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Archive for December, 2011

Papers on new year fireworks and atmosphere

Posted by Ari Jokimäki on December 31, 2011

This is a list of papers on the effect of new year fireworks on atmosphere. Papers relating to other firework events than new year are also included. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.

Physical characterization of aerosol particles during the Chinese New Year’s firework events – Zhang et al. (2010) “Measurements for particles 10 nm to 10 μm were taken using a Wide-range Particle Spectrometer during the Chinese New Year (CNY) celebrations in 2009 in Shanghai, China. These celebrations provided an opportunity to study the number concentration and size distribution of particles in an especial atmospheric pollution situation due to firework displays. The firework activities had a clear contribution to the number concentration of small accumulation mode particles (100–500 nm) and PM1 mass concentration, with a maximum total number concentration of 3.8 × 104 cm−3. A clear shift of particles from nucleation and Aitken mode to small accumulation mode was observed at the peak of the CNY firework event, which can be explained by reduced atmospheric lifetimes of smaller particles via the concept of the coagulation sink. High particle density (2.7 g cm−3) was identified as being particularly characteristic of the firework aerosols. Recalculated fine particles PM1 exhibited on average above 150 μg m−3 for more than 12 hours, which was a health risk to susceptible individuals. Integral physical parameters of firework aerosols were calculated for understanding their physical properties and further model simulation.” Min Zhang, Xuemei Wang, Jianmin Chen, Tiantao Cheng, Tao Wang, Xin Yang, Youguo Gong, Fuhai Geng, Changhong Chen, Atmospheric Environment, Volume 44, Issue 39, December 2010, Pages 5191-5198, doi:10.1016/j.atmosenv.2010.08.048. [Full text]

Effect of fireworks events on urban background trace metal aerosol concentrations: Is the cocktail worth the show? – Moreno et al. (2010) “We report on the effect of a major firework event on urban background atmospheric PM2.5 chemistry, using 24-h data collected over 8 weeks at two sites in Girona, Spain. The firework pollution episode (Sant Joan fiesta on 23rd June 2008) measured in city centre parkland increased local background PM2.5 concentrations as follows: Sr (x86), K (x26), Ba (x11), Co (x9), Pb (x7), Cu (x5), Zn (x4), Bi (x4), Mg (x4), Rb (x4), Sb (x3), P (x3), Ga (x2), Mn (x2), As (x2), Ti (x2) and SO42− (x2). Marked increases in these elements were also measured outside the park as the pollution cloud drifted over the city centre, and levels of some metals remained elevated above background for days after the event as a reservoir of metalliferous dust persisted within the urban area. Transient high-PM pollution episodes are a proven health hazard, made worse in the case of firework combustion because many of the elements released are both toxic and finely respirable, and because displays commonly take place in an already polluted urban atmosphere.” Teresa Moreno, Xavier Querol, Andrés Alastuey, Fulvio Amato, Jorge Pey, Marco Pandolfi, Nino Kuenzli, Laura Bouso, Marcela Rivera, Wes Gibbons, Journal of Hazardous Materials, Volume 183, Issues 1-3, 15 November 2010, Pages 945-949, doi:10.1016/j.jhazmat.2010.07.082.

Effect of fireworks display on perchlorate in air aerosols during the Spring Festival – Shi et al. (2010) “Perchlorate is regarded as a new emerging persistent inorganic environmental contaminant. It can result in important neurodevelopmental deficits and goiter in infants and children because of its inhibition of iodine uptake into the thyroid tissue. Furthermore, its presence in the human body can cause improper regulation of metabolism for adults. It is often used as ingredient in the production of fireworks. So fireworks display may influence the perchlorate levels in atmospheric particulate matter (PM). In this paper perchlorate was determined in air aerosol samples (Inhalable particulate matter (PM10) and larger particulate matter (PM10-100)) collected from two locations (Lanzhou City and Yuzhong County) in Gansu province over a month period (February 1rst to March 4th) during the Spring Festival (February 18th) in 2007 in order to study the effect of fireworks display on perchlorate in air aerosol. The results showed that different concentrations of perchlorate were detected in almost all samples, ranging from <detection limit value to 39.16 ng m−3. And the detection frequencies of perchlorate were 91% (100%) and 50% (59%) for PM10-100 (PM10) in Lanzhou City and Yuzhong County, respectively. The highest concentrations were all found in the samples from two sites on New Year’s Eve, which was 39.16 ng m−3 (PM10-100) and 9.89 ng m−3 (PM10) for Lanzhou city, 3.43 ng m−3 (PM10-100) and 4.97 ng m−3 (PM10) for Yuzhong County, 6.8-26.2 times as the mean concentrations during the period of no or limited fireworks display. This indicated that the fireworks display during the Spring Festival can result in the levels of perchlorate increase.” Yali Shi, Ning Zhang, Jianmin Gao, Xin Li, Yaqi Cai, Atmospheric Environment, Volume 45, Issue 6, February 2011, Pages 1323-1327, doi:10.1016/j.atmosenv.2010.11.056.

Heavy metals from pyrotechnics in New Years Eve snow – Steinhauser et al. (2008) “Pyrotechnics and fireworks cause pollution with barium aerosols, which is a result of the utilization of barium nitrate as a combined pyrotechnic oxidizer and coloring agent. In this study, the washing-out of barium-rich aerosols by snowflakes during the New Years Eve celebrations in an Austrian village in the Alps has been investigated. It could be shown that the fireworks caused an increase in the barium concentration in snow of up to a factor of 580 compared to the blank value. An increase of the concentrations of strontium and occasionally arsenic in snow was also observed. The geographic distribution of the pyrotechnic combustion products on this snowy evening was restricted to a relatively small area and even in a very local scale, the variations in the concentrations were remarkable. Post-firework snow from the summits of nearby located mountains was found to be as clean as pre-firework snow. However, snow that was visibly contaminated with smoke residues contained exorbitant concentrations of Ba, K, Sr, and Fe.” Georg Steinhauser, Johannes H. Sterba, Michaela Foster, Friedrich Grass, Max Bichler, Atmospheric Environment, Volume 42, Issue 37, December 2008, Pages 8616-8622, doi:10.1016/j.atmosenv.2008.08.023.

The impact of fireworks on airborne particles – Vecchi et al. (2008) “Fireworks are one of the most unusual sources of pollution in atmosphere; although transient, these pollution episodes are responsible for high concentrations of particles (especially metals and organic compounds) and gases. In this paper, results of a study on chemical–physical properties of airborne particles (elements, ions, organic and elemental carbon and particles size distributions) collected during a fireworks episode in Milan (Italy) are reported. Elements typically emitted during pyrotechnic displays increased in 1 h as follows: Sr (120 times), Mg (22 times), Ba (12 times), K (11 times), and Cu (6 times). In our case study, Sr was recognised as the best fireworks tracer because its concentration was very high during the event and lower than, or comparable with, minimum detection limits during other time intervals, suggesting that it was mainly due to pyrotechnic displays. In addition, particles number concentrations increased significantly during the episode (up to 6.7 times in 1 h for the 0.5<d<1 μm size bin). Contributions (e.g. Cu, elemental carbon and nitrogen oxides) to air pollution due to the large traffic volume registered during the same night were also singled out. The original application of Positive Matrix Factorisation and Multiple Linear Regression allowed, as far as we know, here for the first time, the quantification of the fireworks contribution to atmospheric particulate matter (PM) and the resolution of their chemical profile. The contribution of fireworks to the local environment in terms of PM10 mass, elements and chemical components was assessed with 4-h time resolution. PM10 mass apportioned by fireworks was up to 33.6 μg m−3 (about 50% of the total PM10 mass). Major contributors were elemental and organic carbon (2.8 and 8.1 μg m−3, respectively) as well as metals like Mg, K, Sr, Ba, and Cu (0.4, 0.7, 0.07, 0.1, and 0.1 μg m−3, respectively).” Roberta Vecchi, Vera Bernardoni, Diana Cricchio, Alessandra D’Alessandro, Paola Fermo, Franco Lucarelli, Silvia Nava, Andrea Piazzalunga, Gianluigi Valli, Atmospheric Environment, Volume 42, Issue 6, February 2008, Pages 1121-1132, doi:10.1016/j.atmosenv.2007.10.047.

Ambient air quality of Lucknow City (India) during use of fireworks on Diwali Festival – Barman et al. (2008) “The present study deals with the effect of fireworks on ambient air quality during Diwali Festival in Lucknow City. In this study, PM10, SO2, NO x and 10 trace metals associated with PM10 were estimated at four representative locations, during day and night times for Pre Diwali (day before Diwali) and Diwali day. On Diwali day 24 h average concentration of PM10, SO2, and NO x was found to be 753.3, 139.1, and 107.3 μg m−3, respectively, and these concentrations were found to be higher at 2.49 and 5.67 times for PM10, 1.95 and 6.59 times for SO2 and 1.79 and 2.69 for NO x , when compared with the respective concentration of Pre Diwali and normal day, respectively. On Diwali day, 24 h values for PM10, SO2, and NO x were found to be higher than prescribed limit of National Ambient Air Quality Standard (NAAQS), and exceptionally high (7.53 times) for PM10. On Diwali night (12 h) mean level of PM10, SO2 and NO x was 1,206.2, 205.4 and 149.0 μg m−3, respectively, which was 4.02, 2.82 and 2.27 times higher than their respective daytime concentrations and showed strong correlations (p<0.01) with each other. The 24 h mean concentration of metals associated with PM10 was found to be in the order of Ca (3,169.44)>Fe (747.23)>Zn (542.62)>Cu (454.03),>Pb (307.54)>Mn (83.90)>Co (78.69)>Cr (42.10)>Ni (41.47)>Cd (34.69) in ng m−3 and all these values were found to be higher than the Pre Diwali (except Fe) and normal day. The metal concentrations on Diwali day were found to be significantly different than normal day (except Fe & Cu). The concentrations of Co, Ni, Cr and Cd on Diwali night were found to be significantly higher than daytime concentrations for Pre Diwali (control). The inter correlation of metals between Ca with Pb, Zn with Ni and Cr, Cu with Co, Co with Mn, Ni with Cd, Mn with Cd, Ni with Cd and Cr, and Cr with Cd showed significant relation either at p<0.05 or P<0.01 levels, which indicated that their sources were the same. The metals Cu, Co, Ni, Cr and Cd showed significant (p<0.01) association with PM10. These results indicate that fireworks during Diwali festival affected the ambient air quality adversely due to emission and accumulation of PM10, SO2, NO x and trace metals.” S. C. Barman, Ramesh Singh, M. P. S. Negi and S. K. Bhargava, Environmental Monitoring and Assessment, Volume 137, Numbers 1-3, 495-504, DOI: 10.1007/s10661-007-9784-1.

Recreational atmospheric pollution episodes: Inhalable metalliferous particles from firework displays – Moreno et al. (2007) “The use of fireworks creates an unusual and distinctive anthropogenic atmospheric pollution event. We report on aerosol samples collected during Las Fallas in Valencia, a 6-day celebration famous for its firework displays, and add comparative data on firework- and bonfire-contaminated atmospheric aerosol samples collected from elsewhere in Spain (Barcelona, L’Alcora, and Borriana) and during the Guy Fawkes celebrations in London. Specific high-profile official firework events during Las Fallas included the afternoon Mascletà and the nightly aerial displays (especially in the climactic final 2 days of the fiesta) and were accompanied by pollution spikes in suspended particles, NO, SO2, and the creation and dispersal of an aerosol cloud enriched in a range of metallic elements. Notable metal aerosol concentration increases recorded during Las Fallas were potassium (from 500 to 5900 ng m−3), aluminium (as Al2O3 from around 600 to 2200 ng m−3), titanium (from 200 to 700 ng m−3), magnesium (from 100 to 500 ng m−3), lead (from 17 to 379 ng m−3), barium (from 39 to 322 ng m−3), strontium (from 3 to 112 ng m−3), copper (from 12 to 71 ng m−3), and antimony (from 1 to 52 ng m−3). Firework-contaminated aerosols of similarly metalliferous composition were also identified at the other monitoring sites, although different sites show variations attributable to other sources such as bonfires and local industry. Unusual levels of the trace elements Ba, Sr and (to a lesser extent) Cu, always in proportions with Ba dominant, along with strongly enhanced K, Pb, and Sb, are identified as being particularly characteristic of firework aerosols. Although firework-related recreational pollution episodes are transient in nature, they are highly concentrated, contribute significantly to total annual metal emissions, and are on average fine enough to be easily inhaled and a health risk to susceptible individuals.” Teresa Moreno, Xavier Querol, Andrés Alastuey, Mari Cruz Minguillón, b, Jorge Pey, Sergio Rodriguez, José Vicente Miró, Carles Felis, Wes Gibbons, Atmospheric Environment, Volume 41, Issue 5, February 2007, Pages 913-922, doi:10.1016/j.atmosenv.2006.09.019.

