But do we care about last year’s snow?

Another snow-free Christmas is behind us. The school winter holidays are about to begin. Everything is jumping into place without snow, too. Is this a result of global climate change, or a temporary condition? Snow is a water resource that is very important in counteracting the development of drought, in feeding rivers, but also in agriculture. I talk to Mr. Artur Surowiecki, climatologist, synoptician and storm hunter, about whether snow will remain just a winter memory for us.

Marta Saracyn: Winter has been on the calendar for nearly three weeks now. I have this subjective impression that every year we have less and less snow. It dropped a bit in December. We had Christmas this year without snow, the holidays are about to begin, and the prospects for typical winter fun are quite poor. Is there actually less and less snow in Poland in recent years or is it just the feeling of a person craving that white outside the window?

Artur Surowiecki: If we compare the current state and what used to happen, indeed, since around 1990, snow winters in Poland have decreased. In recent times, they happen once in no more than 4 – 5 years. We are talking about such winters in which the snow cover remains for at least a week. This is very short, compared to the times when the average length of snow cover exceeded 60 days in many areas of our country. At the moment we are talking about a maximum of 35 – 40 days. This difference is very big. It is definitely warmer, especially the end of autumn and the beginning of winter is the period of occurrence of high still temperatures.

Let’s also look at what happens in January, in February. Masses of warmer air are increasingly arriving. Of course, this is undoubtedly due in large part to the so-called zonal circulation. She is often most active over Europe just in winter. What is it? These are westerly winds that occur over Europe during the winter months. They are exacerbated due to an increase in the thermal and barometric gradient between north and south. The north is cooling down due to the polar night. In the zone from Newfoundland through Iceland to northern Europe, powerful baric lows are forming. A stratospheric polar vortex also appears, which further modulates the westward flow in the troposphere, the lower layer of the atmosphere.

M. S.: What does the amount of falling snow depend on? What phenomena should occur for snowy winters to occur more often than every 4 to 5 years? What kind of situation would have to occur for this snow to really fall on us and for it not to melt within a few days?

A. S.: Until recently, air masses from over the Atlantic, which were less abundant in warmth, were arriving in the case of zonal circulation. In the last several years or so, however, the air reaching Europe from the west is noticeably warmer. This has to do with the fact that the temperature of the waters has increased significantly. This phenomenon affects the surface of all oceans. This is a clear, measurable manifestation of global climate change. This increase in the surface temperature of the Atlantic is also occurring in the European region. In addition, the snow and ice cover behind the northern Arctic Circle, in Greenland, has been melting very intensively in recent years. This has some impact on local temperature drops in the region of this island, nevertheless, the final result is that the average water temperature is getting higher. Because of this, the zonal circulation, a vortex of air masses from the west is pulling much warmer air into Europe than it was just a few decades ago. These are differences of up to 3 – 4°C. Seemingly, it doesn’t seem like much, but once upon a time, with air masses coming in from the northwest and west, the temperature settled around 0°C and we had weather then that was favorable for snowfall, but also for snowmelt. The ground during winter could become saturated with moisture, and the groundwater level was high.

At the moment, with air masses arriving from the west in winter, we have positive temperatures. Snowfall is no longer occurring. We have 3 – 5°C on the plus side, and in extreme cases, as was the case on New Year’s Day, record high temperatures reaching as high as 17-19°C. This is a very unique event, occurring in January theoretically not more often than once in -sometimes, maybe even 100 years. Meanwhile, in 2022. was also very warm in early January. In the future, the likelihood of such very warm days from December to February will increase.

M. S.: It sounds a bit like we have to say goodbye slowly to the vision of snow and snowy winters and skiing in Poland. It looks like it’s going to get warmer. Do I understand correctly that in the near future we will be forced to go skiing on glaciers in the Alps?

