Greenland ice sheet at its warmest level in past 1,000 years

The ice calving front of the Russel Glacier in Kangerlussuaq, Greenland (The Alfred Wegener Institute)

The Greenland ice sheet was warmer in the first decade of this century compared to all other periods in the past 1,000 years, study suggests.

Researchers have also calculated that between 2001 and 2011, central-north Greenland was on average 1.5C warmer than in the 20th century.

They said the findings, published in the journal Nature, suggest human-led activities are having an impact in the region and may accelerate the rate at which further ice is lost from the sheet.

More than three million cubic kilometres of water are stored in Greenland’s ice sheet.

If global emissions rates remain unmitigated, it is estimated that the Greenland ice sheet will add 50 centimetres to the global mean sea-level by 2100, potentially flooding many coastal cities around the globe.

As part of the study, the scientists analysed data gathered from the ice cores spanning more than a thousand years.

Ice cores – cylinders of ice drilled from the Greenland ice sheet – are essentially frozen time capsules that allow scientists to reconstruct climate far into the past.

The Alfred Wegener Institute ice laboratory Workstation for inspecting and preparing polar ice cores for sawing — The ice laboratory workstation for inspecting and preparing polar ice cores for sawing (The Alfred Wegener Institute)

Dr Maria Horhold, a glaciologist at the Alfred Wegener Institute in Germany and lead author of the study, said: “The time series we recovered from ice cores now continuously covers more than 1,000 years, from year 1000 to 2011.

“This data shows that the warming in 2001 to 2011 clearly differs from natural variations during the past 1,000 years.

“Although grimly expected in the light of global warming, we were surprised by how evident this difference really was.”

In addition to the temperature, the team also reconstructed the melt production of the ice sheet.

Results indicate melting has increased substantially in Greenland since the 2000s and now significantly contributes to global sea-level rise, the researchers said.

Glaciologists working on the drilled ice cores. — Glaciologist Sepp Kipfstuhl, of the Alfred Wegener Institute, working in the ice lab (The Alfred Wegener Institute)

Maria Horhold added: “We were amazed to see how closely temperatures inland are connected to Greenland-wide meltwater drainage – which, after all, occurs in low-elevation areas along the rim of the ice sheet near the coast.”

Commenting on the research, Professor Andrew Shepherd, director of the Centre for Polar Observation and Modelling at University of Leeds, said: “There is plenty of evidence that the Arctic has warmed rapidly over recent decades.

“This study plugs an important gap in our knowledge because it shows that Greenland has warmed too – it’s hotter there now than at any time in the past 1,000 years.

“But the ice cores that are used in this study were collected more than a decade ago, and temperatures have risen even more since then.

“We are now starting to see the first major impacts of this warming on the ice sheet as glaciers in the north of Greenland have started to speed up.

“It’s a timely reminder that even the coldest parts of our planet are not isolated from the effects of global heating, and of course the impacts, in this case, will arrive at our doorsteps immediately as sea levels rise.”