Abstract: Very few moral philosophers have written on climate change. This is puzzling, for several reasons. First, many politicians and policy makers claim that climate change is not only the most serious environmental problem currently facing the world, but also one of the most important international problems per se. Second, many of those working in other disciplines describe climate change as fundamentally an ethical issue.

Abstract: We posit that feasible reversal of the growth of atmospheric CH4 and other trace gases would provide a vital contribution toward averting dangerous anthropogenic interference with global climate. Such trace gas reductions may allow stabilization of atmospheric CO2 at an achievable level of anthropogenic CO2 emissions, even if the added global warming constituting dangerous anthropogenic interference is as small as 1°C. A 1°C limit on global warming, with canonical climate sensitivity, requires peak CO2 ≈ 440 ppm if further non-CO2 forcing is +0.5 W/m2, but peak CO2 ≈ 520 ppm if further non-CO2 forcing is -0.5 W/m2. The practical result is that a decline of non-CO2 forcings allows climate forcing to be stabilized with a significantly higher transient level of CO2 emissions. Increased “natural” emissions of CO2, N2O, and CH4 are expected in response to global warming. These emissions, an indirect effect of all climate forcings, are small compared with human-made climate forcing and occur on a time scale of a few centuries, but they tend to aggravate the task of stabilizing atmospheric composition.

Abstract: Within the frame of PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects, EVK2-CT2001-00132), 5th Framework European programme project (2002–2005) European research project, two 30-year time-slice simulations with a regional climate model (PROMES-RCM) nested in the Hadley Centre global model have been performed: present-day climate (1961–1990) and one of the IPCC greenhouse gases emission future scenario (A2 IPCC-SRES) for 2071–2100. Model domain is centered in the Mediterranean basin, considered one of the most sensitive areas regarding to global warming and future climate extreme conditions. This study is based on objective indices to describe extreme climate events of maximum and minimum temperature and precipitation. The statistical frequency and persistence of cold spells, heat waves and intense rain days simulated in the current climate run are compared against the ones resulting from future scenario numerical experiment. Description of extreme processes in both intensity and frequency give a different and complementary overview of extreme events changes in future climate conditions for any of the magnitudes analyzed. In fact, a common feature obtained from the results is the absence of correlation between both magnitudes, as much as for temperatures as for precipitation. Results also point to the usefulness of very high-resolution models (RCM) to study extreme events, due to the great spatial variability obtained in any of the variables studied.

Abstract: The Rossby Centre Atmospheric Regional Climate Model (RCA2) is described and simulation results, for the present climate over Europe, are evaluated against available observations. Systematic biases in the models mean climate and climate variability are documented and key parameterization weaknesses identified. The quality of near-surface parameters is investigated in some detail, particularly temperature, precipitation, the surface energy budget and cloud cover. The model simulates the recent, observed climate and variability with a high degree of realism. Compensating errors in the components of the surface radiation budget are highlighted and the fundamental causes of these biases are traced to the relevant aspects of the cloud, precipitation and radiation parameterizations. The model has a tendency to precipitate too frequently at small rates, this has a direct impact on the simulation of cloud-radiation interaction and surface temperatures. Great care must be taken in the use of observations to evaluate high resolution RCMs, when they are forced by analyzed boundary conditions. This is particularly true with respect to precipitation and cloudiness, where observational uncertainty is often larger than the RCM bias.

Abstract: This paper utilizes the predictions ofseveral Atmosphere-Ocean GeneralCirculation Models and the Global ImpactModel to create forecasts of the globalmarket impacts from climate change. Theforecasts of market impacts in 2100 varyconsiderably depending on climate scenariosand climate impact sensitivity. The modelsdo concur that tropical nations will behurt, temperate nations will be barelyaffected, and high latitude nations willbenefit. Although the size of theseeffects varies a great deal across models,the beneficial and harmful effects areoffsetting, so that the net impact on theglobe is relatively small in almost alloutcomes. Looking only at market impacts,the forecasts suggest that while the globalnet benefits of abatement are small, thedistribution of damages suggests a largeequity problem that could be addressedthrough a compensation program. The largeuncertainty surrounding these forecastsfurther suggests that continued monitoringof both the climate and impacts isworthwhile.

Abstract: The continuing increase in atmospheric carbon dioxide (CO2) makes it essential that climate sensitivity, the equilibrium change in global mean surface temperature that would result from a given radiative forcing, be quantified with known uncertainty. Present estimates are quite uncertain, 3 ± 1.5 K for doubling of CO2. Model studies examining climate response to forcing by greenhouse gases and aerosols exhibit large differences in sensitivities and imposed aerosol forcings that raise questions regarding claims of their having reproduced observed large-scale changes in surface temperature over the 20th century. Present uncertainty in forcing, caused largely by uncertainty in forcing by aerosols, precludes meaningful model evaluation by comparison with observed global temperature change or empirical determination of climate sensitivity. Uncertainty in aerosol forcing must be reduced at least three-fold for uncertaintyin climate sensitivity to be meaningfully reduced and bounded.

