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Archive for March, 2011

Papers on geoengineering

Posted by Ari Jokimäki on March 31, 2011

This is a list of papers on geoengineering. Focus is on general papers on the subject. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

For lots and lots of additional papers, see Oxford Geoengineering Programme’s Reference Library.

Engineering geo-engineering – Fox & Chapman (2011) “This paper reviews the geo-engineering approach to tackling climate change. The failure of the 15th United Nations Framework Convention on Climate Change Conference of the Parties (COP15) to obtain a legally binding emissions reduction agreement makes the deployment of geo-engineering solutions an increasingly attractive proposition. This review looks at a variety of global and local approaches to geo-engineering covering solar radiation management and carbon cycle engineering and attempts to assess the feasibility of the technologies from an engineering perspective. However, despite the plethora of ideas generated by the science community, it still appears that much work remains to be done in the initial engineering assessment of these techniques and this is a major hurdle to overcome before any geo-engineering scheme can be fully considered. Hence, the paper concludes by calling for the instigation of national and international programmes of research at the feasibility level, to inform discussions regarding future possible deployment of small scale, local geo-engineering and adaptation measures.” Timothy A. Fox, Lee Chapman, Meteorological Applications, Volume 18, Issue 1, pages 1–8, March 2011. [Full text]

History of climate engineering – Bonnheim (2010) “The modern concept of geoengineering as a response to anthropogenic climate change evolved from much earlier proposals to modify the climate. The well-documented history of weather modification provides a much-needed historical perspective on geoengineering in the face of current climate anxiety and the need for responsive action. Drawing on material from the mid-20th century until today, this paper asserts the importance of looking at geoengineering holistically—of integrating social considerations with technical promise, and scientific study with human and moral dimensions. While the debate is often couched in scientific terms, the consequences of geoengineering the climate stretch far beyond the world of science into the realms of ethics, legality, and society. Studying the history of geoengineering can help produce fresh insights about what has happened and about what may happen, and can help frame important decisions that will soon be made as to whether geoengineering is a feasible alternative to mitigation, a possible partner, or a dangerous experiment with our fragile planet.” Noah Byron Bonnheim, Wiley Interdisciplinary Reviews: Climate Change, Volume 1, Issue 6, pages 891–897, November/December 2010, DOI: 10.1002/wcc.82.

The radiative forcing potential of different climate geoengineering options – Lenton & Vaughan (2009) “Climate geoengineering proposals seek to rectify the Earth’s current and potential future radiative imbalance, either by reducing the absorption of incoming solar (shortwave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on energy balance considerations and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. It allows us to compare the relative effectiveness of a range of proposals. We consider geoengineering options as additional to large reductions in CO2 emissions. By 2050, some land carbon cycle geoengineering options could be of comparable magnitude to mitigation “wedges”, but only stratospheric aerosol injections, albedo enhancement of marine stratocumulus clouds, or sunshades in space have the potential to cool the climate back toward its pre-industrial state. Strong mitigation, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition may have greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean upwelling or downwelling have trivial effects on any meaningful timescale. Our approach provides a common framework for the evaluation of climate geoengineering proposals, and our results should help inform the prioritisation of further research into them.” Lenton, T. M. and Vaughan, N. E., Atmos. Chem. Phys., 9, 5539-5561, doi:10.5194/acp-9-5539-2009, 2009. [Full text]

A review of climate geoengineering proposals – Vaughan & Lenton (2009) “Climate geoengineering proposals seek to rectify the current radiative imbalance via either (1) reducing incoming solar radiation (solar radiation management) or (2) removing CO2 from the atmosphere and transferring it to long-lived reservoirs (carbon dioxide removal). For each option, we discuss its effectiveness and potential side effects, also considering lifetime of effect, development and deployment timescale, reversibility, and failure risks. We present a detailed review that builds on earlier work by including the most recent literature, and is more extensive than previous comparative frameworks. Solar radiation management propsals are most effective but short-lived, whilst carbon dioxide removal measures gain effectiveness the longer they are pursued. Solar radiation management could restore the global radiative balance, but must be maintained to avoid abrupt warming, meanwhile ocean acidification and residual regional climate changes would still occur. Carbon dioxide removal involves less risk, and offers a way to return to a pre-industrial CO2 level and climate on a millennial timescale, but is potentially limited by the CO2 storage capacity of geological reservoirs. Geoengineering could complement mitigation, but it is not an alternative to it. We expand on the possible combinations of mitigation, carbon dioxide removal and solar radiation management that might be used to avoid dangerous climate change.” Naomi E. Vaughan and Timothy M. Lenton, Climatic Change, DOI: 10.1007/s10584-011-0027-7.

Toward ethical norms and institutions for climate engineering research – Morrow et al. (2009) “Climate engineering (CE), the intentional modification of the climate in order to reduce the effects of increasing greenhouse gas concentrations, is sometimes touted as a potential response to climate change. Increasing interest in the topic has led to proposals for empirical tests of hypothesized CE techniques, which raise serious ethical concerns. We propose three ethical guidelines for CE researchers, derived from the ethics literature on research with human and animal subjects, applicable in the event that CE research progresses beyond computer modeling. The Principle of Respect requires that the scientific community secure the global public’s consent, voiced through their governmental representatives, before beginning any empirical research. The Principle of Beneficence and Justice requires that researchers strive for a favorable risk–benefit ratio and a fair distribution of risks and anticipated benefits, all while protecting the basic rights of affected individuals. Finally, the Minimization Principle requires that researchers minimize the extent and intensity of each experiment by ensuring that no experiments last longer, cover a greater geographical extent, or have a greater impact on the climate, ecosystem, or human welfare than is necessary to test the specific hypotheses in question. Field experiments that might affect humans or ecosystems in significant ways should not proceed until a full discussion of the ethics of CE research occurs and appropriate institutions for regulating such experiments are established.” David R Morrow et al 2009 Environ. Res. Lett. 4 045106 doi: 10.1088/1748-9326/4/4/045106. [Full text]

Ranking geo-engineering schemes – Boyd (2008) “Geo-engineering proposals for mitigating climate change continue to proliferate without being tested. It is time to select and assess the most promising ideas according to efficacy, cost, all aspects of risk and, importantly, their rate of mitigation. Propelling aerosols into the upper atmosphere or pumping carbon dioxide into the deep ocean are just two schemes that have been proposed to repair the Earth’s climate through geo-engineering (see Box 1). In the absence of adequate reductions in anthropogenic CO2 emissions, geo-engineering has been put forward as the only remaining option that might fix our rapidly changing climate.” Philip W. Boyd, Nature Geoscience 1, 722 – 724 (2008), doi:10.1038/ngeo348. [Full text]

The Incredible Economics of Geoengineering – Barrett (2008) “The focus of climate policy so far has been on reducing the accumulation of greenhouse gases. That approach, however, requires broad international cooperation and, being expensive, has been hindered by free riding; so far, little action has been taken. An alternative approach is to counteract climate change by reducing the amount of solar radiation that strikes the Earth—“geoengineering.” In contrast to emission reductions, this approach is inexpensive and can be undertaken by a single country, unilaterally. But geoengineering also has worrying consequences: it may harm some countries; it would not address ocean acidification; it would pose new risks. The fundamental challenge posed by this new technology is not free riding but governance: who should decide if and under what circumstances geoengineering should be used?” Scott Barrett, Environmental and Resource Economics, Volume 39, Number 1, 45-54, DOI: 10.1007/s10640-007-9174-8. [Full text]

Geoengineering: could we or should we make it work? – Schneider (2008) “Schemes to modify large-scale environment systems or control climate have been proposed for over 50 years to (i) increase temperatures in high latitudes, (ii) increase precipitation, (iii) decrease sea ice, (iv) create irrigation opportunities, or (v) offset potential global warming by injecting iron in the oceans or sea-salt aerosol in the marine boundary layer or spreading dust in the stratosphere to reflect away an amount of solar energy equivalent to the amount of heat trapped by increased greenhouse gases from human activities. These and other proposed geoengineering schemes are briefly reviewed. Recent schemes to intentionally modify climate have been proposed as either cheaper methods to counteract inadvertent climatic modifications than conventional mitigation techniques such as carbon taxes or pollutant emissions regulations or as a counter to rising emissions as governments delay policy action. Whereas proponents argue cost-effectiveness or the need to be prepared if mitigation and adaptation policies are not strong enough or enacted quickly enough to avoid the worst widespread impacts, critics point to the uncertainty that (i) any geoengineering scheme would work as planned or (ii) that the many centuries of international political stability and cooperation needed for the continuous maintenance of such schemes to offset century-long inadvertent effects is socially feasible. Moreover, the potential exists for transboundary conflicts should negative climatic events occur during geoengineering activities.” Stephen H Schneider, Phil. Trans. R. Soc. A 13 November 2008 vol. 366 no. 1882 3843-3862, doi: 10.1098/rsta.2008.0145. [Full text]

A geophysiologist’s thoughts on geoengineering – Lovelock (2008) “The Earth is now recognized as a self-regulating system that includes a reactive biosphere; the system maintains a long-term steady-state climate and surface chemical composition favourable for life. We are perturbing the steady state by changing the land surface from mainly forests to farm land and by adding greenhouse gases and aerosol pollutants to the air. We appear to have exceeded the natural capacity to counter our perturbation and consequently the system is changing to a new and as yet unknown but probably adverse state. I suggest here that we regard the Earth as a physiological system and consider amelioration techniques, geoengineering, as comparable to nineteenth century medicine.” James Lovelock, Phil. Trans. R. Soc. A 13 November 2008 vol. 366 no. 1882 3883-3890, doi: 10.1098/rsta.2008.0135. [Full text]

Geoengineering: Encouraging Research and Overseeing Implementation – Cicerone (2006) No abstract Ralph J. Cicerone, Climatic Change, Volume 77, Numbers 3-4, 221-226, DOI: 10.1007/s10584-006-9102-x. [Full text]

The pathological history of weather and climate modification: Three cycles of promise and hype – Fleming (2006) No abstract.” James Rodger Fleming, Historical Studies in the Physical and Biological Sciences, 2006, Vol. 37, Number 1, pps 3-25. [Full text]

Geoengineering the Climate: History and Prospect – Keith (2000) “Geoengineering is the intentional large-scale manipulation of the environment, particularly manipulation that is intended to reduce undesired anthropogenic climate change. The post-war rise of climate and weather modification and the history of U.S. assessments of the CO2-climate problem is reviewed. Proposals to engineer the climate are shown to be an integral element of this history. Climate engineering is reviewed with an emphasis on recent developments, including low-mass space-based scattering systems for altering the planetary albedo, simulation of the climate’s response to albedo modification, and new findings on iron fertilization in oceanic ecosystems. There is a continuum of human responses to the climate problem that vary in resemblance to hard geoengineering schemes such as space-based mirrors. The distinction between geoengineering and mitigation is therefore fuzzy. A definition is advanced that clarifies the distinction between geoengineering and industrial carbon management. Assessment of geoengineering is reviewed under various framings including economics, risk, politics, and environmental ethics. Finally, arguments are presented for the importance of explicit debate about the implications of countervailing measures such as geoengineering.” David W. Keith, Annual Review of Energy and the Environment, Vol. 25: 245-284 (Volume publication date November 2000), DOI: 10.1146/annurev.energy.25.1.245. [Full text]

Earth systems engineering and management – Schneider (2001) “Imagine that we could let the world’s economy continue to grow, bring the disadvantaged classes up from poverty and at the same time not threaten the atmosphere or global ecosystems with unprecedented build-up of greenhouse gases and the projected climatic risks of such growth. Earth systems engineering and management may just be such a panacea, some have suggested. But could we anticipate the costs or ever truly predict the consequences?” Stephen H. Schneider, Nature 409, 417-421 (18 January 2001) | doi:10.1038/35053203. [Full text]

Geoengineering Earth’s radiation balance to mitigate CO2‐induced climate change – Govindasamy & Caldeira (2000) “To counteract anthropogenic climate change, several schemes have been proposed to diminish solar radiation incident on Earth’s surface. These geoengineering schemes could reverse global annual mean warming; however, it is unclear to what extent they would mitigate regional and seasonal climate change, because radiative forcing from greenhouse gases such as CO2 differs from that of sunlight. No previous study has directly addressed this issue. In the NCAR CCM3 atmospheric general circulation model, we reduced the solar luminosity to balance the increased radiative forcing from doubling atmospheric CO2. Our results indicate that geoengineering schemes could markedly diminish regional and seasonal climate change from increased atmospheric CO2, despite differences in radiative forcing patterns. Nevertheless, geoengineering schemes could prove environmentally risky.” Govindasamy, B., and K. Caldeira (2000), Geophys. Res. Lett., 27(14), 2141–2144, doi:10.1029/1999GL006086. [Full text]

The economic diplomacy of geoengineering – Schelling (1996) “‘Geoengineering’ is a new term, still seeking a definition. It seems to imply something global, intentional, and unnatural. For the radiation balance, geoengineering may be fifty years in the future; today’s means may be out of date then, and the future means are not yet known. It might immensely simplify greenhouse policy, transforming it from an exceedingly complicated regulatory regime to a problem in international cost sharing, a problem that we are familiar with. Putting things in the stratosphere or in orbit can probably be done by exo-national programs, not depending on the behavior of populations, not requiring national regulations or incentives, not dependent on universal participation. It will involve merely deciding what to do, how much to do, and who is to pay for it.” Thomas C. Schelling, Climatic Change, Volume 33, Number 3, 303-307, DOI: 10.1007/BF00142578.

May we engineer the climate? – Bodansky (1996) “Not only is the science of climate engineering uncertain; the legal issues are also highly uncertain. Although existing international law does not specifically limit the freedom of states to undertake climate engineering, the international community would likely demand a say should climate engineering move from the realm of speculation to concrete proposals. The experience of other environmental regimes, however, suggests that developing an international decision-making mechanism would be difficult, and that the international community might opt for a simple prohibition on climate engineering on grounds of ‘precaution’.” Daniel Bodansky, Climatic Change, Volume 33, Number 3, 309-321, DOI: 10.1007/BF00142579.

Geoengineering: Could— or should— we do it? – Schneider (1996) “Schemes to modify large-scale environment systems or to control climate have been seriously proposed for over 50 years, some to (1) increase temperatures in high latitudes, (2) increase precipitation, (3) decrease sea ice, (4) create irrigation opportunities or to offset potential global warming by spreading dust in the stratosphere to reflect away an equivalent amount of solar energy. These and other proposed geoengineering schemes are briefly reviewed from a historical perspective. More recently, many such schemes to advertently modify climate have been proposed as cheaper methods to counteract inadvertent climatic modifications than conventional mitigation techniques such as carbon taxes or pollutant emissions regulations. Whereas proponents argue cost effectiveness, critics of geoengineering argue that there is too much uncertainty to either (1) be confident that any geoengineering scheme would work as planned, or (2) that the many decades of international political stability and cooperation needed for the continuous maintenance of such schemes to offset century long inadvertent efforts is problematic. Moreover, there is potential for transboundary conflicts should negative climatic events occur during geoengineering activities since, given all the large uncertainties, it could not be assured to victims of such events that the schemes were entirely unrelated to their damages. Nevertheless, although I believe it would be irresponsible to implement any large-scale geoengineering scheme until scientific, legal and management uncertainties are substantially narrowed, I do agree that, given the potential for large inadvertent climatic changes now being built into the earth system, more systematic study of the potential for geoengineering is probably needed.” Stephen H. Schneider, Climatic Change, Volume 33, Number 3, 291-302, DOI: 10.1007/BF00142577.

