The west worries about Russia and China – but the real threat to global security is climate breakdown

The Irish sea captain who in 1751 discovered the Atlantic Meridional Overturning Circulation (Amoc) – closely connected with, though not identical to, the Gulf Stream – found a practical use for it: he used the frigid deeper water to cool his wine.

That may seem a rather frivolous response, but of course, Capt Henry Ellis had no idea that the oceanic pattern he had stumbled upon had been critical to the climate, the agriculture and indeed the entire development of western Europe. The same excuse can hardly be made for British and European governments today.

The latest scientific analysis based on evidence from the last ice age suggests that there is a possibility that, because of global heating and the resulting influx of fresh water from the melting Greenland ice cap, the Amoc could shut down with surprising speed, and as early as the middle of this century.

If that occurs, the consequences would be catastrophic. With the resulting hypothetical 10C to 15C fall in temperature, Britain’s climate would change to that of Newfoundland’s. Agriculture would collapse, and the entire landscape of the country would be transformed. Housing and infrastructure would have to be radically adapted to withstand the new climate.

The result would be decades, and possibly generations, of economic hardship. And as temperatures fell in western Europe, they would rise in west Africa. The population of Britain would at least survive a collapse in local agriculture, albeit in straitened and rationed circumstances reminiscent of the second world war and its aftermath. People in Africa would not.

The result would be an immense increase in the migration and the political........

© The Guardian