Simon Dietz, da LSE, vai apresentar "Some economics of global methane action"

Abstract: Climate policy is paying increasing attention to methane action, exemplified by the Global Methane Pledge of at least a 30% reduction in global methane emissions below the 2020 level by 2030. But research on the economic benefits of methane action is still sparse. In this paper, we seek to advance the literature by providing the first comprehensive assessment of the economic benefits of methane abatement, primarily via avoided climate change but also including air quality co-benefits. We do so using one of a new generation of social-cost Integrated Assessment Models, META, which couples a benchmark simple climate model from the climate science literature with comprehensive climate damages disaggregated to the national level, and includes a set of climate tipping points. Relative to current policies/trends, we estimate the Global Methane Pledge and continued methane abatement thereafter would avoid 0.13C of warming in 2050. This may sound small, but it would be highly beneficial. It would reduce climate damages in 2050 from 3.5% of global GDP to 3.1%, equivalent to gross benefits of more than $1trn per year in 2050. Using data on air quality co-benefits and abatement costs from the Global Methane Assessment, we estimate overall discounted net benefits of methane action of $9.4-16.5trn, yielding a lower bound of more than six for the benefit-cost ratio of methane action. We provide evidence of how global methane action would improve equity, reducing climate damages relatively more in low-income than high-income countries. We quantify how methane action reduces tipping point intensity and tail risk with respect to climate damages. Our best estimate of the social cost of methane (SC-CH4), i.e., the marginal climate damage cost of methane, is $7,327/tCH4, towards the top end of the range of estimates in the existing literature. We provide the first country-level estimates of the SC-CH4, which indicate that key economies such as the United States, the European Union, China and India would be motivated to act on methane at marginal abatement costs exceeding $500/tCH4 even if they took a parochial view of climate damages, only valuing damages within their own borders.