual fatalities caused by 21.9 MW of wind turbines in Vasco Caves Regional Preserve (within Altamont Pass Wind Resource Area, California, USA) were 13 red-tailed hawks (Buteo jamaicensis), 12 barn owls (Tyto alba), 18 burrowing owls (Athene cunicularia), 48 total raptors, and 99 total birds. Compared to fatality rates estimated from conventional scavenger trials, our estimates were nearly 3 times higher for red-tailed hawk and barn owl, 68% higher for all raptors, and 67% higher for all birds. We also found that deaths/gigawatt-hour of power generation declined quickly with increasing capacity factor among wind turbines, indicating collision hazard increased with greater intermittency in turbine operations. Fatality monitoring at wind turbines might improve by using scavenger removal trials free of scavenger swamping and by relating fatality rates to power output data in addition to rated capacity (i.e., turbine size). The resulting greater precision in mortality estimates will assist wildlife managers to assess wind farm impacts and to more accurately measure the effects of mitigation measures implemented to lessen those impacts.” K. Shawn Smallwood, Douglas A. Bell, Sara A. Snyder, Joseph E. Didonato, The Journal of Wildlife Management, Volume 74, Issue 5, pages 1089–1096, July 2010, DOI: 10.2193/2009-266.

Influence of Behavior on Bird Mortality in Wind Energy Developments – Smallwood et al. (2009) “As wind power generation is rapidly expanding worldwide, there is a need to understand whether and how preconstruction surveys can be used to predict impacts and to place turbines to minimize impacts to birds. Wind turbines in the 165-km2 Altamont Pass Wind Resource Area (APWRA), California, USA, cause thousands of bird fatalities annually, including hundreds of raptors. To test whether avian fatality rates related to rates of utilization and specific behaviors within the APWRA, from March 1998 to April 2000 we performed 1,959 30-minute behavior observation sessions (360° visual scans using binoculars) among 28 nonoverlapping plots varying from 23 ha to 165 ha in area and including 10–67 turbines per plot, totaling 1,165 turbines. Activity levels were highly seasonal and species specific. Only 1% of perch time was on towers of operating turbines, but 22% was on towers of turbines broken, missing, or not operating. Of those species that most often flew through the rotor zone, fatality rates were high for some (e.g., 0.357 deaths/megawatt of rated capacity [MW]/yr for red-tailed hawk [Buteo jamaicensis] and 0.522 deaths/MW/yr for American kestrel [Falco sparverius]) and low for others (e.g., 0.060 deaths/MW/yr for common raven [Corvus corax] and 0.012 deaths/MW/yr for turkey vulture [Cathartes aura]), indicating specific behaviors or visual acuity differentiated these species by susceptibility to collision. Fatality rates did not correlate with utilization rates measured among wind turbine rows or plots for any species except burrowing owl (Athene cunicularia) and mallard (Anas platyrhynchos). However, mean monthly fatality rates of red-tailed hawks increased with mean monthly utilization rates (r2 = 0.67) and especially with mean monthly flights through turbine rows (r2 = 0.92). Fatality rates increased linearly with rates of utilization (r2 = 0.99) and flights near rotor zones (r2 = 1.00) for large raptor species and with rates of perching (r2 = 0.13) and close flights (r2 = 0.77) for small non-raptor species. Fatalities could be minimized or reduced by shutting down turbines during ≥1 season or in very strong winds or by leaving sufficiently large areas within a wind farm free of wind turbines to enable safer foraging and travel by birds.” K. Shawn Smallwood, Lourdes Rugge, Michael L. Morrison, The Journal of Wildlife Management, Volume 73, Issue 7, pages 1082–1098, September 2009, DOI: 10.2193/2008-555.

Collision fatality of raptors in wind farms does not depend on raptor abundance – De Lucas et al. (2008) “The number of wind farms is increasing worldwide. Despite their purported environmental benefits, wind energy developments are not without potential adverse impacts on the environment, and the current pace and scale of development proposals, combined with a poor understanding of their impacts, is a cause for concern. Avian mortality through collision with moving rotor blades is one of the main adverse impacts of wind farms, yet long-term studies are rare. We analyse bird fatalities in relation to bird abundance, and test several factors which have been hypothesized to be associated with bird mortality. Bird abundance was compared with collision fatality records to identify species-specific death risk. Failure time analysis incorporated censored mortality data in which the time of event occurrence (collision) was not known. The analysis was used to test null hypotheses of homogeneity in avian mortality distribution according to several factors. There was no clear relationship between species mortality and species abundance, although all large-bird collision victims were raptors and griffon vulture Gyps fulvus was most frequently killed. Bird mortality and bird abundance varied markedly among seasons, but mortality was not highest in the season with highest bird abundance. Mortality rates of griffon vultures did not differ significantly between years. Bird collision probability depended on species, turbine height (taller = more victims) and elevation above sea level (higher = more victims), implicating species-specific and topographic factors in collision mortality. There was no evidence of an association between collision probability and turbine type or the position of a turbine in a row. Synthesis and applications. Bird abundance and bird mortality through collision with wind turbines were not closely related; this result challenges a frequent assumption of wind-farm assessment studies. Griffon vulture was the most frequently killed species, and species-specific flight behaviour was implicated. Vultures collided more often when uplift wind conditions were poor, such as on gentle slopes, when thermals were weak, and when turbines were taller at higher elevations. New wind installations and/or repowering of older wind farms with griffon vulture populations nearby, should avoid turbines on the top of hills with gentle slopes.” Manuela De Lucas, Guyonne F. E. Janss, D. P. Whitfield, Miguel Ferrer, Journal of Applied Ecology, Volume 45, Issue 6, pages 1695–1703, December 2008, DOI: 10.1111/j.1365-2664.2008.01549.x. [Full text]

Collision Effects of Wind-power Generators and Other Obstacles on Birds – Drewitt & Langston (2008) “There is extensive literature on avian mortality due to collision with man-made structures, including wind turbines, communication masts, tall buildings and windows, power lines, and fences. Many studies describe the consequences of bird-strike rather than address the causes, and there is little data based on long-term, standardized, and systematic assessments. Despite these limitations, it is apparent that bird-strike is a significant cause of mortality. It is therefore important to understand the effects of this mortality on bird populations. The factors which determine avian collision risk are described, including location, structural attributes, such as height and the use of lighting, weather conditions, and bird morphology and behavior. The results of incidental and more systematic observations of bird-strike due to a range of structures are presented and the implications of collision mortality for bird populations, particularly those of scarce and threatened species susceptible to collisions, are discussed. Existing measures for reducing collision mortality are described, both generally and specifically for each type of structure. It is concluded that, in some circumstances, collision mortality can adversely affect bird populations, and that greater effort is needed to derive accurate estimates of mortality levels locally, regionally, and nationally to better assess impacts on avian populations. Priority areas for future work are suggested, including further development of remote technology to monitor collisions, research into the causes of bird-strike, and the design of new, effective mitigation measures.” Allan L. Drewitt, Rowena H.W. Langston, Annals of the New York Academy of Sciences, Volume 1134, Issue 1, pages 233–266, June 2008, DOI: 10.1196/annals.1439.015. [Full text]

Barotrauma is a significant cause of bat fatalities at wind turbines – Baerwald et al. (2008) “Bird fatalities at some wind energy facilities around the world have been documented for decades, but the issue of bat fatalities at such facilities — primarily involving migratory species during autumn migration — has been raised relatively recently [1] and [2] . Given that echolocating bats detect moving objects better than stationary ones [3], their relatively high fatality rate is perplexing, and numerous explanations have been proposed [1]. The decompression hypothesis proposes that bats are killed by barotrauma caused by rapid air-pressure reduction near moving turbine blades [1] , [4] and [5] . Barotrauma involves tissue damage to air-containing structures caused by rapid or excessive pressure change; pulmonary barotrauma is lung damage due to expansion of air in the lungs that is not accommodated by exhalation. We report here the first evidence that barotrauma is the cause of death in a high proportion of bats found at wind energy facilities. We found that 90% of bat fatalities involved internal haemorrhaging consistent with barotrauma, and that direct contact with turbine blades only accounted for about half of the fatalities. Air pressure change at turbine blades is an undetectable hazard and helps explain high bat fatality rates. We suggest that one reason why there are fewer bird than bat fatalities is that the unique respiratory anatomy of birds is less susceptible to barotrauma than that of mammals.” Erin F. Baerwald, Genevieve H. D’Amours, Brandon J. Klug, Robert M.R. Barclay, Current Biology, Volume 18, Issue 16, 26 August 2008, Pages R695-R696, doi:10.1016/j.cub.2008.06.029. [Full text]

Bird Mortality in the Altamont Pass Wind Resource Area, California – Smallwood & Thelander (2008) “The 165-km2 Altamont Pass Wind Resource Area (APWRA) in west-central California includes 5,400 wind turbines, each rated to generate between 40 kW and 400 kW of electric power, or 580 MW total. Many birds residing or passing through the area are killed by collisions with these wind turbines. We searched for bird carcasses within 50 m of 4,074 wind turbines for periods ranging from 6 months to 4.5 years. Using mortality estimates adjusted for searcher detection and scavenger removal rates, we estimated the annual wind turbine–caused bird fatalities to number 67 (80% CI = 25–109) golden eagles (Aquila chrysaetos), 188 (80% CI = 116–259) red-tailed hawks (Buteo jamaicensis), 348 (80% CI = −49 to 749) American kestrels (Falco sparverius), 440 (80% CI = −133 to 1,013) burrowing owls (Athene cunicularia hypugaea), 1,127 (80% CI = −23 to 2,277) raptors, and 2,710 (80% CI = −6,100 to 11,520) birds. Adjusted mortality estimates were most sensitive to scavenger removal rate, which relates to the amount of time between fatality searches. New on-site studies of scavenger removal rates might warrant revising mortality estimates for some small-bodied bird species, although we cannot predict how the mortality estimates would change. Given the magnitude of our mortality estimates, regulatory agencies and the public should decide whether to enforce laws intended to protect species killed by APWRA wind turbines, and given the imprecision of our estimates, directed research is needed of sources of error and bias for use in studies of bird collisions wherever wind farms are developed. Precision of mortality estimates could be improved by deploying technology to remotely detect collisions and by making wind turbine power output data available to researchers so that the number of fatalities can be related directly to the actual power output of the wind turbine since the last fatality search.” K. Shawn Smallwood, Carl Thelander, The Journal of Wildlife Management, Volume 72, Issue 1, pages 215–223, January 2008, DOI: 10.2193/2007-032.

Patterns of Bat Fatalities at Wind Energy Facilities in North America – Arnett et al. (2008) “Wind has become one of the fastest growing sources of renewable energy worldwide, but widespread and often extensive fatalities of bats have increased concern regarding the impacts of wind energy development on bats and other wildlife. We synthesized available information on patterns of bat fatalities from a review of 21 postconstruction fatality studies conducted at 19 facilities in 5 United States regions and one Canadian province. Dominance of migratory, foliage- and tree-roosting lasiurine species (e.g., hoary bat [Lasiurus cinereus]) killed by turbines was consistent among studies. Bat fatalities, although highly variable and periodic, consistently peaked in late summer and fall, coinciding with migration of lasiurines and other species. A notable exception was documented fatalities of pregnant female Brazilian freetailed bats (Tadarida brasiliensis) in May and June at a facility in Oklahoma, USA, and female silver-haired bats (Lasionycteris noctivagans) during spring in Tennessee, USA, and Alberta, Canada. Most studies reported that fatalities were distributed randomly across turbines at a site, although the highest number of fatalities was often found near the end of turbine strings. Two studies conducted simultaneously in the same region documented similar timing of fatalities between sites, which suggests broader patterns of collisions dictated by weather, prey abundance, or other factors. None of the studies found differences in bat fatalities between turbines equipped with lighting required by the Federal Aviation Administration and turbines that were unlit. All studies that addressed relationships between bat fatalities and weather patterns found that most bats were killed on nights with low wind speed (<6 m/sec) and that fatalities increased immediately before and after passage of storm fronts. Weather patterns may be predictors of bat activity and fatality; thus, mitigation efforts that focus on these high-risk periods could reduce bat fatality substantially. We caution that estimates of bat fatality are conditioned by length of study and search interval and that they are biased in relation to how searcher efficiency, scavenger removal, and habitat differences were or were not accounted for. Our review will assist managers, biologists, and decision-makers with understanding unifying and unique patterns of bat fatality, biases, and limitations of existing efforts, and it will aid in designing future research needed to develop mitigation strategies for minimizing or eliminating bat fatality at wind facilities.” Edward B. Arnett, W. Kent Brown, Wallace P. Erickson, Jenny K. Fiedler, Brenda L. Hamilton, Travis H. Henry, Aaftab Jain, Gregory D. Johnson, Jessica Kerns, Rolf R. Koford, Charles P. Nicholson, Timothy J. O’Connell, Martin D. Piorkowski, Roger D. Tankersley JR., The Journal of Wildlife Management, Volume 72, Issue 1, pages 61–78, January 2008, DOI: 10.2193/2007-221.

