There is a difference between abruptly thawing permafrost and gradual thawing permafrost – one poses a higher risk of accelerating climate change than the other. Abrupt permafrost thawing in the Arctic could double carbon emissions, a new study by scientists at the University of Colorado at Boulder finds. The research has been published in the journal Nature Geoscience.
The scientists analyzed the Earth’s polar north permafrost regions, where climate change has already dramatically altered the landscape. What is permafrost? It’s the permanently frozen layer of soil, deep underground, beneath the layers exposed to weathering that freeze and thaw based on the season. A quarter of all exposed land in the northern hemisphere contains permafrost. There are also permafrost regions in the Arctic.
The year-round frozen layer contains soil, rocks, and sometimes pockets of solid ice. When it melts, it can dramatically change what rests on it.
Dr. Merritt Turetsky, director of the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder, said that:
The fast and dramatic thawing in the Arctic is affecting landscapes in unprecedented ways. Forests can become lakes in the course of a month, landslides occur with no warning, and invisible methane seep holes can swallow snowmobiles whole. Systems that you could walk on with regular hiking boots and that were dry enough to support tree growth when frozen can thaw, and now all of a sudden these ecosystems turn into a soupy mess.
Permafrost stores two times as much carbon as is in the atmosphere. It is where once-flourishing Arctic life is now buried – everything from animals to dead plants and even microbes. This carbon-based matter never fully decomposed because it was preserved frozen, locked away beneath the reach of exposure for thousands of years.
Current estimates say the permafrost contains approximately 1,500 petagrams of carbon – which is about the equivalent of 1.5 trillion metric tons of carbon. The biggest problem we face with this is that 20% of the Arctic permafrost layer contains solid ice that is more susceptible to temperature changes. It thaws more efficiently than soil and rock and, therefore, more quickly as well.
To calculate the rate of emissions, the researchers distinguished gradual permafrost thaws from abrupt ones. Gradual thaws release carbon stores slowly over a long period, whereas abrupt thaws release it all at once.
Abrupt thaws are not only large emitters of carbon but also methane, an even more potent greenhouse gas. Less than 5% of Arctic permafrost will indeed be rapidly thawing at any given moment, however the emissions from it equal the emissions from all other areas gradually melting combined.
The new study’s results reveal an urgency to include permafrost-stored carbon in climate change models. Furthermore, seeing how abrupt permafrost thaw can dramatically change the ecology and speed up the rate of global warming, the researchers also urge the implementation of firm climate policy and mitigation.
Dr. Turetsky concludes on an encouraging note:
We can definitely stave off the worst consequences of climate change if we act in the next decade. We have clear evidence that policy is going to help the north and thus it’s going to help dictate our future climate.
Now, all we need to do is listen to the science and speed up our response accordingly!