Abstract: The simulation of sea-ice in global climate models participating in the Coupled Model Intercomparison Project (CMIP1 and CMIP2) is analyzed. CMIP1 simulations are of the unpertubed “control” climate whereas in CMIP2, all models have been forced with the same 1% yr–1 increase in CO2 concentration, starting from a near equilibrium initial condition. These simulations are not intended as forecasts of climate change, but rather provide a means of evaluating the response of current climate models to the same forcing. The difference in modeled response therefore indicates the range (or uncertainty) in model sensitivity to greenhouse gas and other climatic perturbations. The results illustrate a wide range in the ability of climate models to reproduce contemporary sea-ice extent and thickness; however, the errors are not obviously related to the manner in which sea-ice processes are represented in the models (e.g. the inclusion or neglect of sea-ice motion). The implication is that errors in the ocean and atmosphere components of the climate model are at least as important. There is also a large range in the simulated sea-ice response to CO2 change, again with no obvious stratification in terms of model attributes. In contrast to results obtained earlier with a particular model, the CMIP ensemble yields rather mixed results in terms of the dependence of high-latitude warming on sea-ice initial conditions. There is an indication that, in the Arctic, models that produce thick ice in their control integration exhibit less warming than those with thin ice. The opposite tendency appears in the Antarctic (albeit with low statistical significance). There is a tendency for models with more extensive ice coverage in the Southern Hemisphere to exhibit greater Antarctic warming. Results for the Arctic indicate the opposite tendency (though with low statistical significance).

Abstract: Evidence is presented, based on an ensemble of climate change scenarios performed with a global general circulation model of the atmosphere with high horizontal resolution over Europe, to suggest that the end-of-century anthropogenic climate change over the North Atlantic–European region strongly projects onto the positive phase of the North Atlantic Oscillation during wintertime. It is reflected in a doubling of the residence frequency of the climate system in the associated circulation regime, in agreement with the nonlinear climate perspective. The strong increase in the amplitude of the response, compared to coarse-resolution coupled model studies, suggests that improved model representation of regional climate is needed to achieve more reliable projections of anthropogenic climate change on European climate.

Abstract: 1. Introduction 2. Mass Components of the Climate System 3. Energy in the Climate System 4. Motions of the Climate System 5. Ocean-Atmosphere Interactions 6. Changes in the Climate System 7. Modelling the Climate System 8. Weather, Climate and Climate Change of the High Latitudes 9. Weather, Climate and Climate Change of the Mid Latitude Oceanic Margins 10. Weather, Climate and Climate Change of the Mid Latitude Continental Interiors 11. Weather, Climate and Climate Change of the Low Latitudes 12. Human Adjustment to Climate Change

Abstract: Recently the regional impact assessment due to global warming is one of the urgent tasks to every country in the world, under the circumstances of increasing carbon dioxide in the atmosphere. This assessment must include not only meteorological factors, such as surface air temperature and precipitation, etc., but also the response of the local ecosystem. Based on a previous study, for example, it has been known that Phyllostachys’ habitation, which is one of the bamboo species popular in Korea, is quite sensitive to temperature change, in particular during the winter season. Thus, adequate climate information is essential to derive a solid conclusion on the regional impact assessment for future climate change. In this study, we adopted a dynamical downscaling technique to get regional future climate information, with the regional climate model (MM5, Pennsylvania State University/National Center for Atmospheric Research mesoscale model) from the Max-Planck Institute for Meteorology Models and Data Group’s Atmosphere-Ocean General Circulation Model (AOGCM) ECAHM4, and HOPE-G (ECHO-G) simulation for future climate, based on future greenhouse gas (GHG) emission scenario of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2. Through this nesting process we got reasonable regional climate change information. However, we found a couple of systematic differences, such as a cold bias in the surface air temperature, simulated by MM5 compared to that by the AOGCM ECHO-G. This cold bias may cause to loose credibility on the future climate scenario to the impact assessment studies. Accordingly, we introduced a transfer function to correct the systematic bias of the dynamic model in the regional-scale, and to predict the regional cli

Abstract: The diversity of climate variability studies has grown substantially over the last decade, especially as policy makers now demand less uncertainty in future predictions of climate change. Under this umbrella of research, work has focused mainly on either modeling past climates (e.g., experimenting with quasi-realistic climate models, such as general circulation models) or reconstructing past climates from proxies in natural archives. Effectively linking these two approaches has become one of the holy grails of recent climate change research, especially with a view to testing models and improving model parameterization. The Climate in Historical Times: Toward A Synthesis of Holocene Proxy Data and Climate Models reports on progress and findings of such an ambitious program.

