Precipitation and climate change

Denmark's climate is developing continuously, and precipitation volume is one of several indicators that can tell us about developments. This indicator shows that annual precipitation is increasing. The weather in Denmark is expected to be more extreme in future: winters will be wetter, and summers will see heavier showers, which may lead to flooding. This can cause serious and costly damage to buildings, roads and farmland crops if no measures are taken to adapt to climate change.

The annual precipitation volume increased from 636 mm in 1874-1890 to 759mm in 1991-2020 years (see figure 1). That is an increase of almost 20%.

Figure 1: The Danish annual precipitation measured in mm, 1873-2022, with 30-year climate normals indicated. (The first period is only 28 years). 

Denmarks future precipiptation 

Figure 2 shows the percentage change in summer and winter precipitation between 1981–2010 and the future period 2071–2100 in the average amount of precipitation over the year for the whole of Denmark for the scenarios RCP2.5, RCP4.5 and RCP8.5.

Figure 2: Future average winter (December–February) and summer (June–August) precipitation. Source: DMI

The projected end-of-century change for a high emmission scenario is −2% (with an uncertainty range of −17% to 23%) for summer precipitation, and 23% (with an uncertainty range of 8% to 41%) for winter precipitation. The summer rainfall stands out from the other parameters because it is very uncertain whether the summer rainfall will increase, decrease or continue unchanged.

More extreme events

We can expect more heavy precipitation events in the summer despite the minimal change in the amount of summer precipitation. One way to describe heavy rainfall is as a so-called 10-year event, where it rains so much that statistically it only happens once in 10 years. Cloudburst, another indicator of heavy rain, is defined as more than 15 mm of precipitation in 30 minutes.

Figure 3: Future 10-year events (on the top) and frequency of cloudbursts (on the bottom)

On the top the 10-year event for daily precipitation, on the bottom the frequency of cloudbursts. The expected change at the end of the century for a high discharge scenario is 20% for the 10-year event for diurnal precipitation, and 70% for cloudburst.

The climate atlas also shows how much rain a 2-, 5-, 10-, 20-, 50- and 100-year event corresponds to for both hourly and daily precipitation, now and in the future. Read more and explore data at Klimatlas.dk