In pictures: Greenland ice loss faster than expected

Drone imagery that captured lake drainage in unprecedented detail, image(L) and five hours later, the lake started to drain(R), and had lost 5 million cubic metres of water, or two-thirds of its volume.The melting of Greenland's massive ice sheet is happening much faster than expected and could put millions more people at risk by the end of the century, scientists warned Tuesday. Up to three kilometres thick (two miles) in some places, Greenland has lost 3.8 trillion tonnes of ice since 1992, enough on its own to add 10.6 millimetres (1.06 centimetres, 0.4 inches) to sea levels, according to a study in the journal Nature.

A lake draining into the Greenland Ice Sheet. The recent study showed that the rate of ice loss has risen from an average 33 billion tonnes per year in the 1990s to 254 billion tonnes in just three decades. Many scientists fear that global warming driven by greenhouse gas emissions have pushed the ice sheets to a point of no return, with potentially catastrophic consequences for mankind.

A large Iceberg floats away as the sun sets near Kulusuk, Greenland, on Aug. 15, 2019. The Intergovernmental Panel on Climate Change (IPCC) in 2013 gave a central forecast that if global warming continued, sea levels would rise 60 centimetres by 2100, putting 360 million people at risk of annual coastal flooding. The latest study however shows that Greenland's faster-than-expected ice losses are in line with the IPCC's higher-end climate warming scenario which adds seven centimetres to that figure. "As a rule of thumb, for every centimetre rise in global sea level another six million people are exposed to coastal flooding around the planet," said co-author Professor Andrew Shepherd of Leeds University in the UK. "On current trends, Greenland ice melting (alone) will cause 100 million people to be flooded each year by the end of the century, so 400 million in total due to all sea level rise," Shepherd said. "These are not unlikely events or small impacts; they are happening and will be devastating for coastal communities," he added.

An iceberg floats in a fjord near Tasiilaq, Greenland, June 16, 2018. According to the study, half of the ice losses are due to surface melting, with the rest due to increased glacier flow triggered by rising ocean temperatures. Ice losses peaked at 335 billion tonnes in 2011 - 10 times the rate of the 1990s - during a period of intense surface melting, it said.

Sled dogs wading through standing water on the sea ice during an expedition in North Western Greenland, in June.The rate has since dropped to an average 238 billion tonnes per year, but this is still seven times higher than in the early 1990s and does not include all of 2019, which could set new highs due to widespread summer melting. Study co-author Dr Erik Ivins of NASA's Jet Propulsion Laboratory in California said the team's satellite measurements "provide prima facie, rather irrefutable, evidence" of the changes taking place.

Snow covered mountains rise above the harbour and town of Tasiilaq, Greenland, June 15, 2018. The report is the latest in a litany of warnings about the threat posed to the Antarctic and Greenland ice sheets from global warming. Commenting on the findings, Guofinna Aoalgeirsdottir at the University of Iceland and lead author of the IPCC's sixth assessment report, said the study was "timely." "Their satellite observations show that both melting and ice discharge from Greenland have increased since observations started," Aoalgeirsdottir said, warning that 2019 was likely to be a record year for ice loss.