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Vulnerability is an emerging concept for climate science and policy. Over the past decade, efforts to assess vulnerability to climate change triggered a process of theory development and assessment practice, which is reflected in the reports of the Intergovernmental Panel on Climate Change (IPCC). This paper reviews the historical development of the conceptual ideas underpinning assessments of vulnerability to climate change. We distinguish climate impact assessment, first- and second-generation vulnerability assessment, and adaptation policy assessment. The different generations of assessments are described by means of a conceptual framework that defines key concepts of the assessment and their analytical relationships. The purpose of this conceptual framework is two-fold: first, to present a consistent visual glossary of the main concepts underlying the IPCC approach to vulnerability and its assessment; second, to show the evolution of vulnerability assessments. This evolution is characterized by the progressive inclusion of non-climatic determinants of vulnerability to climate change, including adaptive capacity, and the shift from estimating expected damages to attempting to reduce them. We hope that this paper improves the understanding of the main approaches to climate change vulnerability assessment and their evolution, not only within the climate change community but also among researchers from other scientific communities, who are sometimes puzzled by the unfamiliar use of technical terms in the context of climate change. [ABSTRACT FROM AUTHOR]

In 2004, the UK government published advice to planning authorities on ways in which the planning system might respond to climate change. This paper provides an account of the process of the formulation of that advice and the subsequent policy guidance, analysing the tensions revealed and offering an explanation of why the process took some time. It argues that the story can be understood in institutionalist terms, which recognize the different perspectives of planning policy communities and climate change policy communities. The decision to publish advice provided a policy arena in which these different interests sought to influence the agenda, employing competing policy discourses of discretionary enablement and more urgent prescription. These discourses partly reflected different approaches to the role of government, but also revealed the complexities of climate change as a new and uncharted issue facing the planning system. [ABSTRACT FROM AUTHOR]

Copyright of Atti della Società dei Naturalisti e Matematici di Modena is the property of Societa dei Naturalisti e Matematici di Modena and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper traces the history of the use of ships' logbooks in climatological studies from the earliest days of the 17th century to the present day. Although early theories concerning global air circulations by Halley and Hadley were based on information gathered by mariners and recorded in their logbooks, it has only been in the last two decades that interest has returned to this important, but long-overlooked, source of climatic information. Attention is drawn to the many advantages offered by logbooks, in particular the long period of time that they collectively cover, their near-global geographic range, the large number of such documents that have survived, and the degree of detailed and reliable record that they provide. Before the mid-19th century, much of the recorded information is noninstrumental in character but its scientific potential is reflected in the variety of approaches and methods that have been used in its analysis and in the equally wide range of outcomes, from databases to synoptic charts and long-time series indices that have emerged from the most recent research. Attention is also drawn to the benefits to be derived from old and more recent instrumental logbook data. As only a small percentage of the tens of thousands of logbooks that have been preserved have thus far been examined, the potential for yet further development is enormous. [ABSTRACT FROM AUTHOR]

This paper analyses the relationship between field experimentalists and simulation modellers in meteorological research on the one hand, and how this is related to climate change as a common arena of concern on the other. Climate has become the central topic in meteorological research and it is imperative to link specific research problems to climate change in order to receive funding and attract talent. In addition, climate models have become gatekeepers for claims about climate change. Hence, active participation in climate modelling processes is valuable for all parties. Observational data are used in order to develop new components — so-called parameterizations — for the climate models and these novel components therefore emerge as important boundary objects. While they serve different purposes for experimentalists and modellers in terms of translation processes, they also serve to connect these groups and reinforce their mutual dependence. [ABSTRACT FROM AUTHOR]

Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radiative feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general circulation models. By reviewing recent observational, numerical, and theoretical studies, this paper shows that there has been progress since the Third Assessment Report of the Intergovernmental Panel on Climate Change in (i) the understanding of the physical mechanisms involved in these feedbacks, (ii) the interpretation of intermodel differences in global estimates of these feedbacks, and (iii) the development of methodologies of evaluation of these feedbacks (or of some components) using observations. This suggests that continuing developments in climate feedback research will progressively help make it possible to constrain the GCMs’ range of climate feedbacks and climate sensitivity through an ensemble of diagnostics based on physical understanding and observations. [ABSTRACT FROM AUTHOR]

The relative importance of the processes responsible for the annual cycle in the upper-ocean heat content in the Peru Current, in the southeastern tropical Pacific, was diagnosed from an oceanic analysis dataset. It was found that the annual cycle of heat content is forced mainly by insolation. However, the ocean dynamical processes play an important role in producing different regional budget characteristics. In a band 500 km from the coast of Peru, the annual heat content changes in this region are relatively large and can be approximated as sea surface temperature (SST) changes in a fixed-depth mixed layer. The annual cycle of the albedo associated with low-level clouds enhances the annual cycle in insolation, which explains the relatively strong annual cycle of heat content. These clouds, to a large extent, act as a feedback to SST, but a small additional forcing, which is proposed to be cold air advection in this paper, is needed to explain the fact that the maximum cloudiness leads the lowest SST by around a month. Ocean dynamics is important closer to the coast, where upwelling acts partly as damping of the heat content changes and forces it to peak earlier than farther offshore. In a band farther to the southwest, locally wind-forced thermocline motions, which become shallower (deeper) in the warm (cool) season, partially cancel the effect of net surface heat fluxes, whose annual cycle is comparable to that in the region previously mentioned, producing a relatively small annual cycle of heat content. The local forcing appears to be associated with the annual meridional displacements of the South Pacific anticyclone. The annual cycle in SST is also relatively small, which is probably due to the changes in the temperature of the water entrained into the mixed layer associated with the thermocline motions, but also to a mixed layer deeper than that closer to the coast. [ABSTRACT FROM AUTHOR]

Copyright of Atmosphere - Ocean (Canadian Meteorological & Oceanographic Society) is the property of Canadian Meteorological & Oceanographic Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An ensemble of simulations from different versions of the Community Atmosphere Model in the Community Earth System Model (CESM) is used to investigate the processes responsible for the intermodel spread in climate sensitivity. In the CESM simulations, the climate sensitivity spread is primarily explained by shortwave cloud feedbacks on the equatorward flank of the midlatitude storm tracks. Shortwave cloud feedbacks have been found to explain climate sensitivity spread in previous studies, but the location of feedback differences was in the subtropics rather than in the storm tracks as identified in CESM. The cloud-feedback relationships are slightly stronger in the winter hemisphere. The spread in climate sensitivity in this study is related both to the cloud-base state and to the cloud feedbacks. Simulated climate sensitivity is correlated with cloud-fraction changes on the equatorward side of the storm tracks, cloud condensate in the storm tracks, and cloud microphysical state on the poleward side of the storm tracks. Changes in the extent and water content of stratiform clouds (that make up cloud feedback) are regulated by the base-state vertical velocity, humidity, and deep convective mass fluxes. Within the storm tracks, the cloud-base state affects the cloud response to CO2-induced temperature changes and alters the cloud feedbacks, contributing to climate sensitivity spread within the CESM ensemble. [ABSTRACT FROM AUTHOR]

Using historical records on first and last frost and snow, spring cultivation, David peach blossom, autumn crop harvest, grade of sea freeze and change in northern citrus boundary, we reconstructed temperature change during 601-920 AD. The mean temperature of the winter half-year (October to April) over Central East China during this period was about -0.22°C higher than that of the present (1961-2000 AD mean). During 601-820 AD, mean temperature was about -0.52°C higher than the present. During 821-920 AD, the mean temperature was 0.42°C lower than the present. The temperature fluctuations were characterized by a maximum amplitude of 1.05°C at the centennial scale, 1.38°C at the 50-year scale, 2.02°C at the 30-year scale, and 2.3°C at the 20-year scale. There were four peaks warmer than today (601-620 AD, mean of 1°C higher temperature; 641-660 AD, 1.44°C; 701-720 AD, 0.88°C; 781-800 AD, 0.65°C). Three cold periods were in 741-760, 821-840, and 881-900 AD, the mean temperature of which was 0.37-0.87°C lower than the present. [ABSTRACT FROM AUTHOR]