Ethics and intentional climate change – Jamieson (1996) “In recent years the idea of geoengineering climate has begun to attract increasing attention. Although there was some discussion of manipulating regional climates throughout the 1970s and 1980s, the discussion was largely dormant. What has reawakened the conversation is the possibility that Earth may be undergoing a greenhouse-induced global warming, and the paucity of serious measures that have been taken to prevent it. In this paper I assess the ethical acceptability of ICC, based on my impressions of the conversation that is now taking place. Rather than offering a dispassionate analysis, I argue for a point of view. I propose a set of conditions that must be satisfied for an ICC project to be morally permissible and conclude that these conditions are not now satisfied. However, research on ICC should go forward so long as certain other conditions are met. I do not intend this to be the last word on the subject, but rather the first word. My hope is that others will be stimulated to think through the ethics of ICC.” Dale Jamieson, Climatic Change, Volume 33, Number 3, 323-336, DOI: 10.1007/BF00142580. [Full text]

Geoengineering the climate – MacCracken (1991) “Although much can be done to limit greenhouse gas emissions by conservation, improvements in efficiency, and use of alternative technologies, the use of fossil fuels at rates even sharply reduced from US per capita values will lead to rapidly increasing global concentrations of greenhouse gases. The available alternatives then become adapting to the changes, switching to alternative energy sources (e.g., solar, nuclear), or actively taking control of atmospheric composition and/or the climate. This note reviews options for geoengineering the climate.” MacCracken, M.C., UCRL-JC-108014. Lawrence Livermore National Laboratory, June 1991. [Full text]

Climate Stabilization: For Better or for Worse? – Kellogg & Schneider (1974) “Even if we could predict the future of our climate, climate control would be a hazardous venture.” W. W. Kellogg; S. H. Schneider, Science, New Series, Vol. 186, No. 4170. (Dec. 27, 1974), pp. 1163-1172. [Full text]

Posted in Adaptation & Mitigation | 2 Comments »

New research from last week 12/2011

Posted by Ari Jokimäki on March 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. Planet 3.0 also reports new research.

Published last week:

Alpine aquatic species threatened by glacier loss

Climate change links fate of glaciers and an endemic alpine invertebrate – Muhlfeld et al. (2011) “Climate warming in the mid- to high-latitudes and high-elevation mountainous regions is occurring more rapidly than anywhere else on Earth, causing extensive loss of glaciers and snowpack. However, little is known about the effects of climate change on alpine stream biota, especially invertebrates. Here, we show a strong linkage between regional climate change and the fundamental niche of a rare aquatic invertebrate—the meltwater stonefly Lednia tumana—endemic to Waterton-Glacier International Peace Park, Canada and USA. L. tumana has been petitioned for listing under the U.S. Endangered Species Act due to climate-change-induced glacier loss, yet little is known on specifically how climate impacts may threaten this rare species and many other enigmatic alpine aquatic species worldwide. During 14 years of research, we documented that L. tumana inhabits a narrow distribution, restricted to short sections (~500 m) of cold, alpine streams directly below glaciers, permanent snowfields, and springs. Our simulation models suggest that climate change threatens the potential future distribution of these sensitive habitats and the persistence of L. tumana through the loss of glaciers and snowfields. Mountaintop aquatic invertebrates are ideal early warning indicators of climate warming in mountain ecosystems. Research on alpine invertebrates is urgently needed to avoid extinctions and ecosystem change.” Clint C. Muhlfeld, J. Joseph Giersch, F. Richard Hauer, Gregory T. Pederson, Gordon Luikart, Douglas P. Peterson, Christopher C. Downs and Daniel B. Fagre, Climatic Change, DOI: 10.1007/s10584-011-0057-1.

Geoengineering proposals are problematic – a review

A review of climate geoengineering proposals – Vaughan & Lenton (2011) “Climate geoengineering proposals seek to rectify the current radiative imbalance via either (1) reducing incoming solar radiation (solar radiation management) or (2) removing CO2 from the atmosphere and transferring it to long-lived reservoirs (carbon dioxide removal). For each option, we discuss its effectiveness and potential side effects, also considering lifetime of effect, development and deployment timescale, reversibility, and failure risks. We present a detailed review that builds on earlier work by including the most recent literature, and is more extensive than previous comparative frameworks. Solar radiation management propsals are most effective but short-lived, whilst carbon dioxide removal measures gain effectiveness the longer they are pursued. Solar radiation management could restore the global radiative balance, but must be maintained to avoid abrupt warming, meanwhile ocean acidification and residual regional climate changes would still occur. Carbon dioxide removal involves less risk, and offers a way to return to a pre-industrial CO2 level and climate on a millennial timescale, but is potentially limited by the CO2 storage capacity of geological reservoirs. Geoengineering could complement mitigation, but it is not an alternative to it. We expand on the possible combinations of mitigation, carbon dioxide removal and solar radiation management that might be used to avoid dangerous climate change.” Naomi E. Vaughan and Timothy M. Lenton, Climatic Change, DOI: 10.1007/s10584-011-0027-7.

Primate reproduction decreases with global warming

Birth seasonality and offspring production in threatened neotropical primates related to climate – Wiederholt & Post (2011) “Given the threatened status of many primate species, the impacts of global warming on primate reproduction and, consequently, population growth should be of concern. We examined relations between climatic variability and birth seasonality, offspring production, and infant sex ratios in two ateline primates, northern muriquis and woolly monkeys. In both species, the annual birth season was delayed by dry conditions and El Niño years, and delayed birth seasons were linked to lower birth rates. Additionally, increased mean annual temperatures were associated with lower birth rates for northern muriquis. Offspring sex ratios varied with climatic conditions in both species, but in different ways: directly in woolly monkeys, and indirectly in northern muriquis. Woolly monkeys displayed an increase in the proportion of males among offspring in association with El Niño events, whereas in northern muriquis, increases in the proportion of males among offspring were associated with delayed onset of the birth season, which itself was related, although weakly, to warm, dry conditions. These results illustrate that global warming, increased drought frequency, and changes in the frequency of El Niño events could limit primate reproductive output, threatening the persistence and recovery of ateline primate populations.” Ruscena Wiederholt, Eric Post, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02427.x.

Danish forest has increased its carbon uptake

Increasing net CO2 uptake by a Danish beech forest during the period from 1996 to 2009 – Pilegaard et al. (2011) “The exchange of CO2 between the atmosphere and a beech forest near Sorø, Denmark, was measured continuously over 14 years (1996–2009). The simultaneous measurement of many parameters that influence CO2 uptake makes it possible to relate the CO2 exchange to recent changes in e.g. temperature and atmospheric CO2 concentration. The net CO2 exchange (NEE) was measured by the eddy covariance method. Ecosystem respiration (RE) was estimated from nighttime values and gross ecosystem exchange (GEE) was calculated as the sum of RE and NEE. Over the years the beech forest acted as a sink of on average of 157 g C m−2 yr−1. In one of the years only, the forest acted as a small source. During 1996–2009 a significant increase in annual NEE was observed. A significant increase in GEE and a smaller and not significant increase in RE was also found. Thus the increased NEE was mainly attributed to an increase in GEE. The overall trend in NEE was significant with an average increase in uptake of 23 g C m−2 yr−2. The carbon uptake period (i.e. the period with daily net CO2 gain) increased by 1.9 days per year, whereas there was a non significant tendency of increase of the leafed period. This means that the leaves stayed active longer. The analysis of CO2 uptake by the forest by use of light response curves, revealed that the maximum rate of photosynthetic assimilation increased by 15% during the 14-year period. We conclude that the increase in the overall CO2 uptake of the forest is due to a combination of increased growing season length and increased uptake capacity. We also conclude that long time series of flux measurements are necessary to reveal trends in the data because of the substantial inter-annual variation in the flux.” Kim Pilegaard, Andreas Ibrom, Michael S. Courtney, Poul Hummelshøj and Niels Otto Jensen, Agricultural and Forest Meteorology, doi:10.1016/j.agrformet.2011.02.013.

Younger Dryas onset is still a mystery

The Mysterious Onset Of The Younger Dryas – Fiedel (2011) “The 1300-year-long Younger Dryas cold reversal (12,900-11,600 cal BP) is seen most clearly in Greenland ice cores. Contemporaneous changes of climate and environment in more southerly regions were variably expressed. The precise timing of the abrupt Younger Dryas onset is still uncertain. It was linked to a sudden increase in 14C manifest as a “cliff” where 14C dates drop from 11,000 to 10,600 radiocarbon years BP within a century of real time, followed by a long plateau. Changes in ocean and/or atmospheric circulation or solar radiation, and even a comet impact have been proposed as triggers, but the abruptness and severity of YD onset still elude explanation.” S J Fiedel, Quaternary International, doi:10.1016/j.quaint.2011.02.044.

Mixture of divergence and climatic signals in trees of Tibet

Dynamic relationships between Picea crassifolia growth and climate at upper treeline in the Qilian Mts., Northeast Tibetan Plateau, China – Zhang et al. (2011) “Knowledge of the spatial pattern and temporal relationships between tree-growth and climatic factors are important not only for the projection of forest growth under varying climate but for dendroclimatology in general. Here, we systematically investigated tree-growth climate relationships of Picea crassifolia at upper treeline in the Qilian Mts., northwestern China. 297 trees from eleven sites, covering a large part of the natural range of this species, show increasing and partly divergent correlations with temperature in the most recent decades. The dominant signal at all sites was a strengthening of negative correlations of annual radial growth with summer temperature. In a subset of trees at six sites, a strengthening positive correlation with summer temperatures existed as well. Wetter and high altitude sites tended to show a higher percentage of trees that are positively correlated with warming temperatures, indicating that some individuals there may take advantage of warmer conditions. Divergent responses between the two sub-populations clustered by their response to climate factor were significantly stronger in the last 30 years compared to earlier time slices. In the same time frame, hydrothermal conditions of the investigation area changed to a drier and warmer combination. Drought conditions, most likely affecting the radial growth of most P. crassifolia, have been intensifying over time and expanding spatially from the middle Qilian Mts. to most of our study area during the last half century. While explanations such as methodological effects due to trend removal or human disturbance at the sampling sites might be able to explain the result at single sites, the spatial and temporal co-occurrence of large scale changes in climate and tree growth suggests a causal link between them.” Yongxiang Zhang, Xuemei Shao and Martin Wilmking, Dendrochronologia, 2011, doi:10.1016/j.dendro.2010.11.001.

Winter warming events cause damage to Arctic plants

Impacts of multiple extreme winter warming events on sub-Arctic heathland: phenology, reproduction, growth, and CO2 flux responses – Bokhorst et al. (2011) “Extreme weather events can have strong negative impacts on species survival and community structure when surpassing lethal thresholds. Extreme, short-lived, winter warming events in the Arctic rapidly melt snow and expose ecosystems to unseasonably warm air (for instance, 2–10°C for 2–14 days) but upon return to normal winter climate exposes the ecosystem to much colder temperatures due to the loss of insulating snow. Single events have been shown to reduce plant reproduction and increase shoot mortality, but impacts of multiple events are little understood as are the broader impacts on community structure, growth, carbon balance and nutrient cycling. To address these issues, we simulated week-long extreme winter warming events -using infrared heating lamps and soil warming cables- for three consecutive years in a sub-arctic heathland dominated by the dwarf shrubs Empetrum hermaphroditum, Vaccinium vitis-idaea (both evergreen) and V. myrtillus (deciduous). During the growing seasons after the 2nd and 3rd winter event, spring bud burst was delayed by up to a week for E. hermaphroditum and V. myrtillus, and berry production reduced by 11–75% and 52–95% for E. hermaphroditum and V. myrtillus respectively. Greater shoot mortality occurred in E. hermaphroditum (up to 52%), V. vitis-idaea (51%), and V. myrtillus (80%). Root growth was reduced by more than 25% but soil nutrient availability remained unaffected. Gross primary productivity was reduced by more than 50% in the summer following the 3rd simulation. Overall, the extent of damage was considerable, and critically plant responses were opposite in direction to the increased growth seen in long-term summer warming simulations and the ‘greening’ seen for some arctic regions. Given the Arctic is warming more in winter than summer, and extreme events are predicted to become more frequent, this generates large uncertainty in our current understanding of arctic ecosystem responses to climate change.” S. Bokhorst, J. W. Bjerke, L. E. Street, T. V. Callaghan, G. K. Phoenix, Global Change Biology, 2011, DOI: 10.1111/j.1365-2486.2011.02424.x.

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New research from last week 11/2011

Posted by Ari Jokimäki on March 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. Planet 3.0 also reports new research.

Published last week:

Early predictability was low for 2010 Russian heat wave

Was there a basis for anticipating the 2010 Russian heat wave? – Dole et al. (2011) “The 2010 summer heat wave in western Russia was extraordinary, with the region experiencing the warmest July since at least 1880 and numerous locations setting all-time maximum temperature records. This study explores whether early warning could have been provided through knowledge of natural and human-caused climate forcings. Model simulations and observational data are used to determine the impact of observed sea surface temperatures (SSTs), sea ice conditions and greenhouse gas concentrations. Analysis of forced model simulations indicates that neither human influences nor other slowly evolving ocean boundary conditions contributed substantially to the magnitude of this heat wave. They also provide evidence that such an intense event could be produced through natural variability alone. Analysis of observations indicate that this heat wave was mainly due to internal atmospheric dynamical processes that produced and maintained a strong and long-lived blocking event, and that similar atmospheric patterns have occurred with prior heat waves in this region. We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability. Slowly varying boundary conditions that could have provided predictability and the potential for early warning did not appear to play an appreciable role in this event.” Dole, R., M. Hoerling, J. Perlwitz, J. Eischeid, P. Pegion, T. Zhang, X.-W. Quan, T. Xu, and D. Murray (2011), Geophys. Res. Lett., 38, L06702, doi:10.1029/2010GL046582. [full text]

Argo pressure sensor drift analysis

Pressure sensor drifts in Argo and their impacts – Barker et al. (2011) “In recent years, autonomous profiling floats have become the prime component of the in-situ ocean observing system through the implementation of the Argo Programme. These data are now the dominant input to estimates of the evolution of the global ocean heat content and associated thermosteric sea level rise. APEX is the dominant type of Argo float (~62%), and a large portion of these floats report pressure measurements that are uncorrected for sensor drift, the size and source of which we describe. The remaining Argo float types are designed to automatically self-correct for any pressure drift. Only about 57% of APEX float profiles (or ~38% Argo profiles) can be corrected but this typically has not been done by the data centres which distribute the data (as of January 2009). A pressure correction method for APEX floats is described and applied to the Argo data set. A comparison between estimates using our corrected Argo data set and the publically available uncorrected data set (as of January 2009) reveals that our pressure corrections remove significant regional errors from ocean temperature, salinity and thermosteric sea level fields. In the global mean, the 43% of uncorrectable APEX float profiles (or ~28% Argo profiles) appear to largely offset the effect of the correctable APEX float profiles with positive pressure drifts. While about half of the uncorrectable APEX profiles can, in principle, be recovered in the near future (after inclusion of technical information that allows for corrections), the other half have negative pressure drifts truncated to zero (due to firmware limitations) which do not allow for corrections. Therefore, any Argo pressure profile that cannot be corrected for biases should be excluded from global change research. This study underscores the ongoing need for careful analyses to detect and remove subtle but systematic errors in ocean observations.” Paul M. Barker, Jeff R. Dunn, Catia M. Domingues, Susan E. Wijffels, Journal of Atmospheric and Oceanic Technology 2011.