Assessing Impacts of Wind-Energy Development on Nocturnally Active Birds and Bats: A Guidance Document – Kunz et al. (2007) “Our purpose is to provide researchers, consultants, decision-makers, and other stakeholders with guidance to methods and metrics for investigating nocturnally active birds and bats in relation to utility-scale wind-energy development. The primary objectives of such studies are to 1) assess potential impacts on resident and migratory species, 2) quantify fatality rates on resident and migratory populations, 3) determine the causes of bird and bat fatalities, and 4) develop, assess, and implement methods for reducing risks to bird and bat populations and their habitats. We describe methods and tools and their uses, discuss limitations, assumptions, and data interpretation, present case studies and examples, and offer suggestions for improving studies on nocturnally active birds and bats in relation to wind-energy development. We suggest best practices for research and monitoring studies using selected methods and metrics, but this is not intended as cookbook. We caution that each proposed and executed study will be different, and that decisions about which methods and metrics to use will depend upon several considerations, including study objectives, expected and realized risks to bird and bat populations, as well as budgetary and logistical considerations. Developed to complement and extend the existing National Wind Coordinating Committee document “Methods and Metrics for Assessing Impacts of Wind Energy Facilities on Wildlife” (Anderson et al. 1999), we provide information that stakeholders can use to aid in evaluating potential and actual impacts of wind power development on nocturnally active birds and bats. We hope that decision-makers will find these guidelines helpful as they assemble information needed to support the permitting process, and that the public will use this guidance document as they participate in the permitting processes. We further hope that the wind industry will find valuable guidance from this document when 1) complying with data requirements as a part of the permitting process, 2) evaluating sites for potential development, 3) assessing impacts of operational wind-energy facilities, and 4) mitigating local and cumulative impacts on nocturnally active birds and bats.” Thomas H. Kunz, Edward B. Arnett, Brian M. Cooper, Wallace P. Erickson, Ronald P. Larkin, Todd Mabee, Michael L. Morrison, M. Dale Strickland, Joseph M. Szewczak, The Journal of Wildlife Management, Volume 71, Issue 8, pages 2449–2486, November 2007, DOI: 10.2193/2007-270. [Full text]

Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses – Kunz et al. (2007) “At a time of growing concern over the rising costs and long-term environmental impacts of the use of fossil fuels and nuclear energy, wind energy has become an increasingly important sector of the electrical power industry, largely because it has been promoted as being emission-free and is supported by government subsidies and tax credits. However, large numbers of bats are killed at utility-scale wind energy facilities, especially along forested ridgetops in the eastern United States. These fatalities raise important concerns about cumulative impacts of proposed wind energy development on bat populations. This paper summarizes evidence of bat fatalities at wind energy facilities in the US, makes projections of cumulative fatalities of bats in the Mid-Atlantic Highlands, identifies research needs, and proposes hypotheses to better inform researchers, developers, decision makers, and other stakeholders, and to help minimize adverse effects of wind energy development.” Thomas H. Kunz, Edward B. Arnett, Wallace P. Erickson, Alexander R. Hoar, Gregory D. Johnson, Ronald P. Larkin, M Dale Strickland, Robert W. Thresher, and Merlin D. Tuttle, 2007, Frontiers in Ecology and the Environment 5: 315–324, doi:10.1890/1540-9295(2007)5[315:EIOWED]2.0.CO;2. [Full text]

Estimating Wind Turbine-Caused Bird Mortality – Smallwood (2007) “Mortality estimates are needed of birds and bats killed by wind turbines because wind power generation is rapidly expanding worldwide. A mortality estimate is based on the number of fatalities assumed caused by wind turbines and found during periodic searches, plus the estimated number not found. The 2 most commonly used estimators adjust mortality estimates by rates of searcher detection and scavenger removal of carcasses. However, searcher detection trials can be biased by the species used in the trial, the number volitionally placed for a given fatality search, and the disposition of the carcass on the ground. Scavenger removal trials can be biased by the metric representing removal rate, the number of carcasses placed at once, the duration of the trial, species used, whether carcasses were frozen, whether carcasses included injuries consistent with wind turbine collisions, season, distance from the wind turbines, and general location. I summarized searcher detection rates among reported trials, and I developed models to predict the proportion of carcasses remaining since the last fatality search. The summaries I present can be used to adjust previous and future estimates of mortality to improve comparability. I also identify research directions to better understand these and other adjustments needed to compare mortality estimates among wind farms.” K. Shawn Smallwood, The Journal of Wildlife Management, Volume 71, Issue 8, pages 2781–2791, November 2007, DOI: 10.2193/2007-006.

Migration of bats past a remote island offers clues toward the problem of bat fatalities at wind turbines – Cryan & Brown (2007) “Wind energy is rapidly becoming a viable source of alternative energy, but wind turbines are killing bats in many areas of North America. Most of the bats killed by turbines thus far have been migratory species that roost in trees throughout the year, and the highest fatality events appear to coincide with autumn migration. Hoary bats (Lasiurus cinereus) are highly migratory and one of the most frequently killed species at wind turbines. We analyzed a long-term data set to investigate how weather and moonlight influenced the occurrence of hoary bats at an island stopover point along their migration route. We then related our results to the problem of bat fatalities at wind turbines. We found that relatively low wind speeds, low moon illumination, and relatively high degrees of cloud cover were important predictors of bat arrivals and departures, and that low barometric pressure was an additional variable that helped predict arrivals. Slight differences in the conditions under which bats arrived and departed from the island suggest that hoary bats may be more likely to arrive on the island with passing storm fronts in autumn. These results also indicate that fatalities of hoary bats at wind turbines may be predictable events, that the species may be drawn to prominent landmarks that they see during migration, and that they regularly migrate over the ocean. Additional observations from this and other studies suggest that the problem of bat fatalities at wind turbines may be associated with flocking and autumn mating behaviors.” Paul M. Cryan, Adam C. Brown, Biological Conservation, Volume 139, Issues 1-2, September 2007, Pages 1-11, doi:10.1016/j.biocon.2007.05.019. [Full text]

Variation in bat and bird fatalities at wind energy facilities: assessing the effects of rotor size and tower height – Barclay et al. (2007) “Wind energy is a rapidly growing sector of the alternative energy industry in North America, and larger, more productive turbines are being installed. However, there are concerns regarding bird and bat fatalities at wind turbines. To assess the influence of turbine size on bird and bat fatalities, we analyzed data from North American wind energy facilities. Diameter of the turbine rotor did not influence the rate of bird or bat fatality. The height of the turbine tower had no effect on bird fatalities per turbine, but bat fatalities increased exponentially with tower height. This suggests that migrating bats fly at lower altitudes than nocturnally migrating birds and that newer, larger turbines are reaching that airspace. Minimizing tower height may help minimize bat fatalities. In addition, while replacing older, smaller turbines with fewer larger ones may reduce bird fatalities per megawatt, it may result in increased numbers of bat fatalities.” Robert M.R. Barclay, E.F. Baerwald, J.C. Gruver, Canadian Journal of Zoology, 2007, 85:(3) 381-387, 10.1139/Z07-011. [Full text]

Assessing the impacts of wind farms on birds – Drewitt & Langston (2006) “The potential effects of the proposed increase in wind energy developments on birds are explored using information from studies of existing wind farms. Evidence of the four main effects, collision, displacement due to disturbance, barrier effects and habitat loss, is presented and discussed. The consequences of such effects may be direct mortality or more subtle changes to condition and breeding success. The requirements for assessing the impact of future developments are summarized, including relevant environmental legislation and appropriate methods for undertaking baseline surveys and post-construction monitoring, with particular emphasis on the rapidly developing area of offshore wind farm assessments. Mitigation measures which have the potential to minimize impacts are also summarized. Finally, recent developments in the monitoring and research of wind energy impacts on birds are outlined and some areas for future work are described.” Allan L. Drewitt, Rowena H. W. Langston, Ibis, Special Issue: Wind, Fire and Water: Renewable Energy and Birds, Volume 148, Issue Supplement s1, pages 29–42, March 2006, DOI: 10.1111/j.1474-919X.2006.00516.x. [Full text]

The effect of avoidance rates on bird mortality predictions made by wind turbine collision risk models – Chamberlain et al. (2006) No abstract. Dan E. Chamberlain, Mark R. Rehfisch, Antony D. Fox, Mark. Desholm, Sarah J. Anthony, Ibis, Special Issue: Wind, Fire and Water: Renewable Energy and Birds, Volume 148, Issue Supplement s1, pages 198–202, March 2006, DOI: 10.1111/j.1474-919X.2006.00507.x. [Full text]

See also other papers in Ibis special issue.

Behavioural and environmental correlates of soaring-bird mortality at on-shore wind turbines – Barrios & Rodríguez (2004) “Wind power plants represent a risk of bird mortality, but the effects are still poorly quantified. We measured bird mortality, analysed the factors that led birds to fly close to turbines, and proposed mitigation measures at two wind farms installed in the Straits of Gibraltar, one of the most important migration bottlenecks between Europe and Africa. Bird corpses were surveyed along turbine lines and an associated power line to estimate mortality rates. The behaviour of birds observed within 250 m of turbines was also recorded as a putative indicator of risk. The effects of location, weather and flight behaviour on risk situations (passes within 5 m of turbines) were analysed using generalized linear modelling (GLM). Mortality caused by turbines was higher than that caused by the power line. Losses involved mainly resident species, mostly griffon vultures Gyps fulvus (0·15 individuals turbine−1 year−1) and common kestrels Falco tinnunculus (0·19 individuals turbine−1 year−1). Mortalities were not associated with either structural attributes of wind farms or visibility. Vulture collisions occurred in autumn–winter and were aggregated at two turbine lines where risks of collisions were greatest. The absence of thermals in winter forced vultures to use slopes for lift, the most likely mechanism influencing both their exposure to turbines and mortality. Kestrel deaths occurred during the annual peak of abundance in summer. Carcasses were concentrated in the open habitats around a single wind farm and risk may have resulted from hunting habitat preferences. Synthesis and applications. We conclude that bird vulnerability and mortality at wind power facilities reflect a combination of site-specific (wind–relief interaction), species-specific and seasonal factors. Despite the large number of migrating birds in the study area, most follow routes that are displaced from the facilities. Consequently, only a small fraction of birds on migratory flights was actually exposed to turbines. New wind installations must be preceded by detailed behavioural observation of soaring birds as well as careful mapping of migration routes.” Luis Barrios, Alejandro Rodríguez, Journal of Applied Ecology, Volume 41, Issue 1, pages 72–81, February 2004, DOI: 10.1111/j.1365-2664.2004.00876.x. [Full text]

The effects of a wind farm on birds in a migration point: the Strait of Gibraltar – de Lucas et al. (2004) “The interaction between birds and wind turbines is an important factor to consider when a wind farm is constructed. A wind farm and two control areas were studied in Tarifa (Andalusia Province, southern Spain, 30STF590000–30STE610950). Variables were studied along linear transects in each area and observations of flight were also recorded from fixed points in the wind farm. The main purpose of our research was to determine the impact and the degree of flight behavioural change in birds flights resulting from a wind farm. Soaring birds can detect the presence of the turbines because they change their flight direction when they fly near the turbines and their abundance did not seem to be affected. This is also supported by the low amount of dead birds we found in the whole study period in the wind farm area. More studies will be necessary after and before the construction of wind farms to assess changes in passerine populations. Windfarms do not appear to be more detrimental to birds than other man-made structures.” Manuela de Lucas, Guyonne F.E. Janss and Miguel Ferrer, Biodiversity and Conservation, Volume 13, Number 2, 395-407, DOI: 10.1023/B:BIOC.0000006507.22024.93. [Full text]

