Abstracts on Global Climate Change

Nov 2007

Day-to-day variation in sea-surface temperature reduces sooty tern Sterna fuscata foraging success on the Great Barrier Reef, Australia

Erwin, CA Congdon, BC


Many seabird species threatened by global climate change are found mainly or exclusively in tropical regions. A shortage of long-term data linking climatic variation, oceanography and tropical seabird reproductive biology at both within- and between-season temporal scales means that the potential impact of climate change on these species is largely unknown. The sooty tern Sterna fuscata, an almost ubiquitous tropical seabird, has been declining on the Great Barrier Reef (GBR), Australia, over the last 3 decades. We examined the relationship between sooty tern foraging success and sea-surface temperature (SST) at Michaelmas Cay over 2 consecutive breeding seasons. Consistent patterns were observed with significant negative relationships between day-to-day variation in SST and both the amount of food fed to chicks and the feeding frequency during the latter two-thirds of each breeding season. At the beginning of each breeding cycle, rapid changes in foraging success highlighted that other within-season mechanisms also influence sooty tern reproductive potential. Our results suggest a previously undescribed spatial and temporal link between SST and sooty tern reproduction. Combined with previous findings for the southern GBR, this suggests that SST variation can influence the foraging success of multiple tropical seabird species at a reef-wide scale and implies a significant negative effect of forecasted climatic changes on seabirds breeding on the GBR.

SPotGS:endorseimp | /endorse/endorseimp | 076

Sep 2007

Namaqualand’s climate: Recent historical changes and future scenarios

MacKellar, NC Hewitson, BC Tadross, MA


A brief outline of some issues concerning global climate change research is presented before discussing local-scale changes in Namaqaland’s rainfall. Using a gridded data set derived through interpolation of station records, trends in observed rainfall for the period 1950-1999 are discussed. To assess what changes may occur during the 21st century, the downscaled results of six different General Circulation Model projections are presented. The historical trends show some clear spatial patterns, which depict regions of wetting in the central coastal belt and the north-eastern part of the domain, and extensive drying along the escarpment. Reasonably good agreement is shown by the different downscaled projections. These suggest increased late summer convective precipitation in the north-east, but extensive drying along the coast in early and mid winter consistent with the poleward retreat of rain-bearing mid-latitude cyclones. (c) 2006 Elsevier Ltd. All rights reserved.

SPotGS:endorseimp | /endorse/endorseimp | 003

Aug 2007

Coastal flood risk analysis using landsat-7 ETM+ imagery and SRTM DEM: A case study of Izmir, turkey

Demirkesen, AC Evrendilek, F Berberoglu, S Kilic, S


The Intergovernmental Panel on Climate Change (IPCC) reports an acceleration of the global mean sea-level rise (MSLR) in the twentieth century in response to global climate change. If this acceleration remains constant, then some coastal areas are most likely to be inundated by the year 2100. The ability to identify the differential vulnerability of coastlines to future inundation hazards as result of global climate change is necessary for timely actions to be taken. Yildiz et al. (Journal of Mapping, 17, 1 75, 2003) reported that the local MSLR in the city of Izmir rose at a rate of 6.8 +/- 0.9 mm year(-1) between 1984 and 2002. In this study, the spatial distribution of the coastal inundation hazards of Izmir region was determined using not only land-use and land-cover (LULC) types derived from the maximum likelihood classification of Landsat-7 Enhanced Thematic Mapper Plus (ETM+) multi-spectral image set but also the classification of the digital elevation model (DEM) acquired by the shuttle radar topography mission (SRTM). Coastal areas with elevations of 2 and 5 m above mean sea-level vulnerable to inundation were found to cover 2.1 and 3.7% of the study region (6,107 km(2)), respectively. Our findings revealed that Menemen plain along Gediz river, and the settlements of Karsiyaka, Alacati, Aliaga, Candarli and Selcuk are at high risk in order of decreasing vulnerability to permanent and episodic inundation by 2100 under the high MSLR scenarios of 20 to 50 mm year(-1).