The air pollution caused by the burning of fireworks during the lantern festival in Beijing – Wang et al. (2007) “The effects of the burning of fireworks on air quality in Beijing was firstly assessed from the ambient concentrations of various air pollutants (SO2, NO2, PM2.5, PM10 and chemical components in the particles) during the lantern festival in 2006. Eighteen ions, 20 elements, and black carbon were measured in PM2.5 and PM10, and the levels of organic carbon could be well estimated from the concentrations of dicarboxylic acids. Primary components of Ba, K, Sr, Cl, Pb, Mg and secondary components of C5H6O42−, C3H2O42−, C2O42−, C4H4O42−, SO42−, NO3 were over five times higher in the lantern days than in the normal days. The firework particles were acidic and of inorganic matter mostly with less amounts of secondary components. Primary aerosols from the burning of fireworks were mainly in the fine mode, while secondary formation of acidic anions mainly took place on the coarse particles. Nitrate was mainly formed through homogeneous gas-phase reactions of NO2, while sulfate was largely from heterogeneous catalytic transformations of SO2. Fe could catalyze the formation of nitrate through the reaction of α-Fe2O3 with HNO3, while in the formation of sulfate, Fe is not only the catalyst, but also the oxidant. A simple method using the concentration of potassium and a modified method using the ratio of Mg/Al have been developed to quantify the source contribution of fireworks. It was found that over 90% of the total mineral aerosol and 98% of Pb, 43% of total carbon, 28% of Zn, 8% of NO3, and 3% of SO42− in PM2.5 were from the emissions of fireworks on the lantern night.” Ying Wang, Guoshun Zhuang, Chang Xu, Zhisheng An, Atmospheric Environment, Volume 41, Issue 2, January 2007, Pages 417-431, doi:10.1016/j.atmosenv.2006.07.043.

Measurement of fine particulate and gas-phase species during the New Year’s fireworks 2005 in Mainz, Germany – Drewnick et al. (2006) “The chemical composition and chemically resolved size distributions of fine aerosol particles were measured at high time resolution (5 min) with a time-of-flight aerosol mass spectrometer (TOF-AMS) during the New Year’s 2005 fireworks in Mainz, central Germany. In addition, particle number concentrations and trace gas concentrations were measured using a condensation particle counter (CPC) and a proton transfer reaction mass spectrometer (PTR-MS). The main non-refractory components of the firework aerosol were potassium, sulfate, total organics and chloride. Increased trace gas mixing ratios of methanol, acetonitrile, acetone and acetaldehyde were observed. Aerosol nitrate and ammonium concentrations were not significantly affected by the fireworks as well as the measured aromatic trace gases. The sub-micron aerosol concentrations peaked about 20 min after midnight with total mass concentrations larger than 600 μg m−3. The trace gas concentrations peaked about 30 min later. Using the sulfur-to-potassium concentration ratio measured in another fireworks aerosol, it was for the first time possible to estimate the relative ionization efficiency of aerosol potassium, measured with the TOF-AMS. Here we found a value of RIEK=2.9.” Frank Drewnick, Silke S. Hings, Joachim Curtius, Gunter Eerdekens, Jonathan Williams, Atmospheric Environment, Volume 40, Issue 23, July 2006, Pages 4316-4327, doi:10.1016/j.atmosenv.2006.03.040. [Full text]

Short-term variation in air quality associated with firework events: A case study – Ravindra et al. (2003) “The effect of fireworks on air quality was assessed from the ambient concentrations of various air pollutants (SO2, NO2, PM10 and TSP) during Diwali festival in Hisar city (India), in November 1999. The extensive use of fireworks was found to be related to short-term variation in air quality. During the festival the concentration of SO2 was observed to be increased [similar]10-fold at few sites, whereas the concentrations of NO2, PM10 and TSP increased 2–3 times, compared to the data collected on a typical winter day in December 1999. The maximum NO2 concentration was observed a day after the festival. The diurnal pattern of the above pollutants showed a slight increase in the night. The levels of these pollutants observed during Diwali were found to be moderately high, which can be associated with serious health impacts.” Khaiwal Ravindra, Suman Mor and C. P. Kaushik, J. Environ. Monit., 2003, 5, 260-264, DOI: 10.1039/B211943A. [Full text]

Changes in forced expiratory flow due to air pollution from fireworks: Preliminary report – Smith & Dinh (1975) “Spirometry in humans and air sampling have been performed during a brief but intense bout of air pollution due to exploding fireworks on New Year’s Eve in Honolulu, Hawaii. An integrating nephelometer recorded a peak concentration of respirable particles in excess of 3.8 mg/m3. X-ray dispersive analysis, combined with scanning electron microscopy of particles collected with an Anderson cascade impactor, indicated that most of the small particles were probably crystals of KCl. Conditions were ideal for a possible SO2KCl aerosol synergism which may have led to the measured changes in maximal midexpiratory flow (FEV25–75%). Two male subjects with a history of chronic respiratory disease experienced an average decrease of 26% in FEV25–75% when compared to that measured the previous night. Three normal males experienced a 4.7% decrease approaching statistical significance (0.1 > P > 0.05), but the overall difference in FEV25–75% in healthy male and female subjects combined was not statistically significant. Thus, while susceptible people may be measurably affected, the general population of Honolulu probably experienced little, if any, change in FEV25–75% with the air pollution levels reported here.” Richard Merrill Smith, Vu-Dinh Dinh, Environmental Research, Volume 9, Issue 3, June 1975, Pages 321-331, doi:10.1016/0013-9351(75)90012-2.


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New research from last week 51/2011

Posted by Ari Jokimäki on December 26, 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.

Observed decrease in Atlantic meridional overturning circulation is probably natural fluctuation

Observation of decadal change in the Atlantic meridional overturning circulation using 10 years of continuous transport data – Send et al. (2011)“The meridional overturning circulation (MOC) represents the main mechanism for the oceanic northward heat transport in the Atlantic, and fluctuations of this circulation are believed to have major impacts on northern hemisphere climate. While numerical ocean and climate models and paleo-records show large variability in this circulation, the use of direct observations of the MOC for detecting climate-timescale changes has proven difficult so far. This report presents the first observational record of MOC measurements that is continuous and sufficiently long to exhibit decadal-scale changes, here a decrease by 20% over the observational period (Jan. 2000–June 2009) and large interannual changes in the flow and its vertical structure. Data are from a mooring array at 16°N (Meridional Overturning Variability Experiment, MOVE). The observed change agrees with the amplitude of multi-decadal natural fluctuations seen in numerical ocean and climate models. Knowledge of the existence and phasing of such internal cycles provides multi-decadal climate predictability. Recently, some numerical model simulations have produced results that show a weakening of the MOC since the 1990’s and observational confirmation of this now is a high priority.” Send, U., M. Lankhorst, and T. Kanzow (2011), Geophys. Res. Lett., 38, L24606, doi:10.1029/2011GL049801.

Measurements and successful modelling of atmospheric carbon dioxide in 4-D

Three-dimensional variations of atmospheric CO2: aircraft measurements and multi-transport model simulations – Niwa et al. (2011)“Numerical simulation and validation of three-dimensional structure of atmospheric carbon dioxide (CO2) is necessary for quantification of transport model uncertainty and its role on surface flux estimation by inverse modeling. Simulations of atmospheric CO2 were performed using four transport models and two sets of surface fluxes compared with an aircraft measurement dataset of Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL), covering various latitudes, longitudes, and heights. Under this transport model intercomparison project, spatiotemporal variations of CO2 concentration for 2006–2007 were analyzed with a three-dimensional perspective. Results show that the models reasonably simulated vertical profiles and seasonal variations not only over northern latitude areas but also over the tropics and southern latitudes. From CONTRAIL measurements and model simulations, intrusion of northern CO2 in to the Southern Hemisphere, through the upper troposphere, was confirmed. Furthermore, models well simulated the vertical propagation of seasonal variation in the northern free troposphere. However, significant model-observation discrepancies were found in Asian regions, which are attributable to uncertainty of the surface CO2 flux data. In summer season, differences in latitudinal gradients by the fluxes are comparable to or greater than model-model differences even in the free troposphere. This result suggests that active summer vertical transport sufficiently ventilates flux signals up to the free troposphere and the models could use those for inferring surface CO2 fluxes.” Niwa, Y., Patra, P. K., Sawa, Y., Machida, T., Matsueda, H., Belikov, D., Maki, T., Ikegami, M., Imasu, R., Maksyutov, S., Oda, T., Satoh, M., and Takigawa, M., Atmos. Chem. Phys., 11, 13359-13375, doi:10.5194/acp-11-13359-2011, 2011. [Full text]

Hansen et al. new paper on Earth’s energy imbalance

Earth’s energy imbalance and implications – Hansen et al. (2011)“Improving observations of ocean heat content show that Earth is absorbing more energy from the Sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.58 ± 0.15 W m−2 during the 6-yr period 2005–2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be −1.6 ± 0.3 W m−2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade.” Hansen, J., Sato, M., Kharecha, P., and von Schuckmann, K., Atmos. Chem. Phys., 11, 13421-13449, doi:10.5194/acp-11-13421-2011, 2011. [Full text]

Vegetation growth trend has decreased in China due to reduced precipitation

Recent change of vegetation growth trend in China – Peng et al. (2011)“Using satellite-derived normalized difference vegetation index (NDVI) data, several previous studies have indicated that vegetation growth significantly increased in most areas of China during the period 1982–99. In this letter, we extended the study period to 2010. We found that at the national scale the growing season (April–October) NDVI significantly increased by 0.0007 yr−1 from 1982 to 2010, but the increasing trend in NDVI over the last decade decreased in comparison to that of the 1982–99 period. The trends in NDVI show significant seasonal and spatial variances. The increasing trend in April and May (AM) NDVI (0.0013 yr−1) is larger than those in June, July and August (JJA) (0.0003 yr−1) and September and October (SO) (0.0008 yr−1). This relatively small increasing trend of JJA NDVI during 1982–2010 compared with that during 1982–99 (0.0012 yr−1) (Piao et al 2003 J. Geophys. Res.—Atmos. 108 4401) implies a change in the JJA vegetation growth trend, which significantly turned from increasing (0.0039 yr−1) to slightly decreasing ( − 0.0002 yr−1) in 1988. Regarding the spatial pattern of changes in NDVI, the growing season NDVI increased (over 0.0020 yr−1) from 1982 to 2010 in southern China, while its change was close to zero in northern China, as a result of a significant changing trend reversal that occurred in the 1990s and early 2000s. In northern China, the growing season NDVI significantly increased before the 1990s as a result of warming and enhanced precipitation, but decreased after the 1990s due to drought stress strengthened by warming and reduced precipitation. Our results also show that the responses of vegetation growth to climate change vary across different seasons and ecosystems.” Shushi Peng et al 2011 Environ. Res. Lett. 6 044027 doi:10.1088/1748-9326/6/4/044027. [Full text]

How coral communities survived past rapid warming events?

The evolution of mid Paleocene – early Eocene coral communities: How to survive during rapid global warming – Zamagni et al. (2011)“Today, diverse communities of zooxanthellate corals thrive, but do not build reef, under a wide range of environmental conditions. In these settings they inhabit natural bottom communities, sometimes forming patch-reefs, coral carpets and knobs. Episodes in the fossil record, characterized by limited coral-reef development but widespread occurrence of coral-bearing carbonates, may represent the fossil analogues of these non-reef building, zooxanthellate coral communities. If so, the study of these corals could have valuable implications for paleoenvironmental reconstructions. Here we focus on the evolution of early Paleogene corals as a fossil example of coral communities mainly composed by zooxanthellate corals (or likely zooxanthellate), commonly occurring within carbonate biofacies and with relatively high diversity but with a limited bioconstructional potential as testified by the reduced record of coral reefs. We correlate changes of bioconstructional potential and community compositions of these fossil corals with the main ecological/environmental conditions at that time. The early Paleogene greenhouse climate was characterized by relatively short pulses of warming with the most prominent occurring at the Paleocene-Eocene boundary (PETM event), associated with high weathering rates, nutrient fluxes, and pCO2 levels. A synthesis of coral occurrences integrated with our data from the Adriatic Carbonate Platform (SW Slovenia) and the Minervois region (SW France), provide evidence for temporal changes in the reef-building capacity of corals associated with a shift in community composition towards forms adapted to tolerate deteriorating sea-water conditions. During the middle Paleocene coral-algal patch reefs and barrier reefs occurred from shallow-water settings, locally with reef-crest structures. A first shift can be traced from middle Paleocene to late Paleocene, with small coral-algal patch reefs and coral-bearing mounds development in shallow to intermediate water depths. In these mounds corals were highly subordinated as bioconstructors to other groups tolerant to higher levels of trophic resources (calcareous red algae, encrusting foraminifera, microbes, and sponges). A second shift occurred at the onset of the early Eocene with a further reduction of coral framework-building capacity. These coral communities mainly formed knobs in shallow-water, turbid settings associated with abundant foraminiferal deposits. We suggest that environmental conditions other than high temperature determined a combination of interrelated stressors that limited the coral-reef construction. A continuous enhancement of sediment load/nutrients combined with geochemical changes of ocean waters likely displaced corals as the main bioconstructors during the late Paleocene-early Eocene times. Nonetheless, these conditions did not affect the capacity of some corals to colonize the substrate, maintain biodiversity, and act as locally important carbonate-sediment producers, suggesting broad environmental tolerance limits of various species of corals. The implications of this study include clues as to how both ancient and modern zooxanthellate corals could respond to changing climate.” J. Zamagni, M. Mutti, A. Košir, Palaeogeography, Palaeoclimatology, Palaeoecology, doi:10.1016/j.palaeo.2011.12.010.

