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With just under a week left until Christmas Eve, there is no sign that Stockholm’s roof is glowing white this year. 2020 may go down in history as the warmest year ever measured and SMHI estimates that another green Christmas awaits with more degrees and bare ground.
– We really only see mild weather in our forecast for Christmas, even if it’s a few degrees cooler on Christmas Eve it’s still positive. The precipitation until then looks like it’s going to rain, says Sverker Hellström, a climatologist at SMHI.
We like to remember ours Children’s Christmas like a bunch of frozen Christmas cards, but the statistics show otherwise. In the last decade, only two Christmases have delivered a depth of snow worthy of the name in Stockholm. 2010, which was the last Christmas Eve when the whole country had snow and 2012 when Stockholm was able to show off 40 centimeters of snow depth for the Christmas lottery. Other Christmas Eve have been almost as green as the Christmas tree.
DN’s review of the depth of snow in the city of Stockholm a hundred years ago in time shows that about every other Christmas Eve it was completely green, 47 pieces. At the Observatorielunden meteorological station they have also managed to measure one centimeter of snow on ten Christmas nights during the same period. But the shallow depth of the snow is not enough for a blanket, it only gives patches of snow.
– From a purely historical point of view, it is generally said that there is a fifty percent chance of snow for Christmas in Mälardalen, we look at the depth of the snow on Christmas morning as a guide to know if it is a white Christmas or not says Sverker Hellström.
Record heat from last year In winter, Stockholm only had snow on the ground for 13 days, a maximum of four centimeters according to the Stockholm Environmental Barometer. In the past 30 years, the number of snow-covered days has decreased by 20 percent compared to the previous thirty-year period. The maximum depth of snow, which averaged about 35 centimeters in the early 20th century, has now dropped to 22 centimeters in the early 2000s.
No snow in central Stockholm.
Photo: Nicklas Thegerström
According to climate researchers at SMHI, it’s clear that winter weather has already been affected by climate change.
– During the last thirty years, we have almost only had warm winters. We can already observe that. If we compare the end of the 19th century with the end of the 20th century, Sweden has become about two degrees warmer in the winter, says Gustav Strandberg, a climate researcher at the Rossby Center at SMHI.
SMHI: s snökartor sample that the county of Stockholm during the period 1961 and 1990 was covered with snow between 40 and 80 days. But in the last 30 years, the days with a layer of snow of at least 20 millimeters of water content have become less and less. For municipalities around Lake Mälaren where it is hotter, it is only a matter of 10-20 days. By 2050, some municipalities are not expected to have any snow cover, at most you can count on 40 days covered with snow in the county.
– The snow season has been about 20 days shorter in Stockholm County since the 1980s. Stockholm has had an average temperature above freezing in December most years during the 2000s. Even today, it is hardly known. you can count on it snowing on Christmas Eve and warming up, says Gustav Strandberg.
What will Christmas be like in 2050?
– We can probably count on one degree higher and rain, compared to zero degrees today. We will have the same Christmas weather as southern Sweden today. The winter season will start later and end earlier. Precipitation is not expected to decrease, but it will not fall like snow when we have fewer fewer days.
So can we forget about Hammarbybacken?
– Skiing and winter sports are the first to go. In Stockholm, where the current average is close to zero, it makes a big difference. If you go from less degrees to more degrees, you get a very large effect on the snow cover even with a small increase in temperature. This applies to the band around Mälardalen, where the winter season is already broken, then it will be difficult to have a ski slope, says Gustav Strandberg.
No ice on Lake Mälaren in Stockholm.
Photo: Magnus Hallgren
By 2100, the chances that a layer of snow with a water content of 20 millimeters will be adequate for skiing are slim. 0-20 snow days are forecast for the entire county.
– How the climate develops is about how we manage to reduce greenhouse gas emissions, it is up to us. But if warming continues, the snow season will be shorter, maybe just a few weeks, says Gustav Strandberg.
Today is the climatic effects are remarkable, especially in Lake Mälaren. Last winter was the first time that the ice did not settle on Lake Mälaren.
Lake Mälaren is normally covered in ice about 80 days a year, but by the turn of the century, SMHI expects the number of icy days will likely be cut in half. An ice-free Mälarvatten doesn’t just affect the future Vikingaränn and pimping on the lake. Longer growing season also increases algal blooms, and fewer ice days can also lead to reduced water quality, according to research studies from Uppsala University.
The lack of snow also leads to darker surfaces that are expected to contribute to further global warming. Reduced snow cover also has other effects on both forestry and biodiversity.
– The layer of snow insulates and if it is cold when you are naked, you can suffer frost damage. There are both plants and animals that would like to have layers of snow to protect themselves. In forestry, you also want frost on the ground so that you can run the machines with better loading capacity.
Stockholm hasn’t had a single minute of sunshine during December. The last time the capital was shrouded in such prolonged darkness was during the last month of 1934.
Photo: Nicklas Thegerström
A warmer Christmas doesn’t necessarily mean a sunnier Christmas. December this year has also been unusually dark in the capital. The last time Stockholmers saw the sun was on November 28 of this year. High pressure on Russia has formed a so-called inversion that causes the clouds to settle like a lid and prevents sunlight from penetrating.
– It does not shine more because it is hotter, the sun rises just as late. We will not have a Christmas weather in southern Europe, it will be hot, dark and rainy, says Gustav Strandberg.
SMHI forecasts because county climate is based on different climate models and scenarios. The one used by DN in the graph is called RCP 4.5 and is based on the fact that greenhouse gas emissions decrease significantly during the second half of the century and show a temperature increase of about 2.5 degrees until 2100. Some scenario adapted to the goal of the Paris Agreement of 1.5 to two degrees the temperature increase at 2100 is not calculated regionally.
– Both county-level scenarios are above two degrees of warming. This is partly because they were written before the Paris Agreement. But regardless of the scenarios we look at, winters will be warmer, says Gustav Strandberg.
DN has mapped the depth of snow on Christmas Eve morning for the past 100 years based on data from the weather station at Observatorielunden. Years missing data, snow depth is reported on Christmas morning.
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