SPotGS:endorseex | /endorse/endorseex | 004

Jun 2007

Simulated changes in active/break spells during the Indian summer monsoon due to enhanced CO2 concentrations: assessment from selected coupled atmosphere-ocean global climate models

Mandke, SK Sahai, AK Shinde, MA Joseph, S Chattopadhyay, R


The simulations by ten coupled GCMs under the Intergovernmental Panel on Climate Change Assessment Report-4 are used to study the implication of possible global climate change on active/break spells of the Indian summer monsoon (ISM). The validation of the mean daily cycle of the summer monsoon precipitation over the Indian core region and the spatial pattern of the ISM precipitation climatology with observation suggest that six models simulate fairly well, whereas four models differ from observation. Thus, the identification of activelbreak spells is confined to six models. The sensitivity to climate change has been assessed from two experiments, namely, 1% per year CO2 increase to doubling and 1% per year CO2 increase to quadrupling. The changes in the daily mean cycle and the standard deviation of precipitation, frequency, and duration of active/break spells in future climate change are uncertain among the models and at times among two experiments. The break composite precipitation anomalies strengthen and spread moderately (significantly) in the doubled (quadrupled) CO2 experiment. Copyright (c) 2006 Royal Meteorological Society.

SPotGS:endorseimp | /endorse/endorseimp | 007

Evidence for carbon sequestration by agricultural liming

Hamilton, SK Kurzman, AL Arango, C Jin, LX Robertson, GP


[1] Agricultural lime can be a source or a sink for CO2, depending on whether reaction occurs with strong acids or carbonic acid. Here we examine the impact of liming on global warming potential by comparing the sum of Ca2+ and Mg2+ to carbonate alkalinity in soil solutions beneath unmanaged vegetation versus limed row crops, and of streams and rivers in agricultural versus forested watersheds, mainly in southern Michigan. Soil solutions sampled by tension indicated that lime can act as either a source or a sink for CO2. However, infiltrating waters tended to indicate net CO2 uptake, as did tile drainage waters and streams draining agricultural watersheds. As nitrate concentrations increased in infiltrating waters, lime switched from a net CO2 sink to a source, implying nitrification as a major acidifying process. Dissolution of lime may sequester CO2 equal to roughly 25 - 50% of its C content, in contrast to the prevailing assumption that all of the carbon in lime becomes CO2. The similar to 30 Tg/yr of agricultural lime applied in the United States could thus sequester up to 1.9 TgC/ yr, about 15% of the annual change in the U. S. CO2 emissions (12 Tg C/yr for 2002 - 2003). The implications of liming for atmospheric CO2 stabilization should be considered in strategies to mitigate global climate change.

SPotGS:endorseimp | /endorse/endorseimp | 028

Palau’s coral reefs show differential habitat recovery following the 1998-bleaching event

Golbuu, Y Victor, S Penland, L Idip, D Emaurois, C Okaji, K Yukihira, H Iwase, A van Woesik, R

CORAL REEFS 26:2 319-332

Documenting successional dynamics of coral communities following large-scale bleaching events is necessary to predict coral population responses to global climate change. In 1998, high sea surface temperatures and low cloud cover in the western Pacific Ocean caused high coral mortality on the outer exposed reefs of Palau (Micronesia), while coral mortality in sheltered bays was low. Recovery was examined from 2001 to 2005 at 13 sites stratified by habitat (outer reefs, patch reefs and bays) and depth (3 and 10 m). Two hypotheses were tested: (1) rates of change of coral cover vary in accordance with habitat, and (2) recovery rates depend on recruitment. Coral cover increased most in the sheltered bays, despite a low recruitment rate, suggesting that recovery in bays was primarily a consequence of remnant regrowth. Recruitment densities were consistently high on the wave-exposed reefs, particularly the western slopes, where recovery was attributed to both recruitment and regrowth of remnants. Recovery was initially more rapid at 10 m than 3 m on outer reefs, but in 2004, recovery rates were similar at both depths. Rapid recovery was possible because Palau’s coral reefs were buffered by remnant survival and recruitment from the less impacted habitats.

