Large potential future methane emissions from Arctic permafrost Ivar S.A. Isaksen CICERO

CH 4 +OH → CH 3 + H 2 O Global increase in NOx, CO and methane tend to increase tropospheric ozone Increases in tropospheric ozone will increase OH through the reaction: HO 2 +O 3 → OH + 2O 2

Methane emission Indirect effect: Increases its own lifetime through the reaction with the hydroxyl radical (OH) Current feedback factor: Approx. 0.4 Important chemical reactions: Produces ozone in the UTLS region Produces water vapour in the stratosphere Produces CO2 in the atmosphere Global methane emission: Total current GWP due to methane release: Approx. 25 Increases with large methane emission increases in the Arctic

Oslo CTM3 – testing large CH4 emissions Hydrate emissions from Siberian shelf 1000Tg(CH4)/year Emitted during Jun-Nov Emission period: 10 years Simulating additional 15 years of normal emissions

Changes in atmospheric methane burden for 10 years of 1000 Tg/year emission in 10 years The burden increases from 4800 Tg to 12.0 Tg It is reduced to 7.2 Tg after 15 years of no extra emission

Change in average atmospheric methane lifetime for a 1000 Tg /year methane emission from the Arctic over 100 years Average background atmospheric methane lifetime: 8.6 years After 10 years of 1000 Tg/year emission from the Arctic: 11.6 years

Predicted large ozone and methane enhancement from methane emissions

Changes in methane and ozone 15 years after the emission period Methane and ozone recovery is fast, takes only a few decades

Facts you need to know about the Arctic methane timebomb Dismissals of catastrophic methane danger ignore robust science in favour of outdated mythology of climate safety Why the jury's still out on the risk of Arctic methane catastrophe. Can scientists overcome huge uncertainties to pin down how close, or far, we might be to a tipping point? One source of these emissions "may be highly potential and extremely mobile shallow methane hydrates, whose stability zone is seabed permafrost-related and could be disturbed upon permafrost development, degradation, and thawing.” From Skeptical Science: "There is no evidence that methane will run out of control and initiate any sudden, catastrophic effects."