In the report The State of the Climate 2022, the KNMI provides an overview of ‘the Dutch weather in times of climate change’ over the previous calendar year. RTL climate specialist Bart Verheggen explains the most important conclusions.
The Netherlands has warmed up 2.3 degrees in 120 years
“Worldwide, the earth’s surface is 1.2 degrees warmer than at the end of the 19th century. But that warming is not equally strong everywhere: land is warming up more strongly and faster than water.”
“You also notice this, for example, when you walk on the beach on a warm spring day: the sand can already feel nice and warm on your feet, while the sea is still ice cold. The same is also happening on a large scale, which is why the continents have warmed up more than the ocean.”
“The graph below shows how the temperature has changed in De Bilt and over the Earth’s surface as a whole. Besides the fact that the Netherlands has warmed up a lot more than the rest of the world, there is something else striking: the global average temperature fluctuates much less back and forth from year to year than the temperature in De Bilt. This is because random variations are increasingly smoothed out if you take an average over a large surface.”
“What was considered an exceptionally warm year in the Netherlands 100 years ago, would now be exceptionally cold. For the world average, the difference is even stronger in relative terms: the warmest years then are a lot colder than the coldest years now. We are far beyond the bandwidth of our great-grandparents’ historical climate.”
“If the current trend continues, in about ten years global warming will have reached 1.5 degrees, which is internationally seen as the limit we want to stay below.”
Less clouds, more sun
“2022 was the sunniest year since measurements started in 1965. There was no less than 15 percent more solar radiation than the long-term average of the past 30 years. That was not due to the sun – it is not increasing in strength.”
“According to the KNMI, this is mainly due to the decrease in clouds, because there is more often a high pressure area above Europe in spring and summer. This can also be a result of climate change, for example through changing wind patterns in the higher air layers.”
“But there is another potential cause: the cleaner air. Particulate matter is harmful to health, but the same tiny, suspended particles also reflect solar radiation and they are necessary for cloud formation. That is why they have a cooling effect.”
“For health reasons, we have reduced the particulate matter content in the air, but that has the side effect that the cooling effect is lost because more solar radiation can reach the earth’s surface.”
“Both KNMI researcher Peter Siegmund and independent climate researcher Leon Simons agree that this can play a role. The extent to which both processes contribute to the extra solar radiation – more high-pressure areas on the one hand and less particulate matter on the other – is difficult to determine.”
2022 was a bone dry year
“The Rhine, the Elbe, the Loire: European rivers had to endure extremely low water levels in the summer of 2022. The precipitation deficit reached a record high; only in 1976 was it drier.
“The drought had several causes: there was little precipitation in the spring and especially in the summer. But evaporation also plays an important role. Both the high temperature and the large amount of solar radiation enhance evaporation.”
“In the warm months, more water often evaporates than falls as rain. We call the difference the precipitation deficit, and it has been increasing steadily for decades. This trend is expected to continue due to further climate change.”
The sea level is rising faster and faster
“The sea level is rising faster and faster. Until recently, the sea on the Dutch coast seemed to be evading this global trend. But since the seas and oceans are connected, the local sea level can of course not stay too out of step run with the world average.
“By filtering out the effect of the wind from the measurements, the KNMI uncovered the underlying trend, which shows the inescapable: the sea level is also rising faster on our coast. Researchers at TU Delft independently came to the same conclusion.”
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