Researchers found "unprecedented" warmth in the Canadian Arctic, the region is the warmest it has been in at least 44,000, and possibly even 120,000 years.
The study presents the first evidence that the present warm temperatures are higher than what they were in the Early Holocene, when the amount of the Sun's energy reaching the area was about nine percent stronger than it is today, a University of Colorado, Boulder news release reported. The Holocene is an epoch that began after the Earth's last glacial period 11,700 years ago and is still going strong today.
The research team looked at dead moss revealed by the melting ice caps to determine when they had last been uncovered. Using radiocarbon dating found the moss had been iced over for 44,000 to 51,000 years.
"The key piece here is just how unprecedented the warming of Arctic Canada is," study leader Professor Gifford Miller, a fellow at CU-Boulder's Institute of Arctic and Alpine Research, said. "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."
Radiocarbon dating can only accurately pinpoint the age of objects 50,000 years old or younger, so the Arctic may not have been as warms since as far back as 120,000 years ago.
"The oldest radiocarbon dates were a total shock to me," Miller said.
The samples were taken from the 196,000-square-mile Baffin island, which is considered to be the fifth largest island in the world. Most of the island's ice caps lie fairly flat.
"Where the ice is cold and thin, it doesn't flow, so the ancient landscape on which they formed is preserved pretty much intact," Miller said.
The team also looked at ice cores from the island to determine past climate changes. The cores confirmed the last time summer temperatures reached today's heat was about 120,000 years ago. The Arctic summer temperatures are believed to have cooled by about five degrees Fahrenheit from 5,000 years ago, and then started warming within the last century.
"Although the Arctic has been warming since about 1900, the most significant warming in the Baffin Island region didn't really start until the 1970s," Miller. said "And it is really in the past 20 years that the warming signal from that region has been just stunning. All of Baffin Island is melting, and we expect all of the ice caps to eventually disappear, even if there is no additional warming."
