It’s been a long cold snowy winter. It started in late September last year and it only just ended. That’s almost seven months, more than twice as long as a regular winter.
And this is not the first extreme winter we’ve had in Europe lately. The winter 2010/2011 was also very cold, with plenty of snow, as was the winter in 2011/2012.
So what’s this all about? Aren’t we supposed to be suffering from the greenhouse effect? Aren’t the polar ices meting away from global warming, keeping all the polar bears on shore, rooting through our rubbish bins?*
There’s very little doubt that we’re indeed experiencing global warming. Temperatures have been rising drastically for the last hundred years or so. There’s also very little doubt that human-produced emissions are behind this rise. The increased temperatures have already had an effect on the weather systems on the planet. Heavy rainfalls have become more common, as have floods and tropical typhoons. And – rather counter-intuitively – the number of very cold nights have increased as well.
The reason for these meteorological anomalies aren’t completely clear, but it’s pretty certain that we’re pushing our climate out of its point of equilibrium and into a state of chaos. The expected short-term results are extreme weather, failed crops and increased deforestation.
It has also affected the world’s glaciers. The global glacier mass balance has shown negative values for 19 consecutive years now. This means that on average, we’re losing more glacier ice each summer than what builds up during winter.
We’ve already seen the effect of this on the Arctic ice sheet. The amount of summer ice is continuously diminishing and it’s impacting the Arctic wildlife in a drastic way. Polar bears are indeed struggling to find food when they can’t hunt from the ice, and the amount of sunlight hitting the naked ocean surface increases the amount of algae and might even affect the ocean currents.
“But it’s getting colder, not warmer”
I know. This still doesn’t explain why the winters should suddenly have become so much harsher. If the planet is warming up, why are the winters now so cold and snowy?
Well, perhaps global warming could explain the snowy part. The increased precipitation caused by global warming would also result in more snow in the winters.
For the low temperatures we have to look elsewhere, and the obvious culprit is changes in wind patterns. We’ve had a lot of cold Arctic winds the last few winters, and it’s lowered the mean temperatures by several degrees. But that doesn’t really explain the phenomenon in full. The question then would be why has the wind patterns changed?
Before trying to answer that question, let’s call the phenomenon by its proper name (nothing can be investigated thoroughly without having a proper name for it, surely?); it’s known as the Arctic Dipole Anomaly. It’s a pressure pattern over the North American parts of the Arctic that’s accompanied by a low pressure zone over Europe. Since air tend to flow from high pressures to low, cold Arctic winds have replaced the otherwise milder Atlantic winds typically dominating European winters. The origin of this Arctic Dipole Anomaly is not known, however, but it’s likely that it’s also linked to global warming.
The end of something, or the beginning of something else?
As I’ve mentioned before, we’re currently living in an ice age. It might not feel like we do, since we’re enjoying a temporary interglacial thaw, but we do. The presence of polar glaciers – although diminishing – is a clear indicator that so is the case. The current ice age, known as Pleistocene glaciation, is already some 2.58 million years old and shows no signs of ending anytime soon. Every 100,000 years or so, a new glacial period starts which lasts for 70-80,000 years to be followed by an interglacial period of 15-25,000 years.
So what am I saying? Are we on our way into another glacial period? Is this the end of the Holocene epoch? Well, we don’t know. The glacial-interglacial cycles aren’t exactly regular and seem to be partly governed by chaotic climatological events. But there is this theory of an ice-free Arctic ocean acting as a trigger for glacial periods; that the lack of ice cover would promote moist air to move in over land and result in more snow, adding to the glacial mass balance.
If this is indeed the case, we could be in big trouble, as the Arctic ice sheet is expected to be more or less gone in 5-20 years. And once we’re past the pivot point, the Gulf stream would shut down, further reducing the temperature in Europe. It would be like a failing chain of dependent power generators running out of fuel one after another. The temperature would plummet and land-based glaciers would start to form, first in Scandinavia and northern Russia, and then in Western and Central Europe quickly followed by North America. Instant ice age.**
In Norse mythology, we have the concept of Ragnarök – the end of the world, where gods and humanity will perish and all the land will be washed away by a great sea. It begins with a series of particularly harsh winters, where the snow will stay on through the summer, crops will fail and society fall into chaos. We call this Fimbulwinter, the Great Winter.
Perhaps the old Vikings knew something we’re only now starting to figure out?
* I’ve yet to see any polar bears near my rubbish bin, but I’m certain it’s just a matter of time.
** I say instant, but that’s in geological measures. Even if the changes in temperature and the resulting meteorological effects could be felt within years, we would expect the forming of glaciers to take centuries or even millenia.