Increase in the global population living under water-stressed conditions

Modelling global water stress of the recent past: on the relative importance of trends in water demand and climate variability – Wada et al. (2011) “During the past decades, human water use has more than doubled, yet available freshwater resources are finite. As a result, water scarcity has been prevalent in various regions of the world. Here, we present the first global assessment of past development of water stress considering not only climate variability but also growing water demand, desalinated water use and non-renewable groundwater abstraction over the period 1960–2001 at a spatial resolution of 0.5°. Agricultural water demand is estimated based on past extents of irrigated areas and livestock densities. We approximate past economic development based on GDP, energy and household consumption and electricity production, which are subsequently used together with population numbers to estimate industrial and domestic water demand. Climate variability is expressed by simulated blue water availability defined by freshwater in rivers, lakes, wetlands and reservoirs by means of the global hydrological model PCR-GLOBWB. We thus define blue water stress by comparing blue water availability with corresponding net total blue water demand by means of the commonly used, Water Scarcity Index. The results show a drastic increase in the global population living under water-stressed conditions (i.e. moderate to high water stress) due to growing water demand, primarily for irrigation, which has more than doubled from 1708/818 to 3708/1832 km3 yr−1 (gross/net) over the period 1960–2000. We estimate that 800 million people or 27% of the global population were living under water-stressed conditions for 1960. This number is eventually increased to 2.6 billion or 43% for 2000. Our results indicate that increased water demand is a decisive factor for heightened water stress in various regions such as India and North China, enhancing the intensity of water stress up to 200%, while climate variability is often a main determinant of extreme events. However, our results also suggest that in several emerging and developing economies (e.g. India, Turkey, Romania and Cuba) some of past extreme events were anthropogenically driven due to increased water demand rather than being climate-induced.” Wada, Y., van Beek, L. P. H., and Bierkens, M. F. P., Hydrol. Earth Syst. Sci., 15, 3785-3808, doi:10.5194/hess-15-3785-2011, 2011. [Full text]

Many surface albedo geoengineering schemes are useless for global climate change reversal

Climatic effects of surface albedo geoengineering – Irvine et al. (2011) “Various surface albedo modification geoengineering schemes such as those involving desert, urban, or agricultural areas have been proposed as potential strategies for helping counteract the warming caused by greenhouse gas emissions. However, such schemes tend to be inherently limited in their potential and would create a much more heterogeneous radiative forcing than propositions for space-based “reflectors” and enhanced stratospheric aerosol concentrations. Here we present results of a series of atmosphere–ocean general circulation model (GCM) simulations to compare three surface albedo geoengineering proposals: urban, cropland, and desert albedo enhancement. We find that the cooling effect of surface albedo modification is strongly seasonal and mostly confined to the areas of application. For urban and cropland geoengineering, the global effects are minor but, because of being colocated with areas of human activity, they may provide some regional benefits. Global desert geoengineering, which is associated with significant global-scale changes in circulation and the hydrological cycle, causes a smaller reduction in global precipitation per degree of cooling than sunshade geoengineering, 1.1% K−1 and 2.0% K−1 respectively, but a far greater reduction in the precipitation over land, 3.9% K−1 compared with 1.0% K−1. Desert geoengineering also causes large regional-scale changes in precipitation with a large reduction in the intensity of the Indian and African monsoons in particular. None of the schemes studied reverse the climate changes associated with a doubling of CO2, with desert geoengineering profoundly altering the climate and with urban and cropland geoengineering providing only some regional amelioration at most.” Irvine, P. J., A. Ridgwell, and D. J. Lunt (2011), J. Geophys. Res., 116, D24112, doi:10.1029/2011JD016281.

Summer warming expected to permanently show up by 2020 over most areas of the continental United States

Transient regional climate change: Analysis of the summer climate response in a high-resolution, century-scale ensemble experiment over the continental United States – Diffenbaugh et al. (2011) “Integrating the potential for climate change impacts on policy and planning decisions requires quantification of the emergence of subregional climate changes that could occur in response to transient changes in global radiative forcing. Here we report results from a high-resolution, century-scale ensemble simulation of climate in the United States, forced by atmospheric constituent concentrations from the Special Report on Emissions Scenarios A1B scenario. We find that 21st century summer warming permanently emerges beyond the baseline decadal-scale variability prior to 2020 over most areas of the continental United States. Permanent emergence beyond the baseline annual-scale variability shows much greater spatial heterogeneity, with emergence occurring prior to 2030 over areas of the southwestern United States but not prior to the end of the 21st century over much of the south central and southeastern United States. The pattern of emergence of robust summer warming contrasts with the pattern of summer warming magnitude, which is greatest over the central United States and smallest over the western United States. In addition to stronger warming, the central United States also exhibits stronger coupling of changes in surface air temperature, precipitation, and moisture and energy fluxes, along with changes in atmospheric circulation toward increased anticylonic anomalies in the midtroposphere and a poleward shift in the midlatitude jet aloft. However, as a fraction of the baseline variability, the transient warming over the central United States is smaller than the warming over the southwestern or northeastern United States, delaying the emergence of the warming signal over the central United States. Our comparisons with observations and the Coupled Model Intercomparison Project Phase 3 ensemble of global climate model experiments suggest that near-term global warming is likely to cause robust subregional-scale warming over areas that exhibit relatively little baseline variability. In contrast, where there is greater variability in the baseline climate dynamics there can be greater variability in the response to elevated greenhouse forcing, decreasing the robustness of the transient warming signal.” Diffenbaugh, N. S., M. Ashfaq, and M. Scherer (2011), J. Geophys. Res., 116, D24111, doi:10.1029/2011JD016458.

New accurate 20 million year reconstruction of atmospheric CO2

Reconstruction of a continuous high-resolution CO2 record over the past 20 million years – van de Wal et al. (2011) “The gradual cooling of the climate during the Cenozoic has generally been attributed to a decrease in CO2 concentration in the atmosphere. The lack of transient climate models and, in particular, the lack of high-resolution proxy records of CO2, beyond the ice-core record prohibit, however, a full understanding of, for example, the inception of the Northern Hemisphere glaciation and mid-Pleistocene transition. Here we elaborate on an inverse modelling technique to reconstruct a continuous CO2 series over the past 20 million year (Myr), by decomposing the global deep-sea benthic δ18O record into a mutually consistent temperature and sea level record, using a set of 1-D models of the major Northern and Southern Hemisphere ice sheets. We subsequently compared the modelled temperature record with ice core and proxy-derived CO2 data to create a continuous CO2 reconstruction over the past 20 Myr. Results show a gradual decline from 450 ppmv around 15 Myr ago to 225 ppmv for mean conditions of the glacial-interglacial cycles of the last 1 Myr, coinciding with a gradual cooling of the global surface temperature of 10 K. Between 13 to 3 Myr ago there is no long-term sea level variation caused by ice-volume changes. We find no evidence of change in the long-term relation between temperature change and CO2, other than the effect following the saturation of the absorption bands for CO2. The reconstructed CO2 record shows that the Northern Hemisphere glaciation starts once the long-term average CO2 concentration drops below 265 ppmv after a period of strong decrease in CO2. Finally, only a small long-term decline of 23 ppmv is found during the mid-Pleistocene transition, constraining theories on this major transition in the climate system. The approach is not accurate enough to revise current ideas about climate sensitivity.” van de Wal, R. S. W., de Boer, B., Lourens, L. J., Köhler, P., and Bintanja, R., Clim. Past, 7, 1459-1469, doi:10.5194/cp-7-1459-2011, 2011. [Full text]

Shrubs are invading Arctic tundra

Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities – Myers-Smith et al. (2011) “Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of investigation for future research. Satellite observations from around the circumpolar Arctic, showing increased productivity, measured as changes in ‘greenness’, have coincided with a general rise in high-latitude air temperatures and have been partly attributed to increases in shrub cover. Studies indicate that warming temperatures, changes in snow cover, altered disturbance regimes as a result of permafrost thaw, tundra fires, and anthropogenic activities or changes in herbivory intensity are all contributing to observed changes in shrub abundance. A large-scale increase in shrub cover will change the structure of tundra ecosystems and alter energy fluxes, regional climate, soil–atmosphere exchange of water, carbon and nutrients, and ecological interactions between species. In order to project future rates of shrub expansion and understand the feedbacks to ecosystem and climate processes, future research should investigate the species or trait-specific responses of shrubs to climate change including: (1) the temperature sensitivity of shrub growth, (2) factors controlling the recruitment of new individuals, and (3) the relative influence of the positive and negative feedbacks involved in shrub expansion.” Isla H Myers-Smith et al 2011 Environ. Res. Lett. 6 045509 doi:10.1088/1748-9326/6/4/045509. [Full text]

Growing season has gotten longer for nothern vegetation

Recent changes in phenology over the northern high latitudes detected from multi-satellite data – Zeng et al. (2011) “Phenology of vegetation is a sensitive and valuable indicator of the dynamic responses of terrestrial ecosystems to climate change. Therefore, to better understand and predict ecosystems dynamics, it is important to reduce uncertainties in detecting phenological changes. Here, changes in phenology over the past several decades across the northern high-latitude region (≥60°N) were examined by calibrating and analyzing time series of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Very High Resolution Radiometer (AVHRR). Over the past decade (2000–10), an expanded length of the growing season (LOS) was detected by MODIS, largely due to an earlier start of the growing season (SOS) by 4.7 days per decade and a delayed end of the growing season (EOS) by 1.6 days per decade over the northern high latitudes. There were significant differences between North America and Eurasia in phenology from 2000 to 2010 based on MODIS data (SOS: df = 21, F = 49.02, p < 0.0001; EOS: df = 21, F = 49.25, p < 0.0001; LOS: df = 21, F = 79.40, p < 0.0001). In northern America, SOS advanced by 11.5 days per decade, and EOS was delayed by 2.2 days per decade. In Eurasia, SOS advanced by 2.7 days per decade, and EOS was delayed by 3.5 days per decade. SOS has likely advanced due to the warming Arctic during April and May. Our results suggest that in recent decades the longer vegetation growing seasons can be attributed to more advanced SOS rather than delayed EOS. AVHRR detected longer LOS over the past three decades, largely related to delayed EOS rather than advanced SOS. These two datasets are significantly different in key phenological parameters (SOS: df = 17, F = 14.63, p = 0.0015; EOS: df = 17, F = 38.69, p < 0.0001; LOS: df = 17, F = 16.47, p = 0.0009) from 2000 to 2008 over the northern high latitudes. Thus, further inter-calibration between the sensors is needed to resolve the inconsistency and to better understand long-term trends of vegetation growth in the Arctic.” Heqing Zeng et al 2011 Environ. Res. Lett. 6 045508 doi:10.1088/1748-9326/6/4/045508. [Full text]

Study on cloud changes with global warming

Computing and Partitioning Cloud Feedbacks using Cloud Property Histograms. Part II: Attribution to Changes in Cloud Amount, Altitude, and Optical Depth – Zelinka et al. (2011) “Cloud radiative kernels and histograms of cloud fraction, both as functions of cloud top pressure and optical depth, are used to quantify cloud amount, altitude, and optical depth feedbacks. The analysis is applied to doubled CO2 simulations from eleven global climate models in the Cloud Feedback Model Intercomparison Project. Global, annual, and ensemble mean longwave (LW) and shortwave (SW) cloud feedbacks are positive, with the latter nearly twice as as large as the former. The robust increase in cloud top altitude is the dominant contributor to the positive LW cloud feedback. The negative impact of reductions in cloud amount offsets more than half of the positive impact of rising clouds on LW cloud feedback, but the magnitude of compensation varies considerably across models. In contrast, robust reductions in cloud amount make a large and virtually unopposed positive contribution to SW cloud feedback, though the inter-model spread is greater than for any other individual feedback component. Overall reductions in cloud amount have twice as large an impact on SW fluxes as on LW fluxes such that the net cloud amount feedback is moderately positive, with no models exhibiting a negative value. As a consequence of large but partially offsetting effects of cloud amount reductions on LW and SW feedbacks, both the mean and inter-model spread in net cloud amount feedback are smaller than those of the net cloud altitude feedback. Finally, we find that the large negative cloud feedback at high latitudes results from robust increases in cloud optical depth, not from increases in total cloud amount as is commonly assumed.” Mark D. Zelinka, Stephen A. Klein, Dennis L. Hartmann, Journal of Climate 2011, doi: [Full text]

Clean coal power comes with side-effects

The climate penalty for clean fossil fuel combustion – Junkermann et al. (2011) “To cope with the world’s growing demand for energy, a large number of coal-fired power plants are currently in operation or under construction. To prevent environmental damage from acidic sulphur and particulate emissions, many such installations are equipped with flue gas cleaning technology that reduces the emitted amounts of sulphur dioxide (SO2) and nitrogen dioxide (NO2). However, the consequences of this technology for aerosol emissions, and in particular the regional scale impact on cloud microphysics, have not been studied until now. We performed airborne investigations to measure aerosol size distributions in the air masses downwind of coal-fired power installations. We show how the current generation of clean technology reduces the emission of sulphur and fine particulate matter, but leads to an unanticipated increase in the direct emission of ultrafine particles (1–10 nm median diameter) which are highly effective precursors of cloud condensation nuclei (CCN). Our analysis shows how these additional ultrafine particles probably modify cloud microphysics, as well as precipitation intensity and distribution on a regional scale downwind of emission sources. Effectively, the number of small water droplets might be increased, thus reducing the water available for large droplets and rain formation. The possible corresponding changes in the precipitation budget with a shift from more frequent steady rain to occasionally more vigorous rain events, or even a significant regional reduction of annual precipitation, introduce an unanticipated risk for regional climate and agricultural production, especially in semi-arid climate zones.” Junkermann, W., Vogel, B., and Sutton, M. A., Atmos. Chem. Phys., 11, 12917-12924, doi:10.5194/acp-11-12917-2011, 2011. [Full text]

