Do abrupt cryosphere events in High Mountain Asia indicate earlier tipping point than expected?

Abstract

Tipping points of about 16 elements have been identified in Earth system, yet cryospheric tipping point of specific Alpine region has not been studied. Here we analyzed three tipping elements (mountain glacier, snow cover, and permafrost) identified in recent years, evidenced by the facts of frequent occurrence of abrupt massive collapse of glacier mass and the widespread thermakarst of permafrost. Since 2015, strikingly abrupt cryosphere events (ACEs) have been consistently observed over a large range of High Mountain Asia (HMA). Those events were unprecedentedly significant in history, leading to collapses of glaciers following by disconnection of glacier tongue from accumulation basin and recession of thermakarst towards higher elevation. Strong decreasing of snow depth in 2022 was also observed since 2021/2022 winter, coinciding with extreme warming of the year. The widespread high warming rates in the last two decades over HMA might have triggered above ACEs. The dynamic thresholds of ACEs depend largely on high temperature, especially extreme heat wave, for both glaciers and permafrost, closely related to meltwater as a key factor for reaching initial conditions of abrupt changes, suggesting HMA cryosphere is a tipping element under the global warming level of 1.1 °C. The ACEs can cause tremendous damage to local ecosystem and socioeconomy, measures to mitigate risks should be taken when the tipping points are reached.