High temperatures in the Arctic cause extreme cold in North America
The extreme cold experienced in the United States in recent years is connected to rising temperatures in the Arctic, according to a study published this week by the British scientific journal Nature. Scientists at the Massachusetts Center for Atmospheric and Environmental Research evaluated the weather variations in twelve US cities over the past 68 years and compared them to those in the North Pole in the same period.
Although the relationship between the warming of the North Pole and the cold waves in Eurasia and North America have been the subject of extensive debates, it has not been possible to establish, to date, a direct causality between both phenomena. The research, led by Judah Cohen is revolutionary in establishing correlations between temperatures in mid-latitude zones and Arctic meteorological anomalies dating from 1950, while the rest of the studies carried out are limited to a much shorter period of time.
Cohen's research showed that the frequency of episodes of extreme cold have increased on the east coast of the United States since 1990 while to the west coast it have declined in a correlative manner to the warming of the Arctic. The study suggests that the cause of the drastic waves of low temperatures is the weakening of the polar vortex, a kind of cyclone existing in the upper layers of the Arctic region's atmosphere that acts as a barrier to prevent the cold from escaping.
The polar vortex can lead to large outbreaks of cold air anywhere in the Northern Hemisphere, whether in North America, Europe or Asia. This can lead to cold waves in multiple locations, although not always happen. An outbreak of cold air caused by the polar vortex is much more extensive in area and duration than a single storm. However, with the generalized decrease in temperature, significant winter storms may develop, especially when cold air initiates penetration to a previously warm region. The strong cold waves occur several times a year, although in different regions of the world and with different levels of severity. In March 2013 there was a significant decrease in temperature, as a result of a polar vortex that penetrated much of Europe. In many regions of the Old Continent Holy Week was much colder than Christmas. For example, the United Kingdom had its coldest March in 50 years.
The Cohen team clarified that their conclusions do not establish a mechanical explanation for the relationship between the warming of the North Pole and the continental cold waves, although they are consistent with other studies previously conducted.