Instrumental daily series of temperature are often affected by inhomogeneities. Several methods are available for their correction at monthly and annual scales, whereas few exist for daily data. Here, an improved version of the higher-order moments (HOM) method, the higher-order moments for autocorrelated data (HOMAD), is proposed. HOMAD addresses the main weaknesses of HOM, namely, data autocorrelation and the subjective choice of regression parameters. Simulated series are used for the comparison of both methodologies. The results highlight and reveal that HOMAD outperforms HOM for small samples. Additionally, three daily temperature time series from stations in the eastern Mediterranean are used to show the impact of homogenization procedures on trend estimation and the assessment of extremes. HOMAD provides an improved correction of daily temperature time series and further supports the use of corrected daily temperature time series prior to climate change assessment. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The atmospheric response to a North Pacific subsurface oceanic temperature anomaly is studied in a coupled ocean–atmosphere general circulation model using a combined dynamical and statistical approach, with the focus on the evolution at seasonal and longer time scales. The atmospheric response is first assessed dynamically with an ensemble coupled experiment. The atmospheric response is found to exhibit a distinct seasonal evolution and a significant long-term response. The oceanic temperature anomaly reemerges each winter to force the atmosphere through an upward heat flux, forcing a clear seasonal atmospheric response locally over the Aleutian low and downstream over the North America/North Atlantic Ocean and the Arctic regions. The atmospheric response is dominated by the early winter response with a warm SST-equivalent barotropic ridge and a wave train downstream. Starting in later winter, the atmospheric response weakens significantly and remains weak throughout the summer. The seasonal response of the atmosphere is then assessed statistically from the control simulation. It is found that the major features of the seasonal response, especially the strong warm SST–ridge response in early winter, are crudely consistent between the dynamical and statistical assessments. The statistical assessment is finally applied to the observation, which also suggests a strong seasonal atmospheric response locally over the North Pacific dominated by a warm SST–ridge response in early winter. One important conclusion is that the atmospheric response becomes more significant at annual and longer time scales, with the signal/noise ratio increasing up to 4 times from the monthly to the 4-yr mean response. This increased signal/noise ratio is caused by a much faster reduction of the atmospheric internal variability toward longer time scales than that of the response signal. The slow decrease of the response signal is due to the long persistence associated with the subsurface ocean. This suggests that the subsurface extratropical oceanic variability could have a much stronger impact on the extratropical atmosphere (and climate variability) at interannual–interdecadal time scales than at monthly–seasonal time scales. [ABSTRACT FROM AUTHOR]

The article reports on near-surface-temperature lapse rates on the Prince of Wales Icefield in Ellesmere Island in Canada. In this study, screen temperatures were monitored from May 2001 to April 2003 in 25 sites in this location. It is posed that surface-temperature lapse rate in the region are systematically less than the free-air lapse rates that are commonly adopted for extrapolations of sea-level temperature to higher altitudes. Lastly, the low surface-temperature lapse rates and their systematic synoptic variability have essential implications for applications that involve downscaling of surface- or boundary-layer temperatures.

The article investigates the surface temperature changes over different land surface vegetation classes by the dividing the globe into seven regions using a global land cover classification data set. The authors also examine the detection and attribution of surface temperature trends over various vegetation classes for the last 50 years using outputs from three coupled climate models. Findings of the study indicate significant warming in all regions from the year 1900 and antropogenic warming trend in six out of seven regions.

