Less intense snowfall for western Europe in the future

Post date: Oct 25, 2014 8:00:07 PM

A few years ago the Netherlands experienced quite a few snowy winters. The circulation was such that often the wind had a northerly component, resulting in quite cold and wet conditions. The question came up whether such conditions could be expected more frequently in future. We did a preliminary analysis in our paper in Climate Dynamics (see blog-post: Why it will snow less on cold days in the future). After that, we had the idea to check this for a high-resolution regional climate model. The results are out now in GRL (Geophysical Research Letters, doi:10.1002/2014GL059724), Basically, the RCMs show a very similar behaviour, except in the high alpine regions where temperatures are consistently below zero, even in a future, warmer, climate. We now also looked at moderate extremes, namely the seasonal maximum snowfall amount. There we see a notable increase over the coldest areas (see figure below). For all other regions, and for all those people who love snow (like me), the results in the paper were quite dramatic. Future traffic controllers may however have much less days with record length traffic jams.

Figure caption. Linear trends (% per degree local warming) for RACMO output of DJF maximum snowfall. Dotted areas denote regions where the trend is not significant at 95% confidence level.

Abstract: "Snowfall frequency and intensity are influenced strongly by climate change. Here we separate the basic frequency change resulting from a gradually warming climate, from the intensity changes, by focusing on snowfall on days where the mean temperature is below freezing (Hellmann days). Using an ensemble of simulations, obtained with the high-resolution regional climate model KNMI-RACMO2 driven by the EC-EARTH global climate model and RCP4.5 and RCP8.5 forcing scenarios, we show that in addition to the strong decrease in the number of Hellmann days, also a substantial reduction in the mean Hellmann-day snowfall can be expected over large parts of western and central Europe. Moreover, seasonal snowfall extremes display trends that are comparable or even larger. Projected intensity reductions are locally as large as −30% per degree warming, thus being in sharp contrast to mean winter precipitation, which increases in most future climate scenarios. Exceptions are the high Alps and parts of Scandinavia, which may see an increase of up to +10% per degree warming."