Arctic sea ice declined dramatically in 2007 and has never recovered.
New research suggests the loss was a fundamental change unlikely to be reversed this century, if ever – perhaps proof of the sort of climactic tipping point that scientists have warned the planet could pass as it warms.
The conclusion comes from three decades of data on the age and thickness of ice disappearing in the Arctic each year to the east of Greenland.
Scientists at the Norwegian Polar Institute found a marked difference in the ice level before and after it reached an unprecedented low in 2007.
In the years since, the data shows, the Arctic has entered what the researchers called a “new regime” – one that brings with it a trend towards ice cover that is much thinner and younger than it had been before 2007.
The researchers linked the change to rising ocean temperatures in the rapidly warming Arctic, driven by human emissions of greenhouse gases. “Our analysis demonstrates the long-lasting impact of climate change on Arctic sea ice,” they wrote in the journal Nature.
Walt Meier, a senior research scientist at the National Snow and Ice Data Centre at the University of Colorado at Boulder likened the 2007 low to a boxer who is delivered a knockout punch.
All the punches leading up to it weaken the fighter, but that biggest blow is too much for the boxer to overcome.
That’s not to say Arctic ice is knocked out completely, but that it cannot quickly recover.
“You’re in a new situation, a new equilibrium, where you can’t easily get back to where you were,” said Mr Meier, who was not involved in the new research.
The scientists’ analysis relies on data captured from the Fram Strait, a passage between Greenland and the Norwegian archipelago known as Svalbard.
They found a dramatic change happened in 2007, when the ice research centre in Colorado reported a record low sea ice cover that was 38pc smaller than normal and 24pc smaller than the previous record low, set in 2005. That is a concern for a variety of reasons: sea level rise, a loss of habitat for Arctic creatures and a decline in the albedo effect, which is when ice reflects sunlight back into space.
The amount of ice thicker than four metres passing through the Fram Strait dropped by more than 50pc after the 2007 record low.
© Washington Post