Greenland on track to lose ice faster than in any century for over 12,000 years

Greenland is on track to lose ice mass faster this century than during any other century over the last 12,000 years, according to a new study. 

US researchers simulated high-carbon-emission scenarios of the Greenland Ice Sheet – a 660,000 square mile body of ice that covers around 80 per cent of the surface of the island.

Under a scenario of high greenhouse gas emissions, ice mass loss could be four times higher than anything experienced over the past 12,000 years. 

Their new prediction is conditional on whether human societies 'sharply curb' emissions of greenhouse gases like carbon dioxide, which cause global warming. 

Reducing carbon emissions is needed to decrease the contribution of the Greenland Ice Sheet to rising sea levels, which could flood cities in the next 50 years.   

The edge of the Greenland Ice Sheet - the second-largest ice body in the world, after the Antarctic Ice Sheet. If human societies don't sharply curb emissions of greenhouse gases, Greenland's rate of ice loss this century is likely to outpace that of any century over the past 12,000 years

The edge of the Greenland Ice Sheet - the second-largest ice body in the world, after the Antarctic Ice Sheet. If human societies don't sharply curb emissions of greenhouse gases, Greenland's rate of ice loss this century is likely to outpace that of any century over the past 12,000 years

'Basically, we've altered our planet so much that the rates of ice sheet melt this century are on pace to be greater than anything we've seen under natural variability of the ice sheet over the past 12,000 years,' said lead author Jason Briner at the University at Buffalo in the US.

'We'll blow that out of the water if we don't make severe reductions to greenhouse gas emissions.' 

Scientists used new, detailed reconstructions of ancient climate for their simulation model, which was focused on southwestern Greenland.

The model was validated against real-world measurements of the ice sheet's contemporary and ancient size, taken from samples in the field. 

Samples from Greenland boulders, for example, contain chemical isotopes that can help scientists determine the ancient boundaries of Greenland Ice Sheet. 

The experts simulated changes in the sheet from the beginning of the Holocene epoch, around 12,000 years ago, and extending into the future up to 2100.   

Although the current rate of ice loss in Greenland is comparable to the highest rates during the Holocene, the researchers believe future rates are likely to exceed them. 

The research team's data shows Greenland ice loss has veered below zero at points throughout the last 6,000 years, but is set to soar upwards at the end of the 21st century.   

The project focused on southwestern Greenland. The largest ice mass losses in the past, between 10,000 and 7,000 years ago, were at rates of around 6,000 billion tonnes per century

The project focused on southwestern Greenland. The largest ice mass losses in the past, between 10,000 and 7,000 years ago, were at rates of around 6,000 billion tonnes per century

In their simulations, the researchers found that the largest ice mass losses in the past, between 10,000 and 7,000 years ago, were at rates of around 6,000 billion tonnes per century. 

This is similar to the estimated rates of the first two decades of this century (2000–2018) of around 6,100 billion tonnes per century. 

However, projected mass losses for the rest of this century are expected to exceed those maximum rates, they say.  

The melting of the Greenland Ice Sheet is also currently causing sea levels to rise by about 0.02 inches (0.7mm) per year. 

But the new model predicts it could reach somewhere between 0.07 inches and 0.27 inches (2mm to 7mm) per year by 2100. 

a) Map of the present-day Greenland Ice Sheet, showing commonly used domains (as labelled) and our model domain (outlined in red). NO, north; NE, northeast; NW, northwest; CW, central–west; SE, southeast; SW, southwest. b) and c) show moraine sequences - accumulations of unconsolidated glacial debris

a) Map of the present-day Greenland Ice Sheet, showing commonly used domains (as labelled) and our model domain (outlined in red). NO, north; NE, northeast; NW, northwest; CW, central–west; SE, southeast; SW, southwest. b) and c) show moraine sequences - accumulations of unconsolidated glacial debris

A rise in sea levels would see many cities around the world exposed to coastal flooding, which could lead to mass evacuations. 

Researchers also took into account the different climate eventualities as outlined in the UN Intergovernmental Panel on Climate Change's 'RCP' system.

The RCP trajectory ranges from RCP1.9 – where global warming is limited below 2.7°F (1.5°C) as per the goal of the Paris Agreement – to the dreaded RCP8.5, where emissions

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