© NASA / Goddard Space Flight Center Scientific Visualization Studio
On Sunday, the Arctic sea ice hit its lowest extent since consistent satellite records began three decades ago. And it is predicted to continue to shrink towards the end of September, according to NASA.
At 1.58 million square miles, it was 27,000 square miles below the 2007 record low, despite 2007 being a warmer Arctic summer. NASA are attributing the record low to the persistent loss of multi-year sea ice. Single year summer sea ice is thinner and therefore more vulnerable to rising temperatures and break-up during storms.
I asked Professor Jeremy Wilkinson, Head of the Sea Ice Unit at the Scottish Association of Marine Science, about the prediction that the Arctic Ocean could be virtually free of summer sea ice within a generation. Jeremy is one of the most experienced observational sea ice physicists in Europe.
"September is traditionally the month where the extent of Arctic sea ice is at its minimum. As Autumn approaches the air cools, the seawater freezes and sea ice once again begins to extend over the Arctic Ocean. This cycle has been occurring for millennia. However the timing of this cycle is changing, sea ice is melting faster during the summer months and forming later in the Autumn. To put simply, less sea-ice cover means that the Arctic Ocean will reflect less heat back from the sun. Open water is darker than ice, so more heat is absorbed and therefore it takes longer for this heat to be removed and the sea ice to form again. The late formation and early melt leads to a thinner sea ice cover that is more susceptible to melt. And so this 'positive feedback' process continues...
"In reality the evolution of Arctic sea ice is very complex. It is a multifaceted interplay between the ocean, the ice itself and the atmosphere, with potentially strong feedbacks between them. What is particularly disturbing is that climate models now predict that the Arctic could be virtually free of summer sea-ice within a generation, a worrying prospect indeed."
For Arctic peoples, the shrinking ice cover has already made some traditional sea-ice travel routes more treacherous, and has led to increased erosion threatening coastal villages. A week ago in Grise Fiord, Canada's northernmost community, local people were astonished to see an ice-free horizon.
Ice loss has also been shown to have negative effects on Arctic wildlife. For example, sea-ice is critical to the success of polar bears. It is their hunting platform, in particular for ringed and bearded seals.
In the southern range of polar bears, the shorter sea ice season has decreased the amount of time bears can hunt. Sea ice break-up keeps these bears on shore. This forces them to spend the summer without significant feeding, relying on their fat stores from the previous summer to survive.
In 2006, WWF took David Cameron and Greg Barker (now energy and climate change minister) up to Svalbard in the Arctic to witness first-hand the effects of a warming climate; subsequently Mr Cameron pledged that his government would be the 'greenest government ever'.
Two years on, the prime minister must stick by his pledge - and make sure we play our part in reducing carbon emissions. The Arctic sea ice isn't waiting, and nor must we.
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