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Climate Change

Climate change projections in Denmark

When I first started delving into predictions about the climate change in Denmark I thought that there might be more positives for Denmark than negatives from it namely because of the higher temperatures. My simple logic was: Higher temperatures => Less rain => Super awesome summer. However it seems that this would not be the case (it never is). Here are some of the projections for the next 87 years.

Higher sea levels

A general rise in sea level of 0.15–0.75 m is anticipated on the west coast and in Danish coastal waters. In extreme storm surge situations an increase in the maximum water level is expected of between 0.45–1.05 m on the west coast under the A2 scenario.  In the Nordic countries, there will be marked regional differences in the effects of the rising sea level. The main reason for this is that the land is rising in some places, but is stable or sinking in others. The effects of the rising sea level will also depend on topography. Where the land is flat, an increase in sea level will affect a greater area than where the land rises steeply from the sea. More frequent flood tides and increased coastal erosion are other possible effects of climate change.

A rise in sea level will also lead to an increase in coastal erosion. Climate change could also change ocean currents so that new areas will become more vulnerable to erosion. Coastal erosion is a natural process in which land masses are worn down by waves and wind. How vulnerable a coastal area is to erosion depends on its topographical and geomorphological characteristics. A relatively steep coastline consisting of hard rock cliffs will be at little risk compared to a low lying area of loose sediment. One of the vulnerable areas is the coast of Denmark, which consists of sand and loose material. On the west coast of Jutland, the medieval Mårup Church had to be taken down in 2008 to save it from being carried out to sea. The church was then only nine metres from the cliff down to the sea, while in 1793 it had been about 500 metres away from the coastline. Measurements indicate that the speed of erosion is increasing, although the reasons for this are not fully understood.

 

More extreme weather

Calculations with climate models show that increased greenhouse effects result in changes in the frequency, intensity and duration of extreme weather conditions. DMI’s calculations show, for example, more and longer-lasting heat waves and increased wind strength during the strongest storms. It is noteworthy that all three scenarios result in about the same extreme downpours, which are expected to be about 20% stronger than today.

With respect to new construction or renovation of dikes, coastal protection or harbour installations, it is important to consider how many years’ climate change should be included in the basic design, since these installations have a lifetime of 50 –100 years, and the climate is expected to change dramatically in that period. It is also important to consider whether it is possible to accept the reduced safety of dikes and other high water protection resulting from climate changes or indeed whether to give up dikes or coastal protection altogether and return to a more natural coastline with more frequent flooding and natural erosion. No matter which solution is chosen, any emergency or storm surge measures should be adapted to existing conditions. It is important that the chosen lifetime of the installation be announced and the rationale for it. Aside from beach nourishment and channel dredging, other adaptation measures will require socio-economic analysis of the degree to which the coastal area must be adapted to future climate change and how such adaptation can be effected.

What do you think about this information? Which solution do you think is better – dikes and high water protection or more natural coastline? Or may be a third option?

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