The Canadian Arctic permafrost is thawing 70 years earlier than expected, a rate shocking a group of scientists who released the findings of their long-term study this month.

A research team affiliated with the University of Alaska Fairbanks observed three sites over a period of 13 years between 2003 and 2016, according to a brief of their findings. Researchers discovered that a series of unusually warm summers triggered the rapid thawing, which is occurring 150 to 240 percent above the average rate between 1979 to 2000.

Bill Cable, a co-author of the study and engineer at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Germany, tells TIME that the primary purpose of the research was to gather baseline measurements in those areas that didn’t have any data regarding permafrost. While Cable didn’t join the project until 2008, he said that no one anticipated finding the results that they did.

“We were all quite surprised when we went back later and saw how the landscape had been transformed,” says Cable.

Throughout the duration of the study, Cable says the researchers would visit the site once every three years, accessing it via a Twin Otter propeller aircraft that is able to land without runways, which was necessary while conducting research in remote areas without commercial airports.

“The amount that the permafrost thawed isn’t surprising necessarily — we see this in other locations. What is surprising is the speed at which this happened, especially for an area that is very cold permafrost,” says Cable. “We found that this really isn’t as stable as we think it is.”

University of Alaska Fairbanks geophysics professor Vladimir E. Romanovsky told Reuters he was also shocked to see that land frozen for 1,000 or more years is thawing so quickly.

“It’s an indication that the climate is now warmer than at any time in the last 5,000 or more years,” he said.

This isn’t the first study to show the Earth’s climate changing faster than expected. A study published in January by the journal Science found that since the 1950s, ocean temperatures have increased much faster than previously anticipated by researchers.

Climate change has become an issue at the forefront for many in the upcoming 2020 presidential election. Former Vice President Joe Biden, former U.S. Rep. Beto O’Rourke, and Gov. Jay Inslee of Washington state are among the Democratic candidates who are touting climate change proposals on their campaign trails.

Cable, meanwhile, is skeptical that anything can be done to reverse the effects of what has already happened to the Canadian Arctic permafrost. However, he is hopeful that citizens of the world can make positive changes moving forward to protect the planet.

“I think this really requires a very large effort on a global scale,” he says. “Something that not just one government or one entity can can tackle.”

Write to Nadia Suleman at nadia.suleman@time.com.