Mortality of Bats at a Large-scale Wind Power Development at Buffalo Ridge, Minnesota – Johnson et al. (2003) “In 1994 a major wind power development project was initiated in southwest Minnesota that may eventually produce 425 megawatts (MW) of electricity. The wind plant currently consists of 3 phases that total 354 turbines capable of generating 236 MW. During a study conducted from 1996–1999 to assess effects of wind power development on wildlife, 184 bat collision fatalities were documented within the wind plant. Hoary bats (Lasiurus cinereus) and eastern red bats (L. borealis) comprised most of the fatalities. After correcting bat fatality estimates for searcher efficiency and scavenger removal rates, we estimated that the number of bat fatalities per turbine ranged from 0.07 per y at the Phase 1 wind plant to 2.04 per y at the Phase 3 wind plant. The timing of mortalities, and other factors, suggest that most mortality involves migrant rather than resident breeding bats.” Gregory D. Johnson, Wallace P. Erickson, M. Dale Strickland, Maria F. Shepherd, Douglas A. Shepherd, and Sharon A. Sarappo, The American Midland Naturalist 150(2):332-342. 2003, doi: 10.1674/0003-0031(2003)150[0332:MOBAAL]2.0.CO;2. [Full text]

Collision Mortality of Local and Migrant Birds at a Large-Scale Wind-Power Development on Buffalo Ridge, Minnesota – Johnson et al. (2002) “In 1994 Xcel Energy initiated a wind-power development project in southwestern Minnesota that will eventually produce 425 megawatts (MW) of electricity. During our study the wind farm consisted of 3 phases of development totaling 354 turbines capable of generating 236 MW, depending on wind speed. We assessed effects of the wind farm on birds from 1996 to 1999, with 55 documented collision fatalities. Recovered carcasses included 42 passerines, 5 waterbirds, 3 ducks, 3 upland game birds, 1 raptor, and 1 shorebird. Most fatalities (71%) were likely migrants through the area, 20% were species that likely were breeding in the study area, and 9% were permanent residents. Wind farm-related mortality was estimated by extrapolating the number of carcasses found at a sample of the turbines and adjusting for scavenger removal and searcher efficiency rates. We estimated total annual mortality at 72 (90% Cl = 36-108) in the Phase 1 wind farm, 324 (90% Cl = 175-473) in the Phase 2 wind farm, and 613 (90% Cl = 132-1093) in the Phase 3 wind farm. The Phase 3 wind-farm estimate was based on 1 year of data and was largely influenced by a single mortality event involving 14 passerines at 2 adjacent turbines during 1 night. Radar data indicated that approximately 3.5 million birds migrate over the wind farm each year; however, the proportion of birds flying at heights susceptible to turbine collisions is not known. Wind-power development will likely contribute to cumulative collision mortality of birds in the United States.” Gregory D. Johnson, Wallace P. Erickson, M. Dale Strickland, Maria F. Shepherd, Douglas A. Shepherd and Sharon A. Sarappo, Wildlife Society Bulletin, Vol. 30, No. 3 (Autumn, 2002), pp. 879-887.

Bird Mortality Associated with Wind Turbines at the Buffalo Ridge Wind Resource Area, Minnesota – Osborn et al. (2000) “Recent technological advances have made wind power a viable source of alternative energy production and the number of windplant facilities has increased in the United States. Construction was completed on a 73 turbine, 25 megawatt windplant on Buffalo Ridge near Lake Benton, Minnesota in Spring 1994. The number of birds killed at existing windplants in California caused concern about the potential impacts of the Buffalo Ridge facility on the avian community. From April 1994 through Dec. 1995 we searched the Buffalo Ridge windplant site for dead birds. Additionally, we evaluated search efficiency, predator scavenging rates and rate of carcass decomposition. During 20 mo of monitoring we found 12 dead birds. Collisions with wind turbines were suspected for 8 of the 12 birds. During observer efficiency trials searchers found 78.8% of carcasses. Scavengers removed 39.5% of carcasses during scavenging trials. All carcasses remained recognizable during 7 d decomposition trials. After correction for biases we estimated that approximately 36 ± 12 birds (<1 dead bird per turbine) were killed at the Buffalo Ridge windplant in 1 y. Although windplants do not appear to be more detrimental to birds than other man-made structures, proper facility siting is an important first consideration in order to avoid unnecessary fatalities.” Robert G. Osborn, Kenneth F. Higgins, Robert E. Usgaard, Charles D. Dieter, and Regg D. Neiger, The American Midland Naturalist 143(1):41-52. 2000, doi: 10.1674/0003-0031(2000)143[0041:BMAWWT]2.0.CO;2. [Full text]

Effects of Wind Turbines on Upland Nesting Birds in Conservation Reserve Program Grasslands – Leddy et al. (1999) “Grassland passerines were surveyed during summer 1995 on the Buffalo Ridge Wind Resource Area in southwestern Minnesota to determine the relative influence of wind turbines on overall densities of upland nesting birds in Conservation Reserve Program (CRP) grasslands. Birds were surveyed along 40 m fixed width transects that were placed along wind turbine strings within three CRP fields and in three CRP fields without turbines. Conservation Reserve Program grasslands without turbines and areas located 180 m from turbines supported higher densities (261.0-312.5 males/100 ha) of grassland birds than areas within 80 m of turbines (58.2-128.0 males/100 ha). Human disturbance, turbine noise, and physical movements of turbines during operation may have distrurbed nesting birds. We recommend that wind turbines be placed within cropland habitats that support lower densities of grassland passerines than those found in CRP grasslands.” Krecia L. Leddy, Kenneth F. Higgins and David E. Naugle, The Wilson Bulletin, Vol. 111, No. 1 (Mar., 1999), pp. 100-104.

Bird Flight Characteristics Near Wind Turbines in Minnesota – Osborn et al. (1998) “During 1994–1995, we saw 70 species of birds on the Buffalo Ridge Wind Resource Area. In both years bird abundance peaked in spring. Red-winged blackbirds (Agelaius phoeniceus), mallards (Anas platyrhynchos), common grackles (Quiscalus quiscula), and barn swallows (Hirundo rustica) were the species most commonly seen. Most birds (82–84%) flew above or below the height range of wind turbine blades (22–55 m). The Buffalo Ridge Wind Resource Area poses little threat to resident or migrating birds at its current operating level.” Robert G. Osborn, Charles D. Dieter, Kenneth F. Higgins, and Robert E. Usgaard, The American Midland Naturalist 139(1):29-38. 1998, doi: 10.1674/0003-0031(1998)139[0029:BFCNWT]2.0.CO;2. [Full text]

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New research from last week 44/2011

Posted by Ari Jokimäki on November 7, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news.

Fish parasites grow faster in warmer water

Some (worms) like it hot: fish parasites grow faster in warmer water, and alter host thermal preferences – Macnab & Barber (2011) “Elevated environmental temperatures associated with anthropogenic warming have the potential to impact host-parasite interactions, with consequences for population health and ecosystem functioning. One way that elevated temperatures might influence parasite prevalence and intensity is by increasing life cycle completion rates. Here we investigate how elevated temperatures impact a critical phase of the life cycle of the bird tapeworm Schistocephalus solidus – the growth of plerocercoid larvae in host sticklebacks Gasterosteus aculeatus. By 8 weeks post-infection, plerocercoids recovered from experimentally infected sticklebacks held at 20C weighed on average 104.9mg, with all exceeding 50mg, the mass considered consistently infective to definitive hosts. In contrast, plerocercoids from sticklebacks held at 15C weighed on average 26.5mg, with none exceeding 50mg. Because small increases in plerocercoid mass affect adult fecundity disproportionately in this species, enhanced plerocercoid growth at higher temperatures predicts dramatically increased output of infective parasite stages. Subsequent screening of thermal preferences of sticklebacks from a population with endemic S. solidus infection demonstrated that fish harbouring infective plerocercoids show significant preferences for warmer temperatures. Our results therefore indicate that parasite transmission might be affected in at least two ways under anthropogenic warming; by enhancing rates of parasite growth and development, and by increasing the likelihood of hosts being able to seek out proliferating warmer microhabitats. Furthermore, our results suggest the potential for positive feedback between parasite growth and host thermal preferences, which could dramatically increase the effects of even small temperature increases. We discuss the possible mechanisms underpinning our results, their likely ecological consequences and highlight key areas for further research.” Vicki Macnab, Iain Barber, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02595.x.

Knutti & Plattner comment on Schwartz et al. 2010

Comment on “Why Hasn’t Earth Warmed as Much as Expected?” by Schwartz et al. 2010 – Knutti & Plattner (2011) “In a recent paper, Schwartz et al. suggest that (1) over the last century the Earth has warmed less than expected, and they discuss several factors that could explain the discrepancy, including climate sensitivity estimates and aerosol forcing. Schwartz et al. then continue to (2) estimate the allowed carbon emissions for stabilization of global temperature, and find that given the uncertainty in the climate sensitivity even the sign of these allowed carbon emissions is unknown, implying that past emissions may already have committee the Earth to two degrees warming for a best estimate value of climate sensitivity of 3 K. We take issue with both of these conclusions in the Schwartz et al. study and show here that (1) in contrast to Schwartz et al., current assessments of climate sensitivity, radiative forcing and thermal disequilibrium do not support the claim of a discrepancy between expected and observed warming; and (2) the allowed emissions estimated by Schwartz et al. are in conflict with results from a hierarchy of climate-carbon cycle models and strongly underestimated due to erroneous assumptions about the behavior of the carbon cycle and a confusion of the relevant timescales.” Reto Knutti and Gian-Kasper Plattner, Journal of Climate 2011, doi: 10.1175/2011JCLI4038.1.

Link to Schwartz et al. reply (no abstract or full text freely available).

Central Siberia agriculture would likely benefit from climate warming

Agroclimatic potential across central Siberia in an altered twenty-first century – Tchebakova et al. (2011) “Humans have traditionally cultivated steppe and forest-steppe on fertile soils for agriculture. Forests are predicted to shift northwards in a warmer climate and are likely to be replaced by forest-steppe and steppe ecosystems. We analyzed potential climate change impacts on agriculture in south-central Siberia believing that agriculture in traditionally cold Siberia may benefit from warming. Simple models determining crop range and regression models determining crop yields were constructed and applied to climate change scenarios for various time frames: pre-1960, 1960–90 and 1990–2010 using historic data and data taken from 2020 and 2080 HadCM3 B1 and A2 scenarios. From 50 to 85% of central Siberia is predicted to be climatically suitable for agriculture by the end of the century, and only soil potential would limit crop advance and expansion to the north. Crop production could increase twofold. Future Siberian climatic resources could provide the potential for a great variety of crops to grow that previously did not exist on these lands. Traditional Siberian crops could gradually shift as far as 500 km northwards (about 50–70 km/decade) within suitable soil conditions, and new crops nonexistent today may be introduced in the dry south that would necessitate irrigation. Agriculture in central Siberia would likely benefit from climate warming. Adaptation measures would sustain and promote food security in a warmer Siberia.” N M Tchebakova et al 2011 Environ. Res. Lett. 6 045207 doi:10.1088/1748-9326/6/4/045207. [Full text]

Handling uncertainty in science – Philosophical Transactions A special issue

Discussion Meeting Issue ‘Handling uncertainty in science’ organized and edited by T. N. Palmer and P. J. Hardaker – Palmer et al. (2011) “Despite this key role of uncertainty in science, there have been few meetings where working scientists from different disciplines have come together to discuss and compare the methods by which they handle and communicate uncertainty. The Discussion Meeting at the Royal Society on 22-23 March 2010,on which this issue is based, afforded a unique opportunity for such a discussion and comparison. Indeed, this may have been one of the most interdisciplinary Royal Society Discussion Meetings for quite some time, with participation from leaders in the fields of theoretical physics, statistics, philosophy, mathematics, cosmology, health, economics, climate, as well as from the media, government and business. Whether it is in guiding efforts to progress our knowledge and understanding of science, or in developing procedures for rational decision making, or in communicating our science to others, there is much that scientists can learn from one another in developing methodologies to handle uncertainty. It is therefore important that, from time to time, scientists come together to communicate across their disciplinary boundaries, and share experience and expertise in handling this key aspect of the scientific method. The 2010 Discussion Meeting and this collection of papers provides an unrivalled opportunity to do just this. It is hoped that more will follow.” Philosophical Transactions A, December 13, 2011; 369 (1956). [Issue contains some open access papers]

