| Due to global warming,permafrost degradation is occurring,which will inevitably change the role of permafrost and environmental factors.Studying past climate change helps us understand current climate warming and predict future climate.Under the amplification effect in the Arctic,the continuous permafrost in high-latitude areas of the Northern Hemisphere is highly sensitive to climate change;global warming can cause significant changes in the near-surface freeze-thaw index,active layer thickness,and permafrost temperature.Studying the response of active layer thickness and temperature changes at different depths of different types of permafrost in high-latitude regions of the Northern Hemisphere to climate warming is of great scientific and practical significance for global climate change research,ecological environment research,water resources management,and planning and construction of cold region engineering.At the same time,understanding the past climate change history and characteristics of high-latitude regions of the Northern Hemisphere can provide a reference basis for evaluating current and predicting future climate change in the Northern Hemisphere.Permafrost mainly occurs in uninhabited areas with harsh natural environments,resulting in a lack of actual observation data.It is difficult to systematically study the long-term temperature changes of permafrost in high-latitude areas of the Northern Hemisphere based solely on limited observation data.However,modeling provides the possibility for this research.This study used measured surface temperature data at the research site as driving data to test the initial parameters of the Geophysical Institute Permafrost Lab Version2(GIPL2)model.Then,the extracted ERA5(Fifth generation of ECMWF atmospheric Reanalysis)daily scale data was used to test the suitability of the reanalysis dataset for the model.Finally,the ERA5 daily scale data extracted from 1982 to 2021 was used to drive the GIPL2 simulation of temperature changes at different depths of the research site.The response of permafrost temperature and active layer thickness in high-latitude areas of the Northern Hemisphere to climate change was systematically analyzed,and the following main conclusions were drawn:(1)It is found that the ERA5 reanalysis ground temperature data is accurate and reliable in reflecting the actual situation.The measured surface temperature data were input into the GIPL2 model to verify the effectiveness of the simulation of permafrost temperature at different depths.The results show that the GIPL2 model has a better simulation effect on the permafrost research sites with medium ice content and thick soil layer,while the simulation results of the permafrost research sites with less ice and thin soil layer are poor.The simulation results of continuous permafrost with thin soil layer and continuous permafrost with thick soil layer are between the previous two research sites.(2)The warming trend of heavily ice-rich,and thin-layered permafrost is higher than that of continuous,less ice-rich,and thin-layered permafrost.Without considering the influence of soil thickness on the warming trend of permafrost,the highest rate of change is observed in continuous,moderately ice-rich,and thick-layered permafrost,followed by continuous,heavily ice-rich,and thin-layered permafrost,while the lowest warming trend is observed in continuous,less ice-rich,and thin-layered permafrost.Additionally,the relationship between permafrost temperature and depth shows that continuous,thin-layered permafrost experiences an increasing warming magnitude with depth,while continuous,thick-layered permafrost experiences a decreasing warming magnitude with depth.(3)In recent 40 years,the freezing index of active layer and frozen soil layer showed a decreasing trend,while the thawing index of active layer showed an increasing trend.By comparing the change trend of ground temperature of frozen soil at different depths,it can be found that the warming trend decreases with the increase of depth.(4)The simulation results of continuous permafrost with little ice and thin soil layer are compared with those of continuous permafrost with much ice and thick soil layer.The results show that the spatial differences of ground temperature at different depths are obvious in the research sites of continuous permafrost area under future climate scenarios.During 1950-2021 and 2022-2100(SSP126,SSP245),the average annual temperature at different depths of the study site was all lower than 0℃,and the average annual ground temperature at different depths was increasing.The ground temperature data of future climate models were further used to drive GIPL2,and it was found that in the process of temperature gradually rising from SSP126scenario(low emission)to SSP585 scenario(high emission),the continuous permafrost with multi-ice and thick soil layer was the most stable,while the permafrost degradation was the most serious in the research site with continuous,medium ice content and thick soil layer.The warming trend of the study sites is negatively correlated with depth,that is,the response of deep permafrost to global warming is lagging behind.The title of this study is "Response of temperature changes in different depths of ice-rich permafrost in the Northern Hemisphere to climate warming." It analyzes the trend differences in temperature changes at different depths over nearly 40 years using simulated results from the GIPL2 model driven by ERA5 surface temperature data.The study aims to reveal the varying responses of different types of permafrost in high-latitude regions of the Northern Hemisphere to climate change,in order to better understand the role and impact of permafrost in climate change.This research has important implications for predicting the effects of future climate change on high-latitude permafrost and provides scientific references for global carbon flux modeling,climate change predictions,and engineering risk assessments related to the extent of permafrost and temperature at different depths in the Northern Hemisphere. |
