Basic results of IPCC Working Group II, derived in the process of the work at the Fourth Assessment Report, are considered in brief. The results are given in conformity with the Summary for Policymakers adopted at the Plenary Meeting of Working Group II in Brussels on April 6, 2007. The authors’ comments on some results connected with the key vulnerable elements of natural and socioeconomic systems are given in the conclusion. 相似文献
The electric state of the near-surface atmosphere up to a height of 400 m is investigated using a tethered balloon with a measuring platform and a ground-based information-measuring complex of the Borok middle-latitude geophysical observatory. For the first time, measurements were taken simultaneously for vertical profiles of the atmospheric electric field, polar electrical conductivities, size distribution of aerosol particles, and the volume activity of radon, which have allowed estimating the average values and variability of the space charge density and conduction current in the atmosphere. The height dependence of the electric potential with respect to the Earth’s surface and electrical resistance of the near-surface atmospheric column under different conditions of the temperature stratification is studied.
The signal of recent global warming has been detected in meteorological records, borehole temperatures and by several indirect climate indicators. Anthropogenic warming continues to evolve, and various methods are used to study and predict the changes of the global and regional climate. Results derived from GCMs, palaeoclimate reconstructions, and regional climate models differ in detail. An empirical model could be used to predict the spatial pattern of the near-surface air temperature and to narrow the range of regional uncertainties. The idea behind this approach is to study the correlations between regional and global temperature using century-scale meteorological records, and to evaluate the regional pattern of the future climate using regression analysis and the global-mean air temperature as a predictor. This empirical model, however, is only applicable to those parts of the world where regional near-surface air temperature reacts linearly to changes of the global thermal regime. This method and data from a set of approximately 2000 weather stations with continuous century-scale records of the monthly air temperature was applied to develop the empirical map of the regional climate sensitivity. Data analysis indicated that an empirical model could be applied to several large regions of the World, where correlations between local and global air temperature are statistically significant. These regions are the western United States, southern Canada, Alaska, Siberia, south-eastern Asia, southern Africa and Australia, where the correlation coefficient is typically above 0.9. The map of regional climate sensitivity has been constructed using calculated coefficients of linear regression between the global-mean and regional annual air temperature. As long as the correlations between the local and global air temperature are close to those in the last several decades, this map provides an effective tool to scale down the projection of the global air temperature to regional level. According to the results of this study, maximum warming at the beginning of the 21st century will take place in the continental parts of North America and Eurasia. The empirical regional climate sensitivity defined here as the response of the mean-annual regional temperature to 1 °C global warming was found to be 5–6 °C in southern Alaska, central Canada, and over the continental Siberia, 3–4 °C on the North Slope of Alaska and western coast of the U.S.A., and 1–2 °C in most of the central and eastern U.S.A. and eastern Canada. Regions with negative sensitivity are located in the southeastern U.S.A., north-western Europe and Scandinavia. The local tendency towards cooling, although statistically confirmed by modern data, could, however, change in the near future. 相似文献
Developed are the axiomatics and criteria for estimating the critical levels of climate change influence on the natural terrestrial
ecosystems based on the revelation of key climate-dependent environmental elements and model analysis of their variations.
Developed is an empirical statistical vegetation model for the territory of Russia considering 15 vegetation zones including
five ones in the permafrost zone. The model was used to estimate the proximity of the climate impact on the natural terrestrial
ecosystems to the critical level for several climate projections. 相似文献
The formation of the fields of surface winds over the Black Sea occurs under the action of numerous physical factors. One
of the most important factors is the monsoon mechanism connected with the seasonal variations of buoyancy contrasts over the
sea and surrounding land. To separate the effects caused by this mechanism, we performed and described the numerical experiments
aimed at the evaluation of the sensitivity of the regional model of atmospheric circulation to the variations of land–sea
temperature contrasts. It is shown that the influence of these effects is restricted to the lower part of the atmosphere.
The presented estimates of the climatic fields of disturbances enable us to describe the monsoon mechanism specifying the
seasonal variability of the field of vorticity of the wind velocities and, as a consequence, the seasonal variability of the
large-scale circulation of waters in the Black Sea. 相似文献
Land, marine, and satellite observations have been used to study changes in methane concentrations in the lower atmosphere during the warm months of the year (July through October) in Arctic regions having different potentials for methane production. The Atmospheric Infrared Sounder (AIRS) data for 2002–2013 are used to explore the interplay between local methane sources in the terrestrial region of the Eurasian Arctic and on the Arctic shelf over the warm period of the year. Linear trends in atmospheric methane concentrations over different Arctic regions are calculated, and a hypothesis of the relation of concentration variations to climatic parameters is tested. The combination of land, marine, and satellite observation is used to develop a conceptual model of the atmospheric methane field in the terrestrial part of the Russian Arctic and on the Arctic shelf. It is shown that the modern methane growth rate in the Arctic does not exceed the Northern Hemisphere mean. It is concluded that the methane emission in the Arctic has little effect on global climate compared to other factors. 相似文献