|Abstracts on Global Climate Change|
Diversity and zonal distribution of arbuscular mycorrhizal fungi on the northern slopes of the Tianshan Mountains
Shi, ZY Chen, ZC Zhang, LY Feng, G Christie, P Tian, CY Li, XL
SCIENCE IN CHINA SERIES D-EARTH SCIENCES 50: Suppl. 1 135-141
The arbuscular mycorrhizal (AM) fungal status of the 20 most common plant species distributed in 4 vegetation types (meadow steppe, desert steppe, steppe desert and typical desert) on the northern slopes of the Tianshan Mountains was investigated. Samples of the plant species and their rhizosphere soils were collected from the 4 vegetation zones and examined to compare their mycorrhizal status, AM fungal spore densities, biovolumes, and community structures. 28 AM fungal species were isolated from the rhizosphere soils: of these, 5 belonged to Acaulospora, 1 to Archaeospora and 22 to Glomus. 5 AM fungi, Glomus aggregatum, G. claroideum, G. deserticola, G. etunicatum and G. sinuosum, were observed in all 4 zonal types. No significant differences were observed in mean proportion of root length colonized by AM fungi among the plant species within each zonal type. Comparing the 4 zonal types, Plantago minuta (84.5%) in steppe desert and Eremopyrum orientale (83.1%) in typical desert showed the highest root colonizatsion rates. AM fungal spore densities and biovolumes were significantly different in the different zonal types. AM fungal spore densities and biovolumes, species richness and diversity were highest in meadow steppe and lowest in typical desert.
Eustasy and sea water Sr composition: application to high-resolution Sr-isotope stratigraphy of Miocene shallow-water carbonates
Kroeger, KF Reuter, M Forst, MH Breisig, S Hartmann, G Brachert, TC
SEDIMENTOLOGY 54:3 565-585
Oceanic Sr-87/Sr-86-isotope ratios are strongly influenced by rates of silicate weathering and therefore linked not only to glaciation but also to sea-level change. The present study combines analysis of sequence stratigraphy and basin architecture with Sr-isotope stratigraphy in Miocene shallow-water sediments in southern Portugal and Crete (Greece). The common method is to use smoothed global sea water Sr-isotope reference curves but here a different approach is chosen. Instead, measured Sr-isotope curves are correlated with unsmoothed reference curves by identification of similar fluctuations in the order of several 100 kyr. Transgressive intervals are characterized by increasing Sr-isotope ratios interpreted as corresponding to intensified silicate weathering as a consequence of deglaciation, while lowstand deposits have low Sr-isotope ratios. Comparison of Sr-isotope curves and sedimentary sequences in the studied basins with independent global delta O-18 data and data on global sea-level might suggest a general relationship, supporting a connection to global climate change. Because of these relationships, the method presented herein has a high potential for use in high-resolution age dating and is also applicable in shallow-water sediments.
The efficiency gap behind the Annex I parties under the Kyoto Protocol
INTERNATIONAL JOURNAL OF SUSTAINABLE DEVELOPMENT AND WORLD ECOLOGY 14:3 225-234
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.
Expert judgements on the response of the Atlantic meridional overturning circulation to climate change
Zickfeld, K Levermann, A Morgan, MG Kuhlbrodt, T Rahmstorf, S Keith, DW
CLIMATIC CHANGE 82:3-4 235-265
We present results from detailed interviews with 12 leading climate scientists about the possible effects of global climate change on the Atlantic Meridional Overturning Circulation (AMOC). The elicitation sought to examine the range of opinions within the climatic research community about the physical processes that determine the current strength of the AMOC, its future evolution in a changing climate and the consequences of potential AMOC changes. Experts assign different relative importance to physical processes which determine the present-day strength of the AMOC as well as to forcing factors which determine its future evolution under climate change. Many processes and factors deemed important are assessed as poorly known and insufficiently represented in state-of-the-art climate models. All experts anticipate a weakening of the AMOC under scenarios of increase of greenhouse gas concentrations. Two experts expect a permanent collapse of the AMOC as the most likely response under a 4xCO(2) scenario. Assuming a global mean temperature increase in the year 2100 of 4 K, eight experts assess the probability of triggering an AMOC collapse as significantly different from zero, three of them as larger than 40%. Elicited consequences of AMOC reduction include strong changes in temperature, precipitation distribution and sea level in the North Atlantic area. It is expected that an appropriately designed research program, with emphasis on long-term observations and coupled climate modeling, would contribute to substantially reduce uncertainty about the future evolution of the AMOC.
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.
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
REGIONAL ENVIRONMENTAL CHANGE 7:2 63-77
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.
Modelling energy systems for developing countries
Urban, F Benders, RMJ Moll, HC
ENERGY POLICY 35:6 3473-3482
Developing countries’ energy use is rapidly increasing, which affects global climate change and global and regional energy settings. Energy models are helpful for exploring the future of developing and industrialised countries. However, energy systems of developing countries differ from those of industrialised countries, which has consequences for energy modelling. New requirements need to be met by present-day energy models to adequately explore the future of developing countries’ energy systems. This paper aims to assess if the main characteristics of developing countries are adequately incorporated in present-day energy models. We first discuss these main characteristics, focusing particularly on developing Asia, and then present a model comparison of 12 selected energy models to test their suitability for developing countries. We conclude that many models are biased towards industrialised countries, neglecting main characteristics of developing countries, e.g. the informal economy, supply shortages, poor performance of the power sector, structural economic change, electrification, traditional bio-fuels, urban-rural divide. To more adequately address the energy systems of developing countries, energy models have to be adjusted and new models have to be built. We therefore indicate how to improve energy models for increasing their suitability for developing countries and give advice on modelling techniques and data requirements. (c) 2007 Elsevier Ltd. All rights reserved.
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.
A maximum entropy method for combining AOGCMs for regional intra-year climate change assessment
Laurent, R Cai, XM
CLIMATIC CHANGE 82:3-4 411-435
This paper deals with different responses from various Atmosphere-Ocean Global Climate Models (AOGCMs) at the regional scale. What can be the best use of AOGCMs for assessing the climate change in a particular region? The question is complicated by the consideration of intra-year month-to-month variability of a particular climate variable such as precipitation or temperature in a specific region. A maximum entropy method (MEM), which combines limited information with empirical perspectives, is applied to assessing the probability-weighted multimodel ensemble average of a climate variable at the region scale. The method is compared to and coupled with other two methods: the root mean square error minimization method and the simple multimodel ensemble average method. A mechanism is developed to handle a comprehensive range of model uncertainties and to identify the best combination of AOGCMs based on a balance of two rules: depending equally on all models versus giving higher priority to models more strongly verified by the historical observation. As a case study, the method is applied to a central US region to compute the probability-based average changes in monthly precipitation and temperature projected for 2055, based on outputs from a set of AOGCMs. Using the AOGCM data prepared by international climate change study groups and local climate observation data, one can apply the MEM to precipitation or temperature for a particular region to generate an annual cycle, which includes the effects from both global climate change and local intra-year climate variability.
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.
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.