Recent Tropical Pacific cooling and Walker circulation strengthening driven by anthropogenic emissions

The eastern tropical Pacific Ocean has been cooling over the past forty years alongside with a strengthening of the Walker Circulation. Global climate models cannot simulate these trends confounding the causes of environmental changes globally. We address this issue with an unprecedented ensemble of high resolution global climate simulations that produce a response to human emissions explaining observed changes. This forced response is amplified by a positive feedback loop arising from interactions between the tropical Pacific and the Southern Ocean previously not active in climate models. Simulating these interactions depends on an accurate representation of the climatology of the tropical Pacific, as well as ocean mesoscale features – requiring enhanced atmospheric and oceanic resolution. The simulated response reveals a large human influence on observed changes, revising the previous consensus of a natural cause.