The ability of coupled GCMs to correctly simulate the climatology and a prominent mode of variability of the West African monsoon is evaluated, and the results are used to make informed decisions about which models may be producing more reliable projections of future climate in this region. The integrations were made available by the Program for Climate Model Diagnosis and Intercomparison for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The evaluation emphasizes the circulation characteristics that support the precipitation climatology, and the physical processes of a “rainfall dipole” variability mode that is often associated with dry conditions in the Sahel when SSTs in the Gulf of Guinea are anomalously warm. Based on the quality of their twentieth-century simulations over West Africa in summer, three GCMs are chosen for analysis of the twenty-first century integrations under various assumptions about future greenhouse gas increases. Each of these models behaves differently in the twenty-first-century simulations. One model simulates severe drying across the Sahel in the later part of the twenty-first century, while another projects quite wet conditions throughout the twenty-first century. In the third model, warming in the Gulf of Guinea leads to more modest drying in the Sahel due to a doubling of the number of anomalously dry years by the end of the century. An evaluation of the physical processes that cause these climate changes, in the context of the understanding about how the system works in the twentieth century, suggests that the third model provides the most reasonable projection of the twenty-first-century climate. [ABSTRACT FROM AUTHOR]

Global climate models forced by sea surface temperature are standard tools in seasonal climate prediction and in projection of future climate change caused by anthropogenic emissions of greenhouse gases. Assessing the ability of these models to reproduce observed atmospheric circulation given the lower boundary conditions, and thus its ability to predict climate, has been a recurrent concern. Several assessments have shown that the performance of models is seasonally dependent, but there has always been the assumption that, for a given season, the model skill is constant throughout the period being analyzed. Here, it is demonstrated that there are periods when these models perform well and periods when they do not capture observed climate variability. The variations of the model performance have temporal scales and spatial patterns consistent with decadal/interdecadal climate variability. These results suggest that there are unmodeled climate processes that affect seasonal climate prediction as well as scenarios of climate change, particularly regional climate change projections. The reliability of these scenarios may depend on the time slice of the model output being analyzed. Therefore, more comprehensive model assessment should include a verification of the long-term stability of their performance. [ABSTRACT FROM AUTHOR]

This article examines the implications for the social discount rate for damage due to climate change if risk to future generations is handled in accordance with the laws regulating our handling of risk to contemporaries. The conclusions are the following. Under current law, neither geographic distance nor differences in wealth between risk creator and risk hearer play any part in establishing a standard of `reasonable care'. The concept of intergenerational justice requires these same principles to be applied in the intergenerational context too, implying a zero consumption rate of interest for climate damage. Assuming that the extent to which mitigation is at the expense of alternative investments is equal to society's marginal propensity to save, the social discount rate becomes society's marginal propensity to save times the long-term market rate of return on private investment, implying a social discount rate of around one per cent or a fraction of one per cent. This formula is exact under the assumption of average saving behaviour and by attributing consumption losses due to investment in damage prevention before damage occurs to the risk creator and after damage occurs to the risk bearer. [ABSTRACT FROM AUTHOR]

Climate models used to produce global warming scenarios exhibit widely diverging responses of the thermohaline circulation (THC). To investigate the mechanisms responsible for this variability, a regional Atlantic Ocean model driven with forcing diagnosed from two coupled greenhouse gas simulations has been employed. One of the coupled models (MPI) shows an almost constant THC, the other (GFDL) shows a declining THC in the twenty-first century. The THC evolution in the regional model corresponds rather closely to that of the respective coupled simulation, that is, it remains constant when driven with the forcing from the MPI model, and declines when driven with the GFDL forcing. These findings indicate that a detailed representation of ocean processes in the region covered by the Atlantic model may not be critical for the simulation of the overall THC changes in a global warming scenario, and specifically that the coupled model’s rather coarse representation of water mass formation processes in the subpolar North Atlantic is unlikely to be the primary cause for the large differences in the THC evolution. Sensitivity experiments have confirmed that a main parameter governing the THC response to global warming is the density of the intermediate waters in the Greenland–Iceland–Norwegian Seas, which in turn influences the density of the North Atlantic Deep Water, whereas changes in the air–sea heat and freshwater fluxes over the subpolar North Atlantic are only of moderate importance, and mainly influence the interannual–decadal variability of THC. Finally, as a consequence of changing surface fluxes, the Labrador Sea convection ceases by about 2030 under both forcings (i.e., even in a situation where the overall THC is stable) indicating that the eventual breakdown of the convection is likely but need not coincide with substantial THC changes. [ABSTRACT FROM AUTHOR]

