I’ve long been a proponent of the carbon budget way of viewing our climate change predicament. By focusing on the total amount of CO2 (or CO2 equivalent other greenhouse gases) we can emit from this point forward, I think it greatly simplifies the “feeds and speeds” without introducing any inaccuracies or openings for misunderstanding. One problem that any calculation runs into, whether seeking our total remaining carbon budget or our yearly allotment as we try to reduce emissions enough (e.g. 80% over 1990 levels by 2050), is that we have to make some pretty large assumptions about the contribution of positive feedbacks. Those knock-on effects, such as the albedo flip from shrinking Arctic ice or drought converting the Amazon rain forest into desert, can throw your carefully crafted calculation into the nearest recycle bins faster than you can say, “permafrost isn’t permanent???”.

Permafrost, in fact, is at the center of a terrifying research finding that up to 30% of the Russian permafrost could be gone by 2050.

As Joe Romm points out in that linked article, the current estimate is that the world’s permafrost contains 1.5 trillion tons of carbon. (Please read that carefully. Trillion, not billion or mere million, and carbon, not CO2 or methane. This number is large enough that it should terrify any informed follower of climate issues.)

If you extend that prediction of permafrost loss in Russia to all northern hemisphere permafrost (as the UN did in 2009, that means we’re talking about liberating up to 30% of 1.5 trillion tons of carbon in the next 39 years.

Carbon itself isn’t a problem, it’s carbon in the form of methane (CH4) or carbon dioxide (CO2). When vegetation rots it can produce either, depending on whether the decomposition happens in the presence of oxygen (resulting in CO2) or below water (and you get CH4). But how much of each do you get? Joe mentions in passing a mix of half of each, and I was unable to find a reference, but I recall recently seeing a study that mentions a 20% CH4/80% CO2 ratio. (If anyone can find something more definitive, please let me know.) I’ll use that 20/80 mix in calculations below.

So, we have 450 billion tons of carbon (30% of 1.5 trillion tons).

90 billion tons (20% of 450) of carbon wind up in CH4, while the remaining 360 billion tons are turned into CO2.

90 billion tons of carbon yield 119 billion tons of CH4 (multiplying by 16/12, the ratio of the atomic weight of CH4 to the atomic weight of C).

360 billion tons of carbon yields 1,317 billion tons of CO2 (multiplying by 44/12).

But wait — CH4 is a much more powerful greenhouse gas than is CO2, by a factor of 25. So that 119 billion tons of CH4 has the warming effect (over a 100 year time frame) of 2,975 billion tons of CO2. Over 20 years, CH4 is 72 times more powerful than CO2, which gives us a CO2 equivalence of 8,568 billion tons.

So, over a 100-year span we have a total warming effect of 4,292 billion tons of CO2. Pro-rating that evenly over 39 years gives us 110 billion tons of CO2 per year. In 2010, worldwide man-made CO2 emissions were a paltry 30.6 billion tons, meaning the permafrost bomb would deliver the equivalent of about 3.6 times our current worldwide, yearly CO2 emissions.

Looking at the 20-year time span for assessing CH4′s impact, we get a total emission of 9,885 billion CO2 equivalent tons, or 253 billion tons/year, about 8.3 times our current emissions level.

Looking at just the “easy” case of the 100-year time span, in order to offset that defrosting permafrost, we’d have to cut worldwide CO2 emissions to zero, and then find a way to suck another 80 billion tons of CO2 out of the air and sequester it permanently (there’s that funny word again) every year, just to stay at the already far too high 2010 level. Anyone here have a workable plan for that donig that squirreled away on your hard drive?

If you think 30% is too high a percentage for the loss of permafrost, then rerun the numbers above using the lower bound mentioned in the original study that Joe quotes, 15%. We’re still left with a huge, decades-long surge in CO2 emissions.

If you don’t like my assumption about 20% of the carbon turning into methane (which could be low, obviously), let’s go to the limit and assume that it’s zero and miraculously every last carbon atom winds up in a CO2 molecule. That still leaves us with a total of 1,647 billion tons of CO2, about 42 billion tons/year, nearly 1.4 times our 2010 emissions rate.

Please note that this ignores any further “contribution” from the undersea methane hydrates or other feedbacks. It also ignores any aerosol whiplash effect from a crash program to shutdown coal plants, which we would surely do in such a scenario.

If you don’t like these calculations, show me yours. Show me how, without trying to overturn scientific findings or invoking a deus ex machina or resorting to blatant denialism we can possibly escape a climate catastrophe in the next few decades if we stay on our current path.

This scenario is a perfect example of why I’m convinced that not only are we in almost unimaginably deep trouble, but that virtually all attempts to talk about climate change without resorting to even the simple math I used above do more harm than good. You can search your thesaurus all day and not find the right words to describe the magnitude of the greenhouse gas flows or the implications of their knock on effects; sometimes nothing communicates better than a four-function calculator, Google, and a rudimentary understanding of the speeds and feeds.

Results like the one above are also why I’m more convinced than ever that we will have no choice but to employ several geohacking schemes to try to pull our environment back from the edge; we simply can’t cut emissions enough in the time we have left, under any reasonable scenario, to avoid it.

 

Photo by NOAA.