More precipitation, more wind, more heat

Denmark will be seeing a warmer and wetter climate and more extreme weather events in future. The most important changes expected are:

• More rain. More rain in winter and less in summer. The summer season will include both periods of drought and heavier downpours.
• Milder winters. Milder and more humid winters. The growing season of plants may be prolonged.
• Warmer summers. Warmer summers with a risk of more and longer heath waves.
• Higher water levels. A general increase in water levels is expected for the seas around Denmark.
• More wind. More powerful storms can be expected.
• Greater cloud cover. Generally a slight increase in the cloud cover, more so in winter.

 

Climate change up to 2050
For the period up to 2050, Denmark will experience the general changes to its climate shown in the two tables below.
 

Climate change in Denmark up to 2050 according to the A1B scenario
Annual mean temperature	+0.8 degrees
Winter	+1.0 degrees
Summer	+0.4 degrees
Annual mean precipitation	11%
Winter	7%
Summer	8%
Sea:
Mean wind	1%
Sea+land:
Storm strength	3%

   

Changes in extremes up to 2050 according to the A1B scenario
Frosty days	-17 days
Growing season	+21 days
Heath wave	+2 days
Summer nights	+4% percentage points
Number of days with more than 10mm of precipitation	+7 days
5-day precipitation	+7mm
Mean intensity, precipitation	+0.5mm/d
Heavy precipitation events	+6% percentage points

Climate change in Denmark calculated with the Danish Meteorological Institute’s regional climate model HIRHAM5 on the basis of projections carried out with the global climate model ECHAM5 in connection with the EU project ENSEMBLES. All figures in the table show changes for the period 2021/2050 relative to the normal period 1961/1990.

Climate change in the long term
In the long term, the magnitude of changes in climate will depend on how much greenhouse gas is emitted globally in the decades to come. The UN climate panel (IPCC) has therefore set up a number of “what if” scenarios, calculating how the climate will change under different assumptions.

The Danish government’s climate change adaptation strategy is based on three climate scenarios: A2, B2 and the EU 2°C scenario. The A2 and B2 scenarios have been prepared by the UN climate panel, and the 2°C scenario is based on the EU's objective to prevent the global mean temperature from increasing by more than 2°C above the pre-industrial level.

For the period up to 2050 the different scenarios deviate only slightly from each other, and for this period the A1B scenario can serve as the basis for decisions on climate adaptation measures. For decisions with relevance up to 2100, the predictions in more scenarios will have to be taken into account.

The Danish Meteorological Institute has scaled the four scenarios down to Danish conditions and, on this basis, has prepared the table given below. The figures for the A1B scenario have been calculated with another model system than the figures for the other scenarios.



The table shows the calculated Danish climate change relative to the period 1961-1990 for all four climate scenarios. The figures for the A1B scenario have been calculated with a newer version of the Danish Meteorological Institute’s regional climate model (HIRHAM5) than the model used to calculate the figures for the other scenarios (HIRHAM4). Furthermore, the figures for the A1B scenario are based on the global climate model ECHAM5, while the others are based on HasAM3H.

The uncertainty of the temperature calculations is 1.5ºC for the A2 and B2 scenarios, and 0.7ºC for the EU2ºC scenario. This means that there is a 90% probability that temperature increases in the three scenarios will be between 0.7ºC and 4.6ºC in the period 2071-2100.

As is evident from the table, expected precipitation in summer will increase according to the A1B scenario, whereas it will fall according to the other scenarios. This difference can be attributed to the fact that Denmark is situated between two zones with expected increases and decreases in summer precipitation respectively. The differences reflect the uncertainty of the figures.

More extreme weather
The four scenarios (A1B, A2, B2 and EU2ºC) predict more extreme weather in Denmark. This table shows indicators of extremes in the four scenarios. 



The table shows selected extreme weather indicators for the four climate scenarios. The figures show the differences between the periods 2071-2100 and 1961-1990. As described above, the figures for the A1B scenario have been calculated with another model system than the figures for the other scenarios. The last column shows the models’ present value as the average between the two present-value simulations in the study. The present-value results are not completely identical with the measured values for the period 1961-1990, but are fairly consistent with these.