Rhine could become warmer – experts warn of consequences of climate change

Koblenz. The water temperature of the Rhine could rise by up to 4.2 degrees Celsius by the end of the century due to climate change. This is the conclusion of an analysis by the Federal Institute of Hydrology (BfG) and the Dutch research institute Deltares in their work for the International Commission for the Protection of the Rhine (ICPR).

"The Rhine is warming significantly as a result of climate change," it states. There are already ecological and economic impacts that will intensify in the future. The increase in water temperature is directly related to the increase in air temperatures due to climate change, the experts explain in a statement.

The researchers simulated the development of water temperatures and conducted corresponding model calculations. They expect the Rhine water to initially warm by 1.1 to 1.8 degrees by the middle of the century. "By the year 2100, the annual average water temperature could even warm by 2.9 to 4.2 degrees – compared to the period 1990 to 2010, which was used as the reference for all calculations."

Switzerland could be more affected by the warming of the Rhine water – here the river in Basel.

Source: Jens Büttner/dpa

On average, the number of days on which the main Rhine reaches temperatures below 10 degrees Celsius could decrease significantly: from the current 170 to 104. At the same time, according to the model, the number of days with temperatures above 21.5 degrees Celsius would increase from the current 32 to 106 days per year. On 50 of these days, temperatures could even reach an average of between 25 and 28 degrees Celsius. According to the analysis, the southern sections of the Rhine, from Switzerland to Karlsruhe, will be particularly affected.

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

Restrictions on water use are also a possible consequence. "The rise in temperature will result in less capacity being available for existing and new cooling water consumers."

RND/dpa