Freshening episode in Alaska Coastal Current due to glacier melting and rain

Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios – Chan et al. (2011) “Arctic Ocean freshening can exert a controlling influence on global climate, triggering strong feedbacks on ocean-atmospheric processes and affecting the global cycling of the world’s oceans. Glacier-fed ocean currents such as the Alaska Coastal Current are important sources of freshwater for the Bering Sea shelf, and may also influence the Arctic Ocean freshwater budget. Instrumental data indicate a multiyear freshening episode of the Alaska Coastal Current in the early 21st century. It is uncertain whether this freshening is part of natural multidecadal climate variability or a unique feature of anthropogenically induced warming. In order to answer this, a better understanding of past variations in the Alaska Coastal Current is needed. However, continuous long-term high-resolution observations of the Alaska Coastal Current have only been available for the last 2 decades. In this study, specimens of the long-lived crustose coralline alga Clathromorphum nereostratum were collected within the pathway of the Alaska Coastal Current and utilized as archives of past temperature and salinity. Results indicate that coralline algal Mg/Ca ratios provide a 60 year record of sea surface temperatures and track changes of the Pacific Decadal Oscillation, a pattern of decadal-to-multidecadal ocean-atmosphere climate variability centered over the North Pacific. Algal Ba/Ca ratios (used as indicators of coastal freshwater runoff) are inversely correlated to instrumentally measured Alaska Coastal Current salinity and record the period of freshening from 2001 to 2006. Similar multiyear freshening events are not evident in the earlier portion of the 60 year Ba/Ca record. This suggests that the 21st century freshening of the Alaska Coastal Current is a unique feature related to increasing glacial melt and precipitation on mainland Alaska.” Chan, P., J. Halfar, B. Williams, S. Hetzinger, R. Steneck, T. Zack, and D. E. Jacob (2011), J. Geophys. Res., 116, G01032, doi:10.1029/2010JG001548.

Global warming driven enhancement of Arctic biosphere might decline in the future

Ecological controls on net ecosystem productivity of a mesic arctic tundra under current and future climates – Grant et al. (2011) “Changes in arctic C stocks with climate are thought to be caused by rising net primary productivity (NPP) during longer and warmer growing seasons, offset by rising heterotrophic respiration (Rh) in warmer and deeper soil active layers. In this study, we used the process model ecosys to test hypotheses for these changes with CO2 and energy fluxes measured by eddy covariance over a mesic shrub tundra at Daring Lake, Canada, under varying growing seasons. These tests corroborated substantial rises in NPP, smaller rises in Rh, and, hence, rises in net ecosystem productivity (NEP) from 17 to 45 g C m−2 yr−1 (net C sink), modeled with higher Ta and longer growing seasons. However, NEP was found to decline briefly during midsummer warming events (Ta > 20°C). A model run under climate change predicted for Daring Lake indicated that rises in NPP would exceed those in Rh during the first 100 years, causing NEP to rise. Rises in NPP were driven by more rapid net N mineralization from more rapid Rh in warming soils. However, greater declines in NEP were modeled during more frequent and intense midsummer warming events as climate change progressed. Consequently, average annual NEP (± interannual variability) rose from 30 (±13) g C m−2 yr−1 under current climate to 57 (±40) g C m−2 yr−1 after 90 years but declined to 44 (±51) g C m−2 yr−1 after 150 years, indicating that gains in tundra NEP under climate change may not be indefinite.” Grant, R. F., E. R. Humphreys, P. M. Lafleur, and D. D. Dimitrov (2011), J. Geophys. Res., 116, G01031, doi:10.1029/2010JG001555.

NH snow cover decrease has accelerated since 1970

Northern Hemisphere spring snow cover variability and change over 1922–2010 including an assessment of uncertainty – Brown & Robinson (2011) ” An update is provided of Northern Hemisphere (NH) spring (March, April) snow cover extent (SCE) over the 1922–2010 period incorporating the new climate data record (CDR) version of the NOAA weekly SCE dataset, with annual 95% confidence intervals estimated from regression analysis and intercomparison of multiple datasets. The uncertainty analysis indicates a 95% confidence interval in NH spring SCE of ±5–10% over the pre-satellite period and ±3–5% over the satellite era. The multi-dataset analysis shows larger uncertainties monitoring spring SCE over Eurasia (EUR) than North America (NA) due to the more complex regional character of the snow cover variability and larger between-dataset variability over northern Europe and north-central Russia. Trend analysis of the updated SCE series provides evidence that NH spring snow cover extent has undergone significant reductions over the past ~90 yr and that the rate of decrease has accelerated over the past 40 yr. The rate of decrease in March and April NH SCE over the 1970–2010 period is ~0.8 million km2 per decade corresponding to a 7% and 11% decrease in NH March and April SCE respectively from pre-1970 values. In March, most of the change is being driven by Eurasia (NA trends are not significant) but both continents exhibit significant SCE reductions in April. The observed trends in SCE are being mainly driven by warmer air temperatures, with NH mid-latitude air temperatures explaining ~50% of the variance in NH spring snow cover over the 89-yr period analyzed. However, there is also evidence that changes in atmospheric circulation around 1980 involving the North Atlantic Oscillation and Scandinavian pattern have contributed to reductions in March SCE over Eurasia.” Brown, R. D. and Robinson, D. A.: Northern Hemisphere spring snow cover variability and change over 1922–2010 including an assessment of uncertainty, The Cryosphere, 5, 219-229, doi:10.5194/tc-5-219-2011, 2011. [full text]

Was anomalous winter 1783-1784 analogous to winter 2009-2010?

The anomalous winter of 1783–1784: Was the Laki eruption or an analog of the 2009–2010 winter to blame? – D’Arrigo et al. (2011) “The multi-stage eruption of the Icelandic volcano Laki beginning in June, 1783 is speculated to have caused unusual dry fog and heat in western Europe and cold in North America during the 1783 summer, and record cold and snow the subsequent winter across the circum-North Atlantic. Despite the many indisputable impacts of the Laki eruption, however, its effect on climate, particularly during the 1783–1784 winter, may be the most poorly constrained. Here we test an alternative explanation for the unusual conditions during this time: that they were caused primarily by a combined negative phase of the North Atlantic Oscillation (NAO) and an El Niño-Southern Oscillation (ENSO) warm event. A similar combination of NAO-ENSO phases was identified as the cause of record cold and snowy conditions during the 2009–2010 winter in Europe and eastern North America. 600-year tree-ring reconstructions of NAO and ENSO indices reveal values in the 1783–1784 winter second only to their combined severity in 2009–2010. Data sources and model simulations support our hypothesis that a combined, negative NAO-ENSO warm phase was the dominant cause of the anomalous winter of 1783–1784, and that these events likely resulted from natural variability unconnected to Laki.” D’Arrigo, R., R. Seager, J. E. Smerdon, A. N. LeGrande, and E. R. Cook (2011), Geophys. Res. Lett., 38, L05706, doi:10.1029/2011GL046696.

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Papers on atmospheric carbon monoxide

Posted by Ari Jokimäki on March 18, 2011

This is a list of papers on atmospheric carbon monoxide with an emphasis on the observations and on the relation to fossil fuel sources. 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 (May 16, 2012): Wang et al. (2012) added.

The isotopic record of Northern Hemisphere atmospheric carbon monoxide since 1950: implications for the CO budget – Wang et al. (2012) “We present a 60-year record of the stable isotopes of atmospheric carbon monoxide (CO) from firn air samples collected under the framework of the North Greenland Eemian Ice Drilling (NEEM) project. CO concentration, δ13C, and δ18O of CO were measured by gas chromatography/isotope ratio mass spectrometry (gc-IRMS) from trapped gases in the firn. We applied LGGE-GIPSA firn air models (Witrant et al., 2011) to correlate gas age with firn air depth and then reconstructed the trend of atmospheric CO and its stable isotopic composition at high northern latitudes since 1950. The most probable firn air model scenarios show that δ13C decreased slightly from −25.8‰ in 1950 to −26.4‰ in 2000, then decreased more significantly to −27.2‰ in 2008. δ18O decreased more regularly from 9.8‰ in 1950 to 7.1‰ in 2008. Those same scenarios show CO concentration increased gradually from 1950 and peaked in the late 1970s, followed by a gradual decrease to present day values (Petrenko et al., 2012). Results from an isotope mass balance model indicate that a slight increase, followed by a large reduction, in CO derived from fossil fuel combustion has occurred since 1950. The reduction of CO emission from fossil fuel combustion after the mid-1970s is the most plausible mechanism for the drop of CO concentration during this time. Fossil fuel CO emissions decreased as a result of the implementation of catalytic converters and the relative growth of diesel engines, in spite of the global vehicle fleet size having grown several fold over the same time period.” Wang, Z., Chappellaz, J., Martinerie, P., Park, K., Petrenko, V., Witrant, E., Emmons, L. K., Blunier, T., Brenninkmeijer, C. A. M., and Mak, J. E.: The isotopic record of Northern Hemisphere atmospheric carbon monoxide since 1950: implications for the CO budget, Atmos. Chem. Phys., 12, 4365-4377, doi:10.5194/acp-12-4365-2012, 2012. [full text]

Global estimates of CO sources with high resolution by adjoint inversion of multiple satellite datasets (MOPITT, AIRS, SCIAMACHY, TES) – Kopacz et al. (2010) “We combine CO column measurements from the MOPITT, AIRS, SCIAMACHY, and TES satellite instruments in a full-year (May 2004–April 2005) global inversion of CO sources at 4°×5° spatial resolution and monthly temporal resolution. The inversion uses the GEOS-Chem chemical transport model (CTM) and its adjoint applied to MOPITT, AIRS, and SCIAMACHY. Observations from TES, surface sites (NOAA/GMD), and aircraft (MOZAIC) are used for evaluation of the a posteriori solution. Using GEOS-Chem as a common intercomparison platform shows global consistency between the different satellite datasets and with the in situ data. Differences can be largely explained by different averaging kernels and a priori information. The global CO emission from combustion as constrained in the inversion is 1350 Tg a−1. This is much higher than current bottom-up emission inventories. A large fraction of the correction results from a seasonal underestimate of CO sources at northern mid-latitudes in winter and suggests a larger-than-expected CO source from vehicle cold starts and residential heating. Implementing this seasonal variation of emissions solves the long-standing problem of models underestimating CO in the northern extratropics in winter-spring. A posteriori emissions also indicate a general underestimation of biomass burning in the GFED2 inventory. However, the tropical biomass burning constraints are not quantitatively consistent across the different datasets.” Kopacz, M., Jacob, D. J., Fisher, J. A., Logan, J. A., Zhang, L., Megretskaia, I. A., Yantosca, R. M., Singh, K., Henze, D. K., Burrows, J. P., Buchwitz, M., Khlystova, I., McMillan, W. W., Gille, J. C., Edwards, D. P., Eldering, A., Thouret, V., and Nedelec, P., Atmos. Chem. Phys., 10, 855-876, doi:10.5194/acp-10-855-2010, 2010. [full text]

Comparison of adjoint and analytical Bayesian inversion methods for constraining Asian sources of carbon monoxide using satellite (MOPITT) measurements of CO columns – Kopacz et al. (2009) “We apply the adjoint of an atmospheric chemical transport model (GEOS-Chem CTM) to constrain Asian sources of carbon monoxide (CO) with 2° × 2.5° spatial resolution using Measurement of Pollution in the Troposphere (MOPITT) satellite observations of CO columns in February–April 2001. Results are compared to the more common analytical method for solving the same Bayesian inverse problem and applied to the same data set. The analytical method is more exact but because of computational limitations it can only constrain emissions over coarse regions. We find that the correction factors to the a priori CO emission inventory from the adjoint inversion are generally consistent with those of the analytical inversion when averaged over the large regions of the latter. The adjoint solution reveals fine-scale variability (cities, political boundaries) that the analytical inversion cannot resolve, for example, in the Indian subcontinent or between Korea and Japan, and some of that variability is of opposite sign which points to large aggregation errors in the analytical solution. Upward correction factors to Chinese emissions from the prior inventory are largest in central and eastern China, consistent with a recent bottom-up revision of that inventory, although the revised inventory also sees the need for upward corrections in southern China where the adjoint and analytical inversions call for downward correction. Correction factors for biomass burning emissions derived from the adjoint and analytical inversions are consistent with a recent bottom-up inventory on the basis of MODIS satellite fire data.” Kopacz, M., D. J. Jacob, D. K. Henze, C. L. Heald, D. G. Streets, and Q. Zhang (2009), J. Geophys. Res., 114, D04305, doi:10.1029/2007JD009264. [full text]

Model analysis of the factors regulating the trends and variability of carbon monoxide between 1988 and 1997 – Duncan & Logan (2008) “We used a 3-D model of chemistry and transport to investigate trends and variability in tropospheric carbon monoxide (CO) for 1988–1997 caused by changes in the overhead ozone column, fossil fuel emissions, biomass burning emissions, methane, and transport. We found that the decreasing CO burden in the northern extra-tropics (−0.85%/y) was more heavily influenced by the decrease in European emissions during our study period than by the similar increase in Asian emissions, as transport pathways from Europe favored accumulation at higher latitudes in winter and spring. However, the opposite trends in the CO burdens from these two source regions counterbalanced at lower latitudes. Elsewhere, the factors influencing CO often compete, diminishing their cumulative impact, and trends in model CO were small or insignificant for our study period, except in the tropics in boreal fall (1.1%/y), a result of emissions from major fires in Indonesia late in 1997. There was a decrease in the ozone column during the study period as a result of the phase of the solar cycle and the eruption of Pinatubo in 1991. This decrease contributed negatively to the trend in model CO by increasing the hydroxyl radical (OH). The impact of this negative contribution was diminished by a positive contribution of similar magnitude from increasing methane. However, the trends in these two factors did not cancel for tropospheric OH, which responded primarily to changes in the ozone column.” Duncan, B. N. and Logan, J. A., Atmos. Chem. Phys., 8, 7389-7403, doi:10.5194/acp-8-7389-2008, 2008. [full text]

Using CO2:CO correlations to improve inverse analyses of carbon fluxes – Palmer et al. (2006) “Observed correlations between atmospheric concentrations of CO2 and CO represent potentially powerful information for improving CO2 surface flux estimates through coupled CO2-CO inverse analyses. We explore the value of these correlations in improving estimates of regional CO2 fluxes in east Asia by using aircraft observations of CO2 and CO from the TRACE-P campaign over the NW Pacific in March 2001. Our inverse model uses regional CO2 and CO surface fluxes as the state vector, separating biospheric and combustion contributions to CO2. CO2-CO error correlation coefficients are included in the inversion as off-diagonal entries in the a priori and observation error covariance matrices. We derive error correlations in a priori combustion source estimates of CO2 and CO by propagating error estimates of fuel consumption rates and emission factors. However, we find that these correlations are weak because CO source uncertainties are mostly determined by emission factors. Observed correlations between atmospheric CO2 and CO concentrations imply corresponding error correlations in the chemical transport model used as the forward model for the inversion. These error correlations in excess of 0.7, as derived from the TRACE-P data, enable a coupled CO2-CO inversion to achieve significant improvement over a CO2-only inversion for quantifying regional fluxes of CO2.” Palmer, P. I., P. Suntharalingam, D. B. A. Jones, D. J. Jacob, D. G. Streets, Q. Fu, S. A. Vay, and G. W. Sachse (2006), J. Geophys. Res., 111, D12318, doi:10.1029/2005JD006697. [full text]

Adjoint inverse modeling of CO emissions over Eastern Asia using four-dimensional variational data assimilation – Yumimoto & Uno (2006) “We developed a four-dimensional variational (4DVAR) data assimilation system for a regional chemical transport model (CTM). In this study, we applied it to inverse modeling of CO emissions in the eastern Asia during April 2001 and demonstrated the feasibility of our assimilation system. Three ground-based observations were used for data assimilation. Assimilated results showed better agreement with observations; they reduced the RMS difference by 16–27%. Observations obtained on board the R/V Ronald H. Brown were used for independent validation of the assimilated results. The CO emissions over industrialized east central China between Shanghai and Beijing were increased markedly by the assimilation. The results show that the annual anthropogenic (fossil and biofuel combustion) CO emissions over China are 147 Tg. Sensitivity analyses using the adjoint model indicate that the high CO concentration measured on 17 April at Rishiri, Japan (which the assimilation was unable to reproduce) originated in Russia or had traveled from outside the Asian region (e.g. Europe).” Keiya Yumimoto and Itsushi Uno, Atmospheric Environment, Volume 40, Issue 35, November 2006, Pages 6836-6845, doi:10.1016/j.atmosenv.2006.05.042.