Wave energy will have a key role in meeting renewable energy targets en route to a low carbon economy. However, in common with other renewables, it may be sensitive to changes in climate resulting from rising carbon emissions. Changes in wind patterns are widely anticipated, and this will ultimately alter wave regimes. Indeed, evidence indicates that wave heights have been changing over the last 40 years, although there is no proven link to global warming. Changes in the wave climate will affect wave energy conversion. Where the resource is restricted, there may be reductions in energy exports and, consequently, negative economic impacts. On the other hand, increased storm activity will increase installation survival risks. Here a study is presented that, for the first time, indicates the sensitivity of wave energy production and economics to changes in climate. [ABSTRACT FROM AUTHOR]

This study assesses the sensitivity of the fully coupled NCAR-DOE PCM to three different representations of present-day land cover, based on IPCC SRES land cover information. We conclude that there is significant model sensitivity to current land cover characterization, with an observed average global temperature range of 0.21 K between the simulations. Much larger contrasts (up to 5 K) are found on the regional scale; however, these changes are largely offsetting on the global scale. These results show that significant biases can be introduced when outside data sources are used to conduct anthropogenic land cover change experiments in GCMs that have been calibrated to their own representation of present-day land cover. We conclude that hybrid systems that combine the natural vegetation from the native GCM datasets combined with human land cover information from other sources are best for simulating such impacts. We also performed a prehuman simulation, which had a 0.39 K ~higher average global temperature and, perhaps of greater importance, temperature changes regionally of about 2 K. In this study, the larger regional changes coincide with large-scale agricultural areas. The initial cooling from energy balance changes appear to create feedbacks that intensify mid-latitude circulation features and weaken the summer monsoon circulation over Asia, leading to further cooling. From these results, we conclude that land cover change plays a significant role in anthropogenically forced climate change. Because these changes coincide with regions of the highest human population this climate impact could have a disproportionate impact on human systems. Therefore, it is important that land cover change be included in past and future climate change simulations. [ABSTRACT FROM AUTHOR]

This study examines the variability of the monthly average significant wave height (SWH) field in the Mediterranean Sea, in the period 1958–2001. The analysed data are provided by simulations carried out using the WAM model (WAMDI group, 1988) forced by the wind fields of the ERA-40 (ECMWF Re-Analysis). Comparison with buoy observations, satellite data, and simulations forced by higher resolution wind fields shows that, though results underestimate the actual SWH, they provide a reliable representation of its real space and time variability. Principal component analysis (PCA) shows that the annual cycle is characterised by two main empirical orthogonal functions (EOF) patterns. Most inter-monthly variability is associated with the first EOF, whose positive/negative phase is due to the action of Mistral/Etesian wind regimes. The second EOF is related to the action of southerly winds (Libeccio and Sirocco). The annual cycle presents two main seasons, winter and summer characterised, the first, by the prevalence of eastwards and southeastwards propagating waves all over the basin, and the second, by high southwards propagating waves in the Aegean Sea and Levantin Basin. Spring and fall are transitional seasons, characterised by northwards and northeastwards propagating waves, associated to an intense meridional atmospheric circulation, and by attenuation and amplification, respectively, of the action of Mistral. These wave field variability patterns are associated with consistent sea level pressure (SLP) and surface wind field structures. The intensity of the SWH field shows large inter-annual and inter-decadal variability and a statistically significant decreasing trend of mean winter values. The winter average SWH is anti-correlated with the winter NAO (North Atlantic Oscillation) index, which shows a correspondingly increasing trend. During summer, a minor component of the wave field inter-annual variability (associated to the second EOF) presents a statistically significant correlation with the Indian Monsoon reflecting its influence on the meridional Mediterranean circulation. However, the SLP patterns associated with the SWH inter-annual variability reveal structures different from NAO and Monsoon circulation. In fact, wave field variability is conditioned by regional storminess in combination with the effect of fetch. The latter is likely to be the most important. Therefore, the inter-annual variability of the mean SWH is associated to SLP patterns, which present their most intense features above or close to Mediterranean region, where they are most effective for wave generation. [ABSTRACT FROM AUTHOR]

