ENTER: Opening further Doorways to Doom

Until now, the Arctic has been protected from overheating in a number of ways.

Negative Arctic Oscillation conditions are associated with

higher pressure in the Arctic and a weakened polar vortex

(yellow arrows). A weakened jet stream (black arrows) is

characterized by larger-amplitude meanders in its trajectory

and a reduction in the wave speed of those meanders.

Credit: Cornell University, C. Greene & B. Monger, 2012

Snow and ice that grows in winter will act as a buffer when temperatures rise in summer. A bright snow and ice cover will reflect most sunlight back into space. Furthermore, a lot of the sunlight that isn't reflected will be consumed by the process of turning snow and ice into water, which occurs while temperatures remain at the melting point of 0°C (32°F, 273.15 K).

The Arctic is further protected from overheating by the polar vortex and jet stream, which act to keep cold air in the Arctic and keep warm air out. However, accelerated warming in the Arctic is now causing the polar vortex and jet stream to weaken.

Accelerated warming in the Arctic alters the polar jet stream by slowing its speed and by increasing its waviness. Larger swings in the jet stream allow frigid air from the Arctic to plunge farther south, as well as warm, moist tropical air to penetrate northward, explains Jennifer Francis, research
professor at the Institute of Marine and Coastal
Sciences at Rutgers University.

The polar jet stream can travel at speeds greater than 100 mph. Here, the fastest winds are colored red;

slower winds are blue. View animated version here. Credit: NASA/Goddard Space Flight Center

What is described above can be regarded as an "open doors feedback". It's like leaving the doors open when it's cold inside and hot outside.

Accelerated warming in the Arctic comes with many such feedbacks, e.g. higher temperatures and more open water in the Arctic can also be expected to increase the danger that storms will batter the sea ice with greater ferocity. This is depicted in the image below.

In many ways, this is opening the doorways to doom. The biggest danger is that temperature rises will cause Arctic methane stores to weaken, resulting in huge amounts of methane to be released, triggering warming that could escalate into runaway global warming.

The image below shows the sea surface temperature anomaly for August 27, 2012, by the National Oceanic and Atmospheric Administration (NOAA).