Greenland is the warmest it’s been in 1,000 years

Temperature spikes in Greenland since 1995 show the giant northern island is 1.5 C warmer than the 20th century average, the warmest in more than 1,000 years, according to new ice core data.

So far, Greenland’s ice cores — a glimpse into temperatures long before thermometers — haven’t shown a clear signal of global warming in the remote north-central part of the island, at least compared to the rest of the world.

But the ice core also hasn’t been updated since 1995. A newly analyzed core, drilled in 2011, shows a dramatic increase in temperature over the past 15 years, according to a study in the journal Nature this week.

“We continued (to see) temperatures rise between the 1990s and 2011,” said study lead author Maria Hoerhold, a glaciologist at the Alfred Wegener Institute in Germany. “Now we have a clear sign of global warming.”

It takes years to analyze the ice core data. Hoerhold has a new core from 2019 but hasn’t finished studying. They expect the temperature rise to continue as Greenland’s ice sheets and glaciers melt faster.

“This is an important finding and supports the hypothesis that the ‘missing heating’ in the ice core is due to the fact that the core ended before the strong warming,” said climate scientist Martin Stendel of the Danish Meteorological Institute, who did not know. ‘t part of the research.

How Greenland’s temperature has changed over time

The ice cores were used to create a proxy temperature chart for Greenland from 1000 to 2011. It shows temperatures slowly sloping cooler for the first 800 years, then wobbling up and down on the warmer slope to a sharp, sudden spike over hot from the 1990s. One scientist compared it to a hockey stick, a description used for other long-term temperature data that shows climate change.

The jump in temperature after 1995 was so large from the pre-industrial era before the mid-19th century that there was “almost zero” chance of anything but human-caused climate change, Hoerhold said.

The warming spike also reflects an increase in the amount of water coming out of Greenland’s melting ice, the study found.

What’s happening in Greenland is that natural weather variability, undulations due to occasional weather systems called the Greenland block, have in the past masked human-caused climate change, Hoerhold said.

But about 25 years ago, the warming became too great to hide, he said.

Past data also shows Greenland is not warming as fast as the rest of the Arctic, which is currently warming four times faster than the global average. But the island seems to be getting closer.

Why Greenland is warming more slowly than other parts of the Arctic

Ice core data over the years shows Greenland behaves a little differently than the Arctic, possibly because of the Greenland block, Hoerhold said. Other scientists say that as a large land mass, Greenland is less affected by sea ice and other water factors compared to the rest of the Arctic, which is closer to water.

Hoerhold’s team drilled five new cores near the old core to match the established ice core records. They used the difference between the two types of oxygen isotopes found in the ice to calculate the temperature, using a well-established formula checked against the observed data.

Hoerhold and outside scientists say the new warming data is bad news because Greenland’s ice sheet has been melting. In fact, the study ended with data from 2011 and the following year had a record melting in Greenland and the island’s ice loss has been high since then, he said.

“We should be very concerned about the warming of North Greenland because the region has twelve sleeping giants in the form of vast tidal glaciers and ice streams,” said Danish Meteorological Institute ice scientist Jason Box. When awakened, this will ramp up the fusion of Greenland, he said.

And that means “sea level rise that threatens homes, businesses, economies and communities,” said US Snow and Ice Data Center Deputy Principal Scientist Twila Moon.