Madden-Julian Oscillation contributes to Arctic amplification

The impact of the Madden-Julian Oscillation trend on the Arctic amplification of surface air temperature during the 1979–2008 boreal winter – Yoo et al. (2011) “One of the most prominent and important features of climate change is that surface air temperature (SAT) change is greatest at high latitudes. The cause for this Arctic amplification of SAT is uncertain. Using ERA-Interim reanalysis data, we show that Arctic amplification during the past 30 years (1979 to 2008) is linked to the Madden-Julian Oscillation (MJO), the primary mode of intraseasonal variability in the tropics. Specifically, it is shown that interdecadal changes in the frequency of occurrence of individual MJO phases have had considerable influence on the Arctic warming during the boreal winter. During that time period, MJO phases 4–6 exhibited a large increase and phases 1–2 a moderate decrease in their frequency of occurrence. Time lagged composites of the SAT show that MJO phases 4–6, which correspond to enhanced localized tropical heating, are followed 1–2 weeks later by Arctic warming. Similarly, MJO phases 1–2, which are associated with more zonally uniform tropical heating, are followed by Arctic cooling. These relationships between the Arctic SAT and the spatial structure of the tropical heating are consistent with the poleward propagation mechanism of Lee et al. (2011a, 2011b). By incorporating both the trend in MJO phase and the intraseasonal SAT anomaly associated with the MJO, it was found that the MJO-induced SAT trend accounts for 10–20% of the observed Arctic amplification over the Arctic Ocean.” Yoo, C., S. Feldstein, and S. Lee (2011), Geophys. Res. Lett., 38, L24804, doi:10.1029/2011GL049881.

Millennial-scale climate cycles might have been active throughout geologic time

Millennial-scale climate cycles in Permian–Carboniferous rhythmites: Permanent feature throughout geologic time? – Franco et al. (2011) “Two late Paleozoic glacial rhythmite successions from the Itararé Group (Paraná Basin, Brazil) were examined for paleoclimate variations. Paleomagnetic (characteristic remanent magnetization, ChRM) and magnetic susceptibility (Kz) measurements taken from the rhythmites are interpreted as paleoclimatic proxies. Ratios of low-frequency components in the Kz variations suggest Milankovitch periodicities; this leads to recognition of other, millennial-scale variations reminiscent of abrupt climate changes during late Quaternary time, and are suggestive of Bond cycles and the 2.4 k.y. solar cycle. We infer from these patterns that millennial-scale climate change is not restricted to the Quaternary Period, and that millennial forcing mechanisms may have been prevalent throughout geologic time.” Daniel R. Franco, Linda A. Hinnov and Marcia Ernesto, Geology, v. 40 no. 1 p. 19-22, doi: 10.1130/G32338.1.

El Niño might not have been permanent during Late Cretaceous

El Niño–Southern Oscillation variability from the Late Cretaceous Marca Shale of California – Davies et al. (2011) “Changes in the possible behavior of El Niño–Southern Oscillation (ENSO) with global warming have provoked interest in records of ENSO from past “greenhouse” climate states. The latest Cretaceous laminated Marca Shale of California permits a seasonal-scale reconstruction of water column flux events and hence interannual paleoclimate variability. The annual flux cycle resembles that of the modern Gulf of California with diatoms characteristic of spring upwelling blooms followed by silt and clay, and is consistent with the existence of a paleo–North American Monsoon that brought input of terrigenous sediment during summer storms and precipitation runoff. Variation is also indicated in the extent of water column oxygenation by differences in lamina preservation. Time series analysis of interannual variability in terrigenous sediment and diatom flux and in the degree of bioturbation indicates strong periodicities in the quasi-biennial (2.1–2.8 yr) and low-frequency (4.1–6.3 yr) bands both characteristic of ENSO forcing, as well as decadal frequencies. This evidence for robust Late Cretaceous ENSO variability does not support the theory of a “permanent El Niño,” in the sense of a continual El Niño–like state, in periods of warmer climate.” Andrew Davies, Alan E.S. Kemp, Graham P. Weedon and John A. Barron, Geology, v. 40 no. 1 p. 15-18, doi: 10.1130/G32329.1.

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New research from last week 50/2011

Posted by Ari Jokimäki on December 19, 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.

Developing methods for model performance comparison with observations

On the observational assessment of climate model performance – Annan et al. (2011) “Comparison of model outputs with observations of the climate system forms an essential component of model assessment and is crucial for building our confidence in model predictions. Methods for undertaking this comparison are not always clearly justified and understood. Here we show that the popular approach of comparing the ensemble spread to a so-called “observationally-constrained pdf” can be highly misleading. Such a comparison will almost certainly result in disagreement, but in reality tells us little about the performance of the ensemble. We present an alternative approach, and show how it may lead to very different, and rather more encouraging, conclusions. We additionally present some necessary conditions for an ensemble (or more generally, a probabilistic prediction) to be challenged by an observation.” Annan, J. D., J. C. Hargreaves, and K. Tachiiri (2011), Geophys. Res. Lett., 38, L24702, doi:10.1029/2011GL049812.

Revealing annual ice core layers from Eemian interglacial

Annual layering in the NGRIP ice core during the Eemian – Svensson et al. (2011) “The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core, annual layers can be identified from impurity records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye. In this study, we apply a newly developed setup for high-resolution ice core impurity analysis to produce continuous records of dust, sodium and ammonium concentrations as well as conductivity of melt water. We analyzed three 2.2 m sections of ice from the Eemian and the glacial inception. In all of the analyzed ice, annual layers can clearly be recognized, most prominently in the dust and conductivity profiles. Part of the samples is, however, contaminated in dust, most likely from drill liquid. It is interesting that the annual layering is preserved despite a very active crystal growth and grain boundary migration in the deep and warm NGRIP ice. Based on annual layer counting of the new records, we determine a mean annual layer thickness close to 11 mm for all three sections, which, to first order, confirms the modeled NGRIP time scale (ss09sea). The counting does, however, suggest a longer duration of the climatically warmest part of the NGRIP record (MIS5e) of up to 1 ka as compared to the model estimate. Our results suggest that stratigraphic layer counting is possible basically throughout the entire NGRIP ice core, provided sufficiently highly-resolved profiles become available.” Svensson, A., Bigler, M., Kettner, E., Dahl-Jensen, D., Johnsen, S., Kipfstuhl, S., Nielsen, M., and Steffensen, J. P., Clim. Past, 7, 1427-1437, doi:10.5194/cp-7-1427-2011, 2011. [Full text]

Assessment of Southern Hemisphere paleoclimate records

Southern Hemisphere high-resolution palaeoclimate records of the last 2000 years – Neukom & Gergis (2011) “This study presents a comprehensive assessment of high-resolution Southern Hemisphere (SH) paleoarchives covering the last 2000 years. We identified 174 monthly to annually resolved climate proxy (tree ring, coral, ice core, documentary, speleothem and sedimentary) records from the Hemisphere. We assess the interannual and decadal sensitivity of each proxy record to large-scale circulation indices from the Pacific, Indian and Southern Ocean regions over the twentieth century. We then analyse the potential of this newly expanded palaeoclimate network to collectively represent predictands (sea surface temperature, sea level pressure, surface air temperature and precipitation) commonly used in climate reconstructions. The key dynamical centres-of-action of the equatorial Indo-Pacific are well captured by the palaeoclimate network, indicating that there is considerable reconstruction potential in this region, particularly in the post AD 1600 period when a number of long coral records are available. Current spatiotemporal gaps in data coverage and regions where significant potential for future proxy collection exists are discussed. We then highlight the need for new and extended records from key dynamical regions of the Southern Hemisphere. Although large-scale climate field reconstructions for the SH are in their infancy, we report that excellent progress in the development of regional proxies now makes plausible estimates of continental- to hemispheric-scale climate variations possible.” Raphael Neukom, Joëlle Gergis, The Holocene December 16, 2011 0959683611427335, doi: 10.1177/0959683611427335.

Warmer climate makes heavy rain heavier and more frequent and weak rain weaker and less frequent

Mechanisms for global warming impacts on rainfall frequency and intensity – Chou et al. (2011) “Global warming mechanisms that cause changes in frequency and intensity of precipitation in the tropics are examined in climate model simulations. Under global warming, tropical precipitation tends to be more frequent and intense for heavy precipitation, but becomes less frequent and weaker for light precipitation. Changes in precipitation frequency and intensity are both controlled by thermodynamic and dynamic components. The thermodynamic component is induced by changes in atmospheric water vapor, while the dynamic component is associated with changes in vertical motion. A set of equations is derived to estimate both thermodynamic and dynamic contributions to changes in frequency and intensity of precipitation, especially for heavy precipitation. In the thermodynamic contribution, increased water vapor reduces the magnitude of the required vertical motion to generate the same strength of precipitation, so precipitation frequency increases. Increased water vapor also intensifies precipitation due to the enhancement of water vapor availability in the atmosphere. In the dynamic contribution, the more stable atmosphere tends to reduce the frequency and intensity of precipitation, except for the heaviest precipitation. The dynamic component strengthens the heaviest precipitation in most climate model simulations, possibly due to a positive convective feedback.” Chia Chou, Chao-An Chen, Pei-Hua Tan, Kuan Ting Chen, Journal of Climate 2011, doi:

We know how Greenland outlet glaciers respond to warming but how they respond to cooling?

Response of a marine-terminating Greenland outlet glacier to abrupt cooling 8200 and 9300 years ago – Young et al. (2011) “Long-term records of Greenland outlet-glacier change extending beyond the satellite era can inform future predictions of Greenland Ice Sheet behavior. Of particular relevance is elucidating the Greenland Ice Sheet’s response to decadal- and centennial-scale climate change. Here, we reconstruct the early Holocene history of Jakobshavn Isbræ, Greenland’s largest outlet glacier, using 10Be surface exposure ages and 14C-dated lake sediments. Our chronology of ice-margin change demonstrates that Jakobshavn Isbræ advanced to deposit moraines in response to abrupt cooling recorded in central Greenland ice cores ca. 8,200 and 9,300 years ago. While the rapid, dynamically aided retreat of many Greenland outlet glaciers in response to warming is well documented, these results indicate that marine-terminating outlet glaciers are also able to respond quickly to cooling. We suggest that short lag times of high ice flux margins enable a greater magnitude response of marine-terminating outlets to abrupt climate change compared to their land-terminating counterparts.” Young, N. E., J. P. Briner, Y. Axford, B. Csatho, G. S. Babonis, D. H. Rood, and R. C. Finkel (2011), Geophys. Res. Lett., 38, L24701, doi:10.1029/2011GL049639.

The rise but not fall of Taku Glacier late summer transient snowline

Utility of late summer transient snowline migration rate on Taku Glacier, Alaska – Pelto (2011) “On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient derived from the TSL and SWE measured in snowpits at 1000 m from 1998–2010 ranges from 2.6–3.8 mm m−1. Probing transects from 950 m–1100 m directly measure SWE and yield a slightly higher balance gradient of 3.3–3.8 mm m−1. The TSL on Taku Glacier is identified in MODIS and Landsat 4 and 7 Thematic Mapper images for 31 dates during the 2004–2010 period to assess the consistency of its rate of rise and reliability in assessing ablation for mass balance assessment. For example, in 2010, the TSL was 750 m on 28 July, 800 m on 5 August, 875 m on 14 August, 925 m on 30 August, and 975 m on 20 September. The mean observed probing balance gradient was 3.3 mm m−1, combined with the TSL rise of 3.7 m day−1 yields an ablation rate of 12.2 mm day−1 from mid-July to mid-Sept, 2010. The TSL rise in the region from 750–1100 m on Taku Glacier during eleven periods each covering more than 14 days during the ablation season indicates a mean TSL rise of 3.7 m day−1, the rate of rise is relatively consistent ranging from 3.1 to 4.4 m day−1. This rate is useful for ascertaining the final ELA if images or observations are not available near the end of the ablation season. The mean ablation from 750–1100 m during the July–September period determined from the TSL rise and the observed balance gradient is 11–13 mm day−1 on Taku Glacier during the 2004–2010 period. The potential for providing an estimate of bn from TSL observations late in the melt season from satellite images combined with the frequent availability of such images provides a means for efficient mass balance assessment in many years and on many glaciers.” Pelto, M., The Cryosphere, 5, 1127-1133, doi:10.5194/tc-5-1127-2011, 2011. [Full text]

Review article on North Atlantic Oscillation

Past and recent changes in the North Atlantic oscillation – Pinto & Raible (2011) “The North Atlantic oscillation (NAO) is under current climate conditions the leading mode of atmospheric circulation variability over the North Atlantic region. While the pattern is present during the entire year, it is most important during winter, explaining a large part of the variability of the large-scale pressure field, being thus largely determinant for the weather conditions over the North Atlantic basin and over Western Europe. In this study, a review of recent literature on the basic understanding of the NAO, its variability on different time scales and driving physical mechanisms is presented. In particular, the observed NAO variations and long-term trends are put into a long term perspective by considering paleo-proxy evidence. A representative number of recently released NAO reconstructions are discussed. While the reconstructions agree reasonably well with observations during the instrumental overlapping period, there is a rather high uncertainty between the different reconstructions for the pre-instrumental period, which leads to partially incoherent results, that is, periods where the NAO reconstructions do not agree even in sign. Finally, we highlight the future need of a broader definition of the NAO, the assessment of the stability of the teleconnection centers over time, the analysis of the relations to other relevant variables like temperature and precipitation, as well as on the relevant processes involved.” Joaquim G. Pinto, Christoph C. Raible, Wiley Interdisciplinary Reviews: Climate Change, DOI: 10.1002/wcc.150.

