Abstract: In the climateprediction.net project, thousands of individuals have volunteered spare computing capacity on their PCs to help quantify uncertainty in the way our climate responds to increasing levels of greenhouse gases. By running a state-of-the-art climate model thousands of times, it is possible to find out how the model responds to slight changes in the approximations of physical processes that cannot be calculated explicitly. The first batch of results has now been analysed, and surface temperature changes in simulations that capture the climate realistically are ranging from below 2 °C to more than 11 °C. These represent the possible long-term change, averaged over the whole planet, as a result of doubling the levels of atmospheric carbon dioxide in the model. This is the first time that complex models have been found with such a wide range of responses. Their existence will help in quantifying the risks associated with climate change on a regional level. The range of possibilities for future climate evolution1,2,3 needs to be taken into account when planning climate change mitigation and adaptation strategies. This requires ensembles of multi-decadal simulations to assess both chaotic climate variability and model response uncertainty4,5,6,7,8,9. Statistical estimates of model response uncertainty, based on observations of recent climate change10,11,12,13, admit climate sensitivities—defined as the equilibrium response of global mean temperature to doubling levels of atmospheric carbon dioxide—substantially greater than 5 K. But such strong responses are not used in ranges for future climate change14 because they have not been seen in general circulation models. Here we present results from the ‘climateprediction.net’ experiment, the first multi-thousand-member grand ensemble of simulations using a general circulation model and thereby explicitly resolving regional details15,16,17,18,19,20,21. We find model versions as realistic as other state-of-the-art climate models but with climate sensitivities ranging from less than 2 K to more than 11 K. Models with such extreme sensitivities are critical for the study of the full range of possible responses of the climate system to rising greenhouse gas levels, and for assessing the risks associated with specific targets for stabilizing these levels.

Abstract: Two global coupled climate models show that even if the concentrations of greenhouse gases in the atmosphere had been stabilized in the year 2000, we are already committed to further global warming of about another half degree and an additional 320% sea level rise caused by thermal expansion by the end of the 21st century Projected weakening of the meridional overturning circulation in the North Atlantic Ocean does not lead to a net cooling in Europe At any given point in time, even if concentrations are stabilized, there is a commitment to future climate changes that will be greater than those we have already observed

Abstract: This paper reviews recent research that assesses evidence for the detection of anthropogenic and natural external influences on the climate. Externally driven climate change has been detected by a number of investigators in independent data covering many parts of the climate system, including surface temperature on global and large regional scales, ocean heat content, atmospheric circulation, and variables of the free atmosphere, such as atmospheric temperature and tropopause height. The influence of external forcing is also clearly discernible in reconstructions of hemispheric-scale temperature of the last millennium. These observed climate changes are very unlikely to be due only to natural internal climate variability, and they are consistent with the responses to anthropogenic and natural external forcing of the climate system that are simulated with climate models. The evidence indicates that natural drivers such as solar variability and volcanic activity are at most partially responsible fo...

Abstract: Summary Globally we face serious challenges from the effects of climate change. The causal link between global warming and increased greenhouse gas emissions is well established. Carbon dioxide levels are at a higher level than at any time in the past 750 000 years at least, and it is too late to stop further warming and consequent impacts on UK and global societies. Here I summarize the latest scientific evidence for anthropogenic global warming and outline strategies for adapting to its impacts and mitigating the effects in the longer term.

