Rhine could warm by 4°C by 2100, scientists warn

A view of the Rhine River in Basel in northwestern Switzerland. Keystone-SDA

The water temperature of the Rhine River could rise by up to 4.2° degrees Celsius by the end of the century due to climate change, scientists warn.

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This is the result of an analysis by Germany’s Federal Institute of Hydrology (BfG) and the Dutch research institute Deltares on behalf of the International Commission for the Protection of the Rhine (ICPR).

“The Rhine is warming significantly as a result of climate change,” their study states. There are already effects on the ecology and economy that will intensify in the future. The rise in water temperature is directly linked to the rise in air temperatures due to climate change, according to a press release.

The researchers simulated the development of water temperatures and carried out modelling calculations. They expect the water in the Rhine to warm by between 1.1-1.8°C by the middle of the century. “By 2100, the average annual water temperature could even warm by 2.9-4.2°C, compared to the period from 1990 to 2010, which was used as a reference for all calculations,” the authors wrote.

On an annual average, the number of days on which the main part of the Rhine is below 10°C could fall significantly: from the current 170 to 104 days. At the same time, the number of days with temperatures above 21.5°C would increase from the current 32 to 106 days a year, according to the modelling.

On 50 of these days, the average temperature could even reach between 25-28°C. According to the study, the southern sections of the Rhine from Switzerland to Karlsruhe will be particularly affected.

What consequences?

“If critical temperature thresholds are exceeded over longer periods of time, ecological damage can occur,” said Tanja Bergfeld-Wiedemann, a biologist at the BfG. “At higher temperatures, the solubility of gases in the water also decreases, which means less oxygen is available to the animals.”

Restrictions on the use of water are also a possible consequence, according to the press release. “The rise in temperature will lead to less capacity being available for existing and new cooling water consumers.”

Translated from German by DeepL/sb

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