A new study of Greenland’s ice cores indicates that rising temperatures bear the ‘clear signature of global warming’.
New data has revealed that temperatures in Greenland are the warmest they have been in 1,000 years, underscoring the growing impact of human-driven climate change on the natural world.
A study published in the scientific journal Nature on Wednesday found that temperatures have risen 1.5 degrees Celsius (2.7 degrees Fahrenheit) above the 20th-century average since 1995. The data shows that Greenland’s ice cores — samples taken from deep within ice sheets and glaciers — have warmed substantially.
“We keep on [seeing] rising temperatures between the 1990s and 2011,” said the study’s lead author Maria Hoerhold, a glaciologist at the Alfred Wegener Institute in Germany. “We have now a clear signature of global warming.”
As fossil fuel consumption releases carbon into the atmosphere and warms the planet, scientists have warned that governments have yet to make the changes needed to avert the worst repercussions of global warming.
In November, a United Nations report found that many of the world’s most famous glaciers could disappear by 2050 as the planet warms. Of the more than 18,600 glaciers the organisation monitors across 50 World Heritage Sites, about one-third are expected to vanish by mid-century.
Another study found that two-thirds of the world’s glaciers are expected to disappear by 2100.
Greenland’s ice cores, which reveal information about long-term temperature changes, take time to analyse. Data from the cores had last been updated in 1995 and previously suggested that Greenland was not warming as quickly as the rest of the Arctic region.
However, the newly analysed cores, taken in 2011, show a sharp rise over the last 15 years.
“This is an important finding and corroborates the suspicion that the ‘missing warming’ in the ice cores is due to the fact that the cores end before the strong warming sets in,” said climate scientist Martin Stendel of the Danish Meteorological Institute, who was not involved in the research.
Hoerhold said that natural weather variability and undulations caused by an occasional weather system called “Greenland blocking” had previously hidden the toll of human-caused climate change.
But in the 1990s, that change became too large to ignore. Past data showed Greenland warming at a lower pace than the rest of the Arctic, which was warming four times faster than the global average. Now, Greenland appears to be catching up.
The ice cores are used to create a chart approximating temperatures in Greenland over a more than 1,000-year timeframe, stretching from the years 1000 to 2011.
For the first 800 years, the temperatures slowly cooled, then edged up and down before a dramatic spike in the 1990s. Hoerhold said that there is “almost zero” chance that the post-1995 spike is attributable to a factor other than climate change.
Another set of ice cores was taken in 2019, but Hoerhold said they are still being studied.
The study also revealed that more water is being released as Greenland’s ice melts, contributing to rising sea levels.
“We should be very concerned about North Greenland warming,” said Danish Meteorological Institute ice scientist Jason Box. “Because that region has a dozen sleeping giants in the form of wide tidewater glaciers and an ice stream.”
