Northeastern Siberia is home to many of Russia's "thaw lakes." These lakes can release large stores of methane as global warming melts the frozen ground beneath them (known as yedoma). As shown in the photo above, this methane can rise to the surface of these lakes and is highly flammable.1
Studies show that thaw lakes in northeastern Siberia are a large source of methane—a potent heat-trapping gas. If global warming expands the lakes, methane emissions are likely to rise—further accelerating climate change.2
Siberia is a vast Eurasian region that is part of the Russian Federation. Its 5 million square miles (13 million square kilometers) account for some 77 percent of the federation's total area, and 10 percent of Earth's land area.11,12 Though most of the land in Siberia is taigathat is, boreal forest—the northernmost fringe is tundra.11 The latter refers to land at higher latitudes that is permanently frozen (permafrost) and mostly treeless.11,12
During just the past half-century, annual air temperatures in Siberia rose 3.6-5.4° F (2-3° C), and winter temperatures increased at about double that rate.3,4 Even if we reduce our heat-trapping emissions, Siberia could warm by another 5.4-9° F (3-5° C) by the end of the century —and 5.4-12.6° F (3-7° C) in winter.3,4
North Siberia, on the border of the Laptev Sea, near the Arctic Ocean, is home to many thaw lakes, known as thermokarst.2 These relatively shallow bodies of water usually form when permafrost thaws and the ground collapses, creating a depression.2,3 The vast majority of lakes in Russia's permafrost zones are thaw lakes.2 And, unlike lakes in lower latitudes, most of those are underlain with yedoma, which contains some 500 billion metric tonnes (500 petagrams) of carbon. 2,3,5,6,7,8 Yedoma is typically 2-5 percent carbon—some 10-30 times the portion usually found in deep, non-permafrost mineral soils.7
Satellite images show that the total lake area expanded by some 12 percent from 1973 to 1998 in Siberia's continuous permafrost zones (regions where permafrost occurs throughout), and that the number of lakes rose by 4 percent.3,4 Around that same time, the region experienced about a 58 percent increase in methane emissions as a result of melting permafrost associated with lake expansion.2
Recent research shows that these thaw lakes emit on average 3.8 million metric tonnes (3.8 teragrams) of methane each year. That amount represents an increase of 10-63 percent over earlier estimates of methane emissions from northern wetlands.2 Methane emissions can fluctuate greatly because thawing yedoma is such a wild card.
Part of a Larger Pattern
Permafrost is particularly sensitive to changes in air temperature, making it especially vulnerable to climate change.13 Degrading permafrost has significant implications for global warming, because it releases heat-trapping gases that have been stored in soil—often for thousands of years.13
Thawing permafrost can release carbon dioxide and methane, depending on moisture conditions and whether the permafrost has contact with air.13,14,15 Scientists think permafrost degradation causes a thickening of the active layer that thaws in the summer and freezes in the winter, spurring the release of methane and carbon dioxide.
Methane is some 25 times more effective in trapping heat in the atmosphere than carbon dioxide over a hundred-year period.17 Even though methane remains in the atmosphere for only about 10 to 15 years, it converts to carbon dioxide, which can trap heat for a very long time. In fact, about 20 percent of the CO2 can linger for nearly a thousand years.17Though thaw lakes in northern Siberia emit both carbon dioxide and methane,16 estimating future emissions—and their impact on global warming—is difficult, because the lakes release most of these gases through ebullition (bubbling).2 That's why some scientists refer to these lakes as a "global warming wild card."2,8,17,18
What the Future Holds
Degradation of permafrost is likely to mean that thaw lakes temporarily expand.13 These lakes may then disappear as they drain into the permafrost—a phenomenon already observed in Siberia, especially in lower-latitude regions with discontinuous or isolated patches of permafrost.19 Erosion is expected to occur during this process, spurring further thawing of the yedoma, and accelerating the release of heat-trapping emissions.2,19
If Siberia's yedoma lakes were to thaw completely, they could release nearly 50 billion metric tonnes (50 petagrams) of methane into the atmosphere, catalyzing a huge amplified warming or feedback effect.2,8,19 Permafrost and western Siberian peat bogs in the Northern Hemisphere store some 950 billion metric tonnes (950 petagrams) of carbon—1.3 times the amount of carbon already in Earth's atmosphere.7
The fate of northeastern Siberia's yedoma lakes—and the methane frozen under them—depends on the choices we make today. Acting quickly to make deep cuts in our heat-trapping emissions will help safeguard the lakes against a complete thaw, thereby keeping carbon stored in the yedoma underneath.