Sunday 20 May 2018

'Abrupt' climate change to bring icy winters, scorching summers

Scientists fear that global warming and melting of the Greenland ice sheet will weaken or shut off these warm ocean currents, which could result in much colder temperatures across Ireland, Britain and Europe. Photo: PA
Scientists fear that global warming and melting of the Greenland ice sheet will weaken or shut off these warm ocean currents, which could result in much colder temperatures across Ireland, Britain and Europe. Photo: PA
Paul Melia

Paul Melia

Ireland could experience extremely cold winters and very warm summers if the Gulf Stream weakens and climate change takes hold.

Researchers at NUI Galway have found evidence of "abrupt" climate change as Scottish ice fields began melting away some 13,000 years ago, suggesting that Ireland could experience a "highly seasonal climate" in the future.

The last ice age peaked around 20,000 years ago and a study published in the international journal 'Paleoceanography and Paleoclimatology' says warming was not gradual over a prolonged period of time, but characterised by very cold winters, interrupted by periods of extremely warm weather.

The most recent abrupt climate event is called the 'Younger Dryas' and occurred between 12,900 and 11,600 years ago, prior to the onset of our current warm so-called 'Holocene' climate 11,000 years ago.

Ice core records suggest that this 1,300-year period experienced severe cooling and permafrost, possibly caused by the weakening of warm ocean currents, including the Gulf Stream, that transport tropical heat to Europe.

Scientists fear that global warming and melting of the Greenland ice sheet will weaken or shut off these warm ocean currents, which could result in much colder temperatures across Ireland, Britain and Europe. But lead author of the study, Dr Gordon Bromley from the School of Geography and Archaeology at NUI Galway, said that based on glacial evidence from Scotland, we could also see very warm summers.

He examined marine shells and vegetation found in glacial deposits which were "scooped up" as the massive ice sheets moved.

"We used radiocarbon dating of marine shell remains to determine when the last glaciers existed in Scotland," he said.

"There's a lot of geologic evidence of these former glaciers, including deposits of rubble bulldozed up by the ice but their age has not been well established.

"To establish the true age of the glaciers, we dated shells that were already dead or had been killed as the glaciers advanced into the fjords and shovelled up seafloor sediments."

Scientists also dated shells and vegetation which had colonised the newly ice-free landscape to see when the glacial event was over. The findings suggest that the glaciers had melted rapidly.

"Our new radiocarbon data crucially shows that the glaciers existed before the Younger Dryas and that they were melting rapidly and disappeared during that period," he added.

"We found that despite the cold winters, summers had to be warm as it is the intensity of the summer melt season that dictates glacier 'health'. This is controversial and if we are correct, it rewrites our understanding of how abrupt climate change impacts our maritime region, both in the past and potentially into the future."

Irish Independent

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