Solving aviation’s climate-action conundrum

Abstract

Like road and maritime transport, aviation produces carbon dioxide emissions that contribute to climate warming. However, aviation also drives warming through shorter-lived effects mainly related to the formation of trails of condensed water vapour (contrails) and the emission of nitrogen oxide compounds (NOx). This warming is substantial — the energy added to the atmosphere by aviation’s non-CO2 effects over periods of a few years is estimated1 to be comparable to the cumulative energy input from all aircraft CO2 emissions since the start of commercial air traffic in the 1940s. However, uncertainties associated with these estimates have made it hard to decide on the best approach for mitigating warming caused by non-CO2 effects when the actions taken could cause an increase in CO2 emissions. Writing in Nature, Prather et al.2 report a risk-assessment tool that cuts through the uncertainties.