SPotGS:endorseimp | /endorse/endorseimp | 011

Thermal stress and coral cover as drivers of coral disease outbreaks

Bruno, JF Selig, ER Casey, KS Page, CA Willis, BL Harvell, CD Sweatman, H Melendy, AM

PLOS BIOLOGY 5:6 1220-1227

Very little is known about how environmental changes such as increasing temperature affect disease dynamics in the ocean, especially at large spatial scales. We asked whether the frequency of warm temperature anomalies is positively related to the frequency of coral disease across 1,500 km of Australia’s Great Barrier Reef. We used a new high-resolution satellite dataset of ocean temperature and 6 y of coral disease and coral cover data from annual surveys of 48 reefs to answer this question. We found a highly significant relationship between the frequencies of warm temperature anomalies and of white syndrome, an emergent disease, or potentially, a group of diseases, of Pacific reef- building corals. The effect of temperature was highly dependent on coral cover because white syndrome outbreaks followed warm years, but only on high (> 50%) cover reefs, suggesting an important role of host density as a threshold for outbreaks. Our results indicate that the frequency of temperature anomalies, which is predicted to increase in most tropical oceans, can increase the susceptibility of corals to disease, leading to outbreaks where corals are abundant.

SPotGS:endorseimp | /endorse/endorseimp | 013

The efficiency gap behind the Annex I parties under the Kyoto Protocol

Lo, SF


With the ratification of the Kyoto Protocol, an era of global efforts to combat climate change is beginning. Countries belonging to Annex I Parties are obligated to meet their target in reducing greenhouse gas (GHG) emissions. This paper broadens the scope of research to compare the performance between two groups, Annex 11 Parties and economies in transition (EIT) Parties (both of which are in the set of Annex I Parties), undertaking responsibilities for GHG emission reduction. This differs from the traditional application of evaluation and aims to identify inherent efficiency differences across systems, rather than separately from the potential inefficiency of individual countries. An efficiency gap was found between the group of Annex 11 Parties and the group of EIT Parties, by adjusting efficiency levels. Considering a reference set, efficient Annex 11 countries are referenced, both within their own group and within the EIT group; efficient EIT countries are only benchmarked within the group. The evidence provided can shed light on the function of joint implementation, that Annex I countries will cooperate to reduce GHG emissions, based on their common, but differentiated, responsibilities and capacity for global climate change.

SPotGS:endorseimp | /endorse/endorseimp | 005

The evolution of climate change impact studies on hydrology and water resources in California

Vicuna, S Dracup, JA

CLIMATIC CHANGE 82:3-4 327-350

Potential global climate change impacts on hydrology pose a threat to water resources systems throughout the world. The California water system is especially vulnerable to global warming due to its dependence on mountain snow accumulation and the snowmelt process. Since 1983, more than 60 studies have investigated climate change impacts on hydrology and water resources in California. These studies can be categorized in three major fields: (1) Studies of historical trends of streamflow and snowpack in order to determine if there is any evidence of climate change in the geophysical record; (2) Studies of potential future predicted effects of climate change on streamflow and; (3) Studies that use those predicted changes in natural runoff to determine their economic, ecologic, or institutional impacts. In this paper we review these studies with an emphasis on methodological procedures. We provide for each category of studies a summary of significant conclusions and potential areas for future work.

SPotGS:endorseex | /endorse/endorseex | 051

Constructing regional scenarios for sustainable agriculture in European Russia and Ukraine for 2000 to 2070

Romanenko, IA Romanenkov, VA Smith, P Smith, JU Sirotenko, OD Lisovoi, NV Shevtsova, LK Rukhovich, DI Koroleva, PV


This study estimates the consequences of climate change on cropland with and without implementation of adaptation measures, paying special attention to the maintenance of soil organic carbon (C) stocks. We examine the possibility for regional sustainable agricultural management practice that combines both maintenance and gain in soil carbon level with profit maximization. Future scenarios of Regional Agricultural Production Systems (RAPS) were constructed for 2000-2070 based on linking the effects of global climate change, predicted change in productivity parameters for the main agricultural crops, land-use and soil database parameters. The RAPS were used to examine profitability and feasibility of alternative agricultural scenarios, based on an economic model. A number of recommendations for decision making were proposed based on an assessment of the efficiency of adaptation in animal husbandry and in the crop production sector, after analysis of current percentage of perennial grass in rotation in comparison with future economic scenarios.

