Collapse of ocean currents would be a global catastrophe, and it could happen within a lifetime – Scotsman comment

People reading this article in Ayr today are expected to be experiencing brisk spring weather, with a gentle breeze and temperatures reaching ten degrees Celsius.

But, despite being the same distance from the equator as Ayr, the town of Hopedale, Labrador, eastern Canada, is set for snow amid sub-zero temperatures. A major reason is the North Atlantic Drift which brings warm weather from the Caribbean to Scotland, enabling palm trees to be grown on the west coast.

It is an example of just how important ocean currents are to Scotland and, indeed, the world. However new research, published in one of the most prestigious scientific journals in the world, Nature, provides alarming new evidence about just how quickly these vitally important ocean currents are weakening as the world’s climate changes.

The researchers found that global ocean currents are slowing down because melting ice is dumping vast amounts of fresh water into the sea, diluting trillions of tonnes of salty, and therefore dense, water that normally sinks down to the sea bed off, for example, the coasts of Antarctica and Greenland – an ‘overturning’ motion that provides much of the currents’ driving force.

Professor Matthew England, who led the study, said: “Our modelling shows that if global carbon emissions continue at the current rate, then the Antarctic overturning will slow by more than 40 per cent in the next 30 years – and on a trajectory that looks headed towards collapse.” Their model also predicted a 20 per cent weakening of the North Atlantic currents that keep much of Europe’s climate mild.

The Intergovernmental Panel on Climate Change has also expressed only “medium confidence” that the Atlantic Meridional Overturning Circulation, including the North Atlantic Drift, “will not collapse abruptly before 2100”.

The effects of such a collapse are difficult to predict but it might see Scotland experience weather akin to eastern Canada’s within a lifetime. The overall consequences would be worldwide and catastrophic, dramatically changing tropical rainfall patterns, reducing marine nutrients, and speeding up global warming, among a myriad of other effects.

And, as the IPCC has repeatedly made clear, the chances of “irreversible” changes to our relatively benign climate system, which has served humanity so well, get higher with each and every increase in global warming. We are rolling the dice with our children’s future.