A contradiction in terms? – More like Murphy’s Law perhaps. They tell us the world is warming up and it’s all our fault, and I won’t argue against that for a moment. Just look at the mild winter that we hope has just finished. I’m sure most of us are happy to forget how we used to suffer from chilblains and burst pipes every winter in the bad old days before global warming began.
So what am I worried about – apart from that inherent propensity for gloom and doom that you will have noticed in my looking askance’ series ?
Well, in addition to the “2000 scientists” who made recent headlines with their confirmation of the principle of man-made global warming and the hazards that follow from it, there are other scientists specialising in the study of ocean currents who have reached a conclusion of even more immediate concern to us on the north-western edge of Europe.
Before the rest of the world gets fried, it seems that we in England can soon expect to suffer a period of really ice-cold winters equivalent to the north of Newfoundland and the St Lawrence Seaway in Canada – and anyone who has ordered goods for shipment by sea from Quebec will know that the St Lawrence doesn’t open to shipping until the ice melts in March or April. Now that’s what I call Murphy’s Law!.
There is good logic behind this prediction and it is based on the fact that we owe our pleasant climate on the north-eastern edge of the Atlantic to the ocean current called the Gulf Stream. This brings warm water from the Caribbean – you know, Jamaica, Florida and all that – right across the Atlantic, straight to our coastline, along with warm wet winds and surfing waves.
The Gulf Stream is driven by convection currents in the Atlantic where heavy cold water full of icebergs from the Arctic drifts down the western side of the ocean past Newfoundland. By the time it reaches New York the icebergs that have escaped being hit by luxury liners will have melted, and further south the cold water sinks below the lighter warm water of the tropical regions. South of the tropics, it is warming up when it meets even colder water from the Antarctic regions so it is pushed up to the surface where it drifts north to the Caribbean, by which time it is as warm as it gets. This is when we call it the Gulf Stream as it veers north-east across the Atlantic, to warm us up and cool itself down until it mixes with the cold Arctic waters and starts the circuit all over again.
Crucial to this circulatory system is the heat of the sun in the tropics and the cold of the ice caps at the poles. Now, the heat in the tropics is not in question – in fact it is likely to get hotter – but the north polar ice cap is already suffering the effects of global warming. We must all have read or heard about the thinning of the ice cap on the arctic ocean, to the detriment of the polar bears, and the shrinking of the glaciers of Greenland as the ice melts in the warmer summers faster than it builds up in winter. Not something that affects us, we may think, but it is that melting ice in Greenland, melting faster every year, that is likely to have the most striking influence on our personal climate in the immediate future.
Greenland ice is not sea ice. It has formed from snow falling on Greenland for hundreds of thousands of years; it is thousands of metres thick and Greenland is a very big landmass, as big as all of Western Europe; so that is a lot of ice. When Greenland ice melts it forms fresh water, and fresh water is lighter than sea water. The time may come when all this extra melt water pushing south with the present cold current down the coast of North America is no longer heavy enough to sink below the waters of the Gulf Stream, and actually swamps the flow of tropical water that keeps us warm. We would then be exposed to cold currents from the Arctic all year round, leaving us with a climate similar to north-east Canada, as I described earlier.
The scientists have not said yet how soon this may happen, but their computer models indicate that the change could be quite sudden and could take place almost any year now. On the other hand it is still just possible it may not happen at all. Even Murphy’s Law is not infallible!