Rainfall Intensifies More Than Expected in the Arctic
The Arctic is a relatively “dry” region of the planet compared to areas located in the middle and tropical latitudes. Despite the proximity of low pressure systems, precipitation is usually scarce and when it does occur it is usually associated with air masses from much lower latitudes. The areas of high latitudes most prone to receiving intense and / or persistent precipitation are those in which the orography favors it, such as in Greenland or the northwest of the Scandinavian Peninsula.
This relatively weak precipitation regime is due to the low temperatures of the air masses present in the vicinity of the Arctic. The lower the temperature, the less moisture content the air can hold, in such a way that an air mass at 30 ºC can contain, without saturating, 3 times more water in the form of vapor than at 10 ºC and up to 10 times more water than at -10 ºC. It is therefore relatively difficult for strong and generalized precipitation to occur within an air mass of Arctic origin, even though it has a long maritime route.
Nevertheless, the progressive warming of the Earth’s atmosphere over the last decades is behind a change in the Arctic rainfall regime. As observed so far, it is one of the fastest warming regions on the planet and the incursion of warm air masses to Arctic latitudes is more abundant as a result of a weaker polar jet.
With this scenario, and according to climate prediction models, rainfall in the Arctic should be increasingly abundant and it seems to be the case, the problem is that the arctic rains are intensifying much faster than anticipated in past decades.
More snow, but mostly more rain
According to the prediction models, by the end of the 21st century the increase in rainfall will be between 30% and 60% above the current one. According to the last study published in Nature, the models consider that this increase, which is already being observable, exceeds previous predictions or at least it is located in the least conservative scenarios of the same. An important detail is that the rains will gradually replace the snowfalls in warm seasons and will begin to appear more frequently during winter. However, snowfall will also increase during winter.
Among the many factors behind this increase in temperature and rainfall, an important role is played by those that trigger feedback from the process and that, on the other hand, also complicate the prediction. One of the most notable is the reduction of the frozen surface in the Arctic. The evaporation of moisture from the ocean would increase with a smaller ice surface, and also the air masses would have more and more maritime travel and greater potential to generate significant rainfall, especially during the summer and autumn.