A. S.: In our country it will become increasingly difficult to practice winter sports, because in general the average temperature in the world is rising. Admittedly, these are increases in the order of parts of a hundredth of a degree Celsius per year, but if we look at a longer period, we have already recorded an increase of 0.6 – 0.7°C. This is also seemingly not much, but if so far we have had winters with average temperatures around 0°C and with snowfall, when we add this increase, the situation changes dramatically.

In Europe and in our hemisphere in general, in the Arctic Circle region and roughly from 40° north latitude to the Arctic Circle boundary, the temperature rises faster than in other parts of the world. This is known as Arctic Amplification – Arctic Amplification to Global Warming. The result is less and less snowfall in Europe. Of course, the snow will not quite leave us. The hope is that winter weather shaping centers may be arranged in such a way that cool air from deep inside the continent – from beyond the Urals, will begin to flow into Europe. This is where we have very large drops in temperature during the winter months.

M. S.: You talked about climate change and its impact on the reduction of snow in Europe. On the other hand, climate change is also a certain intensification of weather events. Are we in danger of a blizzard like the one we saw in December in the United States? In the US, very heavy snowfall paralyzed the country. There were also fatalities. Could such a situation arise in our country as well?

A. S.: In the US, we have a peculiar meridional alignment of mountain ranges and lowlands. This causes the collisions of two extreme air masses – cold from the north and warm from the south – to be much more violent than in our country. In winter, the effect of these collisions is the development of very strong low-lying centers, which pass through the eastern part of the United States, among other places. They, on their northern and western sides , bring very cold air masses from the north. They are also accompanied by the occurrence of extremely heavy snowfall, as well as just blizzards with winds in gusts often exceeding 100 km/h. This further intensifies the blizzards. In short – the winter of the century. In Poland, such weather phenomena also occur, except that the frequency of their occurrence is incomparably less than in the United States, not more often than once every 30-40 years. In the famous year 1979, when we had a similar winter in Poland, in many places more than 70 – 80 cm of snow fell in just a few dozen hours. Of course, it is not out of the question that global climate change will cause the frequency of such phenomena in Europe to increase. However, I do not think that climate change, due to the amplifying effect of global warming in the northern hemisphere, will result in the regular occurrence of catastrophic snowfall. The temperature gradient between the north and south is gradually decreasing, resulting in a weaker and meandering jet stream, or wind plume that blows about 8 – 10 km in the atmosphere, the formation of circulation blockages and slow-moving highs that can linger over Europe for 2-3 weeks. This is a very unfavorable situation, especially for renewable energy, because in the autumn and winter months it is often associated with the phenomenon of simultaneous lack of wind and the occurrence of total cloud cover (the so-called Dunkelflaute). For a deep low to form, in addition to the temperature gradient between north and south, there must also be a very strong jet stream. Such a low would pull in very cold northern air from over Russia on the one hand, and pull in very warm air lingering in the south over the Mediterranean Sea on the other. It is quite likely that in the next dozen or even several decades such phenomena will be less than before. Not once in 30, but once in 50-60 years. At the same time, it should be emphasized that we have too short a measurement series to try to determine the probable frequency of these phenomena. This is about 100, maybe 150 years of more in-depth meteorological observations in Europe. At this point, we have too little data to make any serious conclusions about the frequency of violent snowstorms or even outright snowstorms. We do know that the occurrence of such weather phenomena in Poland is practically possible from November to even mid-April, because that is when theoretically deep lows with catastrophic snowfalls and gales can take shape.

Deep lows bringing strong snowstorms and very large drops in air temperature in the center of Europe always form south and southwest of Poland. They then pass through our country, pushing from the southwest and heading toward Belarus, Ukraine and Russia. Alternatively, they may move to the Baltic Sea. Then, however, the effect of the collision between these two radically different air masses will be weaker, as the low will draw in fewer cool air masses from over Russia. Particularly dangerous are cases when the low goes from southern Germany, passes through Poland and heads toward Russia.

M. S.: In that case, I will keep a close eye on the weather forecasts and look out for these newtons from the south and west with hopes of snow. Thank you very much for the interview.