Improved quantification of Chinese carbon fluxes using CO2/CO correlations in Asian outflow – Suntharalingam et al. (2004) “We use observed CO2:CO correlations in Asian outflow from the TRACE-P aircraft campaign (February–April 2001), together with a three-dimensional global chemical transport model (GEOS-CHEM), to constrain specific components of the east Asian CO2 budget including, in particular, Chinese emissions. The CO2/CO emission ratio varies with the source of CO2 (different combustion types versus the terrestrial biosphere) and provides a characteristic signature of source regions and source type. Observed CO2/CO correlation slopes in east Asian boundary layer outflow display distinct regional signatures ranging from 10–20 mol/mol (outflow from northeast China) to 80 mol/mol (over Japan). Model simulations using best a priori estimates of regional CO2 and CO sources from Streets et al. [2003] (anthropogenic), the CASA model (biospheric), and Duncan et al. [2003] (biomass burning) overestimate CO2 concentrations and CO2/CO slopes in the boundary layer outflow. Constraints from the CO2/CO slopes indicate that this must arise from an overestimate of the modeled regional net biospheric CO2 flux. Our corrected best estimate of the net biospheric source of CO2 from China for March–April 2001 is 3200 Gg C/d, which represents a 45% reduction of the net flux from the CASA model. Previous analyses of the TRACE-P data had found that anthropogenic Chinese CO emissions must be ∼50% higher than in Streets et al.’s [2003] inventory. We find that such an adjustment improves the simulation of the CO2/CO slopes and that it likely represents both an underreporting of sector activity (domestic and industrial combustion) and an underestimate of CO emission factors. Increases in sector activity would imply increases in Chinese anthropogenic CO2 emissions and would also imply a further reduction of the Chinese biospheric CO2 source to reconcile simulated and observed CO2 concentrations.” Suntharalingam, P., D. J. Jacob, P. I. Palmer, J. A. Logan, R. M. Yantosca, Y. Xiao, M. J. Evans, D. G. Streets, S. L. Vay, and G. W. Sachse (2004), J. Geophys. Res., 109, D18S18, doi:10.1029/2003JD004362. [full text]

Evaluation of pollutant outflow and CO sources during TRACE-P using model-calculated, aircraft-based, and Measurements of Pollution in the Troposphere (MOPITT)-derived CO concentrations – Allen et al. (2004) “Outflow of CO from Asia during March 2001 is evaluated using data from the Transport and Chemical Evolution over the Pacific (TRACE-P) mission and the Measurements of Pollution in the Troposphere (MOPITT) instrument in conjunction with model-calculated CO from the University of Maryland chemistry and transport model (UMD CTM). Comparison of model-calculated CO with aircraft measurements indicates that temporal and spatial variations in CO are well captured by the model (mean correlation coefficient of 0.78); however, model-calculated mixing ratios are lower than observed especially for pressures >850 hPa where negative biases of ∼60 ppbv were seen. Regression analysis is used to optimize the magnitudes of the bottom-up TRACE-P Asian fossil fuel (FF), biofuel (BF), and biomass burning (BB) CO emission inventories. Resulting Asian scaling factors are 1.59 ± 0.34 for FF + BF emissions and 0.47 ± 0.46 for BB emissions. Resulting FF + BF emissions are 27.7 ± 6.1 Tg for March 2001 (301 ± 67 Tg for an entire year). Resulting BB emissions for March 2001 are 8.5 ± 8.3 Tg. These results are consistent with recent inverse modeling studies. Scaling factors are lowest (highest) for experiments that assume a high (low) CO yield for the oxidation of anthropogenic and natural hydrocarbons and for experiments that use (do not use) an aerosol-modified OH distribution. Comparison of model-calculated CO with MOPITT measurements supports the results from our regression analysis. Without exception, mean March 2001 model-calculated CO profiles in the TRACE-P region from a simulation with adjusted CO sources are within a standard deviation of mean March 2001 MOPITT-sampled profiles.” Allen, D., K. Pickering, and M. Fox-Rabinovitz (2004), J. Geophys. Res., 109, D15S03, doi:10.1029/2003JD004250.

Monthly CO surface sources inventory based on the 2000–2001 MOPITT satellite data – Pétron et al. (2004) “This paper presents results of the inverse modeling of carbon monoxide surface sources on a monthly and regional basis using the MOPITT (Measurement Of the Pollution In The Troposphere) CO retrievals. The targeted time period is from April 2000 to March 2001. A sequential and time-dependent inversion scheme is implemented to correct an a priori set of monthly mean CO sources. The a posteriori estimates for the total anthropogenic (fossil fuel + biofuel + biomass burning) surface sources of CO in TgCO/yr are 509 in Asia, 267 in Africa, 140 in North America, 90 in Europe and 84 in Central and South America. Inverting on a monthly scale allows one to assess a corrected seasonality specific to each source type and each region. Forward CTM simulations with the a posteriori emissions show a substantial improvement of the agreement between modeled CO and independent in situ observations.” Pétron, G., C. Granier, B. Khattatov, V. Yudin, J.-F. Lamarque, L. Emmons, J. Gille, and D. P. Edwards (2004), Geophys. Res. Lett., 31, L21107, doi:10.1029/2004GL020560. [full text]

Comparative inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide – Heald et al. (2004) “We use an inverse model analysis to compare the top-down constraints on Asian sources of carbon monoxide (CO) in spring 2001 from (1) daily MOPITT satellite observations of CO columns over Asia and the neighboring oceans and (2) aircraft observations of CO concentrations in Asian outflow from the TRACE-P aircraft mission over the northwest Pacific. The inversion uses the maximum a posteriori method (MAP) and the GEOS-CHEM chemical transport model (CTM) as the forward model. Detailed error characterization is presented, including spatial correlation of the model transport error. Nighttime MOPITT observations appear to be biased and are excluded from the inverse analysis. We find that MOPITT and TRACE-P observations are independently consistent in the constraints that they provide on Asian CO sources, with the exception of southeast Asia for which the MOPITT observations support a more modest decrease in emissions than suggested by the aircraft observations. Our analysis indicates that the observations do not allow us to differentiate source types (i.e., anthropogenic versus biomass burning) within a region. MOPITT provides ten pieces of information to constrain the geographical distribution of CO sources, while TRACE-P provides only four. The greater information from MOPITT reflects its ability to observe all outflow and source regions. We conducted a number of sensitivity studies for the inverse model analysis using the MOPITT data. Temporal averaging of the MOPITT data (weekly and beyond) degrades the ability to constrain regional sources. Merging source regions beyond what is appropriate after careful selection of the state vector leads to significant aggregation errors. Calculations for an ensemble of realistic assumptions lead to a range of inverse model solutions that has greater uncertainty than the a posteriori errors for the MAP solution. Our best estimate of total Asian CO sources is 361 Tg yr−1, over half of which is attributed to east Asia.” Heald, C. L., D. J. Jacob, D. B. A. Jones, P. I. Palmer, J. A. Logan, D. G. Streets, G. W. Sachse, J. C. Gille, R. N. Hoffman, and T. Nehrkorn (2004), J. Geophys. Res., 109, D23306, doi:10.1029/2004JD005185. [full text]

Inverting for emissions of carbon monoxide from Asia using aircraft observations over the western Pacific – Palmer et al. (2003) “We use aircraft observations of continental outflow over the western Pacific from the Transport and Chemical Evolution over the Pacific (TRACE-P) mission (March–April 2001), in combination with an optimal estimation inverse model, to improve emission estimates of carbon monoxide (CO) from Asia. A priori emissions and their errors are from a customized bottom-up Asian emission inventory for the TRACE-P period. The global three-dimensional GEOS-CHEM chemical transport model (CTM) is used as the forward model. The CTM transport error (20–30% of the CO concentration) is quantified from statistics of the difference between the aircraft observations of CO and the forward model results with a priori emissions, after removing the mean bias which is attributed to errors in the a priori emissions. Additional contributions to the error budget in the inverse analysis include the representation error (typically 5% of the CO concentration) and the measurement accuracy (≃2% of the CO concentration). We find that the inverse model can usefully constrain five sources: Chinese fuel consumption, Chinese biomass burning, total emissions from Korea and Japan, total emissions from Southeast Asia, and the ensemble of all other sources. The inversion indicates a 54% increase in anthropogenic emissions from China (to 168 Tg CO yr−1) relative to the a priori; this value is still much lower than had been derived in previous inversions using the CMDL network of surface observations. A posteriori emissions of biomass burning in Southeast Asia and China are much lower than a priori estimates.” Palmer, P. I., D. J. Jacob, D. B. A. Jones, C. L. Heald, R. M. Yantosca, J. A. Logan, G. W. Sachse, and D. G. Streets (2003), J. Geophys. Res., 108(D21), 8828, doi:10.1029/2003JD003397. [full text]

Reanalysis of tropospheric CO trends: Effects of the 1997–1998 wildfires – Novelli et al. (2003) “For the past decade NOAA/CMDL has measured tropospheric carbon monoxide from a global network of sampling sites. The resulting data set provides an internally consistent picture of CO in the lower troposphere that is used to study its distribution, trends and budget. All measurements were referenced to the so-called CMDL Reference Scale (WMO 88), which was based on two sets of primary standards produced at CMDL during the late 1980s and early 1990s. A long-term downward trend in tropospheric CO during the 1990s, overlaid with shorter periods of increase and decrease, was indicated from the air measurements. Primary standards prepared in 1999 and 2000 suggested that the scale had drifted upward over time, and that mixing ratios determined in field samples were underestimated. We have applied a time dependent correction to our CO measurements based upon four sets of primary standards. In this paper, we describe the revision of the CO scale and our atmospheric measurements. A reanalysis of tropospheric trends through 2001 was based on the revised global data set. The results support previous reports of a decline in tropospheric CO. This decrease is now found largely confined to the Northern Hemisphere, where dramatic reductions in fossil fuel emissions have reportedly occurred. In contrast, no significant trend is determined in the Southern Hemisphere between 1991 and 2001. Globally averaged CO exhibits large interannual variability, primarily reflecting year to year changes in emissions from biomass burning. Dramatic enhancements of tropospheric CO in 1997 and 1998 resulted from exceptionally widespread wildfires which provided a strong pulse of CO to the atmosphere. In years of extensive boreal biomass burning, fire emissions can perturb CO levels over regional and global scales, disturbing oxidation/reduction chemistry in the troposphere.” Novelli, P. C., K. A. Masarie, P. M. Lang, B. D. Hall, R. C. Myers, and J. W. Elkins (2003), J. Geophys. Res., 108(D15), 4464, doi:10.1029/2002JD003031. [full text]

Global distribution of carbon monoxide – Holloway et al. (2000) “This study explores the evolution and distribution of carbon monoxide (CO) using the National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory three-dimensional global chemical transport model (GFDL GCTM). The work aims to gain an improved understanding of the global carbon monoxide budget, specifically focusing on the contribution of each of the four source terms to the seasonal variability of CO. The sum of all CO sources in the model is 2.5 Pg CO/yr (1 Pg = 103 Tg), including fossil fuel use (300 Tg CO/yr), biomass burning (748 Tg CO/yr), oxidation of biogenic hydrocarbons (683 Tg CO/yr), and methane oxidation (760 Tg CO/yr). The main sink for CO is destruction by the hydroxyl radical, and we assume a hydroxyl distribution based on three-dimensional monthly varying fields given by Spivakovsky et al. [1990], but we increase this field by 15% uniformly to agree with a methyl chloroform lifetime of 4.8 years [Prinn et al, 1995]. Our simulation produces a carbon monoxide field that agrees well with available measurements from the NOAA/Climate Monitoring and Diagnostics Laboratory global cooperative flask sampling network and from the Jungfraujoch observing station of the Swiss Federal Laboratories for Materials Testing and Research (EMPA) (93% of seasonal-average data points agree within ±25%) and flight data from measurement campaigns of the NASA Global Tropospheric Experiment (79% of regional-average data points agree within ±25%). For all 34 ground-based measurement sites we have calculated the percentage contribution of each CO source term to the total model-simulated distribution and examined how these contributions vary seasonally due to transport, changes in OH concentration, and seasonality of emission sources. CO from all four sources contributes to the total magnitude of CO in all regions. Seasonality, however, is usually governed by the transport and destruction by OH of CO emitted by fossil fuel and/or biomass burning. The sensitivity to the hydroxyl field varies spatially, with a 30% increase in OH yielding decreases in CO ranging from 4–23%, with lower sensitivities near emission regions where advection acts as a strong local sink. The lifetime of CO varies from 10 days over summer continental regions to well over a year at the winter poles, where we define lifetime as the turnover time in the troposphere due to reaction with OH.” Holloway, T., H. Levy II, and P. Kasibhatla (2000), J. Geophys. Res., 105(D10), 12,123–12,147, doi:10.1029/1999JD901173.

