The significance of climate change in the Netherlands. An analysis of historical and future trends (1901-2020) in weather conditions, weather extremes and temperature-related impacts

Several other changes in Dutch climate, such as spring temperatures rising more rapidly than winter temperatures, the increase of the coldest temperature in each year by 0.9 degrees Centigrade and the annual maximum day sum of precipitation, turn out to be not (yet) statistically significant. The changes in Dutch climate have already led to several statistically significant impacts.

The length of the growing season has increased by nearly a month, and the number of heating-degree days, a measure for the energy needed for the heating of houses and buildings, has decreased by 14 about 5%. Projections of future temperature increase in 2020 based on the statistical analysis closely resemble projections based on climate models: temperatures continue to increase from 10.4 about 0.4 degrees Centigrade in 2003 to 10.7 about 0.6 degrees Centigrade in 2010 and 11.1 about 1.0 degrees Centigrade in 2020.

The energy needed for heating of houses and buildings is expected to decrease further. This warming effect is expected to lower projections of future Dutch greenhouse-gas emissions by 3.5 Mton CO₂ equivalents, which is relevant in the context of commitments under the Kyoto Protocol. Finally, over the course of the 20th century the chance on an 'Elfstedentocht', an outdoor skating event in the Netherlands, has decreased from once every five years to once every ten years. Even though this impact change is not yet statistically significant, it resides 'on the edge' of significance: within a few years more evidence may become available to firmly establish the diminishing likelihood of outdoor skating in the Netherlands.