Why is the content of this map important?
Which sectors are affected by this result?
The results are important for the transportation sector, especially transport infrastructure design and maintenance; particularly road, rail and air. The projected changes are actually good news for most of Europe, wherein the 0°C crossings are problematic under present conditions.
What is shown on the maps?
The current map shows that freeze-thaw days are most common in northern Europe with anywhere from 30-60 freeze-thaw days per year. The +2°C global warming period already shows decreases, on average, of over 15 days per year in northern Europe and the near disappearance of the phenomenon at lower latitudes. The few areas that do show an increase are modest, only being a handful of days.
Details and further information:
We have defined freeze-thaw days following the description given by Schmidlin et al. (1986). A day is considered as a freeze-thaw day if the daily minimum temperature is less than or equal to -2.2°C and the maximum temperature is equal to or greater than 0°C. The number of these days is then calculated over each year. There are many alternative definitions. The argument for our approach is that temperatures between zero and -2°C do not constitute a hard freeze and impacts on vegetation and infrastructure are modest. Nevertheless, certain impacts might depend on more detailed indicators, which are not considered in this study, such as the number of crossings of 0°C per day.
To investigate this, the ensemble mean of the five mandatory climate simulations is used. Hence, the ensemble consists of 5 simulations in total.
Thomas W. Schmidlin, Bernard E. Dethier, and Keith L. Eggleston, 1987: Freeze-Thaw Days in the Northeastern United States. J. Climate Appl. Meteor., 26, 142–155.
Stefan SobolowskiUni Research AS (UniRes), Norway