ISSN:1045-6740    

DOI:10.1002/ppp.3430040202

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractData from Yakutia, Siberia, indicate that permafrost has been generally stable for the last 300,000 years. Historic records indicate climatic variability in the last 150 years and predict that, in comparison with the 1980s, winters will be colder and summers warmer in the early part of the twenty‐first century. Predicted man‐induced climate warming, superimposed upon these natural trends, will offset the winter cooling, while summers will be even warmer. Changes in mean annual air temperatures for the mid twenty‐first century are calculated as being half the sum of the winter and summer temperature changes. Permafrost will be preserved in mountainous regions and in the eastern polar and subarctic plains. In western Siberia and subarctic eastern and southern Siberia considerable permafrost thawing will occur and near‐surface ground temperatures wi

ISSN:1045-6740    

DOI:10.1002/ppp.3430040203

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe cryolithozone occupies a considerable part of the territory of the former Soviet Union. During the Zyriansk (50,000–60,000 years BP) and Sartansk (15,000–27,000 years BP) cold periods of the late Pleistocene, permafrost developed to its maximum thickness and spread as far south as 48–49°N on the Russian plain. In western Siberia and the European north‐east, relict Pleistocene permafrost is separated at depth from late Pleistocene permafrost by a thaw layer; in middle and eastern Siberia where no ice sheets developed, the permafrost is continuous and thick. During the late Glacial to early Holocene warming, the extent of the cryolithozone diminished and thermokarst processes intensified. Using geothermal data from deep boreholes, the approximate rock palaeotemperatures for the last 12,000 years are described for the Russian plain, western Siberia and eastern

ISSN:1045-6740    

DOI:10.1002/ppp.3430040204

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractReconstruction of former permafrost is based on specific indicators which represent relics of features developed above or within the permafrost. Their interpretation in terms of genesis and (palaeo)climatic significance, however, is in some cases still under debate. Previously the reconstruction of the periglacial environment in Europe was limited to permafrost mapping during the coldest time of the last glaciation. Today a much more refined evolution of the palaeoclimate of the last glacial has been established, thanks to a considerable increase in registered periglacial indicators, a better understanding of the corresponding climate conditions, and more accurate and reliable dating of the periglacial phenomena.

ISSN:1045-6740    

DOI:10.1002/ppp.3430040205

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWarming induced by the hypothesized greenhouse effect will have profound consequences for permafrost distribution throughout the high‐latitude regions of the globe. Two scenarios of climate change based on the palaeo‐reconstruction method widely employed by Russian scientists were used in conjunction with a model that produces zonal maps of permafrost distribution. Changes associated with both 1.2°C and 2.0°C warming of the mean global temperature are amplified in the high latitudes, which results in the potential for a large reduction of the area underlain by continuous permafrost. Thermokarst development is likely to be particularly acute in the West Siberian plain, where the climate model suggests that conditions will become marginal for the maintenance of perma

ISSN:1045-6740    

DOI:10.1002/ppp.3430040206

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe continuous permafrost zone of the former Soviet Union (FSU) occupies 5% of the land surface area of the earth and stores a significant amount of carbon. Climate warming could disrupt the balance between carbon (C) accumulation and decomposition processes within the permafrost zone. Increased temperatures may accelerate the rate of organic matter decomposition. At the same time, the productivity of vegetation may increase in response to warming. To assess the future carbon cycle within the permafrost zone under a climate‐warming scenario, it is necessary to quantify present carbon pools and fluxes. The present carbon cycle was assessed on the basis of an ecosystem/ecoregion approach. Under the present climate, the phytomass carbon pool was estimated at 17.0 Gt (109t). The mortmass (coarse woody debris) carbon pool was estimated at 16.1 Gt. The soil carbon pool, including peat‐lands, was 139.4 Gt. The present rate of carbon turnover was 1.6 Gt/yr. Under a warming climate 0.46–0.72 Gt C/yr may be gradually released to the atmosphere, mainly due to the increase in mortmass and litter decomposition. The increased efflux may be concurrently balanced by carbon uptake by vegetation as a result of enhanced productivity and forest migration to the north. However, the possibility exists that a lag between increased carbon efflux and uptake by vegetation may occur. The equilibrium of the carbon cycle may be reestablished, but at a higher rate of carbon turnover. Climate warming may not influence the depth of the active layer in peatlands. The depth of the active layer in mineral soils was comparable with the depth of the organic layer. Consequently, degradation of permafrost may not have a substantial influence on future carbon emis

ISSN:1045-6740    

DOI:10.1002/ppp.3430040207

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractPerennially frozen slopes occur in many mountain ranges of the world. Ice‐rich debris or morainic material especially exist under subcontinental to continental‐type climatic conditions with elevated glacier equilibrium lines. Such supersaturated mountain permafrost exhibits pronounced creep movements, thereby forming large numbers of rock glaciers. Reconstructions of late‐glacial palaeotemperature and palaeoprecipitation using combined glacier/permafrost studies reveal dramatic changes in permafrost belts and in the periglacial environments of mountain areas during the pronounced late‐glacial warming. As a consequence of atmospheric warming during the first half of the twentieth century, the lower boundary of mountain permafrost distribution in various mountain ranges such as the Alps may have shifted in altitude, causing local degradation of formerly frozen slopes. Continued or even accelerated future warming is likely to induce further retreat and degradation of high‐altitude p

ISSN:1045-6740    

DOI:10.1002/ppp.3430040208

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1045-6740    

DOI:10.1002/ppp.3430040209

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1045-6740    

DOI:10.1002/ppp.3430040216

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1045-6740    

DOI:10.1002/ppp.3430040219

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY