In recent days many people have read news reports about severe weather in Sweden: for the second day in a row, the temperature dropped to above -40 degrees in the north of the country. In Swedish Lapland, the temperature became -43.6 degrees. This was the lowest January temperature in 25 years.
Then there were pictures of massive amounts of snow. Moreover, the news came that we could carefully remove the irons from the fat in Holland. We are witnessing a light frost that may allow skiing in some areas of the country.
“Reduce to understand”
On social media, and perhaps also in your head, the question may arise: But the Earth is warming, isn't it? how is that possible? “On the one hand, I get it,” says meteorologist Mark De Jong of Boyneradar when we ask him this. “But at the same time I think: people are not stupid. As far as I'm concerned, the debate about whether we're dealing with climate change is already over. You only have to zoom out to understand it.”
Especially since the climate covers a period of 30 years, while your observation covers one day or a few days. If you zoom out, you see that extreme weather conditions, such as the very low temperatures in Sweden, have been occurring for years, De Jong explains.
They are becoming less common, so they may now be more visible, says RTL News climatologist Helen Ecker: “What people often forget is that there have always been extremes in weather. So, extreme cold and extreme heat have always been there and will always be.” Always present. Only the number of hot periods around the world is increasing, while the number of cold records is decreasing.
“The cold period is shorter”
So they happen less frequently, and if they do, they last a shorter time, De Jong says. “The cold period will then last for a shorter period. This also applies to the Netherlands: here too, it is possible to still be very cold despite global warming, but the chance of an Elfstedentocht is becoming increasingly less. Because it is no longer very cold.”
The reason the cold lasts less has to do with the jet stream, De Jong explains.
These are very strong winds that blow at speeds between 100 and 250 kilometers per hour, sometimes peaking at more than 400 kilometers per hour. Such a flow is located at an altitude of about ten kilometers, between warm air around the equator and cold air in the polar regions.
The generally strong winds of the jet stream ensure that the cold air in the Arctic and warm air around the equator remain separate. Because the polar regions warm much faster than the equator, and so the temperature difference decreases, there is sometimes less energy in the jet stream. De Jong compares the jet stream to a fluttering flag (“Because the wind doesn't blow hard, it makes waves, and they flap up and down”).
As it stands now, this causes cold air from the Arctic to move south, creating arctic cold in northern Europe and freezing cold in the Netherlands.
Why did so much snow fall in Scandinavia? “This is because the warmer air — which we are dealing with due to global warming — can hold more moisture,” de Jong says. “And if there is more moisture in the air, more of it can come down as more snow.”
This “raised flag”, i.e. the jet stream, could prevent the temperature in Scandinavia from rising to 15 degrees above average again next week. Since -43.6 was measured at the low point, it becomes Next Tuesday, two degrees above zero. But what we remember next is the maximum number of -43.6 degrees.
Helen Ecker also sees this: “It is important to realize that your personal experience or assessment of the weather is a bad indicator. People are often selective in their thoughts and memories, and the things they remember. So: “The winters were always harsh and with the snow and ice, the summers were always nice and warm.” . But that is not the issue.”
“Just look at the numbers.”
“If you want to evaluate it correctly, you just have to look at the numbers. Whether it's just Dutch weather, or the weather in Scandinavia, or elsewhere. It's clear from those numbers that the weather has already changed dramatically. In “Often without people noticing, because it happens gradually.”
Zoom out, look at the numbers, but – as de Jong stresses – also keep looking around. Because if you do now, you will see that – in addition to the extreme picture in Sweden – it is much warmer in many parts of the world than usual at this time of year.
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