A study finds that short-lived greenhouse gases (GHGs) contribute to sea level rise through thermal expansion (TSLR) over longer timescales than their atmospheric lifetime. Some GHGs, such as methane, remain in the atmosphere for decades, whereas others, such as carbon dioxide, stay in the atmosphere for centuries. Kirsten Zickfeld and colleagues used a climate model to examine the effects of different GHGs on TSLR. The model showed that the impact of short-lived anthropogenic GHGs on sea level is far longer lasting than their atmospheric lifetime. Even if the production of short-lived GHGs ceases, centuries of TSLR should be expected, the authors note. For example, 75% of TSLR due to methane emissions could persist for 100 years after emissions cease, according to the model. Furthermore, under the Montreal Protocol, signatories agreed to phase out chlorofluorocarbons and hydrochlorofluorocarbons. However, if the Montreal Protocol had not been enacted until 2050, the model estimates up to an additional 14 centimeters of TSLR before the end of the 21st century. According to the authors, the long-lasting nature of sea level rise heightens the importance of mitigating GHGs early, even in the case of short-lived chemicals. - Read at PNAS.org
Article #16-12066: “Centuries of thermal sea-level rise due to anthropogenic emissions of short-lived greenhouse gases,” by Kirsten Zickfeld, Susan Solomon, and Daniel M. Gilford.