Written By: Emma Websdale
New research reveals that greenhouse gas emissions have pushed summer temperatures in the Canadian Arctic to the highest they’ve been in 44,000 years.
The University of Colorado has released a new study of the summer temperatures in the Arctic over the last century. The study finds that the Arctic hasn’t been this hot in 44,000 years and quite possibly in 120,000 years. Prior figures dated similar melt- and temperature-dynamics to 2,000–4,000 years ago.
“Our study pushes the clock way back”, says Scott Lehman, co-author of the study.
The scientists conclude that Arctic warming levels now match or exceed a natural warming period that occurred 5,000 to 10,000 years ago, known as the Holocene Thermal Maximum -an event that saw temperature increases of up to 4°C near the North Pole.
Findings from the report, published this week in Geophysical Research Letters, conclude that, despite extreme warming at that time, certain ice caps did not melt. This suggests that today’s increasing warming period can be attributed to greenhouse gas emissions.
“This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere”, says Dr. Gifford Miller, lead author of the report.
He adds, “All of Baffin Island [in the Arctic Circle] is melting, and we expect all of the ice caps to disappear eventually, even if there is no additional warming.”
After radiocarbon-dating, some of 145 rooted tundra plants exposed by recently melted ice caps on Baffin Island, Canada, were found to be over 40,000 years old. The plants ages can be used as indicators of the age of the ice caps, since the mosses would have been preserved by the ice that entombed them. Other tested vegetation samples were younger, meaning that the ice covering them could have started forming between 5,000 and 10,000 years ago.
Pairing these findings with estimates of Arctic temperatures through analysis of gas bubbles trapped in ice cores taken from the same location, the data suggest that current warming in the region hasn’t been this high since up to 120,000 years ago.
The report concludes, “Our results indicate that anthropogenic increases in greenhouse gases have led to unprecedented regional warmth.”