New review article looks at geological fakes and frauds

Geological Fakes and Frauds – Ruffell et al. (2011) “Some geological fakes and frauds are carried out solely for financial gain (mining fraud), whereas others maybe have increasing aesthetic appeal (faked fossils) or academic advancement (fabricated data) as their motive. All types of geological fake or fraud can be ingenious and sophisticated, as demonstrated in this article. Fake gems, faked fossils and mining fraud are common examples where monetary profit is to blame: nonetheless these may impact both scientific theory and the reputation of geologists and Earth scientists. The substitution or fabrication of both physical and intellectual data also occurs for no direct financial gain, such as career advancement or establishment of belief (e.g. evolution vs. creationism). Knowledge of such fakes and frauds may assist in spotting undetected geological crimes: application of geoforensic techniques helps the scientific community to detect such activity, which ultimately undermines scientific integrity.” Alastair Ruffell, Niall Majury, William E. Brooks, Earth-Science Reviews, doi:10.1016/j.earscirev.2011.12.001.

Moon affects the weather

Monthly lunar declination extremes’ influence on tropospheric circulation patterns – Krahenbuhl et al. (2011) “Short-term tidal variations occurring every 27.3 days from southern (negative) to northern (positive) maximum lunar declinations (MLDs), and back to southern declination of the moon have been overlooked in weather studies. These short-term MLD variations’ significance is that when lunar declination is greatest, tidal forces operating on the high latitudes of both hemispheres are maximized. We find that such tidal forces deform the high latitude Rossby longwaves. Using the NCEP/NCAR reanalysis data set, we identify that the 27.3 day MLD cycle’s influence on circulation is greatest in the upper troposphere of both hemispheres’ high latitudes. The effect is distinctly regional with high impact over central North America and the British Isles. Through this lunar variation, midlatitude weather forecasting for two-week forecast periods may be significantly improved.” Krahenbuhl, D. S., M. B. Pace, R. S. Cerveny, and R. C. Balling Jr. (2011), J. Geophys. Res., 116, D23121, doi:10.1029/2011JD016598.

Climate change makes some interacting species drift apart

Increasing range mismatching of interacting species under global change is related to their ecological characteristics – Schweiger et al. (2011) “Aim: We investigate the importance of interacting species for current and potential future species distributions, the influence of their ecological characteristics on projected range shifts when considering or ignoring interacting species, and the consistency of observed relationships across different global change scenarios. Location: Europe. Methods: We developed ecological niche models (generalized linear models) for 36 European butterfly species and their larval host plants based on climate and land-use data. We projected future distributional changes using three integrated global change scenarios for 2080. Observed and projected mismatches in potential butterfly niche space and the niche space of their hosts were first used to assess changing range limitations due to interacting species and then to investigate the importance of different ecological characteristics. Results: Most butterfly species were primarily limited by climate. Species dwelling in warm areas of Europe and tolerant to large variations in moisture conditions were projected to suffer less from global change. However, a gradient from climate to host plant control was apparent, reflecting the range size of the hosts. Future projections indicated increased mismatching of already host-plant-limited butterflies and their hosts. Butterflies that utilize plants with restricted ranges were projected to suffer most from global change. The directions of these relationships were consistent across the scenarios but the level of spatial mismatching of butterflies and their host plants increased with the severity of the scenario. Main conclusions: Future changes in the co-occurrence of interacting species will depend on political and socio-economic development, suggesting that the composition of novel communities due to global change will depend on the way we create our future. A better knowledge of ecological species characteristics can be utilized to project the future fate and potential risk of extinction of interacting species leading to a better understanding of the consequences of changing biotic interactions. This will further enhance our abilities to assess and mitigate potential negative effects on ecosystem functions and services.” Oliver Schweiger, Risto K. Heikkinen, Alexander Harpke, Thomas Hickler, Stefan Klotz, Otakar Kudrna, Ingolf Kühn, Juha Pöyry, Josef Settele, Global Ecology and Biogeography, Special Issue: QUO VADIS, ECOSYSTEM? SCENARIOS AS A TOOL FOR LARGE-SCALE ECOLOGICAL RESEARCH, Volume 21, Issue 1, pages 88–99, January 2012, DOI: 10.1111/j.1466-8238.2010.00607.x. [Full text]

When climate warms California valley oaks gather around water bodies

Predicting species responses to climate change: demography and climate microrefugia in California valley oak (Quercus lobata) – Mclaughlin & Zavaleta (2011) “Anticipating species movement under climate change is a major focus in conservation. Bioclimate models are one of the few predictive tools for adaptation planning, but are limited in accounting for (1) climatic tolerances in pre-adult life stages that are potentially more vulnerable to warming; and (2) local-scale movement and use of climatic refugia as an alternative or complement to large-scale changes in distribution. To assess whether these shortfalls can be addressed with field demographic data, we used California valley oak (Quercus lobata Nee), a long-lived species with juvenile life stages known to be sensitive to climate. We hypothesized that the valley oak bioclimate model, based on adults, would overpredict the species’ ability to remain in the projected persisting area, due to higher climate vulnerability of young life stages; and underpredict the potential for the species to remain in the projected contracting area in local-scale refugia. We assessed the bioclimate model projections against actual demographic patterns in natural populations. We found that saplings were more constricted around surface water than adults in the projected contracting area. We also found that the climate envelope for saplings is narrower than that for adults. Saplings disappeared at a summer maximum temperature 3 degrees C below that associated with adults. Our findings indicate that rather than a complete shift northward and upward, as predicted by the species bioclimate model, valley oaks are more likely to experience constriction around water bodies, and eventual disappearance from areas exceeding a threshold of maximum temperature. Ours is the first study we know of to examine the importance of discrete life stage climate sensitivities in determining bioclimate modeling inputs, and to identify current climate change-related constriction of a species around microrefugia. Our findings illustrate that targeted biological fieldwork can be central to understanding climate change-related movement for long-lived, sessile species.” B.C. Mclaughlin, E.S. Zavaleta, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02630.x.

There’s a general warming trend over western North America

Climatic changes in western North America, 1950–2005 – Booth et al. (2011) “The rate of climatic change over western North America (WNA) is quantified for 485 climate stations for the period 1950–2005. Additionally, six stations with quality long-term records were selected and analysed for the period 1906–2005. The indicators used were developed by the World Meteorological Organization (WMO) and the World Climate Research Program’s Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI). From the 27 core indices, 4 temperature-based and 4 precipitation-based indicators were selected for in-depth analysis. The 8 million km2 study area is comprised of the 22 contiguous US states and 4 Canadian provinces west of the Mississippi River and Great Lakes. The results were divided into six general regions for interpretation and presentation. GIS interpolation of station-specific statistical output was completed to further aid in the identification of spatially coherent trends across WNA. Mean slopes were calculated over the whole study area, and by region, for each index, and then tested to determine if they were significantly different from zero. Results of the study show statistically significant historical climate trends across the study area. As expected in a region as geographically diverse as WNA, results differed between, and within, regions. Overall, temperature-based indicators showed a general warming trend over the entire study area, with the greatest increases along the North American Cordillera. The trends in precipitation-based indicators were more varied. General trends indicate moderately increasing precipitation volume and intensity over much of WNA. The strongest precipitation trends were found in areas with climate largely controlled by air masses originating over the Gulf of Mexico.” Evan L. J. Booth, James M. Byrne, Dan L. Johnson, International Journal of Climatology, DOI: 10.1002/joc.3401.

Climate warms but hot spell mortality declines in Czech Republic

Declining impacts of hot spells on mortality in the Czech Republic, 1986–2009: adaptation to climate change? – Kyselý & Plavcová (2011) “The study examines temporal changes in mortality associated with spells of large positive temperature anomalies (hot spells) in extended summer season in the population of the Czech Republic (Central Europe) during 1986–2009. Declining trends in the mortality impacts are found in spite of rising temperature trends. The finding remains unchanged if possible confounding effects of within-season acclimatization to heat and the mortality displacement effect are taken into account. Recent positive socioeconomic development, following the collapse of communism in Central and Eastern Europe in 1989, and better public awareness of heat-related risks are likely the primary causes of the declining vulnerability. The results suggest that climate change may have relatively little influence on heat-related deaths, since changes in other factors that affect vulnerability of the population are dominant instead of temperature trends. It is essential to better understand the observed nonstationarity of the temperature-mortality relationship and the role of adaptation and its limits, both physiological and technological, and to address associated uncertainties in studies dealing with climate change projections of temperature-related mortality.” Jan Kyselý and Eva Plavcová, Climatic Change, DOI: 10.1007/s10584-011-0358-4.

Frequency of extremely high temperatures has increased 10-fold since early 20th century

Climate change: a new metric to measure changes in the frequency of extreme temperatures using record data – Munasinghe et al. (2011) “Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric—called “record equivalent draws” (RED)—based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900–1929) and the most recent decade (1999–2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002–2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum.” Lalith Munasinghe, Tackseung Jun and David H. Rind, Climatic Change, DOI: 10.1007/s10584-011-0370-8.

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New research from last week 49/2011

Posted by Ari Jokimäki on December 12, 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.

Pacific Decadal Oscillation might contribute to tropical belt widening

Effects of the PDO phase on the tropical belt width – Grassi et al. (2011) “Recent studies have shown that the Tropical Belt (TB) has progressively expanded since at least the late 1970’s. This trend has been largely attributed to the radiative forcing due to GHG increase and stratospheric ozone depletion, even if an influence of Sea Surface Temperature (SST) anomalies has been also suggested. In this work we investigate the impact of the Pacific Decadal Oscillation (PDO) on the TB width. The study is performed by using both AMIP (Atmospheric Model Intercomparison Project) and idealized simulations, produced by NCAR/CAM3 GCM, and reanalysis data (ERA-Interim, ERA-40 and MERRA). Reanalysis show that a switch of the PDO from a positive to a negative phase can lead to a significant TB expansion during the equinoxes. This effect, indicating a possible PDO contribution to the widening that characterized the TB width during the last decades, is not correctly reproduced by model simulations. Deficiencies in the sensitivity of model simulated convective processes to SST anomalies are suggested as a possible cause of the TB widening underestimation.” Barbara Grassi, Gianluca Redaelli, Pablo Osvaldo Canziani, and Guido Visconti, Journal of Climate 2011, doi:

Evaluating anthropogenic carbon and its effect to pH in South Pacific Ocean

Changes in South Pacific anthropogenic carbon – Waters et al. (2011) “The changes in anthropogenic CO2 are evaluated in the South Pacific, along the meridional line P18 (110°W) and the zonal line P06 (32°S), using the extended multiple linear regression (eMLR) method. The structure of the column inventory of anthropogenic CO2 on P18 is similar to the southern section of P16 in the central South Pacific (150°W), but the overall increase is greater by approximately 5–10 μmol kg−1. The value of the anthropogenic CO2 inventory on P18 is in agreement at the crossover point of an earlier evaluation of P06. Subsequent changes in pH due to the increase in anthropogenic CO2 are also evaluated. The change in pH is determined from the changes in anthropogenic CO2 and do not reflect variability in other decadal signals. For both cruise tracks, the average annual change in pH is −0.0016 mol kg−1 yr−1. This value is in good agreement with the average decrease in pH in the North Pacific, at the Hawaii Times Series and the subtropical North Atlantic. The uptake rates of anthropogenic CO2 are within reasonable agreement with similar studies in the South Pacific. There is evidence for greater uptake of anthropogenic CO2 in the western South Pacific and is attributed to the formation of subtropical Mode Water in the region.” Waters, J. F., F. J. Millero, and C. L. Sabine (2011), Global Biogeochem. Cycles, 25, GB4011, doi:10.1029/2010GB003988.

