The Earth is approximately 1.1℃ warmer than it was at the start of the industrial revolution. That warming has not been uniform, with some regions warming at a far greater pace. One such region is the Arctic.
A new study shows that the Arctic has warmed nearly four times faster than the rest of the world over the past 43 years. This means the Arctic is on average around 3℃ warmer than it was in 1980.
This is alarming, because the Arctic contains sensitive and delicately balanced climate components that, if pushed too hard, will respond with global consequences.
Why is the Arctic warming so much faster?
A large part of the explanation relates to sea ice. This is a thin layer (typically one metre to five metres thick) of sea water that freezes in winter and partially melts in the summer.
The sea ice is covered in a bright layer of snow which reflects around 85% of incoming solar radiation back out to space. The opposite occurs in the open ocean. As the darkest natural surface on the planet, the ocean absorbs 90% of solar radiation.
When covered with sea ice, the Arctic Ocean acts like a large reflective blanket, reducing the absorption of solar radiation. As the sea ice melts, absorption rates increase, resulting in a positive feedback loop where the rapid pace of ocean warming further amplifies sea ice melt, contributing to even faster ocean warming.