In a follow up to our May 28, 2018 post, How old is Arctic Ice?, the Washington Post has an article, The Arctic Ocean has lost 95 percent of its oldest ice — a startling sign of what’s to come by Chris Mooney (12/11/18). It notes:
In 1985, the new NOAA report found, 16 percent of the Arctic was covered by the very oldest ice, more than four years old, at the height of winter. But by March, that number had dropped to under 1 percent. That’s a 95 percent decline.
At the same time, the youngest, first-year ice has gone from 55 percent of the pack in the 1980s to 77 percent, the report finds. (The remainder is ice that is two to three years old.)
The loss of sea ice creates a feedback loop:
There is a well-known feedback loop in the Arctic, caused by the reflectivity of ice and the darkness of the ocean. When the Arctic Ocean is covered by lighter, white ice, it reflects more sunlight back to space. But when there is less ice, more heat gets absorbed by the darker ocean — warming the planet further. That warmer ocean then inhibits the growth of future ice, which is why the process feeds upon itself.
Because of this, Arctic sea ice loss has already increased the warming of the planet as a whole. Ramanathan said the impact is equivalent to the warming effect of 250 billion tons of carbon dioxide emissions, or about six years of global emissions.
Ramanathan fears that entirely ice-free summers, if they began to occur regularly, could add another half- degree Celsius (0.9 degrees Fahrenheit) of warming on top of whatever else the planet has experienced by that time.
The Washington Post article has a few nice animated graphics. The graph and map here is from the sea ice sections of the Arctic Report Card: Update for 2018 – Effects of persistent Arctic warming continue to mount from NOAA. The Arctic Report card contains a half dozen charts and graphs including one that compares March and September sea ice extent. A data and project for this is in our Statistics Project page.