Abstract: Within the context of anthropogenic climate change, paleoclimate modeling has become a key technique for studying climate system responses to changes in external forcing. Of current interest is the response of regional-scale climate to global-scale changes in climate forcing, a problem made particularly difficult in regions of topographic complexity. In an effort to understand the role that regional-scale climate processes play in shaping the response of regional climate to changes in external forcing, the sensitivity of a high-resolution regional climate model (RCM) to mid-Holocene orbital forcing was tested, focusing on the Pacific coast region of the western United States as a case study. Mid-Holocene orbital forcing resulted in RCM-simulated summer warming of 1°–2.5°C over most of the western United States. This result is in strong agreement with proxy reconstructions, suggesting that regional mid-Holocene temperature change can be explained by direct orbital forcing alone, independent of cli...

Abstract: Vegetation strongly affects climate by influencing the exchanges of energy and moisture between the land and atmosphere. This paper uses climate modelling studies to discuss four perspectives on the influence of vegetation on climate through biophysical properties of the land surface; (i) the extent to which present-day patterns of climate are modified by the presence of vegetation, and the importance of this for the vegetation itself; (ii) anthropogenic vegetation change as a driver (forcing) of climate change; (iii) the physiological impact of elevated CO 2 on vegetation as a forcing of climate change through the surface energy budget; and (iv) the responses of vegetation to radiatively-forced climate change and resulting feedbacks on the climate change itself. Contemporary vegetation increases continental precipitation while generally reducing temperature extremes, and this is crucial for maintaining present-day global vegetation patterns. Mid-latitude deforestation has acted to cool the climate by increasing surface albedo, while continued tropical deforestation may exert a warming and reduce precipitation. Elevated CO 2 may cause a warming through reduced transpiration by plants in addition to the greenhouse warming. Forest die-back may accelerate a projected precipitation reduction in Amazonia, while expansion of the boreal forests may provide a positive feedback on local warming.

Abstract: This series of assessments uses scenarios developed by the Intergovernmental Panel on Climate Change (IPCC) to characterise a range of different global development pathways. These have come to be called the SRES scenarios, after the IPCCs Special Report on Emissions Scenarios (IPCC, 2000). Although primarily developed to ascertain how different development pathways would affect emissions and climate change, probably more important an outcome from the SRES (at least for impact and adaptation assessment) has been the insight into the differing levels of vulnerability and resilience to climate change implied by different levels of future population and income. What emerges from the papers in this issue is that these differences, flowing from different pathways of development, are frequently more important than climate change itself in influencing the scale and distribution of global and regional impacts. This is the first global assessment of impacts under SRES scenarios, but many regional impact assessments are now underway, and will be published within the next 2 years. They will form a valuable background for the Fourth Assessment Report of the IPCC, due to be completed in 2007. The population and income data used in many of these assessments may be found on the IPCCs Data Distribution Centre (DDC) and a linked site at the Center for International Earth Science Information Network. Established in 1998, the DDC contains and makes available up-to-date quality-controlled climate change and socio-economic data for

Abstract: The impacts of weather and climate extremes (floods, storms, drought, etc) have historically set back development and will continue to do so into the future, especially in developing countries. It is essential to understand how future climate change will be manifest as weather and climate extremes in order to implement policies of sustainable development. The purpose of this article is to demonstrate that natural processes have caused the climate to change and it is unlikely that human influences will dominate the natural processes. Any suggestion that implementation of the Kyoto Protocol will avoid future infrastructure damage, environmental degradation and loss of life from weather and climate extremes is a grand delusion.

Abstract: Current climate change research indicates that the Great Lakes hydrological system will be affected by future climate. Changes in the lake levels and flows will, in turn, impact the ability of Great Lakes hydro–electric power producers to generate electricity. Using technical specifications of turbine capacity, turbine loading orders and climate change projections, the electricity generating capacity is estimated under several climate change scenarios. These estimations are evaluated using a selection of pricing options according to economic assumptions concerning adaptation and time frame for impacts and adaptation. This work is intended to promote interest in further studies on the economic impacts of climate change.

Abstract: In this chapter, we present evidence that changes in landsurface, in particular those relating to vegetation-atmos-phere interaction, affect weather and climate at the global scale. We also show that without understanding vegetation dynamics we are unable to describe long-term climate variability, nor can we fully interpret palaeodimatic reconstructions or predict global weather properly. This chapter is organised as follows (see also Table A.1): In Sect. A.4.1, we present theoretical considerations. We show how vegetation interferes with the atmosphere and the other components of the climate system at the global scale, and we explore the consequences of the nonlinear character of atmosphere-vegetation dynamics. In Sect. A.4.2, we interpret palaeoclimatic and palaeobotanic reconstructions in the light of the theory being developed in Sect. A.4.1. In Sect. A.4.3, emphasis is given to the interaction of atmosphere-vegetation dynamics and the global carbon cycle. We mainly focus on numerical sensitivity experiments which highlight potential changes in the climate system under the condition of increased emissions of CO2. In Sect. A.4.4, we discuss the memory effects which soil moisture imposes on the global climate system. This memory effect becomes important where seasonal climate variability is concerned. In Sect. A.4.5, we present evidence that improved representation of atmosphere-vegetation interaction in a model of global weather forecast has substantially improved prediction skill.