SPotGS:endorseimp | /endorse/endorseimp | 019

Response of macroinvertebrates to warming, nutrient addition and predation in large-scale mesocosm tanks

Feuchtmayr, H McKee, D Harvey, IF Atkinson, D Moss, B

HYDROBIOLOGIA 584: 425-432

There is increasing concern about the effect of climate change on aquatic systems. We examined changes in macroinvertebrate communities caused by increased temperature (3 degrees C above ambient during summer only and continuous 3 degrees C above ambient all year round), influences of fish (Gasterosteus aculeatus L.) and addition of nutrients ( nitrogen and phosphorus) in 48 large-scale (3000 l) tanks over a 2 year period. While numbers of Isopoda, Chaoborus, Corixidae, Ephemeroptera, Notonectidae and Odonata were reduced by the presence of fish, nutrient addition caused isopods, corixids, mayflies and odonates to increase in abundance. Impacts of temperature increase were surprisingly low, with only gastropods increasing in heated tanks, suggesting that, overall abundances of most macroinvertebrate taxa will not be severely affected by the predicted temperature rise. To determine if taxa were sampled representatively during the experiment, net sweep samples taken towards the end of the experiment were compared with final macroinvertebrate abundances when the complete contents of each tank were harvested. We found that net sweeping is an appropriate semi-quantitative method for most taxa in mesocosm tanks. However, mites, coleopteran adults and larvae, dipterans and Chaoborus were not adequately sampled. This might explain why we could not detect any treatment effects of temperature, fish or nutrients on mites, coleopterans and dipterans and calls for different sampling techniques for these taxa, especially in ponds with vegetation stands.

SPotGS:endorseimp | /endorse/endorseimp | 027

Dec 2006

Comparative risk assessment of the burden of disease from climate change

Campbell-Lendrum, D Woodruff, R


The World Health Organization has developed standardized comparative risk assessment methods for estimating aggregate disease burdens attributable to different risk factors. These have been applied to existing and new models for a range of climate-sensitive diseases in order to estimate the effect of global climate change on current disease burdens and likely proportional changes in the future. The comparative risk assessment approach has been used to assess the health consequences of climate change worldwide, to inform decisions on mitigating greenhouse gas emissions, and in a regional assessment of the Oceania region in the Pacific Ocean to provide more location-specific information relevant to local mitigation and adaptation decisions. The approach places climate change within the same criteria for epidemiologic assessment as other health risks and accounts for the size of the burden of climate-sensitive diseases rather than just proportional change, which highlights the importance of small proportional changes in diseases such as diarrhea and malnutrition that cause a large burden. These exercises help clarify important knowledge gaps such as a relatively poor understanding of the role of nonclimatic factors (socioeconomic and other) that may modify future climatic influences and a lack of empiric evidence and methods for quantifying more complex climate-health relationships, which consequently are often excluded from consideration. These exercises highlight the need for risk assessment frameworks that make the best use of traditional epidemiologic methods and that also fully consider the specific characteristics of climate change. These include the long-term and uncertain nature of the exposure and the effects on multiple physical and biotic systems that have the potential for diverse and widespread effects, including high-impact events.

melatonin:endorseimp | /endorse/endorseimp | 134

Growth and physiological responses of canola (Brassica napus) to three components of global climate change: temperature, carbon dioxide and drought

Qaderi, MM Kurepin, LV Reid, DM


Elevated CO2 appears to be a significant factor in global warming, which will likely lead to drought conditions in many areas. Few studies have considered the interactive effects of higher CO2, temperature and drought on plant growth and physiology. We grew canola (Brassica napus cv. 45H72) plants under lower (22/18 degrees C) and higher (28/24 degrees C) temperature regimes in controlled environment chambers at ambient (370 mu mol mol(-1)) and elevated (740 mu mol mol(-1)) CO2 levels. One half of the plants were watered to field capacity and the other half at wilting point. In three separate experiments, we determined growth, various physiological parameters and content of abscisic acid (ABA), indole-3-acetic acid and ethylene. Drought-stressed plants grown under higher temperature at ambient CO2 had decreased stem height and diameter, leaf number and area, dry matter, leaf area ratio, shoot/root weight ratio, net CO2 assimilation and chlorophyll fluorescence. However, these plants had increased specific leaf weight, leaf weight ratio and chlorophyll concentration. Elevated CO2 generally had the opposite effect, and partially reversed the inhibitory effects of higher temperature and drought on leaf dry weight accumulation. This study showed that higher temperature and drought inhibit many processes but elevated CO2 partially mitigate some adverse effects. As expected, drought stress increased ABA but higher temperature inhibited the ability of plants to produce ABA in response to drought.

