Global warming is naturally amplified in the Arctic, where a slight increase in mean annual air temperature can result in a change of state for large regions of frozen ground, in terms of both active layer thickness and area 8, 11.

Warming in these areas is the most significant over this period, reaching up to 2.5 ☌ 16, 19, 20, 21. Regions of significant warming include the high latitudes of the NH, including Arctic and high-elevation areas such as the Qinghai–Tibet Plateau. However, the magnitude of warming shows remarkable regional differences. The increase in observed global average surface temperature between 18 was 0.85 (0.65–1.06) ☌ 18. In particular, over the past 30 years, the Earth has experienced a period of rapid warming. Over the last 100 years, global climate has warmed distinctly, with the global surface temperature increasing by 0.74 ☌ ± 0.18 ☌ between 19 4. The degradation of the permafrost may affect the climate system via many factors such as local ecological balance, hydrological processes, energy exchange and the carbon cycle, as well as the engineering infrastructure in cold regions and even extreme weather events 8, 9, 10, 11, 12, 13, 14, 15, 16, 17. As the global surface temperature has continued to rise over the recent decades 6, 7, the risk of permafrost degradation has also increased. Because of its high sensitivity to, and feedback relationship with, the climate, permafrost plays a critical role as an indicator of global climate change 3, 4, 5. Permafrost is a key component of the cryosphere, which occupies around a quarter of the Earth’s land area in the Northern Hemisphere 1, 2. This outlook gives reason for hope for future maintenance and balance of the cryosphere and climate systems.įrozen ground is composed of various ice-rich soils and rocks, which are the products of lithosphere–soil–atmosphere interactions during the process of material exchange. The results of the study highlight that the NH permafrost might be able to stably exist owing to its relatively slow degradation. When the global surface temperature rises by 2 ☌, about one-third of the permafrost would disappear in other words, most of the NH permafrost would still remain even in the RCP8.5 (2037–2046) scenario. However, uncertainty in the results persists because of distinct discrepancies among the models. Results show that, when global surface temperature rises by 1.5 ☌, the average permafrost extent projected under Representative Concentration Pathway (RCP) scenarios would decrease by 23.58% for RCP2.6 (2027–2036), 24.1% for RCP4.5 (2026–2035) and 25.55% for RCP8.5 (2023–2032).

This study investigates the impacts of global temperature rises of 1.5 ☌ and 2 ☌ on the extent of the permafrost in the Northern Hemisphere (NH), based on the 17 models of Coupled Model Intercomparison Project Phase 5 (CMIP5). A rise of 2 ☌ above pre-industrial global surface temperature is considered to be a risk-level threshold. Degradation of cryospheric components such as arctic sea ice and permafrost may pose a threat to the Earth’s climate system.

All that remains part 1 override