Abstract: A review of the present status of the global warming science is presented in this paper. The term global warming is now popularly used to refer to the recent reported increase in the mean surface temperature of the earth; this increase being attributed to increasing human activity and in particular to the increased concentration of greenhouse gases (carbon dioxide, methane and nitrous oxide) in the atmosphere. Since the mid to late 1980s there has been an intense and often emotional debate on this topic. The various climate change reports (1996, 2001) prepared by the IPCC (Intergovernmental Panel on Climate Change), have provided the scientific framework that ultimately led to the Kyoto protocol on the reduction of greenhouse gas emissions (particularly carbon dioxide) due to the burning of fossil fuels. Numerous peer-reviewed studies reported in recent literature have attempted to verify several of the projections on climate change that have been detailed by the IPCC reports. The global warming debate as presented by the media usually focuses on the increasing mean temperature of the earth, associated extreme weather events and future climate projections of increasing frequency of extreme weather events worldwide. In reality, the climate change issue is considerably more complex than an increase in the earth's mean temperature and in extreme weather events. Several recent studies have questioned many of the projections of climate change made by the IPCC reports and at present there is an emerging dissenting view of the global warming science which is at odds with the IPCC view of the cause and consequence of global warming. Our review suggests that the dissenting view offered by the skeptics or opponents of global warming appears substantially more credible than the supporting view put forth by the proponents of global warming. Further, the projections of future climate change over the next fifty to one hundred years is based on insufficiently verified climate models and are therefore not considered reliable at this point in time.

Abstract: This paper discusses the need for a more integrated approach to modelling changes in climate and crops, and some of the challenges posed by this. While changes in atmospheric composition are expected to exert an increasing radiative forcing of climate change leading to further warming of global mean temperatures and shifts in precipitation patterns, these are not the only climatic processes which may influence crop production. Changes in the physical characteristics of the land cover may also affect climate; these may arise directly from land use activities and may also result from the large-scale responses of crops to seasonal, interannual and decadal changes in the atmospheric state. Climate models used to drive crop models may, therefore, need to consider changes in the land surface, either as imposed boundary conditions or as feedbacks from an interactive climate-vegetation model. Crops may also respond directly to changes in atmospheric composition, such as the concentrations of carbon dioxide (CO2), ozone (03) and compounds of sulphur and nitrogen, so crop models should consider these processes as well as climate change. Changes in these, and the responses of the crops, may be intimately linked with meteorological processes so crop and climate models should consider synergies between climate and atmospheric chemistry. Some crop responses may occur at scales too small to significantly influence meteorology, so may not need to be included as feedbacks within climate models. However, the volume of data required to drive the appropriate crop models may be very large, especially if short-time-scale variability is important. Implementation of crop models within climate models would minimize the need to transfer large quantities of data between separate modelling systems. It should also be noted that crop responses to climate change may interact with other impacts of climate change, such as hydrological changes. For example, the availability of water for irrigation may be affected by changes in runoff as a direct consequence of climate change, and may also be affected by climate-related changes in demand for water for other uses. It is, therefore, necessary to consider the interactions between the responses of several impacts sectors to climate change. Overall, there is a strong case for a much closer coupling between models of climate, crops and hydrology, but this in itself poses challenges arising from issues of scale and errors in the models. A strategy is proposed whereby the pursuit of a fully coupled climate-chemistry-crop-hydrology model is paralleled by continued use of separate climate and land surface models but with a focus on consistency between the models.