melatonin:endorseex | /endorse/endorseex | 129

Predicting woodrat (Neotoma) responses to anthropogenic warming from studies of the palaeomidden record

Smith, FA Betancourt, JL


Aim The influence of anthropogenic climate change on organisms is an area of great scientific concern. Increasingly there is recognition that abrupt climate transitions have occurred over the late Quaternary; studies of these shifts may yield insights into likely biotic responses to contemporary warming. Here, we review research undertaken over the past decade investigating the response of Neotoma (woodrats) body size and distribution to climate change over the late Quaternary (the last 40,000 years). By integrating information from woodrat palaeomiddens, historical museum specimens and field studies of modern populations, we identify potential evolutionary responses to climate change occurring over a variety of temporal and spatial scales. Specifically, we characterize climatic thresholds in the past that led to local species extirpation and/or range alterations rather than in situ adaptation, and apply them to anticipate potential biotic responses to anthropogenic climate change. Location Middens were collected at about 55 sites scattered across the western United States, ranging from about 34 to 46 degrees N and about 104 to 116 degrees W, respectively. Data for modern populations were drawn from studies conducted in Death Valley, California, Missoula, Montana and the Sevilleta LTER site in central New Mexico. Methods We analysed faecal pellets from midden series collected at numerous cave sites across the western United States. From these we estimated body mass using techniques validated in earlier studies. We compared body size fluctuations at different elevations in different regions and integrated these results with studies investigating temperature-body size tradeoffs in modern animals. We also quantify the rapidity of the size changes over the late Quaternary to estimate the evolutionary capacity of woodrats to deal with predicted rates of anthropogenic climate change over the next century. Results We find remarkable similarities across the geographical range to late Quaternary climate change. In the middle of the geographical range woodrats respond in accordance to Bergmann’s rule: colder climatic conditions select for larger body size and warmer conditions select for smaller body size. Patterns are more complicated at range boundaries, and local environmental conditions influence the observed response. In general, woodrat body size fluctuates with approximately the same amplitude and frequency as climate; there is a significant and positive correlation between woodrat body size and generalized climate proxies (such as ice core records). Woodrats have achieved evolutionary rates of change equal to or greater than those needed to adapt in situ to anthropogenic climate change. Main conclusions In situ body size evolution is a likely outcome of climate change, and such shifts are part of a normal spectrum of adaptation. Woodrats appear to be subject to ongoing body size selection in response to fluctuating environmental conditions. Allometric considerations suggest that these shifts in body size lead to substantial changes in the physiology, life history and ecology of woodrats, and on their direct and indirect interactions with other organisms in the ecosystem. Our work highlights the importance of a finely resolved and long-term record in understanding biotic responses to climatic shifts.

melatonin:endorseex | /endorse/endorseex | 149

Nov 2006

An atmosphere-ocean time series model of global climate change

Stern, DI


Time series models of global climate change tend to estimate a low climate-sensitivity (equilibrium effect on global temperature of doubling carbon dioxide concentrations) and a fast adjustment rate to equilibrium. These results may be biased by omission of a key variable-heat stored in the ocean. A time series model of the atmosphere-ocean climate system is developed, in which surface temperature (atmospheric temperature over land and sea surface temperature) moves towards a long-run equilibrium with both radiative forcing and ocean heat content, while ocean heat content accumulates the deviations from atmospheric equilibrium. This model is closely related to Granger and Lee’s multicointegration model. As there are only 55 years of observations on ocean heat content, the Kalman filter is used to estimate heat content as a latent state variable, which is constrained by the available observations. This method could be applied to other climate change problems where there are only limited observations on key variables. The final model adopted relates surface temperature to the heat content of the upper 300m of the ocean. The resulting parameter estimates are closer to theoretically expected values than those of previous time series models and the estimated climate sensitivity to a doubling of carbon dioxide is 4.4 K. (c) 2005 Published by Elsevier B.V.