Carbon monoxide in the U.S. mid‐Atlantic troposphere: Evidence for a decreasing trend – Hallock-Waters et al. (1999) “Nearly continuous measurements of carbon monoxide (CO) were made at Shenandoah National Park‐Big Meadows in rural Virginia, a site considered representative of regional air quality, from December 1994 to November 1997. Similar observations were also made at this location from October 1988 to October 1989. These observations combine to indicate a decreasing trend in CO concentration over the U.S. mid‐Atlantic region of about 5.0 ppbv yr−1, with greater than 95% confidence that the slope is significantly different from zero. The decrease suggests U.S. reductions in anthropogenic CO emissions have been effective in reducing pollutant levels. The observed trend is consistent with the U.S. EPA reported trend in emissions and the decrease in Northern Hemisphere tropospheric background CO mixing ratios observed by other researchers.” Hallock‐Waters, K. A., B. G. Doddridge, R. R. Dickerson, S. Spitzer, and J. D. Ray (1999), Geophys. Res. Lett., 26(18), 2861–2864, doi:10.1029/1999GL900609. [full text]

Distributions and recent changes of carbon monoxide in the lower troposphere – Novelli et al. (1998) “Since 1988, the distribution of carbon monoxide (CO) in the lower troposphere has been determined using a globally distributed air sampling network. Site locations range from 82°N to 90°S, with wide longitudinal coverage, and represent the marine boundary layer, regionally polluted atmospheres, and the free troposphere. These measurements present a unique, intercalibrated, and internally consistent data set that are used to better define the global temporal and spatial distribution of CO. In this paper, times series from 49 sites are discussed. With an average lifetime of ∼2 months, CO showed significant concentration gradients. In the marine boundary layer, mixing ratios were greatest in the northern winter (200–220 ppb) and lowest in the southern summer (35–45 ppb). The interhemispheric gradient showed strong seasonality with a maximum difference between the high latitudes of the northern and southern hemispheres (160–180 ppb) in February and March and a minimum in July and August (10–20 ppb). Higher CO was found in regions near human development relative to those over more remote areas. The distributions provide additional evidence of the widespread pollution of the lower atmosphere. Remote areas in the high northern hemisphere are polluted by anthropogenic activities in the middle latitudes, and those in the southern hemisphere are heavily influenced by the burning of biomass in the tropics. While tropospheric concentrations of CO exhibit periods of increase and decrease, the globally averaged CO mixing ratio over the period from 1990 through 1995 decreased at a rate of approximately 2 ppb yr−1.” Novelli, P. C., K. A. Masarie, and P. M. Lang (1998), J. Geophys. Res., 103(D15), 19,015–19,033, doi:10.1029/98JD01366. [full text]

An internally consistent set of globally distributed atmospheric carbon monoxide mixing ratios developed using results from an intercomparison of measurements – Novelli et al. (1998) “The Measurement of Air Pollution from Satellite (MAPS) instrument measures carbon monoxide (CO) in the middle troposphere from a space platform. In anticipation of the deployment of MAPS aboard the space shuttle Endeavor for two 10-day missions in 1994, plans were made to prepare a set of correlative measurements which would be used as part of the mission validation program. Eleven laboratories participated in the correlative measurement program by providing NASA with the results of their CO field programs during April and October 1994. Measurements of CO in the boundary layer, while not used in the MAPS validation, provide a picture of CO in the lower troposphere. Because measurements of CO made by different laboratories have been known to differ significantly, all correlative team members participated in an intercomparison of their measurements to define potential differences in techniques and calibration scales. While good agreement was found between some laboratories, there were differences between others. The use of similar analytical techniques and calibration scales did not always provide similar results. The results of the intercomparisons were used to normalize all ground-based measurements to the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory CO reference scale. These data provide an internally consistent picture of CO in thelower atmosphere during spring and fall 1994.” Novelli, P. C., et al. (1998), J. Geophys. Res., 103(D15), 19,285–19,293, doi:10.1029/97JD00031.

Recent Changes in Atmospheric Carbon Monoxide – Novelli et al. (1994) “Measurements of carbon monoxide (CO) in air samples collected from 27 locations between 71°N and 41°S show that atmospheric levels of this gas have decreased worldwide over the past 2 to 5 years. During this period, CO decreased at nearly a constant rate in the high northern latitudes. In contrast, in the tropics an abrupt decrease occurred beginning at the end of 1991. In the Northern Hemisphere, CO decreased at a spatially and temporally averaged rate of 7.3 (±0.9) parts per billion per year (6.1 percent per year) from June 1990 to June 1993, whereas in the Southern Hemisphere, CO decreased 4.2 (±0.5) parts per billion per year (7.0 percent per year). This recent change is opposite a long-term trend of a 1 to 2 percent per year increase inferred from measurements made in the Northern Hemisphere during the past 30 years.” Paul C. Novelli, Ken A. Masarie, Pieter P. Tans and Patricia M. Lang, Science 18 March 1994: Vol. 263 no. 5153 pp. 1587-1590, DOI: 10.1126/science.263.5153.1587.

Mixing Ratios of Carbon Monoxide in the Troposphere – Novelli et al. (1992) “Carbon monoxide (CO) mixing ratios were measured in air samples collected weekly at eight locations. The air was collected as part of the CMDL/NOAA cooperative flask sampling program (Climate Monitoring and Diagnostics Laboratory, formerly Geophysical Monitoring for Climatic Change, Air Resources Laboratory/National Oceanic and Atmospheric Administration) at Point Barrow, Alaska (71°N), Niwot Ridge, Colorado (40°N), Mauna Loa and Cape Kumakahi, Hawaii (19°N), Guam, Marianas Islands (13°N), Christmas Island (2°N), Ascension Island (8°S) and American Samoa (14°S). Half-liter or 3-L glass flasks fitted with glass piston stopcocks holding teflon O rings were used for sample collection. CO levels were determined within several weeks of collection using gas chromatography followed by mercuric oxide reduction detection, and mixing ratios were referenced against the CMDL/NOAA carbon monoxide standard scale. During the period of study (mid-1988 through December 1990) CO levels were greatest in the high latitudes of the northern hemisphere (mean mixing ratio from January 1989 to December 1990 at Point Barrow was approximately 154 ppb) and decreased towards the south (mean mixing ratio at Samoa over a similar period was 65 ppb). Mixing ratios varied seasonally, the amplitude of the seasonal cycle was greatest in the north and decreased to the south. Carbon monoxide levels were affected by both local and regional scale processes. The difference in CO levels between northern and southern latitudes also varied seasonally. The greatest difference in CO mixing ratios between Barrow and Samoa was observed during the northern winter (about 150 ppb). The smallest difference, 40 ppb, occurred during the austral winter. The annually averaged CO difference between 71°N and 14°S was approximately 90 ppb in both 1989 and 1990; the annually averaged interhemispheric gradient from 71°N to 41°S is estimated as approximately 95 ppb.” Novelli, P. C., L. P. Steele, and P. P. Tans (1992), J. Geophys. Res., 97(D18), 20,731–20,750, doi:10.1029/92JD02010.

The global cycle of carbon monoxide: Trends and mass balance – Khalil & Rasmussen (1990) “The annual global emissions of CO are estimated to be about 2,600 ± 600 Tg, of which about 60% are from human activities including combustion of fossil fuels and oxidation of hydrocarbons including methane. The remaining 40% of the emissions are from natural processes, mostly from the oxidation of hydrocarbons but also from plants and the oceans. Almost all the CO emitted into the atmosphere each year is removed by reactions with OH radicals (85%), by soils (10%), and by diffusion into the stratosphere. There is a small imbalance between annual emissions and removal, causing an increase of about 1% per year. It is very likely that the imbalance is due to increasing emissions from anthropogenic activities. The average concentration of CO is about 90 ppbv, which amounts to about 400 Tg in the atmosphere, and the average lifetime is about 2 months. This view of the global cycle of CO is consistent with the present estimates of average OH concentrations and the budgets of other trace gases including methane and methylchloroform. There are large remaining uncertainties that may in the future upset the apparently cohesive present budget of CO. If the present view of the global cycle of CO is correct, then it is likely that, in time, increasing levels of CO will contribute to widespread changes in atmospheric chemistry.” M.A.K. Khalil, a and R.A. Rasmussen, Chemosphere, Volume 20, Issues 1-2, 1990, Pages 227-242, doi:10.1016/0045-6535(90)90098-E.

Spectroscopic measurements of atmospheric carbon monoxide and methane. 1: latitudinal distribution – Dianov-Klokov et al. (1989) “The results of spectroscopic total column measurements of CO and CH4 at different points of the Northern and Southern Hemispheres in 1970–1985, are reported. Seasonal cycles of CO are evident for all the sites. The Northern Hemispheric long-term positive trend of CO seems to be 1.5–2% per year. In the Southern Hemisphere, temporal increasing was not detected and a possible upper limit for it is about 0.6% per year. Methane concentration in the Northern Hemisphere increases at a rate of 1.2% per year.” V. I. Dianov-Klokov, L. N. Yurganov, E. I. Grechko and A. V. Dzhola, Journal of Atmospheric Chemistry, Volume 8, Number 2, 139-151, DOI: 10.1007/BF00053719. [full text]

Spectroscopic measurements of atmospheric carbon monoxide and methane. 2: Seasonal variations and long-term trends – Dianov-Klokov & Yurganov (1989) “A spectroscopic technique for measuring CO and CH4 contents is described and the latitudinal distributions of these gases are presented. Carbon monoxide abundance decreases southward, having two local maxima: in midlatitudes and in the tropics. The slope of latitude dependence varies according to the season of the year. The difference in CH4 content does not exceed the accuracy of the method (±8%).” V. I. Dianov-Klokov and L. N. Yurganov, Journal of Atmospheric Chemistry, Volume 8, Number 2, 153-164, DOI: 10.1007/BF00053720.

A survey of continental concentrations of atmospheric CO in the southern hemisphere – Kirchhoff & Marinho (1989) “The first large scale survey of surface CO concentrations at Southern Hemisphere continental sites is described. Marine sites are compared to sites with a true continental character with the objective to identify different ecological surface conditions in terms of CO concentrations. The marine sites at the Atlantic coast show the lowest concentrations, about 100 ppbv, whereas the sites in the savannah region show concentrations 3 times as large owing to the influence of nearby biomass burning activity. The observations were highly variable, with one result as high as 700 ppbv. These high values are comparable to sites near urban developments. Sites in the Amazonian rain forest show concentrations as low as the coastal sites, on the average, but sporadic peaks have been seen when air masses are brought in from city areas or from large forest fires.” V.W.J.H. Kirchhoff and E.V.A. Marinho, Atmospheric Environment, Volume 23, Issue 2, 1989, Pages 461-466, doi:10.1016/0004-6981(89)90589-1.

Carbon monoxide in the Earth’s atmosphere: indications of a global increase – Khalil & Rasmussen (1988) “Over half of the carbon monoxide in the atmosphere comes from human activities including motor traffic, other combustion of fossil fuels, and slash and burn agriculture1–4. Additional anthropogenic sources include the burning of wood, savannah lands, and the oxidation of hydrocarbons including methane. Over the years these sources have increased gradually and may have already caused the concentrations of CO to double since pre-industrial times when human activities did not significantly affect the global cycles of CO and other trace gases. Increasing levels of CO can lead to an increase of tropospheric O3 (refs 5,6) and a build-up of many other trace gases in the Earth’s atmosphere, which may in turn cause widespread perturbations of tropospheric chemistry, global warming, and other climatic changes7. In a recent report8 to senior US Government officials the National Academies stated the urgent need to know the global distribution and trends of CO. During the past 6–8 years we have taken systematic measurements of CO at sites ranging from within the Arctic Circle to the South Pole. The rates of increase of the globally averaged concentration are between 0.8% and 1.4% per year depending on the statistical method used for estimating the trends. These increases may have gone on for much longer because more than half of the atmospheric CO now comes from anthropogenic sources. We find that the rates of increase are largest at mid-northern and tropical latitudes, where most of the sources are located.” M. A. K. Khalil & R. A. Rasmussen, Nature 332, 242 – 245 (17 March 1988); doi:10.1038/332242a0.

The seasonality of CO abundance in the Southern Hemisphere – Seiler et al. (1984) “CO mixing ratios in air have been measured continuously at Cape Point (34°21prime;S; 18°29′E) between 1978 and 1981. The results show a seasonal variation of the CO mixing ratios with minimum values of 53 p.p.b.v. during January/February and maximum values of 87 p.p.b.v. during September/October. Short-term variations of CO mixing ratios in clean, undisturbed air were lacking, indicating that CO is well mixed in the Southern Hemisphere at latitudes of 20–40° S and that the observed seasonal variation is not due to temporal changes of local and regional source strengths. The seasonality of CO is explained by the seasonal variation of OH and by the north–south shift of the intertropical convergence zone. The agreement of CO mixing ratios measured at Cape Point and over the Southern Atlantic in 1971/1972 indicates that the southern hemispheric CO mixing ratios cannot have changed by more than 5–10% during the last decade.” Wolfgang Seiler, Helmut Giehl, Ernst-Günther Brunke, Eric Halliday, Tellus B, Volume 36B, Issue 4, pages 219–231, September 1984, DOI: 10.1111/j.1600-0889.1984.tb00244.x.

The Distribution of Carbon Monoxide and Ozone in the Free Troposphere – Seiler & Fishman (1981) “The two-dimensional distributions of CO and O3 in the free troposphere during July and August, 1974, are discussed. The data confirm the previous findings that both of these gases are considerably more abundant in the northern hemisphere, but the degree of the asymmetry is somewhat different from what had been reported previously, especially for CO. When examined with respect to other available data sets, the conclusion is drawn that a pronounced seasonal cycle exists for CO in both hemispheres which may be driven by the likely seasonal cycle of the OH radical. The data also indicate that CO concentrations exhibit significant variability with height in the northern hemisphere, whereas southern hemispheric concentrations are quite constant with altitude except in cases where interhemispheric exchange of air may be occurring. A discussion on the vertical and horizontal transport processes inferred from the CO and O3 measurements is presented. The possible interdependence of the photochemical cycles of these two trace gases is also discussed.” Seiler, W., and J. Fishman (1981), J. Geophys. Res., 86(C8), 7255–7265, doi:10.1029/JC086iC08p07255.

The cycle of atmospheric CO – Seiler (1974) “New measurements of the CO-mixing ratio in the two hemispheres with the dissolved CO in surface seawater together with previous results are used to set up a detailed budget of CO in the atmosphere. It is shown that CO is produced by technological and by natural sources. The source strengths of both kinds of sources are of the same magnitude. The total CO-production rate is estimated to be 10 × 1014 g per year. The corresponding residence time is 0.5 years. From the observed latitudinal CO-distribution between the hemispheres the production of CO by the oxidation of methane in the troposphere is judged to be a minor source. CO is removed by microbiological processes at the soil surfaces, by photochemical consumption in the stratosphere, and probably also by reaction with OH radicals in the troposphere.” Wolfgang Seiler, Tellus, Volume 26, Issue 1-2, pages 116–135, February 1974, DOI: 10.1111/j.2153-3490.1974.tb01958.x.

The Abundance of Atmospheric Carbon Monoxide above Columbus, Ohio – Shaw (1958) “From measurements of the line R(3) of the 4.7 μ fundamental band appearing in the solar spectrum, the usual CO content of the atmosphere above Columbus, Ohio, during1952-53 has been found to be between 0.04 and 0.07 atm-cm/air mass. There is evidence for some increase in CO content on occasional days during the colder months of the year, but, because the line measured is contaminated by a weak H2O absorption, it is not possible to show that similar increases also occur during the summer months. The occasions of high CO contentare usually associated with periods of low visibility and usually occur during the early part of the day. This is especially true of the period October 20-November 13, 1952, when the worst forest fires for twenty years were burning in southeastern Ohio and states farther south. The present data are compared with the results of other workers.” Shaw, J. H., Astrophysical Journal, vol. 128, p.428, 1958. [full text]

The absorption due to carbon monoxide in the infrared solar spectrum – Locke & Herzberg (1953) “New tracings of the absorption bands due to carbon monoxide in the 4.7 μ and 2.4 μ regions of the solar spectrum were obtained with a spectrometer of high resolving power. From the observed absorption intensity at 4.7 μ the abundance of carbon monoxide in the earth’s atmosphere over Ottawa was found, during spring and fall 1952, to vary between 0.1 and 0.2 cm-atm. Similar observations, made at other stations, were re-evaluated with the laboratory data used at Ottawa. The values for the carbon monoxide abundance in the earth’s atmosphere at different geographical locations, determined in this way, were found to be within the limits of the values obtained at Ottawa. Absorption lines due to solar carbon monoxide in the 4.7 μ region of the spectrum were resolved. Their intensity relative to the intensity of the solar carbon monoxide absorption in the 2.4 μ region of the spectrum was found to be in agreement with expectations based on the theoretical curves of growth for solar absorption lines.” J. L. Locke and L. Herzberg, Can. J. Phys. 31(4): 504–516 (1953), doi:10.1139/p53-050.