Abstract: "Global warming and sea-level rise are the most serious threats to the Pacific region and the survival of some island states." --Communique of the Twenty-Third South Pacific Forum, 1992 (1) "Sea-level rise and other related consequences of climate change are grave security threats to our very existence as homelands and nation-states." --Leo A. Falcam, President of the Federated States of Micronesia, 2001 (2) Global forces often have had detrimental impacts on the Pacific islands. Colonization, island-scale phosphate mining, nuclear weapons testing, the Second World War, the Cold War, globalization and trade liberalization have all wrought significant political, economic and cultural changes in the region. Yet as the epigraphs to this article suggest, among all these global processes, perhaps the most dangerous to the Pacific islands is climate change. Since the 1988 Toronto Conference, "The Changing Atmosphere: Implications for Global Security," climate change has emerged as a major environmental security problem. Among biological and earth scientists, it is widely felt that climate change will significantly alter the distribution and function of most of the world's natural systems. Small islands have repeatedly been identified in science and climate policy discourse as natural systems particularly vulnerable to climate change. A growing body of research suggests that, given the ways in which island ecosystems are likely to change, social systems on small islands are at risk of significant stress due to climate change. This article assesses the consequences of climate change on the Pacific islands and explores the potential to mitigate and adapt to these effects. GLOBAL CLIMATE CHANGE The earth's climate is influenced by incoming and outgoing solar radiation, while the planet's surface absorbs approximately half of the incoming solar energy, which leads to global warming. Some of this heat is re-emitted in the form of infrared radiation, but most is blocked by a blanket of greenhouse gases that keeps the planet some 34[degrees]Celsius warmer than it would be otherwise. (3) Heating of the earth is greatest along the equator, and the world's general climate and weather patterns are determined by atmospheric and oceanic transportation of heat away from the equator and toward the poles. Since the Industrial Revolution, human activities such as land clearing and the burning of oil and coal have increased the concentration of most greenhouse gases in the atmosphere. These emissions have thickened the blanket of greenhouse gases, trapping more of the outgoing infrared radiation, which warms the atmosphere, land and ocean surfaces. In turn, this warming creates a more vigorous redistribution of heat from the equator to the poles, leading to changes in atmospheric and oceanic circulations, weather patterns and the hydrological cycle that will continue into the future. Much of what is known about climate change is compiled into five yearly reports issued by the Intergovernmental Panel on Climate Change (IPCC). (4) In its 2001 Third Assessment Report, the IPCC concluded that during the 20th century, global average surface temperature had increased by 0.6[degrees] Celsius and sea levels rose 10-20 centimeters. (5) The IPCC argued that natural causes could not account for these changes and that they were largely attributable to human activities. Emissions of carbon dioxide (C[O.sub.2]), to which fossil fuel combustion and cement production are major contributors, account for 64 percent of the enhanced greenhouse effect. Since 1751, these sources have been responsible for the release of roughly 290 billion tons of carbon into the atmosphere, half of this total after the mid-1970s. (6) As a result, atmospheric concentrations of C[O.sub.2] have increased by 30 percent since 1750. (7) Land clearing, farming and deforestation are also major sources of greenhouse gas emissions. …

Abstract: 1. The Climate System 2. Solar Radiation and the Energy Budget of the Earth 3. Atmosphere and Climate 4. Clouds and Aerosols 5. Ocean and Climate 6. Radiative Transfer 7. Earth's Energy Budget: The Greenhouse Effect 8. The Ozone Layer 9. Climate Observations by Remote Sensing 10. Climate Sensitivity and Change 11. Climate Models and Predictions 12. Climate on other Planets 13. Epilogue

Abstract: The article examines the dynamics of the Lithuanian climate in the 18th–20th centuries. Evaluation of air temperature, precipitation amount and the intensity of cyclonic circulation during the observation period was made. Seasonal trends of different climatological indices were determined. To predict climate change trends in Lithuania in the 21st century, the outputs of Global Climate Model (GCM) experiments from five modelling centres were used. The results of investigation show that current climate change tendencies in Lithuania will remain in the future: against the background of air temperature rise the continentality of the Lithuanian climate will decrease.

Abstract: The Himalayas, roof of the world, are springing a leak. As the climate warms up, melting glaciers are threatening the livelihoods of millions. David Cyranoski reports.

Abstract: As carbon dioxide and other greenhouse gases accumulate in the atmosphere and contribute to rising global temperatures, it is important to examine how derivative changes in climate may affect natural and managed ecosystems. In this series of papers, we study the impacts of climate change on agriculture, water resources and natural ecosystems in the conterminous United States using twelve scenarios derived from General Circulation Model (GCM) projections to drive biophysical impact models. These scenarios are described in this paper. The scenarios are first put into the context of recent work on climate-change by the IPCC for the 21st century and span two levels of global-mean temperature change and three sets of spatial patterns of change derived from GCM results. In addition, the effect of either the presence or absence of a CO 2 fertilization effect on vegetation is examined by using two levels of atmospheric CO 2 concentration as a proxy variable. Results from three GCM experiments were used to produce different regional patterns of climate change. The three regional patterns for the conterminous United States range from: an increase in temperature above the global-mean level along with a significant decline in precipitation; temperature increases in line with the global-mean with an average increase in precipitation; and, with a sulfate aerosol effect added to in the same model, temperature increases that are lower than the global-mean. The resulting set of scenarios span a wide range of potential climate changes and allows examination of the relative importance of global-mean temperature change, regional climate patterns, aerosol cooling, and CO 2 fertilization effects.