Nuclear power industry affects atmospheric radiocarbon concentration

Continental-scale enrichment of atmospheric 14CO2 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2 – Graven & Gruber (2011) “The 14C-free fossil carbon added to atmospheric CO2 by combustion dilutes the atmospheric 14C/C ratio (Δ14C), potentially providing a means to verify fossil CO2 emissions calculated using economic inventories. However, sources of 14C from nuclear power generation and spent fuel reprocessing can counteract this dilution and may bias 14C/C-based estimates of fossil fuel-derived CO2 if these nuclear influences are not correctly accounted for. Previous studies have examined nuclear influences on local scales, but the potential for continental-scale influences on Δ14C has not yet been explored. We estimate annual 14C emissions from each nuclear site in the world and conduct an Eulerian transport modeling study to investigate the continental-scale, steady-state gradients of Δ14C caused by nuclear activities and fossil fuel combustion. Over large regions of Europe, North America and East Asia, nuclear enrichment may offset at least 20% of the fossil fuel dilution in Δ14C, corresponding to potential biases of more than −0.25 ppm in the CO2 attributed to fossil fuel emissions, larger than the bias from plant and soil respiration in some areas. Model grid cells including high 14C-release reactors or fuel reprocessing sites showed much larger nuclear enrichment, despite the coarse model resolution of 1.8°×1.8°. The recent growth of nuclear 14C emissions increased the potential nuclear bias over 1985–2005, suggesting that changing nuclear activities may complicate the use of Δ14C observations to identify trends in fossil fuel emissions. The magnitude of the potential nuclear bias is largely independent of the choice of reference station in the context of continental-scale Eulerian transport and inversion studies, but could potentially be reduced by an appropriate choice of reference station in the context of local-scale assessments.” Graven, H. D. and Gruber, N., Atmos. Chem. Phys., 11, 12339-12349, doi:10.5194/acp-11-12339-2011, 2011. [Full text]

Human actions are seen in borehole temperatures in Czechia and Slovenia

Detection and quantification of local anthropogenic and regional climatic transient signals in temperature logs from Czechia and Slovenia – Dědeček et al. (2011) “The paper reports on detection and quantification of the impact of local anthropogenic structures and regional climatic changes on subsurface temperature field. The analyzed temperature records were obtained by temperature monitoring in a borehole in Prague-Spořilov (Czechia) and by repeated logging of a borehole in Šempeter (Slovenia). The observed data were compared with temperatures yielded by mathematical 3D time-variable geothermal models of the boreholes’ sites with the aim to decompose the observed transient component of the subsurface temperature into the part affected by construction of new buildings and other anthropogenic structures in surroundings of the boreholes and into the part affected by the ground surface temperature warming due to the surface air temperature rise. A direct human impact on the subsurface temperature warming was proved and contributions of individual anthropogenic structures to this change were evaluated. In the case of Spořilov, where the mean annual warming rate reached 0.034°C per year at the depth of 38.3 m during the period 1993–2008, it turned out that about half of the observed warming can be attributed to the air (ground) surface temperature change and half to the human activity on the surface in the immediate vicinity of the borehole. The situation is similar in Šempeter, where the effect of the recently built surface anthropogenic structures is detectable down to the depth of 80 m and the share of the anthropogenic signal on the non-stationary component of the observed subsurface temperature amounts to 30% at the depth of 50 m.” Petr Dědeček, Jan Šafanda and Dušan Rajver, Climatic Change, DOI: 10.1007/s10584-011-0373-5.

CO2 emissions matter to German car buyers

German car buyers’ willingness to pay to reduce CO2 emissions – Achtnicht (2011) “Motorized individual transport strongly contributes to global CO2 emissions, due to its intensive usage of fossil fuels. Current political efforts addressing this issue (i.e. emission performance standards in the EU) are directed towards car manufacturers. This paper focuses on the demand side. It examines whether CO2 emissions per kilometer is a relevant attribute in car choices. Based on a choice experiment among potential car buyers from Germany, a mixed logit specification is estimated. In addition, distributions of willingness-to-pay measures for an abatement of CO2 emissions are obtained. The results suggest that the emissions performance of a car matters substantially, but its consideration varies heavily across the sampled population. In particular, some evidence on gender, age and education effects on climate concerns is provided.” Martin Achtnicht, Climatic Change, DOI: 10.1007/s10584-011-0362-8.

Arctic Oscillation shows up in Swiss aquifers

Regime shift in groundwater temperature triggered by the Arctic Oscillation – Figura et al. (2011) “Groundwater is the world’s most important source of raw drinking water. However, the potential impact of climate change on this vital resource is unclear because of a lack of relevant long-term data. Here we statistically analyze over 20 years of groundwater temperature data from five Swiss aquifers fed predominantly by river-bank infiltration. The results reveal an abrupt increase in annual mean groundwater temperature centered on 1987–1988 that can also be observed in air and river temperatures. We associate this temperature increase with the Northern Hemisphere late 1980s climate regime shift (CRS), which itself is related to an abrupt change in the behavior of the Arctic Oscillation. Because temperature affects redox conditions in groundwater, groundwater biogeochemistry in aquifers fed by river-bank infiltration is likely to depend on large-scale climatic forcing and will be affected by climate change.” Figura, S., D. M. Livingstone, E. Hoehn, and R. Kipfer (2011), Geophys. Res. Lett., 38, L23401, doi:10.1029/2011GL049749.

Carbon dioxide emissions from global wind power deployment

Environmental implications of large-scale adoption of wind power: a scenario-based life cycle assessment – Arvesen & Hertwich (2011) “We investigate the potential environmental impacts of a large-scale adoption of wind power to meet up to 22% of the world’s growing electricity demand. The analysis builds on life cycle assessments of generic onshore and offshore wind farms, meant to represent average conditions for global deployment of wind power. We scale unit-based findings to estimate aggregated emissions of building, operating and decommissioning wind farms toward 2050, taking into account changes in the electricity mix in manufacturing. The energy scenarios investigated are the International Energy Agency’s BLUE scenarios. We estimate 1.7–2.6 Gt CO2-eq climate change, 2.1–3.2 Mt N-eq marine eutrophication, 9.2–14 Mt NMVOC photochemical oxidant formation, and 9.5–15 Mt SO2-eq terrestrial acidification impact category indicators due to global wind power in 2007–50. Assuming lifetimes 5 yr longer than reference, the total climate change indicator values are reduced by 8%. In the BLUE Map scenario, construction of new capacity contributes 64%, and repowering of existing capacity 38%, to total cumulative greenhouse gas emissions. The total emissions of wind electricity range between 4% and 14% of the direct emissions of the replaced fossil-fueled power plants. For all impact categories, the indirect emissions of displaced fossil power are larger than the total emissions caused by wind power.” Anders Arvesen and Edgar G Hertwich 2011 Environ. Res. Lett. 6 045102 doi:10.1088/1748-9326/6/4/045102. [Full text]

In low crop yield years biofuel production might emit more GHGs than fossil fuel burning

The significance of nitrous oxide emission due to cropping of grain for biofuel production: a Swedish perspective – Klemedtsson & Smith (2011) “The current regulations governing production of biofuels in the European Union require that they have to mitigate climate change, by producing >35% less greenhouse gases (GHG) than fossil fuels. There is a risk that this may not be achievable, since land use for crop production inevitably emits the potent GHG nitrous oxide (N2O), due to nitrogen fertilisation and cycling in the environment. We analyse first-generation biofuel production on agricultural land and conclude that efficient agricultural crop production resulting in a good harvest and low N2O emission can fulfil the EU standard, and is possible under certain conditions for the Swedish agricultural and bioethanol production systems. However, in years having low crop yields, and where cropping is on organic soils, total GHG emissions per unit of fuel produced can be even higher than those released by burning of fossil fuels. In general, the N2O emission size in Sweden and elsewhere in northern Europe is such that there is a >50% chance that the 35% saving requirement will not be met. Thus ecosystem N2O emissions have to be convincingly assessed. Here we compare Swedish emission data with values estimated by means of statistical models and by a global, top-down, approach; the measurements and the predictions often show higher values that would fail to meet the EU standard and thus prevent biofuel production development.” Kasimir Klemedtsson, Å. and Smith, K. A., Biogeosciences, 8, 3581-3591, doi:10.5194/bg-8-3581-2011, 2011. [Full text]

Attribution of climate change is not limited to model simulations

Patterns of change: whose fingerprint is seen in global warming? – Hegerl et al. (2011) “Attributing observed climate change to causes is challenging. This letter communicates the physical arguments used in attribution, and the statistical methods applied to explore to what extent different possible causes can be used to explain the recent climate records. The methods use fingerprints of climate change that are identified on the basis of the physics governing our climate system, and through the use of climate model experiments. These fingerprints characterize the geographical and vertical pattern of the expected changes caused by external influences, for example, greenhouse gas increases and changes in solar radiation, taking also into account how these forcings and their effects vary over time. These time–space fingerprints can be used to discriminate between observed climate changes caused by different external factors. Attribution assessments necessarily take the natural variability of the climate system into account as well, evaluating whether an observed change can be explained in terms of this internal variability alone, and estimating the contribution of this source of variability to the observed change. Hence the assessment that a large part of the observed recent warming is anthropogenic is based on a rigorous quantitative analysis of these joint drivers and their effects, and proceeds through a much more comprehensive and layered analysis than a comparison at face value of model simulations with observations.” Gabriele Hegerl et al 2011 Environ. Res. Lett. 6 044025 doi:10.1088/1748-9326/6/4/044025. [Full text]

Soil maximum freeze depth has decreased in Eurasian high latitudes

An observational 71-year history of seasonally frozen ground changes in the Eurasian high latitudes – Frauenfeld & Zhang (2011) “In recent decades, significant changes have occurred in high-latitude areas, particularly to the cryosphere. Sea ice extent and thickness have declined. In land areas, glaciers and ice sheets are experiencing negative mass balance changes, and there is substantial regional snow cover variability. Subsurface changes are also occurring in northern soils. This study focuses on these changes in the soil thermal regime, specifically the seasonally frozen ground region of Eurasia. We use a database of soil temperatures at 423 stations and estimate the maximum annual soil freezing depth at the 387 sites located on seasonally frozen ground. Evaluating seasonal freeze depth at these sites for 1930–2000 reveals a statistically significant trend of −4.5 cm/decade and a net change of −31.9 cm. Interdecadal variability is also evident such that there was no trend until the late 1960s, after which seasonal freeze depths decreased significantly until the early 1990s. From that point forward, likely through at least 2008, no change is evident. These changes in the soil thermal regime are most closely linked with the freezing index, but also mean annual air temperatures and snow depth. Antecedent conditions from the previous warm season do not appear to play a large role in affecting the subsequent cold season’s seasonal freeze depths. The strong decrease in seasonal freeze depths during the 1970s to 1990s was likely the result of strong atmospheric forcing from the North Atlantic Oscillation during that time period.” Oliver W Frauenfeld and Tingjun Zhang 2011 Environ. Res. Lett. 6 044024 doi:10.1088/1748-9326/6/4/044024. [Full text]

Analysis of tree-ring divergence problem

Who is the new sheriff in town regulating boreal forest growth? – Williams et al. (2011) Without abstract – here’s the first paragraph: “Climate change appears to be altering boreal forests. One recently observed symptom of these changes has been an apparent weakening of the positive relationship between high-latitude boreal tree growth and temperature at some sites (D’Arrigo et al 2008). This phenomenon is referred to as the ‘divergence problem’ or ‘divergence effect’ and is thought to reflect a non-linear relationship between temperature and tree growth, where recent warming has allowed other factors besides growing-season temperature to emerge as dominant regulators of annual growth rates.” A Park Williams et al 2011 Environ. Res. Lett. 6 041004 doi:10.1088/1748-9326/6/4/041004. [Full text available in the abstract page]

Climate change threatens turtle species

On the brink of extinction? How climate change may affect global Chelonian species richness and distribution – Ihlow et al. (2011) “Anthropogenic global climate change has already led to alterations in biodiversity patterns by directly and indirectly affecting species distributions. It has been suggested that poikilothermic animals, including reptiles, will be particularly affected by global change and large-scale reptile declines have already been observed. Currently, half of the world′s freshwater turtles and tortoises are considered threatened with extinction and climate change may exacerbate these declines. In this study, we assess how global chelonian species richness will change in the near future. We use species distribution models developed under current climate conditions for 78% of all extant species and project them onto different Intergovernmental Panel on Climate Change (IPCC) climate change scenarios for 2080. We detect a strong dependence of temperature shaping most species ranges, which coincide with their general temperature related physiological traits (i.e. temperature dependent sex determination). Furthermore, the extent and distribution of the current bioclimatic niches of most chelonians may change remarkably in the near future, likely leading to a substantial decrease of local species abundance and ultimately a reduction in species richness. Future climatic changes may cause the ranges of 86% of the species to contract and of these ranges nearly 12% are predicted to be situated completely outside their currently realized niches. Hence, the interplay of increasing habitat fragmentation and loss due to climatic stress may result in a serious threat for several chelonian species.” Flora Ihlow, Johannes Dambach, Jan O. Engler, Morris Flecks, Timo Hartmann, Sven Nekum, Hossein Rajaei, Dennis Rödder, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02623.x.

