Above diagram was part of a poster displayed at the 2011 AGU meeting in San Francisco by the Arctic Methane Emergency Group (AMEG). It was accompanied by the following text: In the Arctic, three problems are compounding one another: emissions causing global warming, sea ice loss causing accelerated warming, and methane releases further accelerating Arctic warming, with the danger of triggering runaway global warming.
The diagram pictures three kinds of warming and their main causes:
- Emissions by people causing global warming, with temperatures rising around the globe, including the Arctic.
- Soot, dust and volatile organic compounds settling down on snow and ice, causing albedo change. More heat is absorbed, rather than reflected as was previously the case. This causes accelerated warming in the Arctic.
- Accelerated warming in the Arctic threatening to weaken methane stores in the Arctic with the danger that methane releases will trigger runaway global warming.
The diagram also pictures two feedback effects that make things even worse:
Albedo change in the Arctic comprises a number of elements, as depicted in the image below, from the 2004 report Impacts of a Warming Arctic - Arctic Climate Impact Assessment, by the International Arctic Science Committee.
As described in various posts at this blog over time, there are further points that should be taken into account. Regarding sea ice loss, it's clear that where sea ice retreats, more open water appears, with the result that less sunlight is reflected back into space. Accelerated warming will also affect the integrity of the remaining sea ice, as well as of the snow and ice cover on land, including glaciers. This further adds to the albedo effect, causing less sunlight to be reflected back into space. Similarly, further feedbacks could be added or described in more detail.
Accordingly, ten feedbacks can be identified, and described as follows:
- Albedo feedback: Accelerated warming in the Arctic speeds up the decline of ice and snow cover, further accelerating albedo change.
- Methane feedback: Methane releases in the Arctic further add to the acceleration of warming in the Arctic, further contributing to weaken Arctic methane stores and increasing the danger that methane releases will trigger runaway global warming.
- Currents feedback: Sea ice loss can cause vertical sea currents to weaken, reducing the cooling effect they had on the seabed. This can thus further cause sediments to warm up that can contain huge amounts of methane in the form of free gas and hydrates.
- Storms feedback: Increased frequency and intensity of storms can cause substantially more vertical mixing of the sea water column, causing more warming of the seabed, thus further contributing to the warming of sediments, as above.
- Storms feedback: Accelerated warming in the Arctic can result in more storms, causing mixing of cold Arctic air with warmer air from outside the Arctic. The net result is a warmer Arctic.
- Storms feedback: More open waters can result in more storms that can push the ice across the Arctic Ocean, and possibly all the way out of the Arctic Ocean.
- Storms feedback: Storms also cause more waves that break up the sea ice. Smaller pieces of ice melt quicker than large pieces. A large flat and solid layer of ice is also less susceptible to wind than many lighter and smaller pieces of ice that will stand out above the water and capture the wind like the sails of yachts.
- Storms feedback: Storms cause waters to become more wavy. Calm waters can reflect much sunlight back into space, acting as a mirror, especially when the sun shines under a low angle. Wavy waters, on the other hand, absorb more sunlight.
- Fires feedback: More extreme weather comes with heatwaves and storms. Thus, this is in part another storms feedback. The combination of storms and fires can be deadly. Heatwaves can spark fires that, when fueled up by storms, turn into firestorms affecting huge areas and causing huge amounts of emissions. Storms can whip up particles that when deposited on ice, snow or the bare soil, can cause more sunlight to be absorbed.
- Open doors feedback: Accelerated warming in the Arctic causes the polar vortex and jet stream to weaken, causing more extreme weather and making it easier for warm air to enter the Arctic.
These ten feedback are depicted in the diagram below.