Atmospheric methane and other short-lived greenhouse gases are set to keep the global sea level rising for several centuries — even after any potential decline or halt in emissions.

Greenhouse gases in the atmosphere cause ocean warming and thermal expansion that results in sea-level rise. Reducing emissions of methane and hydrofluorocarbons, which have much shorter atmospheric lifetimes than does carbon dioxide, has been proposed as an effective way to slow atmospheric and ocean warming. But when Kirsten Zickfeld at Simon Fraser University in Burnaby, Canada, and her colleagues used an Earth-system model to quantify the effect, they found that the relatively small amount of thermal sea-level rise caused by these short-lived gases is much harder to reverse than their warming effect on the atmosphere.

Even greenhouse gases with an atmospheric lifetime of only a few years have a long-lasting effect on thermal expansion, because oceans absorb and release heat very slowly.

Proc. Natl Acad. Sci. USA http://doi.org/bw2q (2017)