In the long run, we're all dead
— John Maynard Keynes
Every once in a while somebody makes some doomerish comments about the risks of a huge outpouring of greenhouse gases from thawing permafrost in the Arctic. In the past I've tried to assuage these fears, mostly by emphasizing other, more realistic fears
In any case, I will try one more time to place this "positive feedback" in the Arctic in proper perspective. Justin Gillis at the Green Blog takes the subject on in Grappling With the Permafrost Problem.
As I reported last year, one of the most worrisome potential feedbacks involves the permafrost that underlies a quarter of the Northern Hemisphere. Buried in that frozen ground is a lot of ancient organic material, containing twice as much carbon as now exists in the atmosphere. The permafrost is starting to warm and the carbon to escape.
A new report, released Tuesday morning by the United Nations Environment Program, warns that scientists do not have a sufficient handle on the situation. It calls for new monitoring efforts and for a formal assessment of the permafrost feedback by the Intergovernmental Panel on Climate Change, the U.N. body that periodically reviews and summarizes climate science.
The report will be considered in the next few days at a climate negotiating session in Doha, Qatar. If current estimates about the potential for carbon release from permafrost are correct, they mean that tackling climate change is going to be even harder than it once seemed. That is because the long-running global negotiations over emission limits do not take much account of the potentially large carbon release from permafrost.
In essence, the permafrost feedback is a big new emissions source that makes the math of controlling climate change harder than ever.
The new report is available here.
I looked at the UNEP report, and here's the key text, which appears on page iv of the introduction.
Carbon dioxide (CO2) and methane emissions from thawing permafrost could amplify warming due to anthropogenic greenhouse gas emissions. This amplification is called the permafrost carbon feedback. Permafrost contains ~1700 gigatonnes (Gt) of carbon in the form of frozen organic matter, almost twice as much carbon as currently in the atmosphere.
If the permafrost thaws, the organic matter will thaw and decay, potentially releasing large amounts of CO2 and methane into the atmosphere. This organic material was buried and frozen thousands of years ago and its release into the atmosphere is irreversible on human time scales.
Thawing permafrost could emit 43 to 135 Gt of CO2 equivalent by 2100 and 246 to 415 Gt of CO2 equivalent by 2200.
Uncertainties are large, but emissions from thawing permafrost could start within the next few decades and continue for several centuries, influencing both short-term climate (before 2100) and long-term climate (after 2100).
Uncertainties are large because of the large range in the numbers given above. Anthropogenic CO2 emissions set a new record in 2011, and are expected to rise in 2012.
Global carbon dioxide (CO2) emissions are set to rise again in 2012, reaching a record high of 35.6 billion tonnes — according to new figures from the Global Carbon Project, co-led by researchers from the Tyndall Centre for Climate Change Research at the University of East Anglia (UEA).
[My note: 2011 global emissions were 34.7 billion metric tons (gigatons, Gt) ]
Let us compare annual anthropogenic emissions with emissions expected from thawing permafrost.
- 2011 human-caused emissions — 34.7 gigatons of CO2
- total emissions from thawing permafrost by 2100 (est) — 43 to 135 gigatons (CO2-equivalent)
- total emissions from thawing permafrost by 2200 (est) — 246 to 415 gigatons (CO2-equivalent)
At currrent emission rates, and according to our best scientific estimates—
- By the year 2100, total emissions from thawing permafrost will be approximately equivalent to 3.5 years of annual emissions now (at the high end)
- By the year 2200, total emissions from thawing permafrost will be approximately equivalent to 11 years of annual emissions now (at the high end)
And I think we can also agree that 3.5 years of annual emissions (at the 2011 rate) by the year 2100 is not really a serious problem considering just how much catastrophic shit is likely to occur between now and then.
Remember, the people who make these estimates (UNEP in this case) routinely assume that uncertainties in emissions from thawing permafrost by 2100 (or 2200) are very important because they also assume that "normal human life" will be ongoing at those future dates, perhaps with a few minor inconveniences (e.g. there won't be any fossil fuels left). This is a key point, and the source of most of the doomerish confusion about positive feedbacks.
But hang on, Dave! you might say — couldn't some super-duper non-linear event cause a sudden spike of temperatures in the Arctic which could cause the sudden release of many of those 1700 gigatons of CO2? What about that, Dave?
So, who cares?