A key reason the Intergovernmental Panel on Climate Change keeps issuing instantly irrelevant reports is that it keeps ignoring the latest climate science. We have known for years that perhaps the single most important carbon-cycle feedback is the melting of the permafrost.
Yet a must-read new United Nations Environment Programme report, “Policy Implications of Warming Permafrost” reports this jaw-dropping news:
The effect of the permafrost carbon feedback on climate has not been included in the IPCC Assessment Reports. None of the climate projections in the IPCC Fourth Assessment Report include the permafrost carbon feedback (IPCC 2007). Participating modeling teams have completed their climate projections in support of the Fifth Assessment Report, but these projections do not include the permafrost carbon feedback. Consequently, the IPCC Fifth Assessment Report, due for release in stages between September 2013 and October 2014, will not include the potential effects of the permafrost carbon feedback on global climate.
Here’s why that is head-exploding.
Carbon emission (in billions of tons of carbon a year) from thawing permafrost [from Schaefer et al, 2011]
Back in 2005, before the IPCC’s Fourth Assessment, a major study (subs. req’d) led by NCAR climate researcher David Lawrence, found that virtually the entire top 11 feet of permafrost around the globe could disappear by the end of this century. Using the first “fully interactive climate system model” applied to study permafrost, the researchers found that if we tried to stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million.
That matters because the permafrost permamelt contains a staggering “1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which would be released as methane. Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 to 100 times as potent over 20 years!
A 2008 study by leading tundra experts, “Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss,” concluded:
We find that simulated western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than secular 21st century climate-change trends. The accelerated warming signal penetrates up to 1500 km inland….
Considering that 2012 saw a new record low in Arctic sea ice cover — and that Arctic ice loss is occurring many decades faster than climate models had projected — you would think that climate scientists would want to incorporate this accelerated warming and the related tundra melt in their models.
The literature, of course, has continued to refine estimates of permafrost loss from various emissions scenarios. The graph above comes from a study published in February 2011, “Amount and timing of permafrost carbon release in response to climate warming,” which concluded soberly:
The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate…. [Our] estimate may be low because it does not account for amplified surface warming due to the PCF itself….
We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration.
Then last December we had the “Nature Bombshell: Climate Experts Warn Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation!”
And just this October, we had yet another study, which found “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F — 1.5°F To Total Global Warming By 2100.”
Finally, we have the excellent new UNEP report.
It is absurd that IPCC models would continue to ignore this most crucial of carbon cycle feedbacks. As I asked nearly 3 years ago, “The IPCC lowballs likely impacts with its instantly out-of-date reports and is clearly clueless on messaging — should it be booted or just rebooted?”