Full text of ‘Uncertainty in weather and climate prediction’ by Slingo & Palmer

Malaria occurrance linked to temperature in Colombia

Integrating knowledge and management regarding the climate–malaria linkages in Colombia – Poveda et al. (2011) “Malaria is a complex multi-factorial disease whose outcomes are affected by climate and environmental variability. In particular, malaria is endemic in the year-round hot and humid lowlands of Colombia, whose hydro-climatology exhibits clear-cut variability at interannual timescales, mostly driven by both phases of El Niño/Southern Oscillation (ENSO): El Niño (warm phase) and La Niña (cold phase). Here we show highly significant statistical correlations between malaria outbreaks in Colombia during historical El Niño events of 1959–2009. Analyses are performed at national, regional, and municipal spatial scales, and at annual, quarterly, and monthly timescales. Annual malaria incidence in Colombia exhibits a combination of long-term trends (which might be explained by historical increasing trends in average air temperatures throughout Colombia, in turn owing to global warming and deforestation), as well as strong malaria outbreaks during El Niño, as a consequence of the concomitant increases in air temperature. Also, we show that satellite imagery of vegetation activity can be used as an environmental indicator for malaria in Colombia. We discuss how these research results and diverse knowledge-based tools, including mathematical explanatory models and geographical information systems, are being used by the Colombian health authorities as an end-to-end program and early warning system (EWS) for malaria prevention and surveillance countrywide.” Germán Poveda, Óscar A Estrada-Restrepo, Julián E Morales, Ólver O Hernández, Armando Galeano, Salua Osorio, Current Opinion in Environmental Sustainability, doi:10.1016/j.cosust.2011.10.004.

Regeneration potential decreases for some and increases for some eucalypt species

Modelling the potential impact of climate variability and change on species regeneration potential in the temperate forests of South-Eastern Australia – Mok et al. (2011) “The sensitivity of early plant regeneration to environmental change makes regeneration a critical stage for understanding species response to climate change. We investigated the spatial and temporal response of eucalypt trees in the Central Highland region of south eastern Australia to high and low climate change scenarios. We developed a novel mechanistic model incorporating germination processes, TACA-GEM, to evaluate establishment probabilities of five key eucalypt species, Eucalyptus pauciflora, E. delegatensis, E. regnans, E. nitens, and E. obliqua. Changes to regeneration potential at landscape and site levels were calculated to determine climate thresholds. Model results demonstrated that climate change is likely to impact on plant regeneration. We observed increases and decreases of regeneration potential depending on the ecosystem, indicating that some species will increase in abundance in some forest types whilst other forest types will become inhabitable. In general the dry forest ecosystems were most impacted whilst the wet forests were least impacted. We also observed that species with seed dormancy mechanisms, like E. pauciflora and E. delegatensis, are likely to be at higher risk than those without. Landscape and site level analysis revealed heterogeneity in species response at different scales. On a landscape scale, a 4.3°C mean temperature increase and 22% decline in precipitation (predicted for 2080) is predicted to be a threshold for large spatial shifts in species regeneration niches across the study region, while a 2.6°C increase and 15% decline in precipitation (predicted for 2050) will likely result in local site-level shifts. Site-level analysis showed that considerable declines in regeneration potential for E. delegatensis, E. pauciflora, and E. nitens were modelled to occur in some ecosystems by 2050. While overall model performance and accuracy was good, better understanding of effects from extreme events and other underlying processes on regeneration will improve modelling and development of species conservation strategies.” Hoi-Fei Mok, Craig R. Nitschke, Stefan K. Arndt, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02591.x.

Interdependency of aerosol forcing and climate sensitivity increases the uncertainty of projections

Correlation between climate sensitivity and aerosol forcing and its implication for the “climate trap” – Tanaka & Raddatz (2011) “Climate sensitivity and aerosol forcing are dominant uncertain properties of the global climate system. Their estimates based on the inverse approach are interdependent as historical temperature records constrain possible combinations. Nevertheless, many literature projections of future climate are based on the probability density of climate sensitivity and an independent aerosol forcing without considering the interdependency of such estimates. Here we investigate how large such parameter interdependency affects the range of future warming in two distinct settings: one following the A1B emission scenario till the year 2100 and the other assuming a shutdown of all greenhouse gas and aerosol emissions in the year 2020. We demonstrate that the range of projected warming decreases in the former case, but considerably broadens in the latter case, if the correlation between climate sensitivity and aerosol forcing is taken into account. Our conceptual study suggests that, unless the interdependency between the climate sensitivity and aerosol forcing estimates is properly considered, one could underestimate a risk involving the “climate trap”, an unpalatable situation with a high climate sensitivity in which a very drastic mitigation may counter-intuitively accelerate the warming by unmasking the hidden warming due to aerosols.” Katsumasa Tanaka and Thomas Raddatz, Climatic Change, DOI: 10.1007/s10584-011-0323-2.

DeVries cycle of solar activity shows in tree-ring chronologies

Solar and volcanic fingerprints in tree-ring chronologies over the past 2000 years – Breitenmoser et al. (2011) “The Sun is the main driver of Earth’s climate, yet the Sun’s role in forcing decadal-to-centennial climate variations has remained controversial, especially in the context of understanding contributions of natural climate forcings to continuing global warming. To properly address long-term fingerprints of solar forcing on climate, long-term, very high-resolution, globally distributed climate proxy records are necessary. In this study we compile and evaluate a near global collection of annually-resolved tree-ring-based climate proxies spanning the past two millennia. We statistically assess these records in both the time and frequency domains for solar forcing (i.e. Total Solar Irradiance; TSI) and climate variability with emphasis on centennial time scales. Analyses in the frequency domain indicate significant periodicities in the 208-year frequency band, corresponding to the DeVries cycle of solar activity. Additionally, results from superposed epoch analysis (SEA) point toward a possible solar contribution in the temperature and precipitation series. However, solar-climate associations remain weak, with for example no clear linkage distinguishable in the southwestern United States drought records at centennial time scales. Other forcing factors, namely volcanic activity, appear to mask the solar signal in space and time. To investigate this hypothesis, we attempted to extract volcanic signals from the temperature proxies using a statistical modelling approach. Wavelet analysis of the volcanic contribution reveals significant periodicities near the DeVries frequency during the Little Ice Age (LIA). This remarkable and coincidental superposition of the signals makes it very difficult to separate volcanic and solar forcing during the LIA. Nevertheless, the “volcano free” temperature records show significant periodicities near the DeVries periodicity during the entire past 1500 years, further pointing to solar mechanisms and emphasising the need for solar related studies in the absence of strong multi-decadal volcanic forcing.” Petra Breitenmoser, Jürg Beer, Stefan Brönnimann, David Frank, Friedhelm Steinhilber, Heinz Wanner, Palaeogeography, Palaeoclimatology, Palaeoecology, doi:10.1016/j.palaeo.2011.10.014.

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Papers on health effects of increased CO2

Posted by Ari Jokimäki on November 4, 2011

This is a list of papers dealing with different aspects of the health effects of increased carbon dioxide. The list contains subsections for general studies, increasing atmospheric CO2 and allergies, and extreme carbon dioxide events. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (August 27, 2019): Zhang et al. (2017), Zhang et al. (2017), Allen et al. (2016), Hersoug et al. (2012) and Satish et al. (2012) added.
UPDATE (April 11, 2013): New section for atmospheric carbon dioxide and allergies added including 10 papers.
UPDATE (November 9, 2011): Robertson (2006) added.

General studies

Physiological responses during exposure to carbon dioxide and bioeffluents at levels typically occurring indoors – Zhang et al. (2017) [Full text]
Abstract: Twenty‐five subjects were exposed to different levels of carbon dioxide (CO2) and bioeffluents. The ventilation rate was set high enough to create a reference condition of 500 ppm CO2 with subjects present; additional CO2 was then added to supply air to reach levels of 1000 or 3000 ppm, or the ventilation rate was reduced to allow metabolically generated CO2 to reach the same two levels (bioeffluents increased as well). Heart rate, blood pressure, end‐tidal CO2 (ETCO2), oxygen saturation of blood (SPO2), respiration rate, nasal peak flow, and forced expiration were monitored, and the levels of salivary α‐amylase and cortisol were analyzed. The subjects performed a number of mental tasks during exposures and assessed their levels of comfort and the intensity of their acute health symptoms. During exposure to CO2 at 3000 ppm, when CO2 was added or ventilation was restricted, ETCO2 increased more and heart rate decreased less than the changes that occurred in the reference condition. Exposure to bioeffluents, when metabolically generated CO2 was at 3000 ppm, significantly increased diastolic blood pressure and salivary α‐amylase level compared with pre‐exposure levels, and reduced the performance of a cue‐utilization test: These effects may suggest higher arousal/stress. A model is proposed describing how mental performance is affected by exposure to bioeffluents.
Citation: Zhang, X. , Wargocki, P. and Lian, Z. (2017), Physiological responses during exposure to carbon dioxide and bioeffluents at levels typically occurring indoors. Indoor Air, 27: 65-77. doi:10.1111/ina.12286.

Effects of exposure to carbon dioxide and bioeffluents on perceived air quality, self‐assessed acute health symptoms, and cognitive performance – Zhang et al. (2017) [Full text]
Abstract: The purpose of this study was to examine the effects on humans of exposure to carbon dioxide (CO2) and bioeffluents. In three of the five exposures, the outdoor air supply rate was high enough to remove bioeffluents, resulting in a CO2 level of 500 ppm. Chemically pure CO2 was added to this reference condition to create exposure conditions with CO2 at 1000 or 3000 ppm. In two further conditions, the outdoor air supply rate was restricted so that the bioeffluent CO2 reached 1000 or 3000 ppm. The same 25 subjects were exposed for 255 min to each condition. Subjective ratings, physiological responses, and cognitive performance were measured. No statistically significant effects on perceived air quality, acute health symptoms, or cognitive performance were seen during exposures when CO2 was added. Exposures to bioeffluents with CO2 at 3000 ppm reduced perceived air quality; increased the intensity of reported headache, fatigue, sleepiness, and difficulty in thinking clearly; and reduced speed of addition, the response time in a redirection task, and the number of correct links made in the cue‐utilization test. This suggests that moderate concentrations of bioeffluents, but not pure CO2, will result in deleterious effects on occupants during typical indoor exposures.
Citation: Zhang, X. , Wargocki, P. , Lian, Z. and Thyregod, C. (2017), Effects of exposure to carbon dioxide and bioeffluents on perceived air quality, self‐assessed acute health symptoms, and cognitive performance. Indoor Air, 27: 47-64. doi:10.1111/ina.12284.

Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments – Allen et al. (2016) [Full text]
Abstract: Background: The indoor built environment plays a critical role in our overall well-being because of both the amount of time we spend indoors (~90%) and the ability of buildings to positively or negatively influence our health. The advent of sustainable design or green building strategies reinvigorated questions regarding the specific factors in buildings that lead to optimized conditions for health and productivity. Objective: We simulated indoor environmental quality (IEQ) conditions in “Green” and “Conventional” buildings and evaluated the impacts on an objective measure of human performance: higher-order cognitive function. Methods: Twenty-four participants spent 6 full work days (0900–1700 hours) in an environmentally controlled office space, blinded to test conditions. On different days, they were exposed to IEQ conditions representative of Conventional [high concentrations of volatile organic compounds (VOCs)] and Green (low concentrations of VOCs) office buildings in the United States. Additional conditions simulated a Green building with a high outdoor air ventilation rate (labeled Green+) and artificially elevated carbon dioxide (CO2) levels independent of ventilation. Results: On average, cognitive scores were 61% higher on the Green building day and 101% higher on the two Green+ building days than on the Conventional building day (p < 0.0001). VOCs and CO2 were independently associated with cognitive scores. Conclusions: Cognitive function scores were significantly better under Green+ building conditions than in the Conventional building conditions for all nine functional domains. These findings have wide-ranging implications because this study was designed to reflect conditions that are commonly encountered every day in many indoor environments.
Citation: Allen JG, MacNaughton P, Satish U, Santanam S, Vallarino J, Spengler JD. 2016. Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments. Environ Health Perspect 124:805–812;

A proposed potential role for increasing atmospheric CO2 as a promoter of weight gain and obesity – Hersoug et al. (2012) [Full text]
Abstract: Human obesity has evolved into a global epidemic. Interestingly, a similar trend has been observed in many animal species, although diet composition, food availability and physical activity have essentially remained unchanged. This suggests a common factor—potentially an environmental factor affecting all species. Coinciding with the increase in obesity, atmospheric CO2 concentration has increased more than 40%. Furthermore, in modern societies, we spend more time indoors, where CO2 often reaches even higher concentrations. Increased CO2 concentration in inhaled air decreases the pH of blood, which in turn spills over to cerebrospinal fluids. Nerve cells in the hypothalamus that regulate appetite and wakefulness have been shown to be extremely sensitive to pH, doubling their activity if pH decreases by 0.1 units. We hypothesize that an increased acidic load from atmospheric CO2 may potentially lead to increased appetite and energy intake, and decreased energy expenditure, and thereby contribute to the current obesity epidemic.
Citation: L-G Hersoug, A Sjödin & A Astrup (2012). Nutrition & Diabetes volume 2, page e31. doi:10.1038/nutd.2012.2.

Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance – Satish et al. (2012) [Full text]
Abstract: Background: Associations of higher indoor carbon dioxide (CO2) concentrations with impaired work performance, increased health symptoms, and poorer perceived air quality have been attributed to correlation of indoor CO2 with concentrations of other indoor air pollutants that are also influenced by rates of outdoor-air ventilation. Objectives: We assessed direct effects of increased CO2, within the range of indoor concentrations, on decision making. Methods: Twenty-two participants were exposed to CO2 at 600, 1,000, and 2,500 ppm in an office-like chamber, in six groups. Each group was exposed to these conditions in three 2.5-hr sessions, all on 1 day, with exposure order balanced across groups. At 600 ppm, CO2 came from outdoor air and participants’ respiration. Higher concentrations were achieved by injecting ultrapure CO2. Ventilation rate and temperature were constant. Under each condition, participants completed a computer-based test of decision-making performance as well as questionnaires on health symptoms and perceived air quality. Participants and the person administering the decision-making test were blinded to CO2 level. Data were analyzed with analysis of variance models. Results: Relative to 600 ppm, at 1,000 ppm CO2, moderate and statistically significant decrements occurred in six of nine scales of decision-making performance. At 2,500 ppm, large and statistically significant reductions occurred in seven scales of decision-making performance (raw score ratios, 0.06–0.56), but performance on the focused activity scale increased. Conclusions: Direct adverse effects of CO2 on human performance may be economically important and may limit energy-saving reductions in outdoor air ventilation per person in buildings. Confirmation of these findings is needed.
Citation: Usha Satish, Mark J. Mendell, Krishnamurthy Shekhar, Toshifumi Hotchi, Douglas Sullivan, Siegfried Streufert, William J. Fisk (2012). Environmental Health Perspectives, 120(12). doi:10.1289/ehp.1104789.

High carbon dioxide concentrations in the classroom: the need for research on the effects of children’s exposure to poor indoor air quality at school – Miller et al. (2010) “Air quality and its effect on health have received recent attention from the House of Commons Environmental Audit Committee. 1 While outdoor air pollution is clearly important and contributes to indoor air quality, indoor air pollution sources and the time spent in indoor environments are key to understanding exposure.” Janice Miller, Sean Semple, Stephen Turner, Occup Environ Med 2010;67:799 doi:10.1136/oem.2010.057471.

Occupational hazards of carbon dioxide exposure – Scott et al. (2009) “This paper is an overview of the occupational hazards that result from exposure to carbon dioxide. It details the main uses, characteristics, and problems that have been identified when carbon dioxide is utilized in various working environments. Carbon dioxide is always a danger when present in enclosed spaces at elevated concentrations. Situations resulting from acute and chronic exposures involving the gaseous and dry ice forms of carbon dioxide are discussed in detail. Current rationale concerning exposure limits and monitoring recommendations are highlighted.” Jonathan L. Scott, David G. Kraemer, Randal J. Keller, Journal of Chemical Health and Safety, Volume 16, Issue 2, March-April 2009, Pages 18-22, doi:10.1016/j.jchas.2008.06.003.

Effects of carbon dioxide inhalation on psychomotor and mental performance during exercise and recovery – Vercruyssen et al. (2007) “On separate days, 6 highly trained participants performed psychomotor tests while breathing for 60 min 3 carbon dioxide (CO(2)) mixtures (room air, 3% CO(2), or 4% CO(2)) prior to, between, and following two 15-min treadmill exercise bouts (70% VO(2)(max)). Each individual was extensively practiced (at least 4 days) before testing began, and both gas conditions and order of tasks were counterbalanced. Results showed physiological reactions and work-related psychomotor effects, but no effects of gas concentration on addition, multiplication, grammatical reasoning, or dynamic postural balance. These findings help define behavioral toxicity levels and support a re-evaluation of existing standards for the maximum allowable concentrations (also emergency and continuous exposure guidance levels) of CO(2). This research explored the selection of psychometric instruments of sufficient sensitivity and reliability to detect subtle changes in performance caused by exposure to low levels of environmental stress, in this case differential levels of CO(2) in the inspired air.” Vercruyssen M, Kamon E, Hancock PA., Int J Occup Saf Ergon. 2007;13(1):15-27. [Full text]

Health effects of increase in concentration of carbon dioxide in the atmosphere – Robertson (2006) “The toxic effects, to humans and other mammals, of concentrations of carbon dioxide in the atmosphere which are below the safe working level but above the present level are described. The likely physiological effects of the predicted increase in concentration of carbon dioxide in the atmosphere over the next 50 years are detailed.” A quote from the article: “At a carbon dioxide concentration of 600 ppm in an indoor atmosphere, the occupants become aware of deterioration in the atmosphere. At and above this level, some occupants began to display one or more of the classic symptoms of carbon dioxide poisoning, e.g. difficulty in breathing, rapid pulse rate, headache, hearing loss, hyperventilation, sweating and fatigue. At 1000 ppm, nearly all the occupants were affected. […] In the event that the atmospheric concentration of carbon dioxide reaches 600 ppm, the planet will have a permanent outdoor atmosphere exactly like that of a stuffy room. The conditions indoors in buildings of the type now available will become even more unpleasant and could easily reach 1000 ppm permanently with the results outlined above.” D. S. Robertson, Current science, 2006, vol. 90, no12, pp. 1607-1609. [Full text]

Carbon Dioxide Poisoning – Langford (2005) “Carbon dioxide is a physiologically important gas, produced by the body as a result of cellular metabolism. It is widely used in the food industry in the carbonation of beverages, in fire extinguishers as an `inerting’ agent and in the chemical industry. Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death. Solid carbon dioxide may cause burns following direct contact. If it is warmed rapidly, large amounts of carbon dioxide are generated, which can be dangerous, particularly within confined areas. The management of carbon dioxide poisoning requires the immediate removal of the casualty from the toxic environment, the administration of oxygen and appropriate supportive care. In severe cases, assisted ventilation may be required. Dry ice burns are treated similarly to other cryogenic burns, requiring thawing of the tissue and suitable analgesia. Healing may be delayed and surgical intervention may be required in severe cases.” Langford, Nigel J., Toxicological Reviews, Volume 24, Number 4, 2005 , pp. 229-235(7).

Association of Ventilation Rates and CO2 Concentrations with Health andOther Responses in Commercial and Institutional Buildings – Seppänen et al. (1999) “This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non-residential and non-industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates above 10 Ls-1 per person, up to approximately 20 Ls-1 per person, were associated with further significant decreases in the prevalence of sick building syndrome (SBS) symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5–2 for respiratory illnesses and 1.1–6 for sick building syndrome symptoms for low compared to high low ventilation rates.” O. A. Seppänen, W. J. Fisk, M. J. Mendell, Indoor Air, Volume 9, Issue 4, pages 226–252, December 1999, DOI: 10.1111/j.1600-0668.1999.00003.x. [Full text]

Indoor Air Quality Investigations at Five Classrooms – Lee & Chang (1999) “Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter with diameter less than 10 mm (PM10), formaldehyde (HCHO), and total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM10 concentrations exceeded the Hong Kong standards, and the maximum indoor PM10 level was even at 472 μ;g/m3. Air cleaners could be used in classrooms to reduce the high PM10 concentration. Indoor CO2 concentrations often exceeded 1,000 μl/l indicating inadequate ventilation. Lowering the occupancy and increasing breaks between classes could alleviate the high CO2 concentrations. Though the maximum indoor CO2 level reached 5,900 μl/l during class at one of the sites, CO2 concentrations were still at levels that pose no health threats.” S. C. Lee, Maureen Chang, Indoor Air, Volume 9, Issue 2, pages 134–138, June 1999, DOI: 10.1111/j.1600-0668.1999.t01-2-00008.x.

Effects of sustained low-level elevations of carbon dioxide on cerebral blood flow and autoregulation of the intracerebral arteries in humans – Sliwka et al. (1998) “Cerebral blood flow velocity (CBFv) was measured by insonating the middle cerebral arteries of four subjects using a 2 Mhz transcranial Doppler. Ambient CO2 was elevated to 0.7% for 23 d in the first study and to 1.2% for 23 d in the same subjects in the second study. By non-parametric testing CBFv was elevated significantly by +35% above pre-exposure levels during the first 1-3 d at both exposure levels, after which CBFv progressively readjusted to pre-exposure levels. Despite similar CBFv responses, headache was only reported during the initial phase of exposure to 1.2% CO2. Vascular reactivity to CO2 assessed by rebreathing showed a similar pattern with the CBFv increases early in the exposures being greater than those elicited later. An increase in metabolic rate of the visual cortex was evoked by having the subjects open and close their eyes during a visual stimulus. Evoked CBFv responses measured in the posterior cerebral artery were also elevated in the first 1-3 d of both studies returning to pre-exposure levels as hypercapnia continued. Cerebral vascular autoregulation assessed by raising head pressure during 10 degrees head-down tilt both during the low-level exposures and during rebreathing was unaltered. There were no changes in the retinal microcirculation during serial fundoscopy studies. The time-dependent changes in CO2 vascular reactivity might be due either to retention of bicarbonate in brain extracellular fluid or to progressive increases in ventilation, or both. Cerebral vascular autoregulation appears preserved during chronic exposure to these low levels of ambient CO2.” Sliwka U, Krasney JA, Simon SG, Schmidt P, Noth J., Aviat Space Environ Med. 1998 Mar;69(3):299-306.

Sick Building Syndrome Symptoms among the Staff in Schools and Kindergartens: are the Levels of Volatile Organic Compounds and Carbon Dioxide Responsible? – Willers et al. (1996) “From a large questionnaire-based survey investigating the indoor air quality (IAQ) in 48 schools and 74 kindergartens, 21 schools were selected for mea surements of volatile organic compounds (VOC) and carbon dioxide (CO2) based on the prevalence of sick building syndrome (SBS) symptoms reported by the staff. The 10 schools with the lowest prevalence of SBS symptoms ‘healthy’) were compared to 11 schools with the highest prevalence (‘sick’; median value showing twice as many SBS symptoms reported). The concen trations of total VOCs (TVOC) in schools and kindergartens were low and within suggested guidelines. The levels of CO2 were higher than suggested guidelines in several cases. However, neither TVOC nor CO2 concentrations were associated with SBS symptoms. Thus, TVOC and CO2 concentrations do not seem to be useful as SBS risk indicators.” Stefan Willers, Sven Andersson, Rolf Andersson, Jörgen Grantén, Christina Sverdrup, Lars Rosell, Indoor and Built Environment July 1996 vol. 5 no. 4 232-235, doi: 10.1177/1420326X9600500406.

