Wednesday, 14 January 2015

Global Warming: The Coolest Thing That's Happened To Us?

by Ben Stainton

Global warming has been in the back of our minds for the last thirty years, but what people don’t know is that the rapidly accelerating warming that we are predicting may actually hasten the onset of a new Ice Age. I must mention now that we are still within an “interglacial period”, during which the ice has largely retreated to the polar extremities. However we may not be in this for much longer.

The key to these chilling prospects lies in the Gulf Stream - the strongest ocean current in the world. The Gulf Stream brings “warmth” to the UK and northwest Europe and is the reason we have mild winters. Without this conveyor belt of warm water, the UK would have to face winters estimated more than five degrees cooler, bringing the average December temperature in London to about two degrees.

So everyone is aware that the polar ice caps are melting, and fast, but the cold ice melt can bring drastic consequences - far worse to mankind than rising sea levels. The sinking of cold, salty water in the Arctic largely drives the Gulf Stream, but melting glaciers and ice sheets are now adding more fresh water into the surface of the Arctic Ocean than ever before. For roughly a decade, global climate models have been predicting further weakening of the Gulf Stream as a consequence of global warming. Fresh water from melted ice caps is less dense than salty water, does not sink in the arctic seas and in larger quantities is proven to weaken the "pump effect" of the Gulf Stream.

An impaired or blocked Gulf Stream would lead to significantly colder climates in the regions it currently warms and may precipitate an Ice Age affecting much of the middle and higher latitudes of the Northern Hemisphere.  

Yet more worrying to me is the fact that the Gulf Stream is a significant contributor to the worldwide system of ocean currents known as the Global Thermohaline Circulation. The possibility, therefore, must exist that a disruption of the Gulf Stream may in fact have implications far beyond a colder UK and north-west Europe, perhaps bringing dramatic climatic changes to the entire planet. These consequences have far too many factors to take into account to accurately predict - however, one of the possibilities is the return of a global Ice Age. In fact, analyses of models looking at the abrupt climate change during the last glaciation also suggest that the event may have been triggered by changes to the Gulf Stream.

Currently, most of Earth could be considered “dark”, by which I mean the land and oceans absorb much of the solar radiation from the sun, which is how our planet is warmed up. But sheets of ice (that are likely to extend with drastic changes to ocean currents) are white and reflect sunlight like a mirror, meaning the ice-covered parts of the earth absorbs far less solar heat. 

Russian climatologist Mikhail Budyko predicts that the Earth’s climate has a theoretical breaking point; too much ice cover around the earth could trigger a global freeze cycle. This could lead to a position descriptively named ‘snowball Earth’, where our frozen planet, unable to absorb solar radiation, would be locked indefinitely inside a crust of ice. It is thought that the Earth has been in the same situation once before and it was only due to extensive volcanism that the lock was broken. Given that the planet is now much less volcanically active, we may not be able to afford this luxury again.

So, while we may be getting hot under the collar about global warming, our successors may be quite literally chilled out.

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