Abstract: Academic and political debates over long-run climate policy often invoke “stabilization” of atmospheric concentrations of greenhouse gases (GHGs), but only rarely are non-CO 2 greenhouse gases addressed explicitly. Even though the majority of short-term climate policies propose trading between gases on a global warming potential (GWP) basis, discussions of whether CO 2 concentrations should be 450, 550, 650 or perhaps as much as 750 ppm leave unstated whether there should be no additional forcing from other GHGs beyond current levels or whether separate concentration targets should be established for each GHG. Here, we use an integrated modeling framework to examine multi-gas stabilization in terms of temperature, economic costs, carbon uptake and other important consequences. We show that there are significant differences in both costs and climate impacts between different “GWP equivalent” policies and demonstrate the importance of non-CO 2 GHG reduction on timescales of up to several centuries.

Abstract: The global-mean surface temperature has risen by 0.6℃ during the 20th century due to the increase of atmospheric concentrations of greenhouse gases (IPCC, 2001a), and the mean temperature of the Korean Peninsula is also risen by 1.5℃ during the same period due to global warming as well as rapid urbanization. During the 21st century, the global-mean temperature is projected to rise 1.4-5.8℃ associated with the various scenarios from IPCC Special Report on Emission Scenario (SRES) (2000). Reduction in emissions and atmospheric concentrations of greenhouse gases will be very likely to mitigate the degree and likelihood of global warming. However, if the greenhouse gas concentrations were fixed at present level, the global-mean temperature and sea level would continue to rise due to thermal inertia of global climate system. Climate change resulting from increased greenhouse gas concentrations has the potential to harm human societies and natural ecosystems, such as agriculture, forestry, water resources, human health, coastal settlements, and land and ocean ecosystems, which will need to adapt to a changing climate or face adverse impacts. We propose a nation-wide network of research centers from diverse disciplines to study integrated impact assessment of climate change and to develop adaptation measures in Korea.

Abstract: The credibility of regional climate change predictions for the 21st century depends on the ability of climate models to simulate global and regional circulations in a realistic manner. To investigate this issue, a large set of global coupled climate model experiments prepared for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change has been studied. First we compared 20th century model simulations of longterm mean monthly sea level pressure patterns with ERA-40. We found a wide range in performance. Many models performed well on a global scale. For northern midlatitudes and Europe many models showed large errors, while other models simulated realistic pressure fields. Next we focused on the monthly mean climate of West-Central Europe in the 20th century. In this region the climate depends strongly on the circulation. Westerlies bring temperate weather from the Atlantic Ocean, while easterlies bring cold spells in winter and hot weather in summer. In order to be credible for this region, a climate model has to show realistic circulation statistics in the current climate, and a response of temperature and precipitation variations to circulation variations that agrees with observations. We found that even models with a realistic mean pressure pattern over Europe still showed pronounced deviations from the observed circulation distributions. In particular, the frequency distributions of the strength of westerlies appears to be difficult to simulate well. This contributes substantially to biases in simulated temperatures and precipitation, which have to be accounted for when comparing model simulations with observations. Finally we considered changes in climate simulations between the end of the 20th century and the end of the 21st century. Here we found that changes in simulated circulation statistics play an important role in climate scenarios. For temperature, the warm extremes in summer and cold extremes in winter are most sensitive to changes in circulation, because these extremes depend strongly on the simulated frequency of eastery flow. For precipitation, we found that circulation changes have a substantial influence, both on mean changes and on changes in the probability of wet extremes and of long dry spells. Because we do not know how reliable climate models are in their predictions of circulation changes, climate change predictions for Europe are as yet uncertain in many aspects.