Study estimates 0.7% of global methane emissions comes from West Siberia mires

Regional methane emission from West Siberia mire landscapes – Glagolev et al. (2011) “Methane emissions from mires in all climate–vegetation zones of West Siberia (forest steppe, subtaiga, south taiga, middle taiga, north taiga, forest tundra and tundra) were measured using a static chamber method. The observed fluxes varied considerably from small negative values in forested bogs and palsa to hundreds of mgC m − 2 h − 1 in ponds and wet hollows. Observed data were consolidated in the form of the empirical model of methane emissions designated as the ‘standard model’. The model is based on medians of CH4 flux distributions of eight different micro-landscape types depending on their location and estimated duration of methane emission period within the climate–vegetation zone. The current version (Bc8) of the ‘standard model’ estimates methane flux from West Siberia mires at 2.93 ± 0.97 TgC CH4 yr − 1 that accounts for about 2.4% of the total methane emission from all mires or 0.7% of global methane emission from all sources.” M Glagolev et al 2011 Environ. Res. Lett. 6 045214 doi:10.1088/1748-9326/6/4/045214. [Full text]

Removing short term variability from global temperature analysis makes years 2009 and 2010 warmest

Global temperature evolution 1979–2010 – Foster & Rahmstorf (2011) “We analyze five prominent time series of global temperature (over land and ocean) for their common time interval since 1979: three surface temperature records (from NASA/GISS, NOAA/NCDC and HadCRU) and two lower-troposphere (LT) temperature records based on satellite microwave sensors (from RSS and UAH). All five series show consistent global warming trends ranging from 0.014 to 0.018 K yr−1. When the data are adjusted to remove the estimated impact of known factors on short-term temperature variations (El Niño/southern oscillation, volcanic aerosols and solar variability), the global warming signal becomes even more evident as noise is reduced. Lower-troposphere temperature responds more strongly to El Niño/southern oscillation and to volcanic forcing than surface temperature data. The adjusted data show warming at very similar rates to the unadjusted data, with smaller probable errors, and the warming rate is steady over the whole time interval. In all adjusted series, the two hottest years are 2009 and 2010.” Grant Foster and Stefan Rahmstorf 2011 Environ. Res. Lett. 6 044022 doi:10.1088/1748-9326/6/4/044022. [Full text]

Health costs of climate change in Europe are expected to be billions of euros

Projection of economic impacts of climate change in sectors of Europe based on bottom up analysis: human health – Watkiss & Hunt (2011) “This paper scopes a number of the health impacts of climate change in Europe (EU-27) quantitatively, using physical and monetary metrics. Temperature-related mortality effects, salmonellosis and coastal flooding-induced mental health impacts resulting from climate change are isolated from the effects of socio-economic change for the 2011–2040 and 2071–2100 time periods. The temperature-induced mortality effects of climate change include both positive and negative effects, for winter (cold) and summer (heat) effects, respectively, and have welfare costs (and benefits) of up to 100 billion Euro annually by the later time-period, though these are unevenly distributed across countries. The role of uncertainty in quantifying these effects is explored through sensitivity analysis on key parameters. This investigates climate model output, climate scenario, impact function, the existence and extent of acclimatisation, and the choice of physical and monetary metrics. While all of these lead to major differences in reported results, acclimatisation is particularly important in determining the size of the health impacts, and could influence the scale and form of public adaptation at the EU and national level. The welfare costs for salmonellosis from climate change are estimated at potentially several hundred million Euro annually by the period 2071–2100. Finally, a scoping assessment of the health costs of climate change from coastal flooding, focusing on mental health problems such as depression, are estimated at up to 1.5 billion Euro annually by the period 2071–2100.” Paul Watkiss and Alistair Hunt, Climatic Change, DOI: 10.1007/s10584-011-0342-z.

Global and Planetary Change is publishing a special issue on medieval climate

Climate in medieval time: How anomalous? – Diaz (2011) “The climate of the MWP/MCA has been a topic of scholarly research and debate for some 50 years (Diaz et al., in press). There is little doubt that sustained climatic anomalies on regional to hemispheric and global scales have had pronounced impacts on human society, and as events of the past few decades have shown, recent climatic extremes continue to affect humans regardless of their socioeconomic level. The publication of this special issue is meant to enhance the pool of knowledge about this period and hopefully contribute toward future advances.” Henry F. Diaz, Global and Planetary Change, doi:10.1016/j.gloplacha.2011.10.014.

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New research from last week 48/2011

Posted by Ari Jokimäki on December 5, 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.

Tropical high clouds react to surface warming as expected from theories

The observed sensitivity of high clouds to mean surface temperature anomalies in the Tropics – Zelinka & Hartmann (2011) “Cloud feedback represents the source of largest diversity in projections of future warming. Observational constraints on both the sign and magnitude of the feedback are limited, since it is unclear how the natural variability that can be observed is related to secular climate change, and analyses have rarely been focused on testable physical theories for how clouds should respond to climate change. In this study we use observations from a suite of satellite instruments to assess the sensitivity of tropical high clouds to interannual tropical mean surface temperature anomalies. We relate cloud changes to a physical governing mechanism that is sensitive to the vertical structure of warming. Specifically, we demonstrate that the mean and interannual variability in both the altitude and fractional coverage of tropical high clouds as measured by CloudSat, MODIS, AIRS, and ISCCP are well-diagnosed by upper tropospheric convergence computed from the mass and energy budget of the clear-sky atmosphere. Observed high clouds rise approximately isothermally in accordance with theory and exhibit an overall reduction in coverage when the Tropics warms, similar to their behavior in global warming simulations. Such cloud changes cause absorbed solar radiation to increase more than does outgoing longwave radiation, resulting in a positive but statistically insignificant net high cloud feedback in response to ENSO. The results suggest that the convergence metric based on simple mass and energy budget constraints may be a powerful tool for understanding observed and modeled high cloud behavior and for evaluating the realism of modeled high cloud changes in response to a variety of forcings.” Zelinka, M. D. and D. L. Hartmann (2011), J. Geophys. Res., doi:10.1029/2011JD016459, in press.

Oxygen content of global ocean is decreasing

Observed decreases in oxygen content of the global ocean – Helm et al. (2011) “Comparing the high-quality oxygen climatology from the World Ocean Circulation Experiment to earlier data we reveal near-global decreases in oxygen levels in the upper ocean between the 1970s and the 1990s. This globally averaged oxygen decrease is -0.93{plus minus}0.23 μmol l-1, which is equivalent to annual oxygen losses of -0.55{plus minus}0.13×1014 mol yr-1 (100-1000 m). The strongest decreases in oxygen occur in the mid-latitudes of both hemispheres, near regions where there is strong water renewal and exchange between the ocean interior and surface waters. Approximately 15% of global oxygen decrease can be explained by a warmer mixed-layer reducing the capacity of water to store oxygen, while the remainder is consistent with an overall decrease in the exchange between surface waters and the ocean interior. Here we suggest that this reduction in water mass renewal rates on a global scale is a consequence of increased stratification caused by warmer surface waters. These observations support climate model simulations of oxygen change under global warming scenarios.” Helm, K. P., N. L. Bindoff, and J. A. Church (2011), Geophys. Res. Lett., doi:10.1029/2011GL049513, in press.

Melting ice reveals artefacts of ancient reindeer hunting in southern Norway

The climatic significance of artefacts related to prehistoric reindeer hunting exposed at melting ice patches in southern Norway – Nesje et al. (2011) “The main aim of this study is to describe consequences of climate change in the mountain region of southern Norway with respect to recently exposed finds of archaeological remains associated with reindeer hunting and trapping at and around ice patches in central southern Norway. In the early years of the twenty-first century, warm summers caused negative glacier mass balance and significant glacier retreat and melting of ice patches in central southern Norway. As a result, prehistoric remains lost and/or left by past reindeer hunters appeared at ice patches in mountain areas of southern Norway. In the warm summer and autumn of 2006 the number of artefact recoveries at ice patches increased significantly because of melting of snow and ice patches and more than 100 objects were recovered in the Oppland county alone. In 2009, detailed multidisciplinary investigations were carried out at the Juvfonne ice patch in Jotunheimen at an elevation of c. 1850 metres. A well-preserved Iron Age hunting station was discovered and in total c. 600 artefacts have been documented at the Juvfonne site alone. Most of the objects were recovered and brought to the Museum of Cultural History at the University of Oslo for conservation, exhibition and storing. Thirteen so called ‘scaring sticks’ recovered from the recently exposed foreland of Juvfonne were radiocarbon dated, yielding ages that group in two separate time intervals, AD 246–534 and AD 804–898 (±1 sigma). By putting the temporal distribution of the radiocarbon-dated artefacts into the context of late-Holocene glacier-size variations in the Jotunheimen and Jostedalsbreen regions, we conclude that the most extensive reindeer hunting and trapping associated with snow/ice patches was related to periods with prevailing warm summers when the reindeer herds gathered on high-altitude, contracted glaciers and ice patches to avoid insect plagues. The ‘freshness’ of the fragile organic finds strongly indicates that at least some of the artefacts were rapidly covered by snow and ice and that they may have been more-or-less continuously covered by snow and ice since they were first buried.” Atle Nesje, Lars Holger Pilø, Espen Finstad, Brit Solli, Vivian Wangen, Rune Strand Ødegård, Ketil Isaksen, Eivind N. Støren, Dag Inge Bakke, Liss M Andreassen, The Holocene November 30, 2011 0959683611425552, doi: 10.1177/0959683611425552.

Climate record shows several abrupt cooling events during early Holocene in North America

Abrupt cooling repeatedly punctuated early-Holocene climate in eastern North America – Hou et al. (2011) “Climate proxy records and general circulation models suggest that Atlantic Meridional Overturning Circulation (AMOC) plays a key role for global climate changes. Paleoceanographic data document multiple episodes of prominent AMOC weakening during the early Holocene. However, proxy records at adjacent continents have not been demonstrated to fully capture the climate responses to multiple AMOC variation due to temporal resolution and/or the proxy sensitivity. Here we present decadal- to multidecadal-resolution hydrogen isotopic records of aquatic biomarkers from Blood Pond, Massachusetts during the early Holocene. Our data reveal a full series of prominent and abrupt cooling events centered on 10.6, 10.2, 9.5, 9.2, 8.8 and 8.4 ka. These abrupt climatic reversals coincide with key intervals of weakened AMOC, suggesting an apparent relationship between AMOC oscillations and the abrupt continental climate changes in northeastern North America. The noticeable connection implies that the AMOC variation did play an important role in the abrupt climate changes during the early Holocene. Our data also suggest that northeastern North America may experience significant climatic variations should the predicted major disturbance of AMOC occur in the coming century as a result of anthropogenic greenhouse gas emissions.” Juzhi Hou, Yongsong Huang, Bryan N Shuman, W Wyatt Oswald, David R Foster, The Holocene November 30, 2011 0959683611427329, doi: 10.1177/0959683611427329.

Why AMOC had already slowed down when Heinrich events started?

Heinrich event 1: an example of dynamical ice-sheet reaction to oceanic changes – Álvarez-Solas et al. (2011) “Heinrich events, identified as enhanced ice-rafted detritus (IRD) in North Atlantic deep sea sediments (Heinrich, 1988; Hemming, 2004) have classically been attributed to Laurentide ice-sheet (LIS) instabilities (MacAyeal, 1993; Calov et al., 2002; Hulbe et al., 2004) and assumed to lead to important disruptions of the Atlantic meridional overturning circulation (AMOC) and North Atlantic deep water (NADW) formation. However, recent paleoclimate data have revealed that most of these events probably occurred after the AMOC had already slowed down or/and NADW largely collapsed, within about a thousand years (Hall et al., 2006; Hemming, 2004; Jonkers et al., 2010; Roche et al., 2004), implying that the initial AMOC reduction could not have been caused by the Heinrich events themselves. Here we propose an alternative driving mechanism, specifically for Heinrich event 1 (H1; 18 to 15 ka BP), by which North Atlantic ocean circulation changes are found to have strong impacts on LIS dynamics. By combining simulations with a coupled climate model and a three-dimensional ice sheet model, our study illustrates how reduced NADW and AMOC weakening lead to a subsurface warming in the Nordic and Labrador Seas resulting in rapid melting of the Hudson Strait and Labrador ice shelves. Lack of buttressing by the ice shelves implies a substantial ice-stream acceleration, enhanced ice-discharge and sea level rise, with peak values 500–1500 yr after the initial AMOC reduction. Our scenario modifies the previous paradigm of H1 by solving the paradox of its occurrence during a cold surface period, and highlights the importance of taking into account the effects of oceanic circulation on ice-sheets dynamics in order to elucidate the triggering mechanism of Heinrich events.” Álvarez-Solas, J., Montoya, M., Ritz, C., Ramstein, G., Charbit, S., Dumas, C., Nisancioglu, K., Dokken, T., and Ganopolski, A., Clim. Past, 7, 1297-1306, doi:10.5194/cp-7-1297-2011, 2011. [Full text]

Water-related stresses from climate change threaten endangered plant species

Climate change threatens endangered plant species by stronger and interacting water-related stresses – Bartholomeus et al. (2011) “Atmospheric CO2-concentration, temperature and rainfall variability are all expected to increase in the near future. The resulting increased dynamics of soil moisture contents, together with increased plant physiological demands for both oxygen and water, will lead to an increased occurrence of wet and dry extremes of plant stresses, i.e. of oxygen and drought stress, respectively, alone and in interaction. The use of indirect environmental variables of previous studies and their focus on one stress at a time has hampered understanding the causal impact of climate change on plant species composition through changes in abiotic site conditions. Here, we use process-based simulations of oxygen and drought stress and show that both stresses will increase (on average with ca. 20% at sites where both stresses occur) in a warmer and more variable future (2050) climate (applying a national downscaled version of IPCC scenarios). These stresses will increasingly coincide, i.e. both stresses will occur more often (but not at the same time) within the same vegetation plot. We further show that particularly this increased coincidence of water-related stresses will negatively affect the future occurrence of currently endangered plant species (a reduction of 16%), while such a decrease is not apparent for common species. Individual stresses did not affect the occurrence of endangered plant species. Consequently, the species that are already threatened under the current climate, will suffer most from climate change.” Bartholomeus, R. P., F. Witte, P. M. van Bodegom, J.C. Van Dam, and R. Aerts (2011), J. Geophys. Res., doi:10.1029/2011JG001693, in press.