Investigations of Atmospheric CO at the Jungfraujoch – Benesch et al. (1953) “Analysis of high-resolution solar spectra taken at the Jungfraujoch in Switzerland indicates that the terrestrial atmospheric CO content may vary by a factor of five in extreme cases, and is, furthermore, subject to surprisingly large fluctuations within the period of one hour. These variations are apparently unrelated to the more readily available data on general meteorological conditions, but a mechanism is suggested wherein the fluctuations of the CO may depend on atmospheric irregularities of a more finely detailed nature than those which normally come into consideration in meteorological observations.” W. Benesch, M. Migeotte, and L. Neven, JOSA, Vol. 43, Issue 11, pp. 1119-1123 (1953), doi:10.1364/JOSA.43.001119.

Identification of Carbon Monoxide in the Atmosphere above Flagstaff, Arizona – Adel (1952) No abstract. Adel, Arthur, Astrophysical Journal, vol. 116, p.442, 1952. [full text]

The Fundamental Band of Carbon Monoxide at 4.7μ in the Solar Spectrum – Migeotte (1949) No abstract available, but according to Shaw (1958) this is first identification of CO in Earth’s atmosphere. Marcel V. Migeotte, Phys. Rev. 75, 1108–1109 (1949).

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New research from last week 10/2011

Posted by Ari Jokimäki on March 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. Planet 3.0 also reports new research.

Published last week:

Vegetation decrease in Europe since 1997

Changes in satellite-derived vegetation growth trend in temperate and boreal Eurasia from 1982 to 2006 – Piao et al. (2011) “Monitoring changes in vegetation growth has been the subject of considerable research during the past several decades, because of the important role of vegetation in regulating the terrestrial carbon cycle and the climate system. In this study, we combined datasets of satellite-derived Normalized Difference Vegetation Index (NDVI) and climatic factors to analyze spatio-temporal patterns of changes in vegetation growth and their linkage with changes in temperature and precipitation in temperate and boreal regions of Eurasia (>23.5°N) from 1982 to 2006. At the continental scale, although a statistically significant positive trend of average growing season NDVI is observed (0.5×10−3 yr−1, P=0.03) during the entire study period, there are two distinct periods with opposite trends in growing season NDVI. Growing season NDVI has first significantly increased from 1982 to 1997 (1.8×10−3 yr−1, P<0.001), and then decreased from 1997 to 2006 (−1.3×10−3 yr−1, P=0.055). This reversal in the growing season NDVI trends over Eurasia are largely contributed by spring and summer NDVI changes. Both spring and summer NDVI significantly increased from 1982 to 1997 (2.1×10−3 yr−1, P=0.01; 1.6×10−3 yr−1P<0.001, respectively), but then decreased from 1997 to 2006, particularly summer NDVI which may be related to the remarkable decrease in summer precipitation (−2.7 mm yr−1, P=0.009). Further spatial analyses supports the idea that the vegetation greening trend in spring and summer that occurred during the earlier study period 1982–1997 was either stalled or reversed during the following study period 1997–2006. But the turning point of vegetation NDVI is found to vary across different regions.” Shilong Piao, Xuhui Wang, Philippe Ciais, Biao Zhu, Tao Wang, Jie Liu, Global Change Biology, 2011, DOI: 10.1111/j.1365-2486.2011.02419.x.

Cosmic ray contribution to climate change is negligible

Cosmic ray effects on cloud cover and their relevance to climate change – Erlykin et al. (2011) “A survey is made of the evidence for and against the hypothesis that cosmic rays influence cloud cover. The analysis is made principally for the troposphere. It is concluded that for the troposphere there is only a very small overall value for the fraction of cloud attributable to cosmic rays (CR); if there is linearity between CR change and cloud change, the value is probably ~1% for clouds below ~6.5km, but less overall. The apparently higher value for low cloud is an artifact. The contribution of CR to ’climate change’ is quite negligible.” A.D. Erlykin, B.A. Laken and A.W. Wolfendale, Journal of Atmospheric and Solar-Terrestrial Physics, doi:10.1016/j.jastp.2011.03.001.

Wider perspective on dangerous climate change

Beyond 2°C: redefining dangerous climate change for physical systems – Lenton et al. (2011) “Most efforts to define a level of dangerous anthropogenic interference (DAI) with the climate system are framed in terms of global annual mean surface temperature change, with 2°C above preindustrial being the most widely accepted climate policy ‘target’. Yet, no actual large-scale threshold (or ‘tipping point’) in the climate system (of which there are probably several) has been clearly linked to 2°C global warming. Of those that can be indirectly linked to global temperature change, the dangerous levels are necessarily imprecise and vary, with estimates ranging from ∼1°C above preindustrial upwards. Some potential thresholds cannot be meaningfully linked to global temperature change, others are sensitive to rates of climate change, and some are most sensitive to spatial gradients of climate change. In some cases, the heterogeneous distributions of reflective (sulfate) aerosols, absorbing (black carbon) aerosols, and land use could be more dangerous than changes in globally well-mixed greenhouse gases. Hence, the framing of Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC), in terms of stabilization of greenhouse gas concentrations (within a time frame), is too narrow to prevent some types of DAI. To address this, a reframed policy objective is proposed; to limit the overall magnitude, rate of change, and spatial gradients of anthropogenic radiative forcing, and resultant climate change, through restriction of emissions of anthropogenic aerosols, patterns of land use, and concentrations of short-lived, as well as long-lived, greenhouse gases.” Timothy M. Lenton, Wiley Interdisciplinary Reviews: Climate Change, 2011, DOI: 10.1002/wcc.107.

Another Greenland mass balance study supports recent studies

Mass balance of the Greenland ice sheet (2003–2008) from ICESat data – the impact of interpolation, sampling and firn density – Sørensen et al. (2011) “ICESat has provided surface elevation measurements of the ice sheets since the launch in January 2003, resulting in a unique dataset for monitoring the changes of the cryosphere. Here, we present a novel method for determining the mass balance of the Greenland ice sheet, derived from ICESat altimetry data. Three different methods for deriving elevation changes from the ICESat altimetry dataset are used. This multi-method approach provides a method to assess the complexity of deriving elevation changes from this dataset. The altimetry alone can not provide an estimate of the mass balance of the Greenland ice sheet. Firn dynamics and surface densities are important factors that contribute to the mass change derived from remote-sensing altimetry. The volume change derived from ICESat data is corrected for changes in firn compaction over the observation period, vertical bedrock movement and an intercampaign elevation bias in the ICESat data. Subsequently, the corrected volume change is converted into mass change by the application of a simple surface density model, in which some of the ice dynamics are accounted for. The firn compaction and density models are driven by the HIRHAM5 regional climate model, forced by the ERA-Interim re-analysis product, at the lateral boundaries. We find annual mass loss estimates of the Greenland ice sheet in the range of 191 ± 23 Gt yr−1 to 240 ± 28 Gt yr−1 for the period October 2003 to March 2008. These results are in good agreement with several other studies of the Greenland ice sheet mass balance, based on different remote-sensing techniques.” Sørensen, L. S., Simonsen, S. B., Nielsen, K., Lucas-Picher, P., Spada, G., Adalgeirsdottir, G., Forsberg, R., and Hvidberg, C. S., The Cryosphere, 5, 173-186, doi:10.5194/tc-5-173-2011, 2011. [full text]

Tropical clouds major factor for climate sensitivity in models

The role of low clouds in determining climate sensitivity in response to a doubling of CO2 as obtained from 16 mixed-layer models – Wetherald (2011) “The effects that low clouds in sub-tropical to tropical latitudes have in determining a given model’s climate sensitivity is investigated by analyzing the cloud data produced by 16 “slab” or mixed-layer models submitted to the PCMDI and CFMIP archives and their respective response to a doubling of CO2. It is found that, within the context of the 16 models analyzed, changes of these low clouds appear to play a major role in determining model sensitivity but with changes of middle cloud also contributing especially from middle to higher latitudes. It is noted that the models with the smallest overall cloud change produce the smallest climate sensitivities and vice versa although the overall signs of the respective cloud feedbacks are positive. It is also found that the amounts of low cloud as simulated by the respective control runs have very little correlation with their respective climate sensitivities. In general, the overall latitude-height patterns of cloud change as derived from these more recent experiments agree quite well with those obtained from much earlier studies which include increases of the highest cloud, decreases of cloud lower down in the middle and lower tropospheric and small increases of low clouds. Finally, other mitigating factors are mentioned which could also affect the spread of the resulting climate sensitivities.” Richard T. Wetherald, Climatic Change, DOI: 10.1007/s10584-011-0047-3.

Central European farmers face challenges as climate warms

Expected changes in agroclimatic conditions in Central Europe – Trnka et al. (2011) “During the past few decades, the basic assumption of agroclimatic zoning, i.e., that agroclimatic conditions remain relatively stable, has been shattered by ongoing climate change. The first aim of this study was to develop a tool that would allow for effective analysis of various agroclimatic indicators and their dynamics under climate change conditions for a particular region. The results of this effort were summarized in the AgriClim software package, which provides users with a wide range of parameters essential for the evaluation of climate-related stress factors in agricultural crop production. The software was then tested over an area of 114,000 km2 in Central Europe. We have found that by 2020, the combination of increased air temperature and changes in the amount and distribution of precipitation will lead to a prolonged growing season and significant shifts in the agroclimatic zones in Central Europe; in particular, the areas that are currently most productive will be reduced and replaced by warmer but drier conditions in the same time the higher elevations will most likely experience improvement in their agroclimatic conditions. This positive effect might be short-lived, as by 2050, even these areas might experience much drier conditions than observed currently. Both the rate and the scale of the shift are amazing as by 2020 (assuming upper range of the climate change projections) only 20–38% of agriculture land in the evaluated region will remain in the same agroclimatic and by 2050 it might be less than 2%. On the other hand farmers will be able to take advantage of an earlier start to the growing season, at least in the lowland areas, as the proportion of days suitable for sowing increases. As all of these changes might occur within less than four decades, these issues could pose serious adaptation challenges for farmers and governmental policies. The presented results also suggest that the rate of change might be so rapid that the concept of static agroclimatic zoning itself might lose relevance due to perpetual change.” Miroslav Trnka, Josef Eitzinger, Daniela Semerádová, Petr Hlavinka, Jan Balek, Martin Dubrovský, Gerhard Kubu, Petr Štěpánek, Sabina Thaler and Martin Možný, et al., Climatic Change, DOI: 10.1007/s10584-011-0025-9.

Anthropogenic burning makes Holcene forests different

Pre-glacial and interglacial pollen records over the last 3 Ma from northwest Canada: Why do Holocene forests differ from those of previous interglaciations? – Schweger et al. (2011) “We synthesize pollen spectra from eleven dated stratigraphic sections from central and northern Yukon. Palaeomagnetic and tephra dating indicates the earliest assemblages, representing closed canopy Pinus and Picea forest, are middle-late Pliocene age. More open forest conditions, indicated by increased Poaceae and with evidence of permafrost, are dated at ca 3 Ma. While Pinus pollen is abundant at 3 Ma, it is reduced in records after 2.6 Ma, and subsequent Pleistocene interglacial forest records are repeatedly dominated by Picea, along with Alnus and small but significant amounts of Abies. Surface sample comparisons indicate that Abies was more widespread and abundant in past interglaciations than at present and that Middle-Pleistocene Picea–Abies forest grew in the northern Yukon Porcupine Basin, 500 km beyond modern Abies limits. In contrast, Pinus, which occurs today in southern and central Yukon, was not a significant component of these Pleistocene interglacial forests. Late-Holocene pollen assemblages with rare Abies and high Pinus are the most distinct in the past 2.6 Ma. Possible factors driving Holocene difference are paleoclimate, paludification, changes in megafaunal herbivory and an unusual fire regime. Anthropogenic burning is a factor unique to the Holocene, and if it is shown to be important in this case, it would challenge our notion of what constitutes boreal wilderness.” Charles Schweger, Duane Froese, James M. White, and John A. Westgate, Quaternary Science Reviews, doi:10.1016/j.quascirev.2011.01.020.

Watching plants from space

First observations of global and seasonal terrestrial chlorophyll fluorescence from space – Joiner et al. (2011) “Remote sensing of terrestrial vegetation fluorescence from space is of interest because it can potentially provide global coverage of the functional status of vegetation. For example, fluorescence observations may provide a means to detect vegetation stress before chlorophyll reductions take place. Although there have been many measurements of fluorescence from ground- and airborne-based instruments, there has been scant information available from satellites. In this work, we use high-spectral resolution data from the Thermal And Near-infrared Sensor for carbon Observation – Fourier Transform Spectrometer (TANSO-FTS) on the Japanese Greenhouse gases Observing SATellite (GOSAT) that is in a sun-synchronous orbit with an equator crossing time near 13:00 LT. We use filling-in of the potassium (K) I solar Fraunhofer line near 770 nm to derive chlorophyll fluorescence and related parameters such as the fluorescence yield at that wavelength. We map these parameters globally for two months (July and December 2009) and show a full seasonal cycle for several different locations, including two in the Amazonia region. We also compare the derived fluorescence information with that provided by the MODIS Enhanced Vegetation Index (EVI). These comparisons show that for several areas these two indices exhibit different seasonality and/or relative intensity variations, and that changes in fluorescence frequently lead those seen in the EVI for those regions. The derived fluorescence therefore provides information that is related to, but independent of the reflectance.” Joiner, J., Yoshida, Y., Vasilkov, A. P., Yoshida, Y., Corp, L. A., and Middleton, E. M., Biogeosciences, 8, 637-651, doi:10.5194/bg-8-637-2011, 2011. [full text]

Barents Sea micro-fauna shows recent Arctic warming

Foraminiferal faunal evidence of twentieth-century Barents Sea warming – Wilson et al. (2011) “Instrumental monitoring of the climate at high northern latitudes has documented the ongoing warming of the last few decades. Climate modelling has also demonstrated that the global warming signal will be amplified in the polar region. Such temperature increases would have important implications on the ecosystem and biota of the Barents Sea. This study therefore aims to reconstruct the climatic changes of the Barents Sea based on benthic foraminifera over approximately the last 1400 years at the decadal to sub-decadal scale. Oxygen and carbon isotope analysis and benthic foraminiferal species counts indicate an overall warming trend of approximately 2.6°C through the 1400-year record. In addition, the well-documented cooling period equating to the ‘Little Ice Age’ is evident between c. 1650 and 1850. Most notably, a series of highly fluctuating temperatures are observed over the last century.An increase of 1.5°C is shown across this period. Thus for the first time we are able to demonstrate that the recent Arctic warming is also reflected in the oceanic micro-fauna.” L. J. Wilson, M. Hald, F. Godtliebsen, The Holocene March 7, 2011 0959683610385718, doi: 10.1177/0959683610385718.

