SNOW AND GLOBAL WARMING: A PARADOX?
Blossoming daffodils, sprouting tulips, colleagues with hay fever: spring was in the air past December! Although I secretly enjoyed the smell of spring in the air, I must admit there was something scary about the daisies covering my lawn in mid-winter. With a record breaking average of 9.7°C, it was the hottest December ever recorded in the Netherlands, exceeding even average April temperatures. This was not a local signal: globally, average December temperatures were 1°C higher than the monthly average.
The high temperatures witnessed in December are the effect of climate change, with an El Niño effect on top. As a result, ski resorts in the Alps were snow-free around the holidays. My parents-in-law, who always go to the Alps on Christmas, had to dust off their hiking boots instead of wax their ski's this year. With ongoing global warming, this will happen more often, not only in the Alps, but in ski resorts all over the world.
Source: dailymail.co.uk
PARADOX
The spring blossom and bare slopes are very visible, tangible and understandable effects of global warming. That the intense blizzard now blasting the east coast of the USA is another side of the same coin, is more difficult to grasp. How can major blizzards like this be caused by a climate that is supposed to be warmer?
First of all, for a blizzard to occur, two criteria need to be met. It has to be cold enough to snow, and the atmosphere has to be moist. While global warming causes temperatures to rise and winters will get shorter due to climate change, it is often still cold enough to snow occasionally. This is why we will continue to see blizzards, even in a warming climate. However, a warmer atmosphere can contain more moisture. A developing storm brings in all the available moisture and makes it snow harder, which is how global warming intensifies blizzards. In the future, we are therefore likely to see a shorter snow season, but with more intense blizzards.
Blizzard of January 2016, New Jersey. Source: abcnews.go.com
POLAR VORTEX
Intensifying blizzards are not the only counterintuitive effect global warming has on winter events. As odd as it may sound, winters may even become colder locally because of global warming. The cold winter North America experienced in 2014, for example, may have been caused by global warming. In a 'normal' climate, cold polar air is separated from North America by winds known as the polar vortex. An abnormally warm Arctic may erode this polar vortex, causing cold air usually penned in the Arctic to break out and reach North America and Europe, which is what happened in 2014.
UNDERSTANDING CLIMATE CHANGE
Changing winters will have several economic effects. First of all, the skiing industry most likely will suffer from shorter and more irregular winters, as was demonstrated already this season. A shorter snow season can however also be economically beneficial, as it can lead to saving money on snow removal. However, the costs of major densely populated areas being partially shut down are much higher.
Understanding how global warming may affect our winters therefore is crucial in understanding the challanges we face. Winters like we have seen the past years are going to be more common, because of global warming. Now you know why!