21st Century changes in snow climate in Northern Europe:a high-resolution view from ENSEMBLES regional climate models

摘要

Changes in snow amount in northern Europe are analysed from 11 regional model simulations of 21st century climate under the Special Report on Emissions Scenarios A1B scenario. These high-resolution models collectively indicate a future decrease in the water equivalent of the snow pack (SWE). Although winter precipitation increases, this is insufficient to compensate for the increased fraction of liquid precipitation and increased snowmelt caused by higher temperatures. The multi-model mean results suggest a slight increase in March mean SWE only locally in mountains of northern Sweden, and even there, snow is reduced earlier in winter and later in spring. The nature of the changes remains the same throughout the 21st century, but their magnitude increases with time as the greenhouse gas forcing grows larger. The geographical patterns of the change support the physically intuitive view that snow is most vulnerable to warming in areas with relatively mild winter climate. A similar relationship emerges when comparing the 11 simulations with each other: the ratio between the relative SWE decrease and winter mean temperature change is larger (smaller) for simulations with higher (lower) late 20th century winter temperatures. Despite the decrease in long-term mean SWE, individual snow-rich winters do occur in the simulations, but they become increasingly uncommon towards the end of the 21st century.