Precipitation and climate change
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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 650mm in 1870 to 750mm in recent years (see figure 1). That is an increase of around 15%.

 

Precipitation and climate change Figure 1

Figure 1 The trend in Danish annual precipitation from 1874-2019, measured in mm.
Source: The Danish Meteorological Institute 2020.

 

 

Cloudbursts vary in number from year to year. Table 1 below is based on a short time series but has nonetheless been included here to illustrate these variations. Moreover, cloudbursts are often local in nature.

With 152 cloudbursts, 2019 has seen the highest number of recorded cloudbursts. The highest number of days with cloudbursts (34 days) was recorded in 2019. There are no years without cloudbursts, even if we include only at the heaviest cloudbursts (>30 mm).

 

Table 1 Cloudbursts registered in Denmark. Source: The Danish Meteorological Institute.

Precipitation and climate change Figure 2

 

Future precipitation in Denmark
The percentage change in summer and winter precipitation is shown in figure 2 for the period 1981-2010, and the average precipitation volume over the year for all Denmark in the RCP8.5 scenario is shown for the future period 2071-2100.

 

Precipitation and climate change Figure 2

Figure 2 Future summer (June-Aug) and winter (Dec-Feb) precipitation
Source: Climate Atlas vers. 2 2020.

The expected change at the end of the century for RCP8.5 is -2% (with an uncertainty range of -17 to 27%) for summer precipitation and 24% (with an uncertainty range of 10 to 41%) for winter precipitation. Summer precipitation differs from the rest of the parameters by being very uncertain as to whether it will increase, decrease or remain unchanged.

 

More extreme events
We can expect more and heavier precipitation events during summer, even though summers will likely be drier across a large part of the European continent. In a so-called 10-year event, it rains as much as it is statistically likely to do once every 10 years. Cloudbursts are defined by a precipitation intensity of more than 15mm in 30 minutes.

 

Precipitation and climate change Figure 3

Figure 3 Future 10-year events and cloudbursts
Source: Climate Atlas vers. 2 2020.

The 10-year event for daily precipitation is shown left, and the frequency of cloudbursts is shown right. The expected change at the end of the century for RCP8.5 is 21% (with an uncertainty range of 4 to 39%) for the 10-year event for daily precipitation and 70% (with an uncertainty range of 20 to 150%) for cloudbursts.

 

The Climate Atlas also shows how much rain a 2-, 5-, 10-, 20-, 50- and 100-year event corresponds to, for hourly as well as daily precipitation, now and in the future. Read more and explore the data on Klimaatlas.dk

 

Senest redigeret: 03-02-2021