Albedo decreasing changes expected in Siberian forests

Sensitivity of Siberian Larch forests to climate change – Shuman et al. (2011) “The Northern Hemisphere’s boreal forests, particularly the Siberian boreal forest, may have a strong effect on Earth’s climate through changes in dominant vegetation and associated regional surface albedo. We show that warmer climate will likely convert Siberia’s deciduous larch (Larix spp.) to evergreen conifer forests, and thus decrease regional surface albedo. The dynamic vegetation model, FAREAST, simulates Russian boreal forest composition and was used to explore the feedback between climate change and forest composition at continental, regional, and local scales. FAREAST was used to simulate the impact of changes in temperature and precipitation on total and genus-level biomass at sites across Siberia and the Russian Far East, and for six high and low diversity regions. Model runs with and without European Larch (Larix decidua) included in the available species pool were compared to assess the potential for this species, which is adapted to warmer climate conditions, to mitigate the effects of climate change, especially the shift to evergreen dominance. At the continental scale, when temperature is increased, larch-dominated sites become vulnerable to early replacement by evergreen conifers. At the regional and local scales, the diverse Amur region of the Russian Far East does not show a strong response to climate change, but the low diversity regions in central and southern Siberia have an abrupt vegetation shift from larch-dominated forest to evergreen-conifer forest in response to increased temperatures. The introduction of L. decidua prevents the collapse of larch in these low diversity areas and thus mitigates the response to warming. Using contemporary MODIS albedo measurements, we determined that a conversion from larch to evergreen stands in low diversity regions of southern Siberia would generate a local positive radiative forcing of 5.1±2.6 W m−2. This radiative heating would reinforce the warming projected to occur in the area under climate change.” Jacquelyn Kremper Shuman, Herman Henry Shugart, Thomas Liam O’Halloran, Global Change Biology, 2011, DOI: 10.1111/j.1365-2486.2011.02417.x.

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Papers on precipitation and global warming

Posted by Ari Jokimäki on March 11, 2011

This is a list of papers on precipitation changes with global warming. Both observational and model studies are included and there’s own section for regional and local studies where papers are just listed briefly without abstracts. Relatively small number of papers on the list arises from the emphasis on the precipitation papers only. Precipitation is included among other parameters to many papers analysing climate changes in general, but those papers are not included here. So far there has been not much effort to search regional and local papers, but only those were included that were found while searching for global papers. 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 (May 23, 2013): Zhang et al. (2007) and some regional studies added.

How Much Will Precipitation Increase With Global Warming? – Lambert et al. (2008) “The advent of meteorological satellites during the 1970s made possible the observation of the seasonally shifting patterns of global precipitation. It was not until recently, however, that the record could be considered long enough to investigate longer-term trends and the relationship between global precipitation and global warming. Using data from the Special Sensor Microwave Imager (SSM/I) instrument, Wentz et al. [2007] reported that global mean precipitation increased at a rate of 7.4 ± 2.6% per °C between 1987 and 2006.” Lambert, F. H., A. R. Stine, N. Y. Krakauer, and J. C. H. Chiang (2008), Eos Trans. AGU, 89(21), doi:10.1029/2008EO210001. [full text]

Muted precipitation increase in global warming simulations: A surface evaporation perspective – Richter & Xie (2008) “Atmospheric moisture content is expected to rise in response to global warming, but climate models predict a much slower rate of precipitation increase. This muted response of the hydrological cycle is investigated from a surface evaporation perspective, using a multimodel ensemble of simulations under the A1B forcing scenario. A 90-year analysis of surface evaporation based on a standard bulk formula reveals that the following atmospheric changes act to slow down the increase in surface evaporation over ice-free oceans: surface relative humidity increases by 1.0%, surface stability, as measured by air-sea temperature difference, increases by 0.2 K, and surface wind speed decreases by 0.02 m/s. As a result of these changes, surface evaporation increases by only 2% per Kelvin of surface warming, rather than the 7%/K rate simulated for atmospheric moisture. The increased surface stability and relative humidity are robust across models. The former is nearly uniform over ice-free oceans while the latter features a subtropical peak on either side of the equator. While relative humidity changes are positive almost everywhere in a thin surface layer, changes aloft show positive trends in the deep tropics and negative ones in the subtropics. The surface-trapped structure suggests the following mechanism: owing to its thermal inertia, the ocean lags behind the atmospheric warming, and this retarding effect causes an increase in surface stability and relative humidity, analogously to advection fog. Our results call for observational efforts to monitor and detect changes in surface relative humidity and stability over the world ocean.” Richter, I., and S.-P. Xie (2008), J. Geophys. Res., 113, D24118, doi:10.1029/2008JD010561.

Detection of human influence on twentieth-century precipitation trends – Zhang et al. (2007) “Human influence on climate has been detected in surface air temperature, sea level pressure, free atmospheric temperature, tropopause height and ocean heat content. Human-induced changes have not, however, previously been detected in precipitation at the global scale, partly because changes in precipitation in different regions cancel each other out and thereby reduce the strength of the global average signal. Models suggest that anthropogenic forcing should have caused a small increase in global mean precipitation and a latitudinal redistribution of precipitation, increasing precipitation at high latitudes, decreasing precipitation at sub-tropical latitudes, and possibly changing the distribution of precipitation within the tropics by shifting the position of the Intertropical Convergence Zone. Here we compare observed changes in land precipitation during the twentieth century averaged over latitudinal bands with changes simulated by fourteen climate models. We show that anthropogenic forcing has had a detectable influence on observed changes in average precipitation within latitudinal bands, and that these changes cannot be explained by internal climate variability or natural forcing. We estimate that anthropogenic forcing contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics. The observed changes, which are larger than estimated from model simulations, may have already had significant effects on ecosystems, agriculture and human health in regions that are sensitive to changes in precipitation, such as the Sahel.” Xuebin Zhang, Francis W. Zwiers, Gabriele C. Hegerl, F. Hugo Lambert, Nathan P. Gillett, Susan Solomon, Peter A. Stott & Toru Nozawa, Nature 448, 461-465 (26 July 2007) | doi:10.1038/nature06025. [full text]

How Much More Rain Will Global Warming Bring? – Wentz et al. (2007) “Climate models and satellite observations both indicate that the total amount of water in the atmosphere will increase at a rate of 7% per kelvin of surface warming. However, the climate models predict that global precipitation will increase at a much slower rate of 1 to 3% per kelvin. A recent analysis of satellite observations does not support this prediction of a muted response of precipitation to global warming. Rather, the observations suggest that precipitation and total atmospheric water have increased at about the same rate over the past two decades.” Frank J. Wentz, Lucrezia Ricciardulli, Kyle Hilburn and Carl Mears, Science 13 July 2007: Vol. 317 no. 5835 pp. 233-235, DOI: 10.1126/science.1140746. [full text]

On the tropical origin of uncertainties in the global land precipitation response to global warming – Douville et al. (2006) “Understanding the response of the global hydrological cycle to recent and future anthropogenic emissions of greenhouse gases and aerosols is a major challenge for the climate modelling community. Recent climate scenarios produced for the fourth assessment report of the Intergovernmental Panel on Climate Change are analysed here to explore the geographical origin of, and the possible reasons for, uncertainties in the hydrological model response to global warming. Using the twentieth century simulations and the SRES-A2 scenarios from eight different coupled ocean–atmosphere models, it is shown that the main uncertainties originate from the tropics, where even the sign of the zonal mean precipitation change remains uncertain over land. Given the large interannual fluctuations of tropical precipitation, it is then suggested that the El Niño Southern Ocillation (ENSO) variability can be used as a surrogate of climate change to better constrain the model reponse. While the simulated sensitivity of global land precipitation to global mean surface temperature indeed shows a remarkable similarity between the interannual and climate change timescales respectively, the model ability to capture the ENSO-precipitation relationship is not a major constraint on the global hydrological projections. Only the model that exhibits the highest precipitation sensitivity clearly appears as an outlier. Besides deficiencies in the simulation of the ENSO-tropical rainfall teleconnections, the study indicates that uncertainties in the twenty-first century evolution of these teleconnections represent an important contribution to the model spread, thus emphasizing the need for improving the simulation of the tropical Pacific variability to provide more reliable scenarios of the global hydrological cycle. It also suggests that validating the mean present-day climate is not sufficient to assess the reliability of climate projections, and that interannual variability is another suitable and possibly more useful candidate for constraining the model response. Finally, it is shown that uncertainties in precipitation change are, like precipitation itself, very unevenly distributed over the globe, the most vulnerable countries sometimes being those where the anticipated precipitation changes are the most uncertain.” H. Douville, D. Salas-Mélia and S. Tyteca, Climate Dynamics, Volume 26, Number 4, 367-385, DOI: 10.1007/s00382-005-0088-2. [full text]

Global observed changes in daily climate extremes of temperature and precipitation – Alexander et al. (2006) “A suite of climate change indices derived from daily temperature and precipitation data, with a primary focus on extreme events, were computed and analyzed. By setting an exact formula for each index and using specially designed software, analyses done in different countries have been combined seamlessly. This has enabled the presentation of the most up-to-date and comprehensive global picture of trends in extreme temperature and precipitation indices using results from a number of workshops held in data-sparse regions and high-quality station data supplied by numerous scientists world wide. Seasonal and annual indices for the period 1951–2003 were gridded. Trends in the gridded fields were computed and tested for statistical significance. Results showed widespread significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. Over 70% of the global land area sampled showed a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Some regions experienced a more than doubling of these indices. This implies a positive shift in the distribution of daily minimum temperature throughout the globe. Daily maximum temperature indices showed similar changes but with smaller magnitudes. Precipitation changes showed a widespread and significant increase, but the changes are much less spatially coherent compared with temperature change. Probability distributions of indices derived from approximately 200 temperature and 600 precipitation stations, with near-complete data for 1901–2003 and covering a very large region of the Northern Hemisphere midlatitudes (and parts of Australia for precipitation) were analyzed for the periods 1901–1950, 1951–1978 and 1979–2003. Results indicate a significant warming throughout the 20th century. Differences in temperature indices distributions are particularly pronounced between the most recent two periods and for those indices related to minimum temperature. An analysis of those indices for which seasonal time series are available shows that these changes occur for all seasons although they are generally least pronounced for September to November. Precipitation indices show a tendency toward wetter conditions throughout the 20th century.” Alexander, L. V., et al. (2006), J. Geophys. Res., 111, D05109, doi:10.1029/2005JD006290. [full text]

The Version-2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979–Present) – Adler et al. (2003) “The Global Precipitation Climatology Project (GPCP) Version-2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5° latitude × 2.5° longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit satellite infrared data, and surface rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The dataset is extended back into the premicrowave era (before mid-1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the rain gauge analysis. The dataset archive also contains the individual input fields, a combined satellite estimate, and error estimates for each field. This monthly analysis is the foundation for the GPCP suite of products, including those at finer temporal resolution. The 23-yr GPCP climatology is characterized, along with time and space variations of precipitation.” Adler, Robert F., and Coauthors, 2003, J. Hydrometeor, 4, 1147–1167. [full text]

Simulated changes due to global warming in daily precipitation means and extremes and their interpretation using the gamma distribution – Watterson & Dix (2003) “The potential change in precipitation due to global warming is studied using five-member ensembles of climate simulations by the CSIRO Mark 2 atmosphere-ocean model for the period 1871–1990 and forward to 2100 under both the Special Report on Emission Scenarios (SRES) A2 (rapid CO2 increase) and B2 (moderate increase) forcing scenarios. The mean surface warming for the period 1961–1990 is 0.3 K. The warming from 1961–1990 to 2071–2100 is 3.5 K under A2, 29% more than for B2, and with a very similar spatial pattern. The daily precipitation (P) frequency distributions for January and July days in these periods are presented, focusing on the A2 case. The distributions for wet days at each point are approximated by the gamma distribution. The global mean P increase of around 6%, in both months, is related to a mean increase in the gamma’s scale parameter of 18%, offset by small decreases in the shape parameter and wet day frequency. However, local changes of opposite signs also occur, especially in the tropics. Ensemble averages of 30-year extreme daily precipitation for January and July, and other months, are generally greater for 2071–2100 than for 1961–1990, with an average increase of 14%. Extreme value theory based on the monthly gamma distributions provides a good match to these values. The theory is extended to the annual case. In general, the 1961–1990 extremes peak in the subtropical rainbands in the model, where increases of 10 to 30% are common. Larger relative increases occur in polar regions, and also over northern land in January.” Watterson, I. G., and M. R. Dix (2003), J. Geophys. Res., 108(D13), 4379, doi:10.1029/2002JD002928.

Changes in the Probability of Heavy Precipitation: Important Indicators of Climatic Change – Groisman et al. (1999) “A simple statistical model of daily precipitation based on the gamma distribution is applied to summer (JJA in Northern Hemisphere, DJF in Southern Hemisphere) data from eight countries: Canada, the United States, Mexico, the former Soviet Union, China, Australia, Norway, and Poland. These constitute more than 40% of the global land mass, and more than 80% of the extratropical land area. It is shown that the shape parameter of this distribution remains relatively stable, while the scale parameter is most variable spatially and temporally. This implies that the changes in mean monthly precipitation totals tend to have the most influence on the heavy precipitation rates in these countries. Observations show that in each country under consideration (except China), mean summer precipitation has increased by at least 5% in the past century. In the USA, Norway, and Australia the frequency of summer precipitation events has also increased, but there is little evidence of such increases in any of the countries considered during the past fifty years. A scenario is considered, whereby mean summer precipitation increases by 5% with no change in the number of days with precipitation or the shape parameter. When applied in the statistical model, the probability of daily precipitation exceeding 25.4 mm (1 inch) in northern countries (Canada, Norway, Russia, and Poland) or 50.8 mm (2 inches) in mid-latitude countries (the USA, Mexico, China, and Australia) increases by about 20% (nearly four times the increase in mean). The contribution of heavy rains (above these thresholds) to the total 5% increase of precipitation is disproportionally high (up to 50%), while heavy rain usually constitutes a significantly smaller fraction of the precipitation events and totals in extratropical regions (but up to 40% in the tropics, e.g., in southern Mexico). Scenarios with moderate changes in the number of days with precipitation coupled with changes in the scale parameter were also investigated and found to produce smaller increases in heavy rainfall but still support the above conclusions. These scenarios give changes in heavy rainfall which are comparable to those observed and are consistent with the greenhouse-gas-induced increases in heavy precipitation simulated by some climate models for the next century. In regions with adequate data coverage such as the eastern two-thirds of contiguous United States, Norway, eastern Australia, and the European part of the former USSR, the statistical model helps to explain the disproportionate high changes in heavy precipitation which have been observed.” Pavel Ya. Groisman, Thomas R. Karl, David R. Easterling, Richard W. Knight, Paul F. Jamason, Kevin J. Hennessy, Ramasamy Suppiah, Cher M. Page, Joanna Wibig and Krzysztof Fortuniak, et al., Climatic Change, Volume 42, Number 1, 243-283, DOI: 10.1023/A:1005432803188. [full text]

Precipitation sensitivity to global warming: Comparison of observations with HadCM2 simulations – Hulme et al. (1998) “Recent century‐long experiments performed with global climate models have simulated observed trends in global‐mean temperature quite successfully when both greenhouse gas and aerosol forcing has been included. The performance of these same experiments in simulating observed global‐scale changes in precipitation has not previously been examined. Here we use a gridded terrestrial precipitation dataset for the period 1900 to 1996 to examine the extent to which observed global and zonal‐mean precipitation sensitivities to global warming have been captured by a series of model simulations recently completed by the UK Hadley Centre. There are signs that the model has been able to reproduce at least some of the observed zonal‐mean variations in the precipitation sensitivity to warming. Questions remain both about the quality of the observed precipitation data and about the spatial scale at which anthropogenically‐forced global climate models can be expected to reproduce observed variations in precipitation.” Hulme, M., T. J. Osborn, and T. C. Johns (1998), Geophys. Res. Lett., 25(17), 3379–3382, doi:10.1029/98GL02562.

