Data for "Responses of El Niño and La Niña precipitation to CO₂ removal"

The El Niño-Southern Oscillation (ENSO)-induced tropical Pacific rainfall anomaly is central to ENSO dynamics and has broad socio-economic and ecosystem relevance through ocean-atmosphere teleconnections, but its response to climate change mitigation remains less explored. Using large ensemble simulations of an idealized CO₂ removal pathway, we found pronounced hysteresis and asymmetric features of equatorial Pacific rainfall changes between two ENSO phases. El Niño rainfall inherits its intensification and eastward shift changes under global warming throughout the CO₂ removal phase, showing strong hysteresis on a century scale. This is primarily due to the hysteretic southward shift of the background Intertropical Convergence Zone in the eastern Pacific, whose low-level cross-equatorial winds enhance near-equatorial surface convergence and high cloudiness, facilitating El Niño deep convection through cloud-longwave radiation feedback. In contrast, El Niño rainfall reduction in the shallow convection-dominated central Pacific is driven by the eastward shift of El Niño-induced sea surface temperature (SST) anomalies and associated boundary layer divergences. The intensification of La Niña precipitation, mainly contributed by increased background moisture and shallow convective precipitation anomalies related to the SST anomaly structure, is confined to the central western Pacific, with a hysteresis timescale of a few decades following the thermal inertia of the upper ocean. The distinct regimes and resilience of El Niño and La Niña precipitation climate change, shaped by their respective mean state forcers, can provide a reference for climate change mitigation, and shed light on ENSO characteristic changes in past and future climate.