Scientists in the US are predicting that within 30 years there will no longer be summer sea ice in the Arctic.
This summer the ice was thinner and it dropped to its third lowest point since measurements began.
Scientist Julienne Stroeve from the National Snow and Ice Data Centre (NSIDC) in Colorado says the results are surprising.
“Typically, on average, as you look back to the ’80s, late ’70s, even early ’90s, the average was about seven million square kilometres at the end of the summer melt season,” she said.
“Basically, from about 2002, but more importantly since 2007, we’ve been dropping below five million square kilometres.
“And of course, 2007 was the record lowest at 4.3 [million square kilometres].”
Other scientists on Ms Stroeve’s team predict the ice decline means that in 20 to 30 years the Arctic will be ice-free in the summer.
Ms Stroeve says that will cause a jump in global warming and strange weather anomalies.
She says during the summer, the ice will no longer be there to reflect solar radiation back into space.
“As you lose that cover and you expose the ocean … you then absorb that sun energy throughout summer,” she said.
“In order for the ocean to once again refreeze in autumn, you’re going to have to re-release that heat that the ocean gained back to the atmosphere.
“And we’re seeing the effects of that already – we’re seeing some temperature anomalies in autumn over the Arctic in the order of three to five degrees Celsius right now.”
Ms Stroeve says her team still predicts there to be sea ice over winter.
“We still expect temperatures to get cold enough in winter for the ocean to refreeze, and even when you look at your climate models and you show the extreme predictions of different scenarios of greenhouse gas at the end of the century, none of them show the winter ice cover disappearing,” she said.
“They still show that winter ice cover will be there – it’s the summer ice cover that most of the models – actually all of the models – predict is going to disappear at some point as we continue to increase atmospheric concentrations of greenhouse gases.”
Ice decline
Ms Stroeve says the recent ice decline is disturbing as the Arctic is now losing a lot of older, thicker ice.
She says that in the 1980s there was a lot of ice which was about 10 years old, but now none of that ice remains.
“There’s definitely a shift in the distribution of the ice in the Arctic and how thick that ice is,” she said.
“I think that’s the key behind why we’re continually seeing these kind of dramatic, weird years.
“You keep getting close to these record low years because it doesn’t seem to matter what the summer circulation pattern does any more, if the ice is really thin it’s going to melt out during summer regardless.”
Ms Stroeve says during the 1980s, the average ice thickness in the Arctic basin was about three metres, but today the thickness is closer to one metre.
“It seems like we’re starting to move towards this transition of a seasonally ice-free Arctic state,” she said.