Global Precipitation: A 17-Year Monthly Analysis Based on Gauge Observations, Satellite Estimates, and Numerical Model Outputs – Xie & Arkin (1997) “Gridded fields (analyses) of global monthly precipitation have been constructed on a 2.5° latitude–longitude grid for the 17-yr period from 1979 to 1995 by merging several kinds of information sources with different characteristics, including gauge observations, estimates inferred from a variety of satellite observations, and the NCEP–NCAR reanalysis. This new dataset, which the authors have named the CPC Merged Analysis of Precipitation (CMAP), contains precipitation distributions with full global coverage and improved quality compared to the individual data sources. Examinations showed no discontinuity during the 17-yr period, despite the different data sources used for the different subperiods. Comparisons of the CMAP with the merged analysis of Huffman et al. revealed remarkable agreements over the global land areas and over tropical and subtropical oceanic areas, with differences observed over extratropical oceanic areas. The 17-yr CMAP dataset is used to investigate the annual and interannual variability in large-scale precipitation. The mean distribution and the annual cycle in the 17-yr dataset exhibit reasonable agreement with existing long-term means except over the eastern tropical Pacific. The interannual variability associated with the El Niño–Southern Oscillation phenomenon resembles that found in previous studies, but with substantial additional details, particularly over the oceans. With complete global coverage, extended period and improved quality, the 17-yr dataset of the CMAP provides very useful information for climate analysis, numerical model validation, hydrological research, and many other applications. Further work is under way to improve the quality, extend the temporal coverage, and to refine the resolution of the merged analysis.” Xie, Pingping, Phillip A. Arkin, 1997, Bull. Amer. Meteor. Soc., 78, 2539–2558. [full text]

Potential impacts of global warming on the frequency and magnitude of heavy precipitation – Fowler & Hennessy (1995) “It is now widely recognised that the most significant impacts of global warming are likely to be experienced through changes in the frequency of extreme events, including flooding. This paper reviews physical and empirical arguments which suggest that global warming may result in a more intense hydrological cycle, with an associated increase in the frequency and/or magnitude of heavy precipitation. Results derived from enhanced-greenhouse experiments using global climate models (GCMs) are shown to be consistent with these physical and empirical arguments. Detailed analysis of output from three GCMs indicates the possibility of substantial increases in the frequency and magnitude of extreme daily precipitation, with amplification of the effect as the return period increases. Moreover, return period analyses for locations in Australia, Europe, India, China and the USA indicate that the results are global in scope. Subsequent discussion of the limitations of GCMs for this sort of analysis highlights the need for caution when interpreting the precipitation results presented here. However, the consistency between physically-based expectations, empirical observations, and GCM results is considered sufficient for the GCM results to be taken seriously, at least in a qualitative sense, especially considering that the alternative seems to be reliance by planners on the fundamentally flawed concept of a stationary climate.” A. M. Fowler and K. J. Hennessy, Natural Hazards, Volume 11, Number 3, 283-303, DOI: 10.1007/BF00613411.

Regional and local studies

Tropics: Chou et al. (2009) [abstract, full text], Chou & Neelin (2004) [abstract, full text], Kumar et al. (2004) [abstract, full text]

Africa

  • Nigeria: Oguntunde et al. (2011) [abstract]
  • South Africa: Fauchereau et al. (2003) [abstract]

Asia Takayabu et al. (2007) [abstract, full text]

Australia and Oceania

Europe Pal et al. (2004) [abstract], Moberg et al. (2006) [abstract, full text]

North-America Kunkel et al. (2010) [abstract]

South-America

  • Brazil: Dufek & Ambrizzi (2008) [abstract]

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Carbon sink weakening undermines the climate benefits from forest energy

Posted by Ari Jokimäki on March 9, 2011

There’s a new report out on the climate impacts of Finnish forest energy production by Jari Liski et al. from Finnish Environment Institute (SYKE):

“If forest energy production is increased as planned by the Government, the carbon sink capacity of Finnish forests will suffer. A weaker carbon sink capacity will cut actual reductions in greenhouse gas emissions achievable through forest energy in Finland by 60-80 per cent by 2020. A study commissioned by the Ministry of the Environment from the Finnish Environment Institute, published in February, examines the climate impacts of, and particulate matter emissions attributable to, rapidly increasing forest energy production.”

Full news release is available in English.

The report is also available (4 MB PDF), but only the abstract is in English (at the end of the document).

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New research from last week 9/2011

Posted by Ari Jokimäki on March 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. Planet 3.0 also reports new research.

Published last week:

New global CO2 emission time series

Monthly, global emissions of carbon dioxide from fossil fuel consumption – Andres et al. (2011) “This paper examines available data, develops a strategy, and presents a monthly, global time series of fossil-fuel carbon dioxide emissions for the years 1950 to 2006. This monthly time series was constructed from detailed study of monthly data from the 21 countries that account for approximately 80% of global total emissions. These data were then used in a Monte Carlo approach to proxy for all remaining countries. The proportional-proxy methodology estimates by fuel group the fraction of annual emissions emitted in each country and month. Emissions from solid, liquid, and gas fuels are explicitly modeled by the proportional-proxy method. The primary conclusion from this study is the global monthly time series is statistically significantly different from a uniform distribution throughout the year. Uncertainty analysis of the data presented show that the proportional-proxy method used faithfully reproduces monthly patterns in the data and the global monthly pattern of emissions is relatively insensitive to the exact proxy assignments used. The data and results presented here should lead to a better understanding of global and regional carbon cycles, especially when the mass data are combined with the stable carbon isotope data in atmospheric transport models.” R. J. Andres, J. S. Gregg, L. Losey, G. Marland, T. A. Boden, Tellus B, 2011, DOI: 10.1111/j.1600-0889.2011.00530.x.

Clouds not credible as Faint Young Sun Paradox resolvers

Clouds and the Faint Young Sun Paradox – Goldblatt & Zahnle (2011) “We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of −50 W m−2 during the late Archean), but geological evidence points to the Earth having been at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduced the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m−2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m−2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m−2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more than +15 W m−2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m−2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.” Goldblatt, C. and Zahnle, K. J.: Clouds and the Faint Young Sun Paradox, Clim. Past, 7, 203-220, doi:10.5194/cp-7-203-2011, 2011. [full text]

Deep ocean heat important for global heat balance

Deep ocean heat content changes estimated from observation and reanalysis product and their influence on sea level change – Kouketsu et al. (2011) “We calculated basin-scale and global ocean decadal temperature change rates from the 1990s to the 2000s for waters below 3000 m. Large temperature increases were detected around Antarctica, and a relatively large temperature increase was detected along the northward path of Circumpolar Deep Water in the Pacific. The global heat content (HC) change estimated from the temperature change rates below 3000 m was 0.8 × 1022 J decade−1; a value that cannot be neglected for precise estimation of the global heat balance. We reproduced the observed temperature changes in the deep ocean using a data assimilation system and examined virtual observations in the reproduced data field to evaluate the uncertainty of the HC changes estimated from the actual temporally and spatially sparse observations. From the analysis of the virtual observations, it is shown that the global HC increase below 3000 m during recent decades can be detected using the available observation system of periodic revisits to the same sampling sections, although the uncertainty is large.” Kouketsu, S., et al. (2011), J. Geophys. Res., 116, C03012, doi:10.1029/2010JC006464. [full text]

Greenland and Antarctic ice mass losses are accelerating

Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise – Rignot et al. (2011) “Ice sheet mass balance estimates have improved substantially in recent years using a variety of techniques, over different time periods, and at various levels of spatial detail. Considerable disparity remains between these estimates due to the inherent uncertainties of each method, the lack of detailed comparison between independent estimates, and the effect of temporal modulations in ice sheet surface mass balance. Here, we present a consistent record of mass balance for the Greenland and Antarctic ice sheets over the past two decades, validated by the comparison of two independent techniques over the last 8 years: one differencing perimeter loss from net accumulation, and one using a dense time series of time-variable gravity. We find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss. In 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise. Notably, the acceleration in ice sheet loss over the last 18 years was 21.9 ± 1 Gt/yr2 for Greenland and 14.5 ± 2 Gt/yr2 for Antarctica, for a combined total of 36.3 ± 2 Gt/yr2. This acceleration is 3 times larger than for mountain glaciers and ice caps (12 ± 6 Gt/yr2). If this trend continues, ice sheets will be the dominant contributor to sea level rise in the 21st century.” Rignot, E., I. Velicogna, M. R. van den Broeke, A. Monaghan, and J. Lenaerts (2011), Geophys. Res. Lett., 38, L05503, doi:10.1029/2011GL046583. [full text]

Measuring London’s carbon dioxide emissions

Controls of carbon dioxide concentrations and fluxes above central London – Helfter et al. (2011) “Eddy-covariance measurements of carbon dioxide fluxes were taken continuously between October 2006 and May 2008 at 190 m height in central London (UK) to quantify emissions and study their controls. Inner London, with a population of 8.2 million (~5000 inhabitants per km2) is heavily built up with 8% vegetation cover within the central boroughs. CO2 emissions were found to be mainly controlled by fossil fuel combustion (e.g. traffic, commercial and domestic heating). The measurement period allowed investigation of both diurnal patterns and seasonal trends. Diurnal averages of CO2 fluxes were found to be correlated with traffic but also exhibited an inverse dependency on atmospheric stability in the near-neutral range, with higher fluxes coinciding with unstable stratification during most seasons and perhaps reflecting how changes in heating-related natural gas consumption and, to a lesser extent, photosynthetic activity controlled the seasonal variability. Despite measurements being taken at ca. 22 times the mean building height, coupling with street level was adequate, especially during daytime. Night-time saw a higher occurrence of stable or neutral stratification, especially in autumn and winter, which resulted in data loss in post-processing and caused the tower to become decoupled from street level. CO2 fluxes observed at night were not always correlated with traffic counts, probably reflecting this decoupling, but also the fact that at night heating was always a larger source than traffic. No significant difference was found between the annual estimate of net exchange of CO2 for the expected measurement footprint and the values derived from the National Atmospheric Emissions Inventory (NAEI), with daytime fluxes differing by only 3%. This agreement with NAEI data also supported the use of the simple flux footprint model which was applied to the London site; this also suggests that individual roughness elements did not significantly affect the measurements due to the large ratio of measurement height to mean building height.” Helfter, C., Famulari, D., Phillips, G. J., Barlow, J. F., Wood, C. R., Grimmond, C. S. B., and Nemitz, E., Atmos. Chem. Phys., 11, 1913-1928, doi:10.5194/acp-11-1913-2011, 2011. [full text]

Native American Records of Weather and Climate

Waniyetu Wówapi: Native American Records of Weather and Climate – Therrell & Trotter (2011) “Pictographic calendars called Waniyetu wówapi or ‘winter counts’ kept by several Great Plains Indian cultures (principally the Sioux or Lakota peoples) preserve a record of events important to these peoples from roughly the 17th through 19th centuries. A number of these memorable events include natural phenomena such as meteor storms, eclipses, and unusual weather and climate. Examination of a selection of the available winter count records and related interpretive writings indicates that the Lakota and other native Plains cultures recorded many instances of unusual weather or climate and associated impacts. Analysis of the winter count records in conjunction with observational and proxy climate records and other historical documentation suggests that the winter counts preserve a unique record of some of the most unusual and severe climate events of the early American period and provide valuable insight into the impacts upon people and their perceptions of such events in the ethnographically important region of the Great Plains.” Matthew D. Therrell, Makayla J. Trotter, Bulletin of the American Meteorological Society 2011. [full text]

Hottest spot of Earth is in Iran’s Lut Desert

Satellite Finds Highest Land Skin Temperatures on Earth – Mildrexler et al. (2011) Without abstract. The hottest spots of the Earth are being located in this study. David J. Mildrexler, Maosheng Zhao, Steven W. Running, Bulletin of the American Meteorological Society 2011. [full text]

Rainfall causing Pakistan floods should have happened in India

Anomalous Atmospheric Events Leading to the Summer 2010 Floods in Pakistan – Houze et al. (2011) “The development of a highly anomalous pressure pattern brought rainstorms of a type that normally occur in the region of Bangladesh into the arid mountainous region of Pakistan.” R. A. Houze, Jr., K. L. Rasmussen, S. Medina, S. R. Brodzik, and U. Romatschke, Bulletin of the American Meteorological Society 2011. [full text]

Negative SW cloud feedback in Fennoscandia during last 1000 years

Cloud response to summer temperatures in Fennoscandia over the last thousand years – Gagen et al. (2011) “Cloud cover is one of the most important factors controlling the radiation balance of the Earth. The response of cloud cover to increasing global temperatures represents the largest uncertainty in model estimates of future climate because the cloud response to temperature is not well-constrained. Here we present the first regional reconstruction of summer sunshine over the past millennium, based on the stable carbon isotope ratios of pine treerings from Fennoscandia. Comparison with the regional temperature evolution reveals the Little Ice Age (LIA) to have been sunny, with cloudy conditions in the warmest periods of the Medieval at this site. A negative shortwave cloud feedback is indicated at high latitude. A millennial climate simulation suggests that regionally low temperatures during the LIA were mostly maintained by a weaker greenhouse effect due to lower humidity. Simulations of future climate that display a negative shortwave cloud feedback for high-latitudes are consistent with our proxy interpretation.” Gagen, M., E. Zorita, D. McCarroll, G. H. F. Young, H. Grudd, R. Jalkanen, N. J. Loader, I. Robertson, and A. Kirchhefer (2011), Geophys. Res. Lett., 38, L05701, doi:10.1029/2010GL046216.

Madden–Julian Oscillation might get more active in future

Will global warming modify the activity of the Madden–Julian Oscillation? – Jones & Carvalho (2011) “The Madden–Julian Oscillation (MJO) is the most prominent form of tropical intraseasonal variability in the climate system. Observations suggest that warming in the tropical Indian and Pacific Oceans in recent decades may have contributed to increased trends in the annual number of MJO events. A stochastic model is used to project changes in MJO activity under a global warming scenario. The mean number of events per year may rise from ∼3.9 (1948–2008) to ∼5.7 (2049–2099) and the probability of very active years (5 or more events) may significantly increase from 0.51 ± 0.01 (1990–2008) to 0.75 ± 0.01 (2010–2027) and 0.92 ± 0.01 (2094–2099).” Charles Jones, Leila M. V. Carvalho, Quarterly Journal of the Royal Meteorological Society, 2011, DOI: 10.1002/qj.765.

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