Abstract: The Earth's climate system has been experiencing a significant change characterized by global warming in the past century. The trend of climate change over China is approximately consistent with that of the globe. The climate warming in recent 50 years is mainly due to the enhanced green-house effects produced by green-house gases emission into the atmosphere as a result of fossil fuels burning. Current modeling projections indicate that the climate of China and the globe will continue to be warmer in the coming 50 to 100 years. At the present, the world is negotiating the Kyoto Protocol to the United Nations Framework Convention on Climate Change on how to mitigate the climate warming and control the emission of green house gases. Firstly,IPCC TAR and the state of the art scientific advances are referred to present the facts of climate change and future possible change. The responses of Cryosphere to climate change are summarized in the second section. The third section addresses the impact of climate change on ecosystem and socio-economy and the challenges and opportunities to China derived from climate change are analyzed in the fourth section, followed by the strategies addressing climate change.

Abstract: The climate system is in perpetual evolution as it responds to a range of forcing factors. It is possible to distinguish between external and internal forcings of the system. External forcings are essentially linked to changes in the orbital parameters of the Earth that control the intensity and location of incident solar radiation, and fluctuations in solar energy.

Abstract: The atmospheric concentration of CO2 and other greenhouse gases are increasing and changing the radiative properties of the atmosphere. To study the response of the ocean-climate system to this climate perturbation, investigators have integrated ocean-climate models with an atmospheric CO2 concentration that rises over time to double, triple or quadruple the control CO2 level [Bi et al., 2001; Hirst, 1999; Manabe and Stouffer, 1993; Goosse and Renssen, 2001]. The oceanic response in these experiments typically includes widespread surface warming, retreat of sea ice and a general increase in upper ocean stratification, all of which may impact upon the ocean biogeochemistry. The substantial reductions in formation rate and/or density of intermediate and deep water masses that occur in these simulations would likely affect biogeochemical cycling in the ocean and the air-sea exchange of oxygen and CO2. This chapter uses a biogeochemical model to examine the effect of global warming on biogeochemical cycling in the ocean focusing on the oceanic oxygen distribution. The chapter discusses the simulated oxygen changes in the ocean and demonstrates the potential of using oxygen changes to track global warming and provide observations to assess climate model simulations.

Abstract: The objective of the Climate Change Convention requires that atmospheric concentrations of greenhouse gases should be stabilised at a level which allows ecosystems to adapt naturally to climate change Yet there is substantial and compelling evidence that the degree of climate change which has already occurred is affecting both species and ecosystems, in many cases adversely It appears very likely that species will increasingly become extinct and ecosystems will be lost as a result of little further change in the climate In the context of the objective of the Convention, it can thus be reasonably be argued that at least some ecosystems are not “adapting naturally” to climate change and that atmospheric concentrations of greenhouse gases are already too high 1 Introduction and background

Abstract: The ongoing debate on the global warming and climate change highlights the possibility of increased incidences of extreme weather events world-wide, as the earth’s mean temperature is expected to rise steadily in the next 100 years according to most climate model projections. The recent IPCC (Intergovernmental Panel on Climate Change) document (IPCC, 2001) categorically states: The globally average surface temperature is projected to increase by 1.4C to 5.8C over the period 1990 to 2100. The projected warming is much larger than the observed changes during the twentieth century and is very likely to be without precedent during at least the last 10,000 years. The Climate Change document also summarizes various extreme weather events and their observed and projected changes based on model simulations. Among the extreme weather events summarized by IPCC are: Higher maximum temperature and more hot days over nearly all land areas; increase of heat index over land areas; more intense precipitation events and increased summer continental drying and associated risk of drought. Besides these weather events, the Climate change document also makes projections of major climatic events and states: El Nino events may show small increase in amplitude but its impact in terms of droughts and floods will increase. The warming associated with increasing greenhouse gas concentration will cause an increase of Asian summer monsoon variability. A number of recent papers appearing in peer-reviewed literature have questioned many of the IPCC projections on future warming of the earth’s surface and associated increase in extreme weather events. It is important to briefly review these recent studies and make an assessment of present status of the global warming science. Such an assessment is essential for developing a Climate Policy consistent with the emerging view of the state of science. In this viewpoint, some of the climate model projections are briefly assessed in the light of recent studies.