In this second instalment of Arctic Episodes, we talk about perhaps the largest single game-changing component of the Earth system, the sleeping giant of Climate Change -- Permafrost.
The Arctic is an isolated potpourri of untouched natural beauty and ecosystems. Despite its serenity, the white polar landscape is one of the coldest and harshest environments to live in. The fact that both simple and complex organisms thrive in its characteristic tundra climate is astonishing.
Over recent years, regrettably, climate scientists have been observing an unprecedented anomaly in the Arctic region which might disrupt the region’s ecology and the global climate as a whole.
With 9 of the 10 hottest years on record being after the year 2000, the tipping point in Climate Change may be upon us; potential effects of global warming which themselves contribute to further warming have started to emerge, forming self-reinforcing (positive feedback) loops and accelerating Climate Change.
The first observable trend of such a feedback loop was covered in the previous Arctic Episode – the melting of Arctic sea ice. As we described, the disappearing sea ice has become both an effect and a cause of Climate Change. In this second Arctic Episode, we will discuss how thawing permafrost is increasingly becoming a major contributor to the same cause-effect-cause cycle of Climate Change and discuss its regional and global impacts.
First Things First, What is Permafrost?
About a quarter of the Northern Hemisphere and a staggering 17% of Earth’s entire exposed land surface is comprised of Permafrost or permanently frozen ground, which is nothing but land that has been frozen at or below 0°C for two or more consecutive years.
Composed of rock, sediments, soil and varying degrees of ice, permafrost is mainly found at the poles covering parts of Greenland, Alaska, Northern Canada, Siberia and Scandinavia. Additionally, it is also found at high-altitude areas such as the Rocky Mountains and the Tibetan Plateau and at the bottom of the ocean floor mainly in the Arctic and the Antarctic.
Ranging from a few inches to several feet, the top layer of the soil rich in plant and animal matter thaws each summer and refreezes during the winters. Called the Active Layer, this seasonally frozen layer packs organic matter which got buried in the snow a long time ago before it could be decomposed.
Recent observations have shown that the yearly phenomenon of seasonal thawing is being disrupted as the active layer is thawing for longer and getting deeper, due to Climate Change!
As permafrost thaws, microbes in the soil decompose the stored organic matter and release carbon dioxide when oxygen is present during decomposition. In the absence of oxygen, methane is released which is believed to be at least 80 times more potent on a decadal timescale than carbon dioxide. As a result of increasing temperatures in the Arctic, previously untapped carbon is now getting released to the atmosphere raising the concentration of greenhouse gases.
Furthermore, when the meltwater from the thawing permafrost makes its way to the surface, ponds of water are formed which are called thermokarst lakes, sometimes so big that they can be seen from space! The water collected in these lakes can heat up significantly in a short period of time and keep the land underneath warmer for longer which deepens the thaw. In some cases, an abrupt thaw from thermokarst lake formation could be several metres deep!
The release of greenhouse gases from the thawing permafrost will only lead to further warming which, in turn, will cause more thawing and trigger an irreversible self-reinforcing feedback loop that may cause runaway Climate Change.
The Tipping Point: Net Sink to Net Source
Historically, the Arctic region has been a carbon sink rather than a carbon source. The summer months in the Arctic are traditionally growing seasons as the warmer temperatures coupled with the atmospheric carbon act as a catalyst for the growth of plants and vegetation.
Although, in principle, a warmer Arctic would support more vegetation and in turn, more carbon dioxide will be captured from the atmosphere due to photosynthesis. The amount of carbon released from the thawing of the permafrost would far outweigh the amount captured by plants. In fact, this new growth is projected to offset only about 20 percent of the permafrost carbon release.
Climate scientists believe that if the current rise in global temperatures remains unabated, the Arctic could soon transition from a net carbon sink to a net source. Such an occurrence would be irreversible and a major climate tipping point.
It is due to this reason that prominent economists like Dr. Gail Whiteman, a Cambridge researcher and the Founder of the Arctic Basecamp at Davos, have called permafrost thawing as an ‘invisible time-bomb’ since permafrost happens to be the largest carbon reservoir in the world!
Tantamount to twice the carbon currently present in the atmosphere, a staggering 1700 billion tons of carbon is estimated to be locked-in in Permafrost! Truly, this is one Pandora’s box we do not want to open.
Evidence and Impacts
The Arctic has been warming at a rate that is at least twice as fast as the global average. In 2016, the average surface temperature in the Arctic was 3.5˚C warmer than at the start of the 20th century. That year, permafrost temperatures in the Arctic were the warmest ever recorded.
As a result, the circumpolar region has constantly been losing its snow cover year after year. A recent study based on observational trends, projects that every 1˚C increase in temperature would lead to thawing of approximately 1.5 million square miles of permafrost which is larger than the size of India.
Studies predict that if all the world’s permafrost ceases to exist, it could lead to an increase in global average temperatures by as much as 1.7°C by the year 2300. According to recent estimates, economic impact of such an event would be huge, thawing of this nature could lead to ~$60 trillion in damage. To put this in context, the size of the entire global economy in 2012 was about $70 trillion.
