Royal Netherlands Meteorological Institute (KNMI), Utrechtseweg 297, 3731GA, De Bilt, The Netherlands.
Nature. 2014 May 22;509(7501):479-82. doi: 10.1038/nature13259. Epub 2014 May 7.
Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation.
预计在二十一世纪末，北极地区的降水变化将增加超过 50%。这种显著的增长是全球最高的增长之一，以前主要归因于从低纬度地区增强的极向水汽输送。在这里，我们使用最先进的全球气候模型表明，二十一世纪北极降水的预计增加，在晚秋和冬季达到峰值，主要是由于当地表面蒸发的强烈增强（冬季最大），而不是由于从低纬度地区增强的水汽流入（夏季和秋季最大）。此外，我们表明，增强的表面蒸发主要是由于冬季海冰退缩所致，这表明北极水文循环得到了放大。这表明，北极降水的增加与北极变暖以及海冰减少密切相关。因此，北极平均降水敏感性（每升温 4.5%）远大于全球值（每开尔文 1.6 至 1.9%）。北极降水随季节变化的增加可能会增加河流流量和冰盖的降雪量（从而影响全球海平面），甚至可能通过北极海洋的变咸以及随后对大西洋经向翻转环流的调制来影响全球气候。
