Climate change - the escalating risk of methane from the melting Arctic permafrost

Permafrost melt lake - Above Arctic Circle, Canada - Shutterstock

While much of the focus on limiting greenhouse gas emissions is rightly focussed on carbon dioxide, increasing attention is being paid to another an equally concerning threat - the increasing levels of methane gas being emitted from the melting permafrost found in the Arctic areas of the planet.

The need for monitoring of this evolving and increasing source of greenhouse gases and its potential impact could not be more stark not the least for the risk of a feedback loop. A feedback loop would occur where the planet commences a phase of unstoppable warming as greenhouse gases continue to increase global warming which in turn increased more greenhouse gas emissions which again increases global warming. This is a nightmare scenario.

The Arctic Circle and its permafrost is one such risk. The permafrost is melting and releasing increasing levels of methane, a very potent greenhouse gas.

In summary -

• Methane is a greenhouse gas with a potency around 20 times the warming power of carbon dioxide.
• Large quantities of methane is locked into the permafrost of the Arctic Circle. Permafrost measures around 23 million square kilometres of land surface comprising 85% of Alaska and near 50% of Canada and Russia.
• Permafrost originates from the Ice Ages when glaciers and ice sheets covered large tracks of the planet's surface. Over tens of thousands of years, rocks were ground into a form of substance called 'glacial flour'  by the ice with plants and animals becoming part of the mix in the permafrost layers. When the glaciers and ice sheets retreated, this semi frozen layer was left behind. Measurements of permafrost have found detected deposits up to 1,500 metres thick aand overall it is estimated that 1.7 trillion tonnes of carbon are trapped in them.
• Permafrost supports vast tracts of forests more than twice the size of the Amazon rainforest. These evergreen forests are effectively a carbon sink capturing more carbon from the atmosphere than is released by ther melting permafrost. This is now changing and some regions of forest are now releasing more carbon than they are absorbing.
• The actual source of greenhouse gases in the permafrost are frozen microbes that are entombed. As the permafrost melts the microbes begin to consume plant and animal remnants around them releasing greenhouse gases. Where the microbes are located in mainly dry territory with access to oxygen, they emit mainly carbon dioxide. However where they are in water with no oxygen, they emit methane. 

The evidence of increasing emissions is already available. In the Yenisey-Khatanga Basin in Siberia, temperatures in 2020 were 11 degrees Fahrenheit about average and limestone rock formations commenced releasing ancient methane deposits. 

The IPCC reports and models do not include permafrost methane emissions due to the uncertainty and difficulty of measuring this source of greenhouse gas. Yet this critical risk may yet upend most climate change projections.

Information for this post has been drawn from: Proceedings of the National Academy of Sciences in 2015; Nature.