Continued Warming of the Permafrost Regions Over the Northern Hemisphere Under Future Climate Change. Issue 9 (16th September 2022)

• Record Type: Journal Article
• Authors: Hu, Guojie; Zhao, Lin; Wu, Tonghua; Wu, Xiaodong; Park, Hotaek; Li, Ren; Zhu, Xiaofan; Ni, Jie; Zou, Defu; Hao, Junming; Li, Wangping
• Is Part Of: Earth's future. Volume 10:Issue 9(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-16
• Subjects: air temperature -- permafrost -- warming trend -- CMIP6 -- Northern Hemisphere -- PRONH; Environmental sciences -- Periodicals; Environmental sciences; Periodicals; 550
• DOI: 10.1029/2022EF002835
• Languages: English
• ISSNs: 2328-4277

Abstract

Abstract: Surface air temperatures can directly affect the thermal state of permafrost in the permafrost region of the Northern Hemisphere (PRONH). It is necessary to understand the trends in air temperatures and consider actual CMIP future scenario output instead of a linear temperature increase over different permafrost regions. In this study, air temperatures from 23 models of the sixth coupled‐model intercomparison project (CMIP6) are evaluated against observational data from the PRONH. It is shown that most of the models reasonably represent the dominant characteristics of air temperature variations. Under three different future scenarios, air temperature and warming trends are examined using an optimal model ensemble. Results show that mean annual air temperature (MAAT) is higher in sporadic‐permafrost and isolated‐permafrost regions than in continuous‐permafrost regions. MAAT warming rates were 0.10°C/decade and 0.35°C/decade from 1900 to 2014 and from 1980 to 2014, respectively, and were 0.09°C/decade, 0.38°C/decade, and 0.95°C/decade from 2015 to 2100 under the low‐ to high‐emission scenarios. Air temperature varies considerably between the high‐altitude, transitional, and high‐latitude permafrost regions (HLR), and warming trends are the greatest in HLR under future scenarios. Moreover, warming trends in different permafrost classes vary little from the historical values from 1900 to 2014, and with a gradual increase from isolated‐permafrost regions to continuous‐permafrost regions under future scenarios. The results suggested that air temperatures in the PRONH warmed approximately 1.6 times faster than global air temperatures from 1980 to 2014 and under the three future scenarios. Plain Language Summary: In recent years, permafrost has experienced extensive degradation but with broad regional differences in the permafrost regions over the Northern Hemisphere. Surface air temperatures could directly affect the permafrost degradation processes. Therefore, it is important to understand air temperature variations and regional differences in permafrost degradation under climate change. After evaluating the sixth phase of the coupled model intercomparison project (CMIP6), the air temperature characteristics and warming trends were examined by the optimal models ensemble. The results reveal that the annual mean air temperature and warming trends had largely regional differences from continuous permafrost regions to isolated permafrost regions, and with respect to high‐latitude, transitional, and high‐altitude permafrost regions. In addition, the results indicated that the air temperature warming rate in the permafrost regions was approximately 1.6 times that of the global warming rate from 1980 to 2014 and under the SSP1‐2.6, SSP2‐4.5 and SSP5‐5.8 scenarios. These findings could provide a preliminary understanding of the performance of the new generation of CMIP6 models in permafrost regions, providing a foundation for permafrost simulations and improving land surface models across different regions under climate change. Key Points: Evaluate the performance of the sixth coupled‐model intercomparison project model for air temperature in the permafrost regions of the Northern Hemisphere Air temperature exhibits a significant warming trend in permafrost regions and has obviously differed in different permafrost regions Examined the difference in warming trend of air temperature under climate change and discussed the possible reasons for these differences