Climate and weather | I have found a critical turning point

(The newspaper online): If winters are warmer than minus 8 degrees on average, snowy winters are over, according to a new report.

Despite the cold records and large amounts of snow; Climate scientists are sticking to their warnings about mild winters. Now they claim to have found a critical temperature limit:

If the winter is warmer than 8 degrees below zero on average, then the snowy winter is over, this is the conclusion of a research article published in the well-known British research journal nature this week.

After exceeding this limit, we see that everything is heading towards the abyss, says Justin Mankin, a professor at Dartmouth College in the United States of America and one of the authors of the study, New York times.

Low snow in the Northern Hemisphere

Norwegians have frozen and shoveled snow in large quantities this winter, but the climate scientists behind the report insist that global warming and man-made climate change are the driving force.

In the coming decades, we can expect to see milder winters with less snowfall in the Northern Hemisphere.

According to researchers, the development process will accelerate and have far-reaching consequences for everything from water resources to ski destinations. The researchers also believe they have identified a temperature tipping point, or winter gain or loss, as many in Norway know it. Their models show that when a region warms to an average temperature above minus 8 degrees throughout the winter, snow will quickly disappear.

– An interesting discovery

“We are aware of the findings that more and more areas will exceed the threshold in winter where precipitation will come in the form of rain, but the threshold that these researchers found, an average of 8 degrees below zero, is new to me and very interesting,” says Anita. Ferby. Dyrdal to Nettavisen. She is a climate researcher at the Meteorological Institute and head of the Norwegian Climate Service Centre, which contributes factual information about climate change in Norway to Norwegian decision-makers.

– There are those who question climate forecasts and the reasons, especially with snowfall and low temperatures. “Very cold. “We need more CO2,” read a comment in Nettavisen’s comments section recently. What is your response to skeptics?

-We live in a little bubble here in the north. There are significant differences between different regions of the world at any given time. Recently, there was a freeze in Scandinavia that brought a cold while large parts of the world were record warm. We know that the Earth is getting warmer and that there will be more rain in our regions. Where winters are stable below zero, it is normal for increased precipitation to come in the form of snow. Therefore, some areas may witness an increase in the amount of snow in the winter. But more and more areas will exceed the threshold where precipitation comes in the form of rain. Then you will see less snow, and this has consequences.

Southern landslides are becoming more common

-What are the consequences?

– In Norway, we are all about skiing, and many ski destinations can expect changes. But we can also expect larger and more frequent floods and stronger and more frequent periods of heavy rain. Then we have the problem of landslides. There we can expect some types of avalanches in steep terrain to become more common, including mud avalanches, Dyrdal says. She refers to forecasts by the Norwegian Water Resources and Energy Directorate (NVE), who are experts on the impact of climate change on snow and avalanches in Norway.

Where will the consequences be most evident in Norway?

– Norway is a long country with a lot of terrain, so there are big differences. In the lowlands, we already see that the amount of snow has decreased in winter. In the higher mountains and in the northern parts, changes occur more slowly, and in some places we have seen increased amounts of snow, but mostly the snow line creeps higher and higher up the mountain.

In a research article on climate change and road closures in Tromsø as of 2020, Dyrdal and her colleague Kjetil Isaksen provide accounts for two areas, the Mifjord in outer Senja and the village of Olderbakken, which are low-lying areas where the amount of snow has decreased. Winterization is expected to occur rapidly from 2040, with precipitation and water-related incidents expected to increase by 34 and 65 percent, respectively, until 2100. These research findings point in the same direction as the findings in the Nature article. .

More rainwater and floods

For Norway, it is rainwater and floods in particular that are expected to create the greatest climate challenges. In the report “Climate in Norway 2100” (2015), the Norwegian Climate Service points out these expected changes under the assumption of a high emissions scenario:

• Annual temperature: increase approx. 4.5°C (range: 3.3 to 6.4°)
• Annual rainfall: approximately increased. 18 percent (range: 7 to 23 percent)
• Driving rain will become stronger and occur more frequently
• Rain floods are becoming larger and coming more often
• Floods after the snow melted became less and less
• In lower areas, snow will be virtually gone for many years
• In the high mountains, larger amounts of snow may fall in some areas
• Much fewer and smaller glaciers
• Sea level is rising

The figures are from a 2015 climate report which compares to the reference period 1971-2000. Figures are based on a high emissions scenario (rcp8.5).