Future Changes And Potential Hazard Of Permafrost In The Northern Hemisphere

Permafrost is widely distributed in the Northern Hemisphere,accounting for about 24% of the land area.The change of permafrost significantly affects the groundair water and heat exchange,ecological hydrological process and geochemical process.In addition,there is a large amount of organic carbon stored in the permafrost,and also with large amount of ground ice.The degradation of permafrost decomposes organic carbon into the atmosphere as greenhouse gases,and the melting of the ground ice will also cause land subsidence which will affect climate change and the stable development of the permafrost regions.Therefore,exploring the future changes of permafrost and the impact of the potential risk in the future development of the permafrost in the Northern Hemisphere are very important.This paper is mainly based on the CMIP6 data under different historical and future social and economic sharing paths scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0,SSP5-8.5),relevant work has been carried out from the assessment of climate change in the permafrost(nearsurface air temperature,precipitation),the changes of the permafrost in the Northern Hemisphere(active layer thickness,annual mean average ground temperature),including the impact of permafrost degradation,and the future changes and potential hazard of permafrost in the Northern Hemisphere have been analyzed.The conclusions are as follows:1.From the historical to the future,the near-surface air temperature in the Northern Hemisphere permafrost regions has been rising,and the annual precipitation has been increasing,their change have accelerated with the rise of the radiation forcing level.In the historical scenario,the warming rate of the near-surface air temperature is 0.093℃/10 yr,and the annual precipitation increasing rate is12mm/10 yr.The change is most obvious under the SSP5-8.5 scenario,warming rate in the permafrost regions is 0.95℃/10 yr,and the annual precipitation increasing rate is20mm/10 yr.In addition,there are obvious differences in the climate change of different types of permafrost regions and Northern Hemisphere.The warming rate in permafrost regions is 1.4-1.6 times of that in non-permafrost regions under each scenario.The average annual precipitation in the Northern Hemisphere is higher than that in permafrost regions under the historical and four future scenarios,but the increasing rate of annual precipitation in permafrost regions is 1.4-1.5 times of that in the Northern Hemisphere.The warming rate of continuous permafrost regions is 1.2-1.4 times that of other permafrost regions.The annual precipitation in isolated permafrost regions is the largest,and the annual precipitation in discontinuous permafrost regions increases the fastest.2.In the future,the active layer thickness in the permafrost regions will continue to deepen,and the annual average ground temperature will also continue to rise,their change will accelerate with the rise of the level of radiation forcing.Under the SSP5-8.5 scenario,the change rate is the fastest.The deepening rate of the active layer in the Northern Hemisphere permafrost regions is 4.1cm/10 yr,and the annual average ground temperature rising rate is 0.54℃/10 yr.The continuous permafrost regions and the isolated permafrost regions are the two regions with the lowest and highest active layer thickness.The continuous permafrost region and the isolated permafrost regions are the two regions with the lowest and highest annual average ground temperature.The deepening rate of active layer thickness and annual average ground temperature rising rate of isolated permafrost are the highest in all types of permafrost regions.3.Under different future scenarios,the proportion of medium and high hazard areas in continuous permafrost regions is significantly lower than that of other types of permafrost regions.Under the SSP5-8.5 scenario,the proportion of medium and high hazard areas in continuous permafrost regions is 81.16%,while the proportion in other types of permafrost regions is more than 90%.The population and infrastructure in the Northern Hemisphere permafrost regions will also face different degrees of hazard in the future scenario.Under the SSP5-8.5 scenario,the proportion of population and infrastructure facing high risk will be the highest.More than 34% of population,44% of roads,44% of railways,47% of oil and gas pipelines and 45% of airports will be in the high hazard areas in the future period(2071-2100),In order to maintain the normal operation of the existing infrastructure in the permafrost regions,an additional cost of US $205.2 billion to US $572 billion is required.This paper explores the impact of the future change of permafrost in the Northern Hemisphere and its potential hazard from the aspects of climate change,future change of permafrost and potential hazard assessment.These results are helpful to quantify the economic losses caused by the potential hazard of the permafrost degeneration in the future,and provide scientific and technological support for the future sustainable development of permafrost regions.