Effects of carbon dioxide inhalation on psychomotor and mental performance during exercise and recovery – Sheehy et al. (1982) “Psychomotor and mental tests involving reaction time, rotor pursuit, short-term memory for digits and letters, and reasoning ability were administered to subjects inhaling up to 5% CO2 in air and in gas mixtures containing 50% O2. The psychomotor and mental tests were given during the 6 min of recovery following 10 min of treadmill running at 80% of aerobic capacity. Although the subjects inhaled the CO2 during the entire exercise and recovery period there was no difference in performance between the CO2 inhalation condition and the control condition for any of the performance measures.” Sheehy, J B; Kamon, E; Kiser, D., Human Factors. Vol. 24, pp. 581-588. Oct. 1982.

Effects on man of high concentrations of carbon dioxide in relation to various oxygen pressures during exposures as long as 72 hours – Consolazio et al. (1947) No abstract. W. V. Consolazio, M. B. Fisher, N. Pace, I. J. Pecora, G. C. Pitts, A. R. Behnke, American Journal of Physiology, November 1947 vol. 151 no. 2 479-503.

Increasing atmospheric CO2 and allergies

Changes in Atmospheric CO2 Influence the Allergenicity of Aspergillus fumigatus – Lang-Yona et al. (2013) “Increased susceptibility to allergies has been documented in the Western world in recent decades. However, a comprehensive understanding of its causes is not yet available. It is therefore essential to understand trends and mechanisms of allergy-inducing agents, such as fungal conidia. In this study we investigated the hypothesis that environmental conditions linked to global atmospheric changes can affect the allergenicity of Aspergillus fumigatus, a common allergenic fungal species in indoor and outdoor environments and in airborne particulate matter. We show that fungi grown under present day CO2 levels (392 ppm) exhibit 8.5 and 3.5 fold higher allergenicity compared to fungi grown at preindustrial (280 ppm) and double (560 ppm) CO2 levels, respectively. A corresponding trend is observed in the expression of genes encoding for known allergenic proteins and in the major allergen Asp f1 concentrations, possibly due to physiological changes such as respiration rates and the nitrogen content of the fungus, influenced by the CO2 concentrations. Increased carbon and nitrogen levels in the growth medium also lead to a significant increase in the allergenicity. We propose that climatic changes such as increasing atmospheric CO2 levels and changes in the fungal growth medium may impact the ability of allergenic fungi such as Aspergillus fumigatus to induce allergies.” Naama Lang-Yona, Yishai Levin, Karen C. Dannemiller, Oded Yarden, Jordan Peccia, Yinon Rudich, Global Change Biology, DOI: 10.1111/gcb.12219.

Anthropogenic climate change and allergen exposure: The role of plant biology – Ziska & Beggs (2012) “Accumulation of anthropogenic gases, particularly CO2, is likely to have 2 fundamental effects on plant biology. The first is an indirect effect through Earth’s increasing average surface temperatures, with subsequent effects on other aspects of climate, such as rainfall and extreme weather events. The second is a direct effect caused by CO2-induced stimulation of photosynthesis and plant growth. Both effects are likely to alter a number of fundamental aspects of plant biology and human health, including aerobiology and allergic diseases, respectively. This review highlights the current and projected effect of increasing CO2 and climate change in the context of plants and allergen exposure, emphasizing direct effects on plant physiologic parameters (eg, pollen production) and indirect effects (eg, fungal sporulation) related to diverse biotic and abiotic interactions. Overall, the review assumes that future global mitigation efforts will be limited and suggests a number of key research areas that will assist in adapting to the ongoing challenges to public health associated with increased allergen exposure.” Lewis H. Ziska, Paul J. Beggs, Journal of Allergy and Clinical Immunology, Volume 129, Issue 1, January 2012, Pages 27–32,

Elevated atmospheric carbon dioxide concentrations amplify Alternaria alternata sporulation and total antigen production – Wolf et al. (2010) “BACKGROUND: Although the effect of elevated carbon dioxide (CO2) concentration on pollen production has been established in some plant species, impacts on fungal sporulation and antigen production have not been elucidated. OBJECTIVE: Our purpose was to examine the effects of rising atmospheric CO2 concentrations on the quantity and quality of fungal spores produced on timothy (Phleum pratense) leaves. METHODS: Timothy plants were grown at four CO2 concentrations (300, 400, 500, and 600 micromol/mol). Leaves were used as growth substrate for Alternaria alternata and Cladosporium phlei. The spore abundance produced by both fungi, as well as the size (microscopy) and antigenic protein content (ELISA) of A. alternata, were quantified. RESULTS: Leaf carbon-to-nitrogen ratio was greater at 500 and 600 micromol/mol, and leaf biomass was greater at 600 micromol/mol than at the lower CO2 concentrations. Leaf carbon-to-nitrogen ratio was positively correlated with A. alternata spore production per gram of leaf but negatively correlated with antigenic protein content per spore. At 500 and 600 micromol/mol CO2 concentrations, A. alternata produced nearly three times the number of spores and more than twice the total antigenic protein per plant than at lower concentrations. C. phlei spore production was positively correlated with leaf carbon-to-nitrogen ratio, but overall spore production was much lower than in A. alternata, and total per-plant production did not vary among CO2 concentrations. CONCLUSIONS: Elevated CO2 concentrations often increase plant leaf biomass and carbon-to-nitrogen ratio. Here we demonstrate for the first time that these leaf changes are associated with increased spore production by A. alternata, a ubiquitous allergenic fungus. This response may contribute to the increasing prevalence of allergies and asthma.” Wolf J, O’Neill NR, Rogers CA, Muilenberg ML, Ziska LH., Environ Health Perspect. 2010 Sep;118(9):1223-8. doi: 10.1289/ehp.0901867. [Full text]

Impacts of climate change on plant food allergens: a previously unrecognized threat to human health – Beggs & Walczyk (2008) “Global climate change has had, and will continue to have, many significant impacts on biological and human systems. There are now many studies of climate change impacts on aeroallergens, particularly pollen, including a study demonstrating significant increases in the major allergen content of ragweed pollen as a function of rising atmospheric carbon dioxide concentration ([CO2]). Recent research has also demonstrated more allergenic poison ivy in response to elevated [CO2]. Here, we suggest, for the first time, the potential for global climate change, and, in particular, increased [CO2] and temperature, to have an impact on the allergenicity of plant food allergens such as peanut. Such impacts could have significant impacts on associated allergic diseases, and pose a previously unrecognized threat to human health. There is an urgent need for research on the impacts of climate change on plant food allergens.” Paul John Beggs, Nicole Ewa Walczyk, Air Quality, Atmosphere & Health, October 2008, Volume 1, Issue 2, pp 119-123, DOI: 10.1007/s11869-008-0013-z. [Full text]

Pollen production by Pinus taeda growing in elevated atmospheric CO2 – Ladeau & Clark (2006) “Rising concentrations of atmospheric CO2 may have important consequences for reproductive allocation in forest trees. Changes in pollen production could influence population dynamics and is likely to have important consequences for human health. This is the first study to evaluate pollen production by forest trees in response to rising atmospheric CO2. Our research objective was to quantify pollen production by Loblolly Pine (Pinus taeda L.) trees growing in elevated CO2 (ambient + 200 µl l−1) since 1996. Trees grown in high-CO2 plots first began producing pollen while younger and at smaller sizes relative to ambient-grown trees. Pollen cone and airborne pollen grain abundances were significantly greater in the fumigated stands. We conclude that the greater number of mature trees in high-CO2 plots resulted in greater pollen production at the stand level. Precocious pollen production has important implications for fertilization and pollen dispersal from young, dense stands. Increasing levels of airborne pollen raise concerns for escalating rates of human respiratory disease.” S. L. Ladeau, J. S. Clark, Functional Ecology, Volume 20, Issue 3, pages 541–547, June 2006, DOI: 10.1111/j.1365-2435.2006.01133.x. [Full text]

Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2 – Mohan et al. (2006) “Contact with poison ivy (Toxicodendron radicans) is one of the most widely reported ailments at poison centers in the United States, and this plant has been introduced throughout the world, where it occurs with other allergenic members of the cashew family (Anacardiaceae). Approximately 80% of humans develop dermatitis upon exposure to the carbon-based active compound, urushiol. It is not known how poison ivy might respond to increasing concentrations of atmospheric carbon dioxide (CO2), but previous work done in controlled growth chambers shows that other vines exhibit large growth enhancement from elevated CO2. Rising CO2 is potentially responsible for the increased vine abundance that is inhibiting forest regeneration and increasing tree mortality around the world. In this 6-year study at the Duke University Free-Air CO2 Enrichment experiment, we show that elevated atmospheric CO2 in an intact forest ecosystem increases photosynthesis, water use efficiency, growth, and population biomass of poison ivy. The CO2 growth stimulation exceeds that of most other woody species. Furthermore, high-CO2 plants produce a more allergenic form of urushiol. Our results indicate that Toxicodendron taxa will become more abundant and more “toxic” in the future, potentially affecting global forest dynamics and human health.” Jacqueline E. Mohan, Lewis H. Ziska, William H. Schlesinger, Richard B. Thomas, Richard C. Sicher, Kate George, and James S. Clark, PNAS June 13, 2006 vol. 103 no. 24 9086-9089, doi: 10.1073/pnas.0602392103. [Full text]

Increasing Amb a 1 content in common ragweed (Ambrosia artemisiifolia) pollen as a function of rising atmospheric CO2 concentration – Singer et al. (2005) “Although the impact of increasing atmospheric carbon dioxide concentration ([CO2]) on production of common ragweed (Ambrosia artemisiifolia L.) pollen has been examined in both indoor and outdoor experiments, the relationship between allergen expression and [CO2] is not known. An enzyme-linked immunosorbent assay (ELISA) was used to quantify Amb a 1, ragweed’s major allergen, in protein extracted from pollen of A. artemisiifolia grown at different [CO2] values in a previous experiment. The concentrations used approximated atmospheric pre-industrial conditions (i.e. at the end of the 19th century), current conditions, and the CO2 concentration projected for the middle of the 21st century (280, 370 and 600 μmol mol–1 CO2, respectively). Although total pollen protein remained unchanged, significant increases in Amb a 1 allergen were observed between pre-industrial and projected future [CO2] and between current and projected future [CO2] (1.8 and 1.6 times, respectively). These data suggest that recent and projected increases in [CO2] could directly increase the allergenicity of ragweed pollen and consequently the prevalence and / or severity of seasonal allergic disease. However, genetic and abiotic factors governing allergen expression will need to be better established to fully understand these data and their implications for public health.” Ben D. Singer A C, Lewis H. Ziska B D, David A. Frenz C, Dennis E. Gebhard C, James G. Straka, Functional Plant Biology 32(7) 667–670, [Full text]

Production of allergenic pollen by ragweed (Ambrosia artemisiifolia L.) is increased in CO2-enriched atmospheres – Wayne et al. (2002) “Background: The potential effects of global climate change on allergenic pollen production are still poorly understood. Objective: To study the direct impact of rising atmospheric CO2 concentrations on ragweed (Ambrosia artemisiifolia L.) pollen production and growth. Methods: In environmentally controlled greenhouses, stands of ragweed plants were grown from seed through flowering stages at both ambient and twice-ambient CO2 levels (350 vs 700 μL L−1). Outcome measures included stand-level total pollen production and end-of-season measures of plant mass, height, and seed production. Results: A doubling of the atmospheric CO2 concentration stimulated ragweed-pollen production by 61% (P = 0.005). Conclusions: These results suggest that there may be significant increases in exposure to allergenic pollen under the present scenarios of global warming. Further studies may enable public health groups to more accurately evaluate the future risks of hay fever and respiratory diseases (eg, asthma) exacerbated by allergenic pollen, and to develop strategies to mitigate them.” Peter Wayne, Susannah Foster, John Connolly, Fakhri Bazzaz, Paul Epstein, Annals of Allergy, Asthma & Immunology, Volume 88, Issue 3, March 2002, Pages 279–282, [Full text]

Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia L.), a known allergy-inducing species: implications for public health – Ziska & Caulfield (2000) “Although environmental factors such as precipitation and temperature are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide concentration ([CO2]) on the potential growth and pollen production of hay-fever-inducing plants is unknown. Here we present measurements of growth and pollen production of common ragweed (Ambrosia artemisiifolia L.) from pre-industrial [CO2] (280 mol mol–1) to current concentrations (370 mol mol–1) to a projected 21st century concentration (600 mol mol–1). We found that exposure to current and elevated [CO2] increased ragweed pollen production by 131 and 320%, respectively, compared to plants grown at pre-industrial [CO2]. The observed stimulations of pollen production from the pre-industrial [CO2] were due to an increase in the number (at 370 mol mol–1) and number and size (at 600 mol mol–1) of floral spikes. Overall, floral weight as a percentage of total plant weight decreased (from 21% to 13%), while investment in pollen increased (from 3.6 to 6%) between 280 and 600 mol mol–1 CO2. Our results suggest that the continuing increase in atmospheric [CO2] could directly influence public health by stimulating the growth and pollen production of allergy-inducing species such as ragweed.” Lewis H. Ziska and Frances A. Caulfield, Australian Journal of Plant Physiology 27(10) 893 – 898, doi:10.1071/PP00032. [Full text]

Increased levels of airborne fungal spores in response to Populus tremuloides grown under elevated atmospheric CO2 – Klironomos et al. (1997) “Soil fungi are important components of terrestrial ecosystems. They function as decomposers, pathogens, parasites, and mutualistic symbionts. Their main mode of dispersal is to liberate spores into the atmosphere. In this study we tested the hypothesis that a higher atmospheric CO2 concentration will induce greater sporulation in common soil fungi, leading to higher concentrations of fungal propagules in the atmosphere. In our field experiment, the concentration of airborne fungal propagules, mostly spores, increased fourfold under twice-ambient CO2 concentrations. Analysis of decomposing leaf litter (likely the main source of airborne fungal propagules) indicated that the fungi produced fivefold more spores under elevated CO2. Our results provide evidence that elevations in atmospheric CO2 concentration can directly affect microbial function, which may have important implications for litter decay, fungal dispersal, and human respiratory health. Key words: atmospheric CO2, fungal spores, global change, Populus tremuloides.” John N. Klironomos, Matthias C. Rillig, Michael F. Allen, Donald R. Zak, Kurt S. Pregitzer, Mark E. Kubiske, Canadian Journal of Botany, 1997, 75(10): 1670-1673, 10.1139/b97-880.

Extreme carbon dioxide events

This section lists papers on some extreme events where carbon dioxide has caused deaths or serious harm. It should be noted that this is not very relevant to the carbon dioxide levels associated with current global warming. However, for some carbon capture and storage scenarios these events serve as practical examples to what happens during high local carbon dioxide levels.

Non-volcanic CO2 Earth degassing: Case of Mefite d’Ansanto (southern Apennines), Italy – Chiodini et al. (2010) “Mefite d’Ansanto, southern Apennines, Italy is the largest natural emission of low temperature CO2 rich gases, from non-volcanic environment, ever measured in the Earth. The emission is fed by a buried reservoir, made up of permeable limestones and covered by clayey sediments. We estimated a total gas flux of ~2000 tons per day. Under low wind conditions, the gas flows along a narrow natural channel producing a persistent gas river which has killed over a period of time people and animals. The application of a physical numerical model allowed us to define the zones which potentially can be affected by dangerous CO2 concentration at breathing height for humans.” Chiodini, G., D. Granieri, R. Avino, S. Caliro, A. Costa, C. Minopoli, and G. Vilardo (2010), Geophys. Res. Lett., 37, L11303, doi:10.1029/2010GL042858.

Asphyxiation Due to Dry Ice in a Walk-in Freezer – Dunford et al. (2009) “Background: Exposure to a high concentration of environmental carbon dioxide (CO2) can result in poisoning through direct toxicity and by displacing atmospheric oxygen (O2). Dry ice undergoes sublimation to a gaseous state at −78.5°C (−109.3°F), which is heavier than air and can accumulate in dependent areas. Case Report: We report the case of a 59-year-old man found in cardiac arrest shortly after entering a recently repaired walk-in freezer that contained dry ice. First responders and bystanders did not recognize the proximate hazardous environment but were fortunately uninjured. A careful Emergency Department history coupled with rapid case investigation by the Medical Examiner’s Office led to the determination of the cause of death and the elimination of the ongoing hazard. Conclusion: This case illustrates the lethal consequences of improper storage of dry ice and the need to consider toxic environmental exposure as a cause of sudden cardiac arrest.” James V. Dunford, Jon Lucas, Nick Vent, Richard F. Clark, F. Lee Cantrell, The Journal of Emergency Medicine, Volume 36, Issue 4, May 2009, Pages 353-356, doi:10.1016/j.jemermed.2008.02.051.

A Carbon Dioxide Fatality from Dry Ice – Srisont et al. (2009) “This report documents a rare case of carbon dioxide intoxication in a young healthy male. The deceased hid in a small plastic container, size 1.5 × 1 × 1 m, and within 5 min he was located suffering convulsions and was reported as dead within minutes. Scene investigation revealed dry ice in the container. Autopsy findings were unremarkable. The probable cause of the convulsions was carbon dioxide intoxication due to both the dry ice sublimation and the small confined space in which he was hiding. This report emphasizes the significance of scene investigation in establishing the cause of the death.” Smith Srisont, Thamrong Chirachariyavej, A. V. M. Vichan Peonim, Journal of Forensic Sciences, Volume 54, Issue 4, pages 961–962, July 2009, DOI: 10.1111/j.1556-4029.2009.01057.x. [Full text]

A shallow-layer model for heavy gas dispersion from natural sources: Application and hazard assessment at Caldara di Manziana, Italy – Costa et al. (2008) “Several nonvolcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in the presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow-layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment by evaluating where and when lethal concentrations for humans and animals are reached.” Costa, A., G. Chiodini, D. Granieri, A. Folch, R. K. S. Hankin, S. Caliro, R. Avino, and C. Cardellini (2008), Geochem. Geophys. Geosyst., 9, Q03002, doi:10.1029/2007GC001762. [Full text]

Degassing Lakes Nyos and Monoun: Defusing certain disaster – Kling et al. (2005) “Since the catastrophic releases of CO2 in the 1980s, Lakes Nyos and Monoun in Cameroon experienced CO2 recharge at alarming rates of up to 80 mol/m2 per yr. Total gas pressures reached 8.3 and 15.6 bar in Monoun (2003) and Nyos (2001), respectively, resulting in gas saturation levels up to 97%. These natural hazards are distinguished by the potential for mitigation to prevent future disasters. Controlled degassing was initiated at Nyos (2001) and Monoun (2003) amid speculation it could inadvertently destabilize the lakes and trigger another gas burst. Our measurements indicate that water column structure has not been compromised by the degassing and local stability is increasing in the zones of degassing. Furthermore, gas content has been reduced in the lakes ≈12-14%. However, as gas is removed, the pressure at pipe inlets is reduced, and the removal rate will decrease over time. Based on 12 years of limnological measurements we developed a model of future removal rates and gas inventory, which predicts that in Monoun the current pipe will remove ≈30% of the gas remaining before the natural gas recharge balances the removal rate. In Nyos the single pipe will remove ≈25% of the gas remaining by 2015; this slow removal extends the present risk to local populations. More pipes and continued vigilance are required to reduce the risk of repeat disasters. Our model indicates that 75-99% of the gas remaining would be removed by 2010 with two pipes in Monoun and five pipes in Nyos, substantially reducing the risks.” George W. Kling, William C. Evans, Greg Tanyileke, Minoru Kusakabe, Takeshi Ohba, Yutaka Yoshida, and Joseph V. Hell, PNAS October 4, 2005 vol. 102 no. 40 14185-14190, doi: 10.1073/pnas.0502274102. [Full text]

Recent pH and CO2 profiles at Lakes Nyos and Monoun, Cameroon: implications for the degassing strategy and its numerical simulation – Kusakabe et al. (2000) “In situ pH profiles are reported for the first time for Lakes Nyos and Monoun. The pH profiles were converted to CO2 profiles using HCO3− profiles calculated from conductivity data. Recent observations (1993–1996) at Lake Nyos indicates that CO2 still accumulates below 180 m depth at a rate of 125 Mmol year−1. At Lake Monoun, the majority of CO2 is present below a depth of 60 m, only 25 m below the saturation depth. Consequently, a potential danger of gas explosion is high at both lakes, and artificial degassing of the lakes should be performed as soon as possible. A system for industrial degassing of the lakes is proposed. The system, based on the self-sustained gas lift principle, consists of multiple pipes (14 cm in diameter) with different intake depths; 12 pipes for Lake Nyos (four each at 185, 195 and 205 m) and three pipes for Lake Monoun (at 70, 80 and 90 m). The stepped degassing at different depths is intended to keep the maximum stability of the lakes. The proposed degassing operation was simulated using the dyresm code for both lakes. In 5 years, approximately 50% of currently dissolved CO2 in Lake Nyos and 90% in Lake Monoun will be removed. The expected changes in the thermal and chemical structures of the lakes as degassing proceeds will be most easily monitored with a carefully calibrated CTD equipped with a pH sensor. The simulation indicates that the discharged degassed water will sink to a level of neutral buoyancy, i.e. to a maximum of 70 m at Lake Nyos and 35 m at Lake Monoun. There would be no possibility of triggering a gas explosion by this plunge of discharged water because the water present there would have already been replaced by water at lower CO2 concentration, during the degassing from shallower pipes.” M Kusakabe, G.Z Tanyileke, S.A McCord, S.G Schladow, Journal of Volcanology and Geothermal Research, Volume 97, Issues 1-4, April 2000, Pages 241-260, doi:10.1016/S0377-0273(99)00170-5.

Possible asphyxiation from carbon dioxide of a cross-country skier in eastern California: a deadly volcanic hazard – Hill (2000) “This report describes an incident in which exceedingly high levels of carbon dioxide may have contributed to the death of a skier in eastern California. A cross-country skier was found dead inside a large, mostly covered snow cave, 1 day after he was reported missing. The autopsy report suggests that the skier died of acute pulmonary edema consistent with asphyxiation; carbon dioxide measurements inside the hole in which he was found reached 70%. This area is known for having a high carbon dioxide flux attributed to degassing of a large body of magma (molten rock) 10 to 20 km beneath the ski area. The literature describes many incidents of fatal carbon dioxide exposures associated with volcanic systems in other parts of the world. We believe this case represents the first reported death associated with volcanically produced carbon dioxide in the United States. Disaster and wilderness medicine specialists should be aware of and plan for this potential health hazard associated with active volcanoes.” Peter M. Hill, Wilderness & Environmental Medicine, Volume 11, Issue 3, September 2000, Pages 192-195, doi:10.1580/1080-6032(2000)011[0192:PAFCDO]2.3.CO;2.

Fatal intoxication due to an unexpected presence of carbon dioxide – Guillemin & Horisberger (1994) “A fatal accident which occurred in a tank containing a sludge made of wine and activated charcoal is described. Similar accidents in the wine industry seem to have never been reported before. Initially, the cause of death was not obvious and became clear only after the autopsy confirmed the presence of a very high concentration of carbon dioxide in blood. It is shown in this paper how the concentration of carbon dioxide in the tank could be estimated from its solubility in water, assuming a realistic content of this gas in the wine remaining in the sludge. Moreover the accident was analysed by the fault tree method which revealed that, as well as the deficiencies in risk management of such companies, the unsuspected presence of carbon dioxide played a significant role.” Michel P. Guillemin and B. Horisberger, Ann Occup Hyg (1994) 38 (6): 951-957. doi: 10.1093/annhyg/38.6.951.