Abstract: The present work analyzes the climate change impacts on the runoff regimes of mountainous catchments in the Swiss Alps having current glaciation rates between 0 and 50 %. The hydrological response of 11 catchments to a given climate scenario is simulated through a conceptual, reservoir-based precipitation-runoff transformation model called GSM-SOCONT (Schaefli, 2005). For the glacierized catchments, the glacier surface corresponding to this future scenario is updated through a conceptual glacier surface evolution model. The analyzed climate change scenarios were derived from 19 climate experiments obtained within the EU research project PRUDENCE (Christensen et al. 2002). They are the results of 9 state-to-the-art Regional Climate Models (RCMs) driven by three coupled Atmosphere-Ocean General Circulation Models (AOGCMs), respectively HadCM3/HadAM3H, ECHAM4/OPYC3 and ARPEGE. The two first families of climate change scenarios correspond to changes in seasonal temperatures and precipitations simulated for the period 2070-2099 under the two green house gas emission scenarios A2 and B2 defined by the Intergovernmental Panel on Climate Change (12 experiments are available for A2 and 7 for B2). From the 19 PRUDENCE experiments 19 climate changes scenarios were additionally developed for a transient period (2020-2049) corresponding in first approximation to a global warming scenario of +1°C.

Abstract: Global climate has been already perturbed due to variations in orbital forcing and man made factors and the footprints of it are traceable in the world climate spectrum (IPCC 1995). It is also evidenced world-wide that man made factors are aggravating the global effects of climate change in terms of triggering extreme weather events. The present paper address critically not only the spatiotemporal variations of moisture and thermal regimes of India through water balance model but also the occurrence of varied degrees of humidness and droughts in moist and dry climates respectively for selected stations that are drawn from its climate spectrum by selecting not less than two stations representing north and south of each of its climate zones. The paper then proceeds in analyzing proneness to varied degrees of droughts on All India basis. Climate stability and the basic water budget elements in extreme climate shifts for the selected stations are also studied. The investigation presents the modulation of basic water budget elements of All India during extreme climate shifts of wetness and dryness in the context of LNSO and ENSO signals and their climate implications are discussed. Finally, trends in All India moisture regime in the context of LNSO and ENSO signals are also reported.

Abstract: A numerical experiment investigating climate change due to the gradual increase in atmospheric carbon dioxide (CO2) has been performed with the community climate system model (CCSM) developed by National Center for Atmospheric Research (NCAR). Composed of four independent component models simulating the earth’s atmosphere, ocean, land surface, and sea-ice and one central coupler, the CCSM is used to simulate and understand the earth’s past, present and future climate states. The model experiment consists of a control run with a fixed atmospheric CO2 concentration at a standardized value for 1990 to 2000 (355 ppmv) and a transient run with a gradually increased atmospheric CO2 at the rate of 1% per year. jaThe initial CO2 concentration of the transient run is 355 ppmv. Each run has been performed for 80 simulated years. In this experiment, climate change due to the gradually increased atmospheric CO2 is defined as the difference between the results from the transient and control runs. At the time of CO2 doubling (about year 70), the globally averaged surface air temperature increases by 1.25°C. The surface air temperature increases are more predominant over the higher-latitude land areas than over other areas, especially in boreal winter. With an increase in the surface air temperature, there is a decrease in the diurnal temperature range, with the nighttime minimum temperature increasing more than the daytime maximum temperature. And air temperature shows tropospheric warming and stratospheric cooling causing the strong temperature gradient and polar jet intensifications.

Abstract: Water resources are sensitive to climate variability and change; predictions of seasonal to interannual climate variations and projections of long-term climate trends can provide significant values in managing water resources. This study examines the control (1975–1995) and future (1995–2100) climate simulated by a global climate model (GCM) and a regional climate simulation driven by the GCM control simulation for the U.S. Comparison of the regional climate simulation with observations across 13 subregions showed that the simulation captured the seasonality and the distributions of precipitation rate quite well. The GCM control and climate change simulations showed that, as a result of a 1% increase in greenhouse gas concentrations per year, there will be a warming of 2–3°C across the U.S. from 2000 to 2100. Although precipitation is not projected to change during this century, the warming trend will increase evapotranspiration to reduce annual basin mean runoff over five subregions along the coastal and south-central U.S.