Abstract: Conceptual models linking climate change with fluctuations in fish population abundances are based on how cyclic patterns in air–sea interactions influence pelagic food web dynamics. The effect of changing mixed layer dynamics on phytoplankton light and nutrient exposure is a prominent focal point in the overall mechanism. The Extended Reconstruction (ER) of Sea Surface Temperature (SST) version one (ERSSTv1) and version two (ERSSTv2) monthly time series from 1854 to 2003, interpreted with the aid of a historically based global Nitrate Depletion Temperature (NDT) climatology, provide a qualitative tool for examining relative temporal and spatial patterns in nitrate availability in normal salinity areas of the world ocean. After an analysis of local NDT variability at four time series stations demonstrated temporal stability compared to SST, [SST–NDT] as a Nitrate Availability Index (NAI) was calculated for April (boreal spring or austral fall) and October (boreal fall and austral spring) for the whole ERSSTv1 data set and for selected years of the ERSSTv2 data set using the global NDT climatology. The more negative the NAI difference, the greater the expected surface nitrate. The more positive the NAI difference, the greater the intensity of temperature stratification between the surface and the nitracline and thus the less likely that nitrate mixed to the surface. The records from April and October both showed that decreased nitrate availability, defined by both smaller negative NAI differences and larger positive NAI differences, generally though not universally occurred throughout the 20th century in association with global warming. The greatest decreases in nitrate availability occurred in two warming events in the time periods 1909–1937 and 1977–present in the Northern Hemisphere and 1926–1937 and 1950–1990 in the Southern Hemisphere. Different areas of the world ocean were affected in each warming event. Prominent exceptions in the ERSSTv1 analysis where 20th century nitrate availability actually increased in at least one season were in western parts of the South Indian, the North Pacific, the equatorial Pacific, the South Pacific, the North Atlantic, and the South Atlantic and in eastern parts of the South Pacific and South Atlantic. The ERSSTv2 analysis also showed increased 20th century nitrate availability in the eastern subarctic Pacific. The nitrate availability trends resulting from the present analysis agree with various literature reports on regional changes in plant nutrient availability, on increased occurrences of harmful algal blooms often associated with dinoflagellates that are better able to access subsurface nitrate pools, and on decadal changes in marine fisheries. They also raise concerns about the resilience of historical patterns of pelagic community structure and function in response to a warming trend continuing into the 21st century. [Copyright &y& Elsevier]