melatonin:endorseex | /endorse/endorseex | 137

The influence of the possible global climate change on the properties of Mexican soils

Nikol’skii, YN Castillo-Alvarez, M Bakhlaeva, OS Roma-Calleros, XA Maslov, BS


To estimate the changes in the integral fertility index of virgin soils in Mexico upon the expected global climate changes, we applied a method based on revealing the quantitative relationship between the Budyko radiation index of dryness and the modal values of the regional agrochemical properties of soils located on a nearly horizontal surface (with slope of less than 0.001) at elevations ranging from 0 to 2500 m a.s.l. The results of existing forecasts of the alteration of the global air temperature, radiation, and precipitation were also used. In the case that the carbon dioxide content is doubled in the atmosphere by the end of the 21st century, a medium and weak decrease in the soil fertility will be observed in the central (cereal) regions of Mexico; furthermore, a significant (over 20%) decrease in fertility will be observed in the tropical regions, where sugar cane is cultivated.

melatonin:endorseimp | /endorse/endorseimp | 065

Study on the trace species in the stratosphere and their impact on climate

Chen, YJ Zhou, RJ Shi, CH Bi, Y


The trace gases (O-3, HCl, CH4, H2O, NO, NO2) in the stratosphere play an important role, not only in the photochemical processes in which the ozone layer destroyed, but also in the radiative processes. In this paper, we review the works on the distribution and variation of the trace gases in the stratosphere and their impact on climate, which have been carried out at the University of Science and Technology of China in the recent 20 years. The Halogen Occultation Experiment (HALOE) data were used to analyse the distribution and variation of the mixing ratio of these trace gases and the temperature trends in the stratosphere in the most recent decade. And the reanalyzed National Centers of Environmental Prediction (NCEP)/NCAR data were also used to give the temperature trends and compared with the results from HALOE data. Numerical simulations were also carried out to study the impact of ozone depletion on the global climate. In this review, the distributions of the trace gases, especially those over the Qinghai-Xizang Plateau, are discussed, and the variations and trends for the trace gases in various levels in the stratosphere have been given for the most recent decade. The temperature variation and the cooling trend obtained from HALOE data in the middle and lower stratosphere for the last 13 years are significant, which agree well with the results from NCEP/NCAR data. While the temperature trend in the upper stratosphere in this period do not seem to have much cooling. The numerical simulations show that either the Antarctic ozone hole or the ozone valley over Qinghai-Xizang Plateau affect not only the temperature and circulation in the stratosphere, but also the temperature, pressure and wind fields in the troposphere, then lead to the global climate change.

melatonin:endorseimp | /endorse/endorseimp | 138

Oceanic implications for climate change policy

McNeil, BI


Under the United Nations convention on the law of the sea (1982), each participating country maintains exclusive economic and environmental rights within the oceanic region extending 200 nm from its territorial sea, known as the exclusive economic zone (EEZ). Although the ocean within each EEZ is undoubtedly an anthropogenic CO2 sink, it has been overlooked within international climate policy. In this paper I use an area-weighted scaling argument to show that the inclusion of the EEZ CO2 sink within national carbon accounts would have significant implications in tracking national greenhouse commitments to any future climate change policy initiative. The advantages and disadvantages for inclusion of the EEZ CO2 sink into global climate change policy are also explored. The most compelling argument for including the EEZ CO2 sink is that it would enhance the equity and resources among coastal nations to combat and adapt against future climate change that will inherently impact coastal nations more so than land locked nations. If included, the funds raised could be used for either monitoring or adaptive coastal infrastructure among the most vulnerable nations. On the other hand, the EEZ anthropogenic CO2 sink cannot be directly controlled by human activities and could be used as a disincentive for some developed nations to reduce fossil-fuel related greenhouse gas emissions. This may therefore dampen efforts to ultimately reduce atmospheric greenhouse gas concentrations. In consideration of these arguments it is therefore suggested that an “EEZ clause” be added to Kyoto and any future international climate policy that explicitly excludes its use within national carbon accounts under these international climate frameworks. (c) 2006 Elsevier Ltd. All rights reserved.

