Fossils in Greenland ice sheet reveal increased risk of sea level rise

Greenland has melted before and As the weather warmsgoing to melt again — this time triggering what scientists warn could be a 20 to 25 foot rise in sea level.

During one of the warm periods of the past 1.1 million years, the center, not just the edges, of Greenland's massive ice sheet melted, according to a new study, giving way to a dry, arid “tundra landscape” that was home to diverse insects and plants. The findings were reported in a new paper published today in the journal Nature. proceedings of the National Academy of Sciences.

When the ice sheet initially melted, there were lower levels of greenhouse gases in the atmosphere than there are today. More carbon dioxide in the atmosphereScientists say the Greenland ice sheet is more susceptible to melting than previously thought.

“Greenland has existed for 2.7 million years with its ice,” he said. Paul Biermana University of Vermont scientist who led the new study. “There is now some evidence that this ice sheet is fragile.”

Researchers have been studying materials from beneath the Greenland ice sheet, largest in the northern hemispheresince 2014. They examined sediments from the bottom of an ice core, called GISP2, extracted two miles below the surface in the center of the ice sheet nearly 30 years ago.

The 28-gram sediment sample was packed with clues about Greenland's past. When placed under a microscope, tiny black flecks revealed an insect's eye, an Arctic poppy seed, parts of an Arctic willow and tiny bits of soil fungi and prickly moss — what Bierman called a “frozen ecosystem beneath the ice.”

Willow bud scales, arctic poppy seeds, fungal bodies, and rock moss megaspores found in soil sample GISP2 observed under a microscope. / Credit: Halley Mastro

Willow bud scales, arctic poppy seeds, fungal bodies, and rock moss megaspores found in soil sample GISP2 observed under a microscope. / Credit: Halley Mastro

According to the researchers, the fossils provide “direct confirmation” that 90% of the ice sheet had disappeared.

“Finding these fossils in the centre of the ice sheet is unequivocal evidence that Greenland's ice sheet has disappeared. [in the past]”Bierman said. “And once you lose the core of the ice sheet, you lose everything.”

The findings support the so-called “fragile Greenland” hypothesis: that nature, outside of human influence, has caused the ice sheet to melt at least once since it formed, Bierman said.

At 656,000 square miles, the Greenland ice sheet It currently covers around 80% of the island's territory.To put that in perspective, it's about three times the size of Texas.

Drilling dome and camp for GISP2, at Summit Greenland. / Credit: Christine MasseyDrilling dome and camp for GISP2, at Summit Greenland. / Credit: Christine Massey

Drilling dome and camp for GISP2, at Summit Greenland. / Credit: Christine Massey

NASA, which has mapped Greenland's ice loss, says the blade has “deteriorated rapidly in recent years,” Melting of the Greenland ice sheet is now the main driver of rising sea levels, according to Bierman.

“In the early years of global warming, mountain glaciers were the ones that melted the most and contributed water to the ocean,” he said. “Now it's Greenland's turn.”

Although it could take several thousand years before the entire landmass of Greenland melts, Bierman said, the consequences would be dire: Hundreds of millions of people could lose their homes and businesses. Places we hold dear would be lost.

“When people ask me why it's important, I like to say think about your favorite beach and then imagine your favorite beach with 25 feet of water above it,” Bierman said.

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