Ever since the Paris Agreement, the world is moving to put in place efforts and policies to limit the global warming trend since pre-industrial levels to well within 2˚C (aiming to eventually reach 1.5˚C) in order to avoid the most devastating effects of climate change. It is not hard to imagine that a 1.7˚C rise from a single source would have serious ramifications for the international effort to keep warming below 2˚C.
Single source carbon emissions of such enormous scale come at a significant cost not just to the global climate, but to Arctic infrastructure and human health as well.
Whole towns and cities are built on top of permafrost which was considered permanently frozen. But as the ground is softening, the infrastructure for an estimated 35 million people is literally falling apart! Alaska (USA) alone is staring at an estimated $5.5 billion in permafrost related damages by the end of this century.
Effects of permafrost thaw on houses in interior Alaska (2001, top left), roads in eastern Alaska (1982, top right), and the estimated costs (with and without climate change) of replacing public infrastructure in Alaska, assuming a mid-range emissions scenario (A1B, with some decrease from current emissions growth trends).
Unfortunately, our problems don’t end there.
Scientists believe that thawing of permafrost brings with it a heightened risk of potential diseases. Old forms of diseases which had once been eradicated have been found in the dead remains recovered from the permafrost zones. This threat became very real after an Anthrax outbreak occurred in 2016 when a reindeer carcass carrying the bacteria was discovered in Russia. We could potentially see future outbreaks from Zombie Pathogens of ancient diseases like Smallpox and Spanish Flu as well but the extent of the threat is not yet certain.
Furthermore, according to the National Resources Defence Council (NRDC), a non-profit international environmental advocacy group, based in the United States:
We have to understand that things in the Arctic are changing fast and what happens in the Arctic doesn't stay in the Arctic!
If countries meet the goals laid out in the Paris Agreement and get on a more sustainable course, permafrost should stay frozen. Enough alarm bells have been raised by climatologists. For instance, William Colgan, a Senior Researcher at the Geological Survey of Denmark and Greenland, in Copenhagen, believes that if we don't do anything the toxic wastes will likely begin to melt out of the permafrost, irreversibly, within 75 years. While we have not reached the tipping point yet, political apathy might soon bring the world to the brink of such a catastrophe.
Considering the first two feedback loops that we have covered in the Arctic Episodes series so far, it is clear that as the global thermometer rises, the Albedo reduction feedback and permafrost thawing could soon put climate change into high-gear. In the next part of the series, we talk about another crucial component of this cause-effect-cause cycle -- the melting of Greenland.
References and Further Reading:
1. Tarnocai, C., Canadell, J. G., Schuur, E. A. G., Kuhry, P., Mazhitova, G., and Zimov, S.; Soil organic carbon pools in the northern circumpolar permafrost region, Global Biogeochemical Cycles, 23 , 2009.
2. McGuire, A. D., Anderson, L. G., Christensen, T. R., Dallimore, S., Guo, L., Hayes, D. J., Heimann, M., Lorenson, T. D., Macdonald, R. W., and Roulet, N.; Sensitivity of the carbon cycle in the Arctic to climate change, Ecological Monographs, 2009.
3. MacDougall, A. H., Avis, C. A., and Weaver, A. J.; Significant contribution to climate warming from the permafrost carbon feedback, Nature Geoscience, 5, pp. 719–721, 2012.
4. Chadburn, S. E., Burke, E. J., Cox, P. M., Friedlingstein, R., Hugelius, G., and Westermann, S.; An observation-based constraint on permafrost loss as a function of global warming, Nature Climate Change, 7, pp. 340–344, 2017.
5. Anthony, K. W., Deimling, T. S. von, Nitze, T., Frolking, S., Emond, A., Daanen, R., Anthony, P., Lindgren, A., Jones, B., and Grosse, G.; 21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes, Nature Communications, 9, 2018.
6. Global Climate Report – Annual 2017. NOAA. Retrieved 18 January 2018.
7. US NOAA Arctic Report Card 2018.
8. Permafrost: Everything you need to know. NRDC.
9. Schuster, P. F., et. al.; Permafrost Stores a Globally Significant Amount of Mercury, Geophys. Res. Lett., 45, pp. 1463-1471, 2018.
10. Huge permafrost thaw can be limited by ambitious climate targets. University of Leeds.
11. As Earth warms, the diseases that may lie within permafrost become a bigger worry. Scientific American.
12. Coastal erosion in the Arctic intensifies global warming: Sea level rise in the past led to the release of greenhouse gases from permafrost.
13. Whiteman, G., Hope, C., and Wadhams, P.; Climate science: Vast costs of Arctic change, Nature, 499, 2013.
14. Cost of Arctic methane release could be 'size of global economy', experts warn.
15. James Hansen: Fossil fuel addiction could trigger runaway global warming. The Guardian.
16. Arctic permafrost may thaw faster than expected. National Geographic.
17. Thawing permafrost matters.
18. Arctic meltdown: We're already feeling the consequences of thawing permafrost. Discover Magazine.
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