Permafrost feedback update 2015: is it good or bad news?

This article was originally posted at Skeptical Science on April 20th, 2015

We have good reason to be concerned about the potential for nasty climate feedbacks from thawing permafrost in the Arctic. Consider:

  • The Arctic contains huge stores of plant matter in its frozen soils. Over one-third of all the carbon stored in all of the soils of the Earth are found in this region, which hosts just 15% of the planet’s soil-covered area.
  • The Arctic is warming at twice the rate of the rest of the planet. The vegetable matter in the soils is being taken out of the northern freezer and placed on the global kitchen counter to decompose. Microbes will take full advantage of this exceptional dining opportunity and will convert part of these plant remains into carbon dioxide and methane.
  • These gases will add to the already enhanced greenhouse effect that caused the Arctic warming, providing a further boost to warming. There’s plenty of scope for these emissions to cause significant climatic mischief: the amount of carbon in the permafrost is double the amount currently in the air.

But exactly how bad will it be, and how quickly will it cause problems for us? Does the latest research bring good news or bad?

Ted Schuur and sixteen other permafrost experts have just published a review paper inNature: Climate change and the permafrost feedback (paywalled). This long and authoritative article (7 pages of text, plus 97 references) provides a state-of-the-art update on the expected response of permafrost thawing to man-made climate change. Much of the work reported on in this paper has been published since the 2013 IPCC AR5 report. It covers new observations of permafrost thickness and carbon content, along with laboratory experiments on permafrost decomposition and the results of several modelling exercises.

The overall conclusion is that, although the permafrost feedback is unlikely to cause abrupt climate change in the near future, the feedback is going to make climate change worse over the second half of this century and beyond. The emissions quantities are still uncertain, but the central estimate would be like adding an additional country with the unmitigated emissions the current size of the United States’ for at least the rest of the century. This will not cause a climate catastrophe by itself, but it will make preventing dangerous climate change that much more difficult. As if it wasn’t hard enough already.


There’s a lot of information in this paper and, rather than attempt to describe it all in long form, I’ll try to capture the main findings in bullet points.

  • The top three metres of permafrost contain about 1035 PgC (billion tonnes of carbon). This is similar to previous estimates, but is now supported by ten times as many observations below the top 1 m depth. Very roughly, the deepest deposits richest in carbon are near the Russian, Alaskan and Canadian Arctic coasts, with the poorest in mountainous regions and in areas close to glaciers and the Greenland ice sheet.

perm4The carbon content in the top three metres of permafrost soils. From Hugelius et al (2013).

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Skeptical Science is running a MOOC

The volunteers at Skeptical Science, along with staff at the University of Queensland, have been busy over the past several months putting together a Massive Open Online Course (MOOC) on climate change. The course, Making Sense of Climate Science Denial, starts on April 28th and is free to anyone who wants to participate. It will last for seven weeks and will require an hour or two of attention every week.

The University of Queensland has a press release.

Thousands of people have already signed up, but we are hoping for many more. Learning will not just come from watching the many short video lectures we have prepared, but from discussions with fellow students. So, no matter what your level of knowledge, or  your point of view on man-made climate change might be, please join us. I’m looking forward to learning from this course, too.

All anyone needs is an Internet connection, a desire to learn and share your knowledge, and an ability to understand English spoken in American, British, Canadian and Australian accents.

Watch the trailer:

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The history of emissions and the Great Acceleration

One of my pastimes is downloading data and playing around with it on Excel. I’m not kidding myself that doing this means anything in terms of original research, but I do find that I learn quite a lot about the particularities of the data and about the science in general by doing some simple calculations and graphing the numbers. There’s even occasionally a small feeling of discovery, a bit like the kind that you experience when you follow a well-trodden path in the mountains for the first time:

We were not pioneers ourselves, but we journeyed over old trails that were new to us, and with hearts open. Who shall distinguish? J. Monroe Thorington

Anyway, I downloaded some historical emissions data from the CDIAC site and played around with it. To repeat, there’s nothing new to science here, but there were a few things that I found that were new to me. First, let’s look at historical emissions of CO2 from man-made sources from 1850 to 2010. Note that for all of these graphs there are no data shown for 2011-2015.

What immediately struck me—something I hadn’t fully appreciated before—was how small oil consumption was before 1950. Both world wars were carried out without huge increases in oil use, despite the massive mobilizations of armies, navies and air forces. You can make out some downward blips in coal consumption for the Great Depression (~1930) and around the end of WW2 (~1945).

It wasn’t until after 1950 that fossil-fuel consumption went nuts. Some people have taken to calling this inflection point The Great Acceleration, there’s more on this later. Continue reading