Abstract: In this paper,firstly,the science background is simply summarized about the global climate change,then based on the compartmentalized time scale,the cau global climate warming. change and its effect factors in different time scales are discussed. By analyzed the key natural factors which could cause the climate change in different time scales and the anthropogenic influence upon climate change,it will be help for us to understand the present global climate warming. At the same time,the science diverging and perplexity on the study of climate change are also reviewed.

Abstract: Research on factors of climate variations on a seasonal to multi-decadal timescale is surveyed. However, it is difficult to fully cover wide-ranging research on climate systems including the latest results. This paper focuses on phenomena such as QBO that interact with the other factors. Oceans, which have a clqse relationship with climate change, are considered. Although there is overlapping with dissertations in another chapter, the main contents are as follows: 1) ENSO is a quasi-periodic air-sea interaction, which has been studied closely. If evolvement of ENSO is predicted, it will make seasonal weather forecasts more precise. 2) The effects of stratospheric QBO on climate systems in the troposphere might have been exercised as grave cool damage that occurs in summers when QBO was in the W-phase, and some correlations have been found. QBO probably holds a significant key explaining climate variations. Therefore, elucidation of the QBO mechanism that influences the troposphere can be expected. 3) The relationship between solar activities and climate remains obscure. However, some influences of solar activities on the tropospheric circulation have been felt through sea surface temperature or interaction with stratospheric QBO. 4) In the air-sea interaction the ocean responds to solar radiation more slowly than the atmosphere, so the ocean seems to play a dominant role in long-lived teleconnections such as PDO. In addition, regime shifts of oceans sometimes have major effects on climate. We cannot discuss climate change without referring to oceans. 5) Global warming is in progress. As a result, shifts in general circulation might lead to abnormal weather, which means increased danger of frequent developments of the Okhotsk high, which is responsible for cool summer damage. 6) It is important to evaluate which factors contribute greatly to climate change. Understanding the mechanisms of weather fluctuations ranging from a few months to several years is a pressing matter to prevent recurrence of meteorological disasters.

Abstract: Time series models of global climate change have tended to estimate a low climate sensitivity and a fast adjustment rate to equilibrium. These results appear to be biased by omission of a key variable - heat stored in the ocean. I develop a time series model of the ocean atmosphere climate system where atmospheric temperature moves towards a long-run equilibrium with both radiative forcing and ocean heat content, which is distributed between upper ocean and deep ocean components. The time series model utilizes the notion of multicointegration to impose energy balance relations on an autoregressive model. As there are only around fifty years of observations on ocean heat content I use the Kalman filter to estimate heat content as a latent state variable constrained by the available observations. The estimate of the equilibrium climate sensitivity is 8.4K with a confidence interval of 5.0 to 11.7K. Temperature takes centuries to adjust to an increase in radiative forcing. The transient climate sensitivity at the point of carbon dioxide doubling is 1.7K.

Abstract: This paper reviews recent research that assesses evidence for the detection of anthropogenic and natural external influences on the climate. Externally driven climate change has been detected by a number of investigators in independent data covering many parts of the climate system, including surface temperature on global and large regional scales, ocean heat content, atmospheric circulation, and variables of the free atmosphere, such as atmospheric temperature and tropopause height. The influence of external forcing is also clearly discernible in reconstructions of hemispheric-scale temperature of the last millennium. These observed climate changes are very unlikely to be due only to natural internal climate variability, and they are consistent with the responses to anthropogenic and natural external forcing of the climate system that are simulated with climate models. The evidence indicates that natural drivers such as solar variability and volcanic activity are at most partially responsible for the large-scale temperature changes observed over the past century, and that a large fraction of the warming over the last 50 yr can be attributed to greenhouse gas increases. Thus, the recent research supports and strengthens the IPCC Third Assessment Report conclusion that “most of the global warming over the past 50 years is likely due to the increase in greenhouse gases.”