Accurate and reliable predictions and an understanding of future changes in the stratosphere are major aspects of the subject of climate change. Simulating the interaction between chemistry and climate is of particular importance, because continued increases in greenhouse gases and a slow decrease in halogen loading are expected. These both influence the abundance of stratospheric ozone. In recent years a number of coupled chemistry–climate models (CCMs) with different levels of complexity have been developed. They produce a wide range of results concerning the timing and extent of ozone-layer recovery. Interest in reducing this range has created a need to address how the main dynamical, chemical, and physical processes that determine the long-term behavior of ozone are represented in the models and to validate these model processes through comparisons with observations and other models. A set of core validation processes structured around four major topics (transport, dynamics, radiation, and stratospheric chemistry and microphysics) has been developed. Each process is associated with one or more model diagnostics and with relevant datasets that can be used for validation. This approach provides a coherent framework for validating CCMs and can be used as a basis for future assessments. Similar efforts may benefit other modeling communities with a focus on earth science research as their models increase in complexity. [ABSTRACT FROM AUTHOR]

Climate model simulations of the latter part of the twentieth century indicate a warming of the troposphere that is equal to or larger than the warming at the surface, while satellite observations from the Microwave Sounding Unit (MSU) indicate little warming of the troposphere relative to surface observations. Recently, Fu et al. proposed a new approach to retrieving free tropospheric temperature trends from MSU data that better accounts for stratospheric cooling, which contaminates the tropospheric signal and leads to a smaller trend in tropospheric warming. In this study, climate model simulations are used as a self-consistent dataset to test these retrieval algorithms. The two methods of retrieving tropospheric temperature trends are applied to three climate model simulations of the twentieth century. The Fu et al. algorithm is found to be in very good agreement with the model-simulated tropospheric warming, indicating that it accurately accounts for cooling from the lower stratosphere. [ABSTRACT FROM AUTHOR]

Climate is a major determinant of energy demand. Changes in climate may alter energy demand as well as energy demand patterns. This study investigates the implications of climate change for energy demand under the hypothesis that impacts are scale dependent due to region-specific climatic variables, infrastructure, socioeconomic, and energy use profiles. [ABSTRACT FROM AUTHOR]

Tropical–extratropical climate interactions are studied by idealized experiments with a prescribed 2°C SST anomaly at different latitude bands in a coupled climate model. Instead of focusing on intrinsic climate variability, this work investigates the mean climate adjustment to remote external forcing. The extratropical impact on tropical climate can be as strong as the tropical impact on extratropical climate, with the remote sea surface temperature (SST) response being about half the magnitude of the imposed SST change in the forcing region. The equatorward impact of extratropical climate is accomplished by both the atmospheric bridge and the oceanic tunnel. About two-thirds of the tropical SST change comes from the atmospheric bridge, while the remaining one-third comes from the oceanic tunnel. The equatorial SST increase is first driven by the reduced latent heat flux and the weakened poleward surface Ekman transport, and then enhanced by the decrease in subtropical cells’ strength and the equatorward subduction of warm anomalies. In contrast, the poleward impact of tropical climate is accomplished mainly by the atmospheric bridge, which is responsible for extratropical temperature changes in both the surface and subsurface. Sensitivity experiments also show the dominant role of the Southern Hemisphere oceans in the tropical climate change. [ABSTRACT FROM AUTHOR]

Statistical tests were used to detect the variations of winter (December to February), summer (June to August), and annual mean temperatures of 160 representative stations in China during the period from 1951 to 2000. Changes of temperature in the observed time series that exceed the confidence level of 0.01 were classified as significant temperature rises or drops. The stations with significant temperature rises were classified into several temperature rise types, by the use of a clustering method. A search was made for sudden, or abrupt, temperature changes at each of the 160 stations. Possible reasons for the observed temperature variations are discussed. The statistical analysis reveals that for the 160 stations, significant rises occur in 53.1% of their annual mean temperatures, 51.9% of their winter temperatures, and 13.8% of their summer temperatures. Temperature rises increase with latitude. In contrast, significant drops occur in annual mean temperatures at 1 station, winter temperatures at 3 stations, and summer temperatures at 5 stations. Approximately 50% of stations with significant temperature variations are in the form of abrupt changes. The abrupt temperature changes all occurred in the 1970s, most often in 1979 and 1980. The abrupt changes are shown to be related to the subtropical high in South China Sea. The temperature rises in winter are shown to be linked to the presence of an anomalously strong zonal circulation in Eurasia, and a weak polar vortex, since the 1980s. The summer temperature rise in South China also has a link with the increase in size and intensity of the subtropical high, over the same period. Some of the station temperature drops in summer were related to a weaker summer monsoon. The annual mean temperature rise at 71.8% of the stations was influenced mainly by their winter temperature rises. For 8.2% of the stations, the annual mean temperature rise was connected to their summer temperature rise, and for 12.9% of the stations it was related to both the summer and winter temperature rises. [ABSTRACT FROM AUTHOR]

