Greenland temperatures haven’t been this hot for at least 1,000 years, scientists report | CNN



CNN

As humans play with the planet’s thermostat, scientists piece together Greenland’s history by drilling ice cores to analyze the impact of the climate crisis on the island nation over the years. The more they drilled, the further they went back in time, allowing them to distinguish natural temperature fluctuations from those caused by humans.

After years of research on the Greenland Ice Sheet — which CNN visited when the cores were drilled — scientists reported in the journal Nature on Wednesday that temperatures were the warmest there in at least the past 1,000 years — the longer period during which their ice cores could be analyzed. And they found that between 2001 and 2011, the average temperature was 1.5 degrees Celsius warmer than in the 20th century.

The report’s authors said human-caused climate change has played a significant role in dramatically increasing temperatures in the critical Arctic region, where melting ice is having a huge global impact.

“Greenland is currently the largest contributor to sea level rise,” Maria Hörhold, lead author of the study and a glaciologist at the Alfred Wegener Institute, told CNN. “And if we continue with carbon emissions as we are doing now, then by 2100 Greenland will have contributed up to 50 centimeters to sea level rise and that will affect millions of people who live in coastal areas.”

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CNN
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Greenland: the secrets of the ice – Part 5

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– Source: CNN

Weather stations along the edge of Greenland’s ice sheet have detected that its coastal regions are warming, but scientists’ understanding of the effects of rising temperatures there has been limited due to a lack of long-term observations. .

Understanding the past, Hörhold said, is important in preparing for future consequences.

“If you want to say something is global warming, you have to know what the natural variation was before humans actually interacted with the atmosphere,” she said. “For that, you have to go back in time – to the pre-industrial era – when humans weren’t emitting [carbon dioxide] in the air.

In pre-industrial times, there were no weather stations in Greenland that collected temperature data like there are today. That’s why scientists have relied on paleoclimate data, such as ice cores, to study warming patterns in the region. The last robust analysis of ice cores in Greenland was completed in 1995, and those data detected no warming despite climate change already apparent elsewhere, Hörhold said.

“With this extension to 2011, we can show that, ‘Well, there’s actually a warming going on,'” she added. “The warming trend has been there since 1800, but we had the high natural variability that hid that warming.”

Before humans started dumping fossil fuel emissions into the atmosphere, temperatures near 32 degrees Fahrenheit in Greenland were unheard of. But recent research shows that the Arctic region is warming four times faster than the rest of the planet.

Significant warming of the Greenland ice sheet is approaching a tipping point, which could trigger a catastrophic melt, scientists say. Greenland contains enough ice that, if it all melted, it could raise global sea levels by about 24 feet, according to NASA.

Although the study only covered temperatures up to 2011, Greenland has experienced extreme events since then. In 2019, an unexpected hot spring and heat wave in July melted almost the entire surface of the ice sheet, dumping an estimated 532 billion tonnes of ice into the sea. Global sea levels would rise by 1 .5 millimeters as a result, the scientists later reported.

Then in 2021, rain fell on top of Greenland – about two miles above sea level – for the first time on record. The warm air then fueled an extreme rain event, dumping 7 billion tons of water onto the ice sheet, enough to fill the Reflecting Pool at the National Mall in Washington, DC nearly 250,000 times.

With these extreme events in Greenland occurring more often, Hörhold said the team will continue to monitor changes.

“Every degree counts,” Hörhold said. “At some point we will return to Greenland and we will continue to extend these records.”

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