The polar ice and the glaciers are melting, but that problem might be just the tip of the iceberg so to speak:
In the film, ‘The Day After Tomorrow’ the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.
William Patterson, from the University of Saskatchewan in Canada, and his colleagues have shown that switching off the North Atlantic circulation can force the Northern hemisphere into a mini ‘ice age’ in a matter of months. Previous work has indicated that this process would take tens of years.
All that melting ice could deposit enough fresh water into the oceans to disrupt the flow of the thermohaline, the deep ocean current that helps distribute heat and cooling around the globe.
Around 12,800 years ago the northern hemisphere was hit by a mini ice-age, known by scientists as the Younger Dryas, and nicknamed the ‘Big Freeze’, which lasted around 1300 years. Geological evidence shows that the Big Freeze was brought about by a sudden influx of freshwater, when the glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans. This vast pulse, a greater volume than all of North America’s Great Lakes combined, diluted the North Atlantic conveyor belt and brought it to a halt.
Without the warming influence of this ocean circulation temperatures across the Northern hemisphere plummeted, ice sheets grew and human civilisation fell apart.
Previous evidence from Greenland ice cores has indicated that this sudden change in climate occurred over the space of a decade or so. Now new data shows that the change was amazingly abrupt, taking place over the course of a few months, or a year or two at most.
Patterson and his team, who work with mud cores taken from ancient lake beds to create a record of early climate history, recently presented their findings at the European Science Foundation BOREAS conference on humans in the Arctic. He points out that precipitous melting of the Greenland ice sheet is all it could take to make the "Big Freeze" happen again.
And the change could be rapid, within a year or two, or even within a few months. Basically, one winter simply wouldn't come to an end. Who knows - it could be this one.
"That the climate system can turn on and off that quickly is extremely important," said earth system scientist Henry Mullins at Syracuse University, who did not take part in this research. "Once the tipping point is reached, there would be essentially no opportunity for humans to react."
On the upside, we'd have far less worrying to do about the escalation in Afghanistan.