Can we avoid the permafrost carbon tipping point?

Kevin M. Schaefer, National Snow and Ice Data Center, kevin.schaefer@nsidc.org (Presenter)
Tingjun Zhang, National Snow and Ice Data Center, tzhang@nsidc.org
Lori Bruhwiler, NOAA Earth System Research Laboratory, lori.bruhwiler@noaa.gov
Andrew Barrett, National Snow and Ice Data Center, apbarret@nsidc.org
Zhuxiao Li, National Snow and Ice Data Center, zhuxiao.li@nsidc.org

If we reduce fossil fuel emissions and slow the Arctic warming rate, can we delay or even avoid the permafrost carbon tipping point? Permafrost currently contains about 1466 Gt of carbon frozen during or since the last ice age. As permafrost thaws in the 21st century, this organic matter will thaw and decay, increasing atmospheric CO2 concentrations and amplifying the warming rate to create the Permafrost Carbon Feedback (PCF) on climate. The permafrost carbon tipping point occurs when the release of carbon from thawing permafrost overpowers enhanced uptake due to warmer temperatures, irreversibly changing the Arctic from a carbon sink to a source relative to the atmosphere and marking the start of the PCF. Like the burning of fossil fuels, the tipping point is irreversible: once the carbon thaws and decays into the atmosphere, there is no way to put it back into the permafrost. Projections using the Simple Biosphere/Carnegie-Ames-Stanford Approach (SiBCASA) model and the A1B IPCC scenario indicate that the PCF tipping point will occur between 2020 and 2030, with a total of 190±64 Gt of carbon released into the atmosphere by 2300. We ran a new series of model projections out to 2300 with fossil fuel emissions capped at various levels, each representing a different overall Arctic warming. We present the area of permafrost lost, the permafrost carbon tipping point, and total permafrost carbon flux as a function of Arctic temperature increase. We show the maximum allowed CO2 concentration and associated Arctic temperature increase before initiating the permafrost carbon feedback. If we cannot avoid the tipping point, then we estimate that Global treaties to reduce fossil fuel emissions should include a 15% allocation for permafrost carbon emissions or we will overshoot our target CO2 concentration and end up with a warmer climate than planned.

Presentation: 2011_Oct05_AM_Schaefer_346.ppt (176k)

Presentation Type:  Plenary Talk

Session:  Poster Speed Talks:

Presentation Time:  Wed 9:50 AM  (5 minutes)