This study quantifies the impact of large-scale cryosphere element disintegration (Arctic summer sea ice, mountain glaciers, Greenland and West Antarctic Ice Sheets) on global mean temperature (GMT) using an Earth system model of intermediate complexity (CLIMBER-2). The results indicate a median additional global warming of 0.43 °C (interquartile range: 0.39–0.46 °C) at a CO2 concentration of 400 ppm. Albedo changes account for 55% of this warming, with lapse rate/water vapor (30%) and cloud feedbacks (15%) also contributing significantly. While ice sheet decay occurs on centennial to millennial timescales, the Arctic may become ice-free in summer within the 21st century, leading to additional GMT increases on intermediate to long timescales.

Nico Wunderling, Matteo Willeit, Jonathan F. Donges, Ricarda Winkelmann