Drought-induced tree mortality has increased in Canada’s boreal forests

A drought-induced pervasive increase in tree mortality across Canada’s boreal forests – Peng et al. (2011) “Drought-induced tree mortality is expected to increase worldwide under projected future climate changes. The Canadian boreal forests, which occupy about 30% of the boreal forests worldwide and 77% of Canada’s total forested land, play a critical role in the albedo of Earth’s surface and in its global carbon budget. Many of the previously reported regional-scale impacts of drought on tree mortality have affected low- and middle-latitude tropical regions and the temperate forests of the western United States, but no study has examined high-latitude boreal regions with multiple species at a regional scale using long-term forest permanent sampling plots. Here, we estimated tree mortality in natural stands throughout Canada’s boreal forests using data from the permanent sampling plots and statistical models. We found that tree mortality rates increased by an overall average of 4.7% yr−1 from 1963 to 2008, with higher mortality rate increases in western regions than in eastern regions (about 4.9 and 1.9% yr−1, respectively). The water stress created by regional drought may be the dominant contributor to these widespread increases in tree mortality rates across tree species, sizes, elevations, longitudes and latitudes. Western Canada seems to have been more sensitive to drought than eastern Canada.” Changhui Peng, Zhihai Ma, Xiangdong Lei, Qiuan Zhu, Huai Chen, Weifeng Wang, Shirong Liu, Weizhong Li, Xiuqin Fang & Xiaolu Zhou, Nature Climate Change 1,467–471(2011)doi:10.1038/nclimate1293.

Snowfall to total winter precipitation ratio has decreased in Poland

Long-term variability of occurrence of precipitation forms in winter in Kraków, Poland – Twardosz et al. (2011) “The paper discusses long-term change in snowfall, rainfall and mixed precipitation viewed in conjunction with air temperature and North Atlantic Oscillation (NAO) in winter (December–February). In the study of contemporary climate change and its effect on the hydrological cycle it is useful to focus on winter precipitation forms. A 146-year secular observation series from Kraków, spanning the period 1863–2008, was used to extract data on the number of days with precipitation and on precipitation amount broken down by form. Statistically significant trends were found in total and mixed precipitation, but not in snowfall and rainfall. The climate warming effect has contributed to a material decrease in the snowfall to total winter precipitation ratio during the second half of the 20th c. The highest impact of air temperature was found in the wintertime variation in number of days with snowfall while the NAO had a significant influence on the frequency and amount of both rainfall and snowfall.” Robert Twardosz, Ewa Łupikasza, Tadeusz Niedźwiedź and Adam Walanus, Climatic Change, DOI: 10.1007/s10584-011-0352-x. [Full text]

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Papers on 1940s dip in atmospheric CO2

Posted by Ari Jokimäki on December 1, 2011

This is a list of papers on 1940s dip in atmospheric CO2 concentration. 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 (February 1, 2016): Bastos et al. (2016) added. Thanks to Cathy Trudinger for pointing it out.
Update: (February 1, 2016) Rubino et al. (2013) added.

Re-evaluating the 1940s CO2 plateau – Bastos et al. (2016) [Full text]
Abstract: The high-resolution CO2 record from Law Dome ice core reveals that atmospheric CO2 concentration stalled during the 1940s (so-called CO2 plateau). Since the fossil-fuel emissions did not decrease during the period, this stalling implies the persistence of a strong sink, perhaps sustained for as long as a decade or more. Double-deconvolution analyses have attributed this sink to the ocean, conceivably as a response to the very strong El Niño event in 1940–1942. However, this explanation is questionable, as recent ocean CO2 data indicate that the range of variability in the ocean sink has been rather modest in recent decades, and El Niño events have generally led to higher growth rates of atmospheric CO2 due to the offsetting terrestrial response. Here, we use the most up-to-date information on the different terms of the carbon budget: fossil-fuel emissions, four estimates of land-use change (LUC) emissions, ocean uptake from two different reconstructions, and the terrestrial sink modelled by the TRENDY project to identify the most likely causes of the 1940s plateau. We find that they greatly overestimate atmospheric CO2 growth rate during the plateau period, as well as in the 1960s, in spite of giving a plausible explanation for most of the 20th century carbon budget, especially from 1970 onwards. The mismatch between reconstructions and observations during the CO2 plateau epoch of 1940–1950 ranges between 0.9 and 2.0PgCyr−1, depending on the LUC dataset considered. This mismatch may be explained by (i) decadal variability in the ocean carbon sink not accounted for in the reconstructions we used, (ii) a further terrestrial sink currently missing in the estimates by land-surface models, or (iii) LUC processes not included in the current datasets. Ocean carbon models from CMIP5 indicate that natural variability in the ocean carbon sink could explain an additional 0.5PgCyr−1 uptake, but it is unlikely to be higher. The impact of the 1940–1942 El Niño on the observed stabilization of atmospheric CO2 cannot be confirmed nor discarded, as TRENDY models do not reproduce the expected concurrent strong decrease in terrestrial uptake. Nevertheless, this would further increase the mismatch between observed and modelled CO2 growth rate during the CO2 plateau epoch. Tests performed using the OSCAR (v2.2) model indicate that changes in land use not correctly accounted for during the period (coinciding with drastic socioeconomic changes during the Second World War) could contribute to the additional sink required. Thus, the previously proposed ocean hypothesis for the 1940s plateau cannot be confirmed by independent data. Further efforts are required to reduce uncertainty in the different terms of the carbon budget during the first half of the 20th century and to better understand the long-term variability of the ocean and terrestrial CO2 sinks.
Citation: Bastos, A., Ciais, P., Barichivich, J., Bopp, L., Brovkin, V., Gasser, T., Peng, S., Pongratz, J., Viovy, N., and Trudinger, C. M.: Re-evaluating the 1940s CO2 plateau, Biogeosciences, 13, 4877-4897,, 2016.

A revised 1000 year atmospheric δ13C-CO2 record from Law Dome and South Pole, Antarctica – Rubino et al. (2013) “We present new measurements of δ13C of CO2 extracted from a high-resolution ice core from Law Dome (East Antarctica), together with firn measurements performed at Law Dome and South Pole, covering the last 150 years. Our analysis is motivated by the need to better understand the role and feedback of the carbon (C) cycle in climate change, by advances in measurement methods, and by apparent anomalies when comparing ice core and firn air δ13C records from Law Dome and South Pole. We demonstrate improved consistency between Law Dome ice, South Pole firn, and the Cape Grim (Tasmania) atmospheric δ13C data, providing evidence that our new record reliably extends direct atmospheric measurements back in time. We also show a revised version of early δ13C measurements covering the last 1000 years, with a mean preindustrial level of −6.50‰. Finally, we use a Kalman Filter Double Deconvolution to infer net natural CO2 fluxes between atmosphere, ocean, and land, which cause small δ13C deviations from the predominant anthropogenically induced δ13C decrease. The main features found from the previous δ13C record are confirmed, including the ocean as the dominant cause for the 1940 A.D. CO2 leveling. Our new record provides a solid basis for future investigation of the causes of decadal to centennial variations of the preindustrial atmospheric CO2 concentration. Those causes are of potential significance for predicting future CO2 levels and when attempting atmospheric verification of recent and future global carbon emission mitigation measures through Coupled Climate Carbon Cycle Models.” Rubino, M., et al. (2013), A revised 1000 year atmospheric δ13C-CO2 record from Law Dome and South Pole, Antarctica, J. Geophys. Res. Atmos., 118, 8482–8499, doi:10.1002/jgrd.50668. [Full text]

Climate effects on atmospheric carbon dioxide over the last century – Rafelski et al. (2009) “The buildup of atmospheric CO2 since 1958 is surprisingly well explained by the simple premise that 57% of the industrial emissions (fossil fuel burning and cement manufacture) has remained airborne. This premise accounts well for the rise both before and after 1980 despite a decrease in the growth rate of fossil fuel CO2 emissions, which occurred at that time, and by itself should have caused the airborne fraction to decrease. In contrast, the buildup prior to 1958 was not simply proportional to cumulative fossil fuel emissions, and notably included a period during the 1940s when CO2 growth stalled despite continued fossil fuel emissions. Here we show that the constancy of the airborne fraction since 1958 can be in part explained by decadal variations in global land air temperature, which caused a warming-induced release of CO2 from the land biosphere to the atmosphere. We also show that the 1940s plateau may be related to these decadal temperature variations. Furthermore, we show that there is a close connection between the phenomenology producing CO2 variability on multidecadal and El Niño timescales.” Lauren Elmegreen Rafelski, Stephen C. Piper, Ralph F. Keeling, Tellus B, Volume 61, Issue 5, pages 718–731, November 2009, DOI: 10.1111/j.1600-0889.2009.00439.x.

Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP – MacFarling Meure et al. (2006) “New measurements of atmospheric greenhouse gas concentrations in ice from Law Dome, Antarctica reproduce published Law Dome CO2 and CH4 records, extend them back to 2000 years BP, and include N2O. They have very high air age resolution, data density and measurement precision. Firn air measurements span the past 65 years and overlap with the ice core and direct atmospheric observations. Major increases in CO2, CH4 and N2O concentrations during the past 200 years followed a period of relative stability beforehand. Decadal variations during the industrial period include the stabilization of CO2 and slowing of CH4 and N2O growth in the 1940s and 1950s. Variations of up to 10 ppm CO2, 40 ppb CH4 and 10 ppb N2O occurred throughout the preindustrial period. Methane concentrations grew by 100 ppb from AD 0 to 1800, possibly due to early anthropogenic emissions.” MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith, and J. Elkins (2006), Geophys. Res. Lett., 33, L14810, doi:10.1029/2006GL026152.

Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 years – Brovkin et al. (2004) Not mentioned in the abstract, but in the article they say: “The period between 1938 and 1950 is interesting because of an almost constant atmospheric CO2 recorded at Law Dome, despite substantial fossil fuel emissions (about 1.3 PgCyr-1). … We conclude that the stalling of atmospheric CO2 during the 1940s was unlikely to have been caused by changes in land cover, although this might be one of the contributing factors. Other factors, like internal variability of the climate system, may also be responsible (Joos et al., 1999). Better statistics for land cover changes during the 1940s would help to clarify the role of land cover changes in this period.” Victor Brovkin, Stephen Sitch, Werner Von Bloh, Martin Claussen, Eva Bauer, Wolfgang Cramer, Global Change Biology, Volume 10, Issue 8, pages 1253–1266, August 2004, DOI: 10.1111/j.1365-2486.2004.00812.x. [Full text]

Kalman filter analysis of ice core data 2. Double deconvolution of CO2 and δ13C measurements – Trudinger et al. (2002) “A new method for deconvolving ice core CO2 and δ13CO2 measurements to estimate net CO2 uptake by the terrestrial biosphere and the oceans has been developed. The method, which uses the Kalman filter, incorporates statistical analysis into the calculation. This allows a more rigorous analysis of CO2 variability than the usual deconvolution method. The Kalman filter method estimates uncertainties on the deduced fluxes as part of the calculation. The deconvolution method is applied to the Law Dome CO2 and δ13C ice core record. The calculation suggests that natural variability in CO2 fluxes may be as large as 1 GtC yr−1 (GtC is gigatonnes carbon, 1 Gt = 1015 g) on the timescale of just less than a decade. The Law Dome CO2 measurements show a slight decrease in CO2 around the 1940s. Analysis with the carbon cycle model and a numerical model of firn processes suggests that about 3 GtC yr−1 uptake (mostly oceanic) is required in the 1940s to match the ice core measurements. The estimates of variation in the terrestrial biospheric flux between 1950 and 1980 from the double deconvolution calculation are in very good agreement with an independent estimate of the global terrestrial flux from a climate-driven ecosystem model.” Trudinger, C. M., I. G. Enting, P. J. Rayner, and R. J. Francey (2002), J. Geophys. Res., 107(D20), 4423, doi:10.1029/2001JD001112.

Biotic Feedbacks in the Warming of the Earth – Woodwell et al. (1998) Not mentioned in the abstract, but in the article they say: “Except for the brief period 1935–1945 heat-trapping gases continued to accumulate in the atmosphere (Etheridge et al., 1996). The coincidence between the cooling and the brief stabilization of concentration around 1940 is, perhaps, significant.” G. M. Woodwell, F. T. Mackenzie, R. A. Houghton, M. Apps, E. Gorham and E. Davidson, Climatic Change, Volume 40, Numbers 3-4, 495-518, DOI: 10.1023/A:1005345429236. [Full text]

Terrestrial carbon storage during the past 200 years: A Monte Carlo Analysis of CO2 data from ice core and atmospheric measurements – Bruno & Joos (1997) Issue is mentioned here and there in the article. Bruno, M., and F. Joos (1997), Global Biogeochem. Cycles, 11(1), 111–124, doi:10.1029/96GB03611. [Full text]

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