Arctic Methane Emissions: The Economic Impact

Introduction

Fig. 1: The skeletal formula of methane. (Source: Wikimedia Commons)

Methane (CH₄) (see Fig. 1) is an important greenhouse gas that is second only to carbon dioxide (CO₂) among the anthropogenic (originating in human activity) gases. [1] Large quantities of methane are currently stored in the Arctic region. These Arctic sources of methane include: organic methane that becomes available as permafrost thaws, gas hydrate deposits (a solid, ice-like form of methane), tundra fires, and industrial gas leaks. [2] As the temperature of the planet rises, more and more of this previously trapped methane is expected to be released into the atmosphere. [2] A 1400 gigaton (Gt) reservoir of methane currently exists along the East Siberian Arctic Shelf with a 50 Gt release expected to occur either suddenly or steadily over a 50 year period. [3,4] The release of these large quantities of methane into the atmosphere will have a significant effect on the economic impacts of global warming.

Contribution to Global Warming

Methane is a far more powerful greenhouse gas when compared to CO₂. Over a 20 year time period, one pound of methane in the atmosphere traps as much heat as at least 72 pounds of CO₂. [5] The potency of methane decreases over time, but even over a 100 year time period, the gas is still at least 25 times more powerful than CO₂. [5] Warming Arctic temperatures and methane emission constitute a positive feedback loop, i.e. as temperatures rise, permafrost thaws and releases methane; methane gas contributes to global warming, causing rising temperatures. [1] If the current rate of temperature increase continues as it currently is, the permafrost in certain parts of Arctic Canada will have completely disappeared by the end of the century. [1] Furthermore, rising temperatures cause destabilization of underwater methane hydrates. Methane that does not reach the atmosphere and, instead, dissolves in the water is converted via microbial anaerobic oxidation into CO₂, causing ocean acidification. [6]

Economic Impacts

There is a large global price tag associated with the physical changes coming to the Arctic region (referring to the mitigation and adaptation measures necessary to deal with the changes). According to the PAGE09 model, without the release of methane, the net present value of global climate change impacts is estimated at $82 trillion. The methane release will add, at least, an extra $37 trillion - and only if an aggressive emission abatement policy is in place. [4,7] This number takes into account direct effects on gross domestic product, i.e. agricultural losses and cost of air conditioning, and impacts on human health and the environment. [7] This impact will be felt globally, but modeling shows that about 80% will be felt by poorer economies in Asia, Africa, and South America. [4] However, the PAGE09 model only considers the effects of extra greenhouse gas emission on temperature, sea level, health, and extreme weather risks. It does not, for example, consider ocean acidification, changes in ocean or atmospheric circulation, or impacts on human infrastructure. Therefore, the economic impact of methane gas emission is expected to be even greater. [4,7]

© Rachel Smith. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] I. S. A. Isaksen et al., "Strong Atmospheric Chemisry Feedback to Climate Warming From Arctic Methane Emissions," Global Biogeochem. Cy. 25, GB2002 (2011).

[2] R. E. Fisher et al., "Arctic Methane Sources: Isotopic Evidence for Atmospheric Inputs," Geophys. Res. Lett. 38, L21803 (2011).

[3] N. Shakhova et al., "Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf," Science 327, 1246 (2010).

[4] G. Whiteman, C. Hope, and P. Wadhams, "Vast Costs of Arctic Change," Nature 499, 401 (2013).

[5] A.R. Ingraffea, "Gangplank to a Warm Future," New York Times, 28 Jul 13.

[6] A. Biastoch et al., "Rising Arctic Ocean Temperatures Cause Gas Hydrate Destabilization and Ocean Acidification," Geophys. Res. Lett. 38, L08602 (2011).

[7] C. Hope and K. Schaefer, "Economic Impacts of Carbon Dioxide and Methane Released From Thawing Permafrost," Nature 6, 56 (2016).