The response of Northern Hemisphere snow cover to a changing climate


Brown, R.D., Mote, P.W. 2009. The response of Northern Hemisphere snow cover to a changing climate. Journal of Climate 22(8):2124-2145, doi: 10.1175/2008JCLI2665.1.


A snowpack model sensitivity study, observed changes of snow cover in the NOAA satellite data set and snow cover simulations from the CMIP3 multi-model dataset are used to provide new insights into the climate response of northern hemisphere snow cover. Under conditions of warming and increasing precipitation which characterizes both observed and projected climate change over much of the Northern Hemisphere land area with seasonal snow cover, the sensitivity analysis indicated snow cover duration (SCD) was the snow cover variable exhibiting the strongest climate sensitivity with sensitivity varying with climate regime and elevation. The highest snow cover-climate sensitivity was found in maritime climates with extensive winter snowfall e.g. the coastal mountains of western North America (NA). Analysis of trends in snow cover duration over the 1966-2007 period of NOAA data showed the largest decreases were concentrated in a zone where seasonal mean air temperatures were in the range of _5° to +5°C which extended around the mid-latitudinal coastal margins of the continents. These findings were echoed by the climate models which showed earlier and more widespread decreases in SCD than annual maximum snow water equivalent (SWEmax) with the zone of earliest significant decrease located over the maritime margins of NA and Western Europe. The lowest SCD-climate sensitivity was observed in continental interior climates with relatively cold, dry winters where precipitation plays a greater role in snow cover variability. The sensitivity analysis suggested a potentially complex elevation response of SCD and SWEmax to increasing temperature and precipitation in mountain regions due to non-linear interactions between the duration of the snow season and snow accumulation rates.