Abstract: Introduction In the early 1980s scientists began raising concerns about global warming and climate changes. Initially these concerns about human-induced climate changes were met with skepticism because there are natural cycles of climate changes that occur over hundreds of years. Those who tried to raise the importance of this issue, and suggest that perhaps we were over-consuming or unsustainably using our resources, were faced with a lot of criticism and ridicule (Shah, 2005). That early skepticism of the 1980s and 1990s has been replaced with a mainstream scientific consensus on global warming--that changes in our climate are real and that continued human-induced global warming cannot be ignored. Today, the body of research accumulated over the past 25 years indicates that humans are a major factor in the current climate changes. More and more we are realizing that the Industrial Revolution has changed forever the relationship between humanity and nature. There is real concern that by the middle or the end of the next century, human activities will have changed the basic conditions that have allowed life to thrive on earth. The results are uncertain, but if current predictions prove correct, the climatic changes over the coming century will be larger than any since the dawn of human civilization (UNEP/WMO, 1994). What is Global Warming? Global warming is the progressive, gradual rise of the earth's average surface temperature, thought to be caused in part by increased concentrations of "greenhouse" gases (GHGs) in the atmosphere. According to the National Academy of Sciences, the Earth's temperature has risen by about one degree Fahrenheit in the past century, with accelerated warming during the past two decades. Analysis of the various human and natural influences on the global climate indicates that this warming cannot be explained without taking into account human emissions of GHGs. Current scientific data indicates that these "greenhouse" gases have been the dominant force driving temperature increases over the past 50 years. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases--primarily carbon dioxide, methane, and nitrous oxide. The heat-trapping property of these gases is undisputed, although uncertainties exist about exactly how earth's climate responds to them (Environmental, 2005). The Greenhouse Effect The term greenhouse is used in conjunction with the phenomenon known as the "greenhouse effect." Energy from the sun drives the earth's weather and climate and heats the earth's surface; in turn, the earth radiates energy back into space. Roughly 30 percent of the total solar energy that strikes the earth is reflected back into space by clouds, atmospheric aerosols, reflective ground surfaces, and ocean surfaces, Figure 2. The land, air, and the oceans absorb the remaining 70 percent. Atmospheric greenhouse gases (water vapor, carbon dioxide, methane, nitrous oxide, and other gases) trap some of the out-going energy, retaining heat much like the glass panels of a greenhouse. Without this natural "greenhouse effect," temperatures would be much lower than they are now and life as we know it would not be possible. Greenhouse gases are responsible for maintaining the earth's average temperature at approximately 60 degrees Fahrenheit. What has many people worried now is that, since the Industrial Revolution, humans have been artificially raising the concentration of greenhouse gases in the atmosphere, causing the greenhouse effect to get stronger, trapping more heat than needed and raising the average temperature of the earth's surface, which, if left unchecked, could eventually cause the planet to become much less habitable for humans, plants, and animals. [FIGURE 2 OMITTED] Our factories, power plants, and cars burn coal and gasoline, pumping millions of tons of carbon dioxide into our atmosphere. …

Abstract: Sea level rise is an important aspect of future climate change because, without upgraded coastal defences, it is likely to lead to significant impacts. Here we report on several aspects of sea level rise that have implications for the avoidance of dangerous climate change and stabilisation of climate. If the Greenland ice sheet were to melt it would raise global sea levels by around 7m. We discuss the likelihood of such an event occurring in the coming centuries and the possibility that it might be irreversible. We also discuss the time scales controlling sea level rise and estimate how long after atmospheric greenhouse gas concentrations or global temperature have been stabilised that coastal impacts will stop increasing.

Abstract: Global warming or, more accurately, climate change remains a hotly debated issue in scientific, government and public circles. While the extent of the human contribution to climate change through greenhouse gas (GHG) emissions remains highly controversial, the scientific evidence of significant changes in climate per se appears to be mounting (Intergovernmental Panel on Climate Change, 2001). Since changes in climate typically will include greater variability in temperatures, more extreme weather events and changes in precipitation patterns as well as a general warming trend, there are significant risks for agriculture.(2) If human activity does turn out to have a significant causal effect on climate change, the Kyoto Protocol and other related multilateral environmental agreements appear to have the potential to reduce these risks. The Kyoto Protocol, however, leaves possible channels for increases in emissions or so-called carbon leakage.