As a further risk for the Netherlands, the report specifically mentions an increase in drought in the spring and summer, and an increase in the number of extreme summer showers.

Disturbing and insecure

With the Climate Signal ’21, the KNMI has elaborated the latest findings of the IPCC, the climate agency of the United Nations, for the Netherlands. The IPCC presented those findings in early August. She then unequivocally established that humans are responsible for global warming, which is now 1.1 degrees Celsius, compared to the pre-industrial era. In 2015, the Paris Agreement was concluded, which stipulates that warming should be limited to 2 °C, and preferably to 1.5 °C.

Most disturbing in the new KNMI report, but at the same time highly uncertain, are the predictions about possible sea level rise. The developments of the Antarctic ice sheet are particularly important for the Netherlands. “With global average warming of between 2 and 3°C relative to pre-industrial levels, the future of Antarctica becomes very uncertain,” the report said. For example, there is a still controversial theory that describes how glacier tongues, ie the outcrops of glaciers in the sea, can break up at an accelerated rate. That could “extremely accelerate” the ice sheet’s erosion. And that could lead to global sea levels rising by an average of 17 meters by 2300. “Then the end of the Kingdom of the Netherlands,” said professor of physical oceanography Sybren Drijfhout, associated with the KNMI and the University of Southampton, in an explanation.

More downpours

In the report, the KNMI shows that summer downpours have increased since 1950, more on the coast than in the interior. In the future, especially heavy showers (with more than 50 millimeters of precipitation in an hour) will intensify, the KNMI predicts based on a new generation of regional climate models. Relatively light showers (less than 10mm in an hour) could abate. There is also uncertainty in the forecasts here.

The same goes for drought. The KNMI expects an increase in summer droughts, especially in the interior. But that will also depend on the development in large-scale air currents – westerly winds supply moist air, while easterly winds are usually dry. However, climate models are not unambiguous about whether and how the circulation will change in the future.

Outgoing State Secretary Steven van Weyenberg (Infrastructure and Water Management, D66) received the report. “The urgency has been underestimated,” he said. “The climate crisis is already with us.”