CO2-rich gases from Lakes Nyos and Monoun, Cameroon; Laacher See, Germany; Dieng, Indonesia, and Mt. Gambier, Australia—variations on a common theme – Giggenbach et al. (1991) “Helium (RA = 3.0 to 5.6) and carbon (δ13C from −7.2 to −3.4‰) isotopic compositions, and relative CO2, CH4, N2, He and Ar contents of CO2-rich gases from Lakes Nyos and Monoun, Cameroon; Laacher See, Germany; Dieng Volcanic Plateau, Indonesia, and a well at Mt. Gambier, Australia, point to a common, essentially magmatic origin. … Otherwise, gas may accumulate to form a stable pocket (Mt. Gambier). Minor leakage from such pockets may lead to surface discharges of CO2-rich gases as at Laacher See, re-absorption into shallow groundwater to the formation of the low-salinity, CO2-charged waters encountered at Lakes Nyos and Monoun. The occurrence of these high-CO2, low-temperature systems is likely to be favored in tectonically active regions, allowing deep, possibly mantle gases to rise, but with sufficiently low regional heat flows to prevent the establishment of large-scale geothermal activity.” W.F. Giggenbach, Y. Sano, H.U. Schmincke, Journal of Volcanology and Geothermal Research, Volume 45, Issues 3-4, April 1991, Pages 311-323, doi:10.1016/0377-0273(91)90065-8.

Water and gas chemistry of Lake Nyos and its bearing on the eruptive process – W.F. Giggenbach (1990) “The isotopic and chemical composition of water samples collected from Lake Nyos some two and eight weeks after the eruption of August 21, 1986 point to the existence of three distinct mixing regimes involving three water components. An essentially homogeneous, unmixed body of water at depths > 100 m, overlain by water increasingly affected by surface evaporation and a 5–10-m layer containing recent, but pre-eruption rain water. The cationic constituents (Na, K, Mg, Ca, Mn, Fe) of the lake water correspond to the dissolution of around 0.1 g of local rock, the waters are close to saturation with respect to siderite. The composition of the gas dissolved in the deep lake waters (0.65% b.w. of CO2, PCO2 = 4.4b) corresponds (in mmol mol−1) to 996 CO2, 2.0 CH4, 2.0 N2, 0.05 Ar, 0.004 He, 0.0002 H2, 0.0001 Ne, < 0.01 O2, < 0.004 H2S, < 0.001 CO. The isotopic compositions of CO213C = -3.4‰) and of He (Rair = 5.5) suggest deep magmatic origins, the 13C and 2H content of CH4 organic sedimentary origin, the presence of aromatic hydrocarbons indicates very high temperatures of hydrocarbon formation. Exsolution of gas will first lead to the precipitation of siderite then iron hydroxide. The chemistry of the lake waters points to a loss of some 240,000 t of CO2 from the upper 100 m of the lake, their isotopic composition is consistent with the assumption that the eruption was triggered by the accumulation of cold rain waters at the lake surface prior to the eruption inducing partial convective overturn. There is no need to invoke addition of chemical or isotopic constituents from deeper levels during the eruption.” W.F. Giggenbach, Journal of Volcanology and Geothermal Research, Volume 42, Issue 4, 15 August 1990, Pages 337-362, doi:10.1016/0377-0273(90)90031-A.

The Lake Nyos gas disaster: chemical and isotopic evidence in waters and dissolved gases from three Cameroonian crater lakes, Nyos, Monoun and Wum – Kusakabe et al. (1989) “To better understand the cause of the Nyos gas disaster of August 21, 1986, we conducted geochemical and limnological surveys in October 1986, of three lakes (Nyos, Monoun and Wum) which are located in the Cameroon volcanic zone that is characterized by a prevalence of young alkaline basalts and basanitoids. … The August 1986 gas bursts from Lake Nyos were most likely caused by rapid exsolution of dissolved CO2 within the lake; an explosive process such as a phreatic eruption or a CO2 gas-jetting from beneath the bottom is unlikely because of low concentrations of Cl and SO42−, no oxygen isotopic shift, low turbidity, and no reported perturbation of the bottom sediments. Exsolution of CO2 bubbles could occur if CO2-saturated bottom water was displaced upwards by an increased influx of high salinity water from the bottom during the rainy season. Exsolution of CO2 at the upper layers was possibly accelerated by upwelling of a two-phase fluid (CO2 bubbles and solution), a mechanism known as a pneumatic lift pump, resulting in discharge of a large amount of CO2 gas. The H2S concentration in the gas cloud must have been kept far below the lethal level because of a high Fe2+ concentration of the lake water.” Minoru Kusakabe, Takashi Ohsumi, Shigeo Aramaki, Journal of Volcanology and Geothermal Research, Volume 39, Issues 2-3, November 1989, Pages 167-185, doi:10.1016/0377-0273(89)90056-5.

The gas cloud of Lake Nyos (Cameroon, 1986): Results of the Italian technical mission – Barberi et al. (1989) “On August 21, 1986, a gas cloud issued from Lake Nyos in Cameroon killed over 1700 people. An Italian technical mission reached the area seven days later and obtained the first field evidences of the catastrophe. On the basis of observations and measurements in the field and of samples collected, the origin of the gas outburst is attributed to a phreatic explosion from beneath the bed of the lake. This interpretation appears to fit well the observed and reported phenomena, and seems perfectly consistent with the geological-geothermal conditions of the area.” F. Barberi, W. Chelini, G. Marinelli, M. Martini, Journal of Volcanology and Geothermal Research, Volume 39, Issues 2-3, November 1989, Pages 125-134, doi:10.1016/0377-0273(89)90053-X.

Lake Nyos disaster, Cameroon, 1986: the medical effects of large scale emission of carbon dioxide? – Baxter et al. (1989) “Carbon dioxide was blamed for the deaths of around 1700 people in Cameroon, west Africa, in 1986 when a massive release of gas occurred from Lake Nyos, a volcanic crater lake. The clinical findings in 845 survivors seen at or admitted to hospital were compatible with exposure to an asphyxiant gas. Rescuers noted cutaneous erythema and bullae on an unknown proportion of corpses and 161 (19%) survivors treated in hospital; though these lesions were initially believed to be burns from acidic gases, further investigation suggested that they were associated with coma states caused by exposure to carbon dioxide in air. The disaster at Lake Nyos and a similar event at Lake Monoun, Cameroon, two years previously provide new information on the possible medical effects of large scale emissions of carbon dioxide, though the presence of other toxic factors in these gas releases cannot be excluded.” P. J. Baxter, M. Kapila, D. Mfonfu, BMJ 298 : 1437 doi: 10.1136/bmj.298.6685.1437 (Published 27 May 1989). [Full text]

Mechanisms of the Nyos carbon dioxide disaster and of so-called phreatic steam eruptions – Tazieff (1989) “During the night of August 21, 1986, a huge volume of concentrated CO2 was emitted by the crater (maar) of Nyos, Cameroon. It killed more than 1700 people and all animal life as far as 14 km away. Two hypotheses have been put forward to account for this disaster. The chronologically first one imputes it to have been a phreatic eruption, exceptionally CO2-rich, as had been the case in February 1979 on the Diëng Plateau in Central Java, Indonesia, where the erupting crater was lake-less. The second one claims a limnic origin for the CO2 release, through an overturn of the 220 m-deep Lake Nyos, the hypolimnium of which was supposed to be oversaturated by dissolved gas of volcanic origin. The present paper points to six observed facts for which the eruptive hypothesis easily accounts, and which the authors of the limnic one do ignore.” Haroun Tazieff, Journal of Volcanology and Geothermal Research, Volume 39, Issues 2-3, November 1989, Pages 109-116, doi:10.1016/0377-0273(89)90051-6.

Origin of carbon dioxide emanation from the 1979 Dieng eruption, Indonesia: Implications for the origin of the 1986 Nyos catastrophe – Allard et al. (1989) “In February 1979, CO2 emanations accompanying a phreatic eruption killed 142 people at Dieng volcano, Central Java. The gas emitted was nearly pure carbon dioxide, with subordinate amounts of methane and sulfur compounds. … It is proposed that magmatic carbon dioxide, accumulated beneath the Dieng volcanic complex, was the source of the lethal gas, the effusion of which was triggered by the pressure release generated by the phreatic eruption. The total CO2 discharge of the 1979 Dieng event might have approached 0.1 km3, i.e. close to the lower output estimated for the 1986 Nyos catastrophe. The Dieng example demonstrates that expansion and then effusion of pure magmatic carbon dioxide, accumulated at shallow levels beneath volcanoes, may account for a major hazard from phreatic eruptions, be it a trigger or only a consequence of the eruptions.” P. Allard, D. Dajlevic, C. Delarue, Journal of Volcanology and Geothermal Research, Volume 39, Issues 2-3, November 1989, Pages 195-206, doi:10.1016/0377-0273(89)90058-9.

Medical evaluation of the victims of the 1986 Lake Nyos disaster – Wagner et al. (1988) “A cloud of carbon dioxide gas, with an estimated volume of 1 km3 was released from Lake Nyos, a volcanic crater lake in Cameroon, Africa, causing 1700 to 2000 human fatalities as well as killing thousands of livestock and wild animals. At the request of the Cameroonian Government, the Office of Foreign Disaster Assistance of the U.S. Department of State sent a multidisciplinary team which included 2 forensic pathologists to assist the Government of Cameroon in investigating this natural disaster. The medical evaluation was concentrated in 3 areas: the autopsy of human and animal fatalities, examination and interview of survivors, and examination of the scene of the disaster. Toxicologic specimens were obtained at autopsy, and numerous samples of lake water were collected. The autopsy findings were consistent with asphyxia. The results of chemical analyses excluded many volatiles but not carbon dioxide as the toxic agent. The exact source of this gas continues to be a subject of a heated geologic debate, but fermentation of organic materials in the lake water has been eliminated on the basis of C14 isotope studies. This investigation underlines the value of forensic pathologists in epidemiological studies and in the examination of living persons.” Wagner GN, Clark MA, Koenigsberg EJ, Decata SJ., J Forensic Sci. 1988 Jul;33(4):899-909.

The 1986 Lake Nyos Gas Disaster in Cameroon, West Africa – Kling et al. (1987) “The sudden, catastrophic release of gas from Lake Nyos on 21 August 1986 caused the deaths of at least 1700 people in the northwest area of Cameroon, West Africa. Chemical, isotopic, geologic, and medical evidence support the hypotheses that (i) the bulk of gas released was carbon dioxide that had been stored in the lake’s hypolimnion, (ii) the victims exposed to the gas cloud died of carbon dioxide asphyxiation, (iii) the carbon dioxide was derived from magmatic sources, and (iv) there was no significant, direct volcanic activity involved. The limnological nature of the gas release suggests that hazardous lakes may be identified and monitored and that the danger of future incidents can be reduced.” George W. Kling, Michael A. Clark, Glen N. Wagner, Harry R. Compton, Alan M. Humphrey, Joseph D. Devine, William C. Evans, John P. Lockwood, Michele L. Tuttle and Edward J. Koenigsberg, Science 10 April 1987: Vol. 236 no. 4798 pp. 169-175, DOI: 10.1126/science.236.4798.169.

Origin of the lethal gas burst from Lake Monoun, Cameroun – Sigurdsson et al. (1987) “On 15 August, 1984, a lethal gas burst issued from a submerged 96-m-deep crater in Lake Monoun in Cameroun, western Africa, killing 37 people. The event was associated with a landslide from the eastern crater rim, which slumped into deep water. … Gases effervescing from depressurized deep waters are dominantly CO2 with minor CH4, having δ13C of −7.18 and −54.8 per mil, respectively. … The resultant ebullition of CO2 from deep lake waters led to a gas burst at the surface and locally generated a water wave up to 5 m high. People travelling through the gas cloud were asphyxiated, presumably from CO2, and suffered skin discoloration from unidentified components.” H. Sigurdsson, J.D. Devine, F.M. Tchua, F.M. Presser, M.K.W. Pringle, W.C. Evans, Journal of Volcanology and Geothermal Research, Volume 31, Issues 1-2, March 1987, Pages 1-16, doi:10.1016/0377-0273(87)90002-3.

An example of health hazard: People killed by gas during a phreatic eruption: Diëng plateau (Java, Indonesia), February 20th 1979 – Le Guern et al. (1982) “On February 20th, 1979, 142 inhabitants of Dieng Plateau (Indonesia) were asphyxiated by poisonous gases during a mild phreatic eruption. From later fields gas collection and analysis, the casualties are considered to be due to CO2 rich volcanic gases.” F. Le Guern, H. Tazieff and R. Faivre Pierret, Bulletin of Volcanology, Volume 45, Number 2, 153-156, DOI: 10.1007/BF02600430.

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