melatonin:endorseimp | /endorse/endorseimp | 127

Evidence for carbon dioxide and moisture interactions from the leaf cell up to global scales: Perspective on human-caused climate change

Alpert, P Niyogi, D Pielke, RA Eastman, JL Xue, YK Raman, S


It is of utmost interest to further understand the mechanisms behind the potential interactions or synergies between the greenhouse gases (GHG) forcing(s), particularly as represented by CO2, and water processes and through different climatic scales down to the leaf scale. Toward this goal, the factor separation methodology introduced by Stein and Alpert [Stein U. and Alpert, P. 1993. Factor separation in numerical simulations, J. Atmos. Sci., 50, 2107-2115.] that allows an explicit separation of atmospheric synergies among different factors, is employed. Three independent experiments carried out recently by the present authors, are reported here, all strongly suggest the existence of a significant CO2-water synergy in all the involved scales. The experiments employed a very wide range of up-to-date atmospheric models that complement the physics currently introduced in most Global Circulation Models (GCMs) for global climate change prediction. Three modeling experiments that go from the small/micro scale (leaf scale and soil moisture) to mesoscale (land-use change and CO2 effects) and to global scale (greenhouse gases and cloudiness) all show that synergies between water and CO2 are essential in predicting carbon assimilation, minimum daily temperature and the global Earth temperature, respectively. The study also highlights the importance of including the physics associated with carbon-water synergy which is mostly unresolved in global climate models suggesting that significant carbon-water interactions are not incorporated or at least well parameterized in current climate models. Hence, there is a need for integrative climate models. As shown in earlier studies, the climate involves physical, chemical and biological processes. To only include a subset of these processes limits the skill of local, regional and global models to simulate the real climate system. In addition, our results provide explicit determination of the direct and the interactive effect of the CO2 response on the terrestrial biosphere response. There is also an implicit scale interactive effect that can be deduced from the multiscale effects discussed in the three examples. Processes at each scale-leaf, regional and global will all synergistically contribute to increase the feedbacks-which can decrease or increase the overall system’s uncertainty depending on specific case/setup and needs to be examined in future coupled, multiscale studies. (C) 2006 Elsevier B.V. All rights reserved.

melatonin:endorseimp | /endorse/endorseimp | 133

Oct 2006

Adverse high temperature effects on pollen viability, seed-set, seed yield and harvest index of grain-sorghum [Sorghum bicolor (L.) Moench] are more severe at elevated carbon dioxide due to higher tissue temperatures

Prasad, PVV Boote, KJ Allen, LH


Global climate change, especially, increases in carbon dioxide (CO2) concentration and the associated increases in temperature will have significant impact on the crop production. Grain-sorghum [Sorghum bicolor (L.) Moench] cultivar DeKalb 28E was grown at daytime maximum/nighttime minimum temperature regimes of 32/22, 36/26, 40/30 and 44/34 degrees C at ambient (350 mu mol CO2 mol(-1)) and elevated (700 mu mol CO2 mol(-1)) CO2 from emergence to maturity in controlled environments to quantify the effects of temperature and CO2 on the reproductive processes and yield. Growth temperatures of 40/30 and 44/34 degrees C inhibited particle emergence. Growth temperatures >= 36/26 degrees C significantly decreased pollen production, pollen viability, seed-set, seed yield and harvest index when compared to 32/22 degrees C. Percentage decreases in pollen viability, seed-set, seed yield and harvest index due to elevated temperature were greater at elevated CO2 when compared with ambient CO2. Elevated CO2 increased seed yield (26%) at 32/22 degrees C, but decreased seed yield (10%) at 36/26 degrees C. At high temperatures, elevated CO2 increased vegetative growth but not seed yield, thus, leading to decreased harvest index. We conclude that the adverse effects of elevated temperature on reproductive processes and yield of grain-sorghum were more severe at elevated CO2 than at ambient CO2; and the beneficial effects of elevated CO2 decreased with increasing temperature. The adverse temperature sensitivity of reproductive processes and yield at elevated CO2 was attributed to higher canopy foliage and seed temperatures. (c) 2006 Elsevier B.V. All rights reserved.

melatonin:endorseex | /endorse/endorseex | 160