• Thawing permafrost will release carbon to the atmosphere that will have an appreciable additional effect on climate change, adding at least one quarter of a degree Celsius by the end of the century and perhaps nearly as much as one degree (about 1.5°F).

• The permafrost feedback response to our historic emissions, even in the absence of future human emissions, is likely to be self-sustaining and will cancel out future natural carbon sinks in the oceans and biosphere over the next two centuries.

• Unfortunately, there are several good reasons to consider the outlook in this study as rosy — as the authors themselves make clear. However, as bad and inevitable as they are, feedbacks from the permafrost are just the (de-)frosting on the fossil fuel cake that we are busy baking. It is still up to us to influence how severe climate change is going to be.

by Andy Skuce, via Skeptical Science

Many papers have looked at the expected contribution of thawing permafrost to climate change. For example, Schaeffer et al. (2011) and Schuur and Abbott (2011) have both published estimates of the effect that the thawing and decomposition of organic matter in Arctic soils will have on future climates. Aspects that these studies neglected were the feedback that the permafrost carbon release would have on causing further permafrost degradation and the varying response that the carbon release would have on the climate in different emission scenarios and for a range of climate sensitivities.

To explore this matter further, a recent paper in Nature Geoscience (paywalled) by Andrew MacDougall, Christopher Avis and Andrew Weaver couples together climate and carbon-cycle models. Using the University of Victoria Earth System Climate Model adapted to include a permafrost response module, the researchers calculated the contribution to climate warming of thawing permafrost over a range of varying parameters.

Figure 1. Taken from MacDougall et al. (2012) showing the additional warming induced by permafrost thawing for four diagnosed emissions pathways (DEP, see text below for explanation). The coloured areas are the ranges of likely additional temperature ranges and the black lines show the median responses. The uncertainty within each DEP run results from uncertainties in the density of carbon in the permafrost and the climate sensitivity (the temperature effect of a given rise in carbon dioxide concentration in the air). Figure with original caption here.

Emissions pathways

The four scenarios or diagnosed emissions pathways (DEP) were derived from the Representative Concentration Pathways (RCP) used for the upcoming Fifth Assessment Report of the IPCC. RCPs are not emissions scenarios but rather curves of atmospheric CO₂ concentration with time. The numbers 2.6, 4.5, 6.0 and 8.5, correspond to the radiative forcing in W/m² in 2100. For use in climate models the emissions scenarios have to be backed out of the RCPs to give the DEPs.

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by David Doniger, via NRDC’s Switchboard

John Hoffman, brilliant leader of the EPA team that saved the ozone layer, founder of the hugely successful Energy Star programs, and climate protection pioneer, passed away last week.  He was only 62 years old.

While the battle to curb the ozone-destroying chlorofluorocarbons had many heroes, in my mind John stood head and shoulders above all.  The best book about saving the ozone layer is Between Earth and Sky, by Seth Cagin and Philip Dray.  They introduce him this way:

Hoffman possessed an ideal background for an EPA official:  a master’s degree in systems modeling from MIT, which combined course work in engineering, business, and urban planning with sophisticated computer programming.

As a young EPA staffer in the early 1980s, John headed a small team focused on “strategic studies.”  This was early in the Reagan administration, before Anne Gorsuch and James Watt had been disgraced and dismissed.   It was not a hospitable time for thinking honestly about big environmental challenges.  But John had the courage to stay focused on things that would matter, and he undertook crucial studies of ozone depletion and global warming.

I met John in 1984.  I had just brought an NRDC lawsuit to compel EPA to take action on CFCs under the Clean Air Act.  Our suit was to force EPA to follow up on its 1980 finding that CFCs endanger the stratospheric ozone layer and, as a result, public health.  One day my phone rang and John introduced himself.  He rather brashly explained that if we pressed our legal rights for a court order forcing EPA to make an immediate decision on CFC limits, “you’ll get the wrong answer.”

I didn’t know it at the time, but John had already helped quash an internal EPA effort to revoke the 1980 science finding, which would have knocked the legs from under our lawsuit.  John confidently told me he needed two years to conduct a comprehensive new scientific assessment and to hold a series of domestic and international meetings designed to build a consensus for action among EPA’s senior appointees, other Reagan administration officials, and the governments of other nations.

His pitch struck me as both extraordinarily audacious and surprisingly dilatory.  Who was this guy with such a grandiose plan?  We had already waited years for action, and we had every reason to expect a forceful court-ordered deadline.  Now we were supposed to sit on our heels for another two years?

But on reflection, John’s proposition made sense.  We had a better chance of getting the right answer if we gave them the time.

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Opine away.

Big Oil Still Sneaking Around the Tax Code

By Chip Bok, the Cartoonist Group

For more on how Big Oil enriches shareholders at the expense of consumers by protecting unneeded tax breaks, see “Big 5 Oil Companies Going For The Gold.”