Variability of subtropical cell (STC) overturning in the upper Pacific Ocean is examined in a coupled climate model in light of large observed changes in STC transport. In a 1000-yr control run, modeled STC variations are smaller than observed, but correlate in a similar way with low-frequency ENSO-like variability. In model runs that include anthropogenically forced climate change, STC pycnocline transports decrease progressively under the influence of global warming, attaining reductions of 8% by 2000 and 46% by 2100. Although the former reduction is insufficient to fully account for the apparent observed decline in STC transport over recent decades, it does suggest that global warming may have contributed to the observed changes. Analysis of coupled model results shows that STC transports play a significant role in modulating tropical Pacific Ocean heat content, and that such changes are dominated by anomalous currents advecting mean temperature, rather than by advection of temperature anomalies by mean currents. [ABSTRACT FROM AUTHOR]

Focuses on the influence of developing countries on the outcome and future implementation of the Kyoto Protocol on climate change. Recognition of the fundamental dilemmas of the issue; Significance of the participation of developing countries in establishing global climate change policy; Forces and interests against a second commitment period of the Kyoto Protocol.

Ocean heat uptake and the thermohaline circulation are analyzed in present-day control, 1% increasing CO2, and doubled CO2 runs of the Community Climate System Model, version 2 (CCSM2). It is concluded that the observed 40-yr trend in the global heat content to 300 m, found by Levitus et al., is somewhat larger than the natural variability in the CCSM2 control run. The observed 40-yr trend in the global heat content down to a depth of 3 km is much closer to trends found in the control run and is not so clearly separated from the natural model variability. It is estimated that, in a 0.7% increasing CO2 scenario that approximates the effect of increasing greenhouse gases between 1958 and 1998, the CCSM2 40-yr trend in the global heat content to 300 m is about the same as the observed value. This gives support for the CCSM2 climate sensitivity, which is 2.2°C. Both the maximum of the meridional overturning streamfunction and the vertical flow across 1-km depth between 60° and 65°N decrease monotonically during the 1% CO2 run. However, the reductions are quite modest, being 3 and 2 Sv, respectively, when CO2 has quadrupled. The reason for this is that the surface potential density in the northern North Atlantic decreases steadily throughout the 1% CO2 run. In the latter part of the doubled CO2 run, the meridional overturning streamfunction recovers in strength back toward its value in the control run, but the deep-water formation rate across 1-km depth between 60° and 65°N remains at 85% of the control run value. The maximum northward heat transport at 22°N is governed by the maximum of the overturning, but the transport poleward of 62°N appears to be independent of the deep-water formation rate. [ABSTRACT FROM AUTHOR]

The article focuses on a report of the Inter-Governmental Panel on Climate Change (IPCC) which was discussed at a meeting on climate change. The experts at the meeting discussed a new proxy record of the world's temperature over the last thousand years. It was based on the analysis of tree rings at a number of sites in the northern hemisphere. It became famously known as the "hockey stick." This was because the rise in measured temperature over the last hundred years seemed, by comparison with the proxy record, to be much greater than any changes over the previous 900 years. Canadian statisticians found that there had been errors and omissions in the report. When the analysis was done properly, the data suggest that the fifteenth century was much warmer than today.