Hysteresis of western North Pacific tropical cyclone activity under multiple CO 2 removal scenarios
Year: 2026
Type: article
Abstract: Tropical cyclone (TC) activity is expected to change under future climate mitigation pathways, yet its response to carbon dioxide removal (CDR) remains poorly understood. Here, we investigate the hysteretic response of the genesis potential index (GPI) over the western North Pacific (WNP) using an Earth system model under four idealized CDR scenarios with different peak CO 2 concentrations. Although the WNP-mean GPI exhibits no significant hysteresis between the ramp-down and ramp-up periods at comparable CO 2 concentrations across all scenarios, the underlying dynamical mechanisms fundamentally differ depending on the forcing magnitude. In the highest-to-moderate forcing scenarios, this lack of basin-mean hysteresis arises from a robust spatial compensation between a suppressed western WNP and an enhanced eastern WNP, forming a west-east dipolar pattern. This pattern is driven by an El Niño–like sea surface temperature hysteresis, which weakens the Walker circulation and alters vertical wind shear in opposite directions across the basin. Conversely, under the lowest forcing scenario, the absence of hysteresis is due to a negligible GPI response, as the El Niño–like warming remains too weak to trigger such dynamical chains. Our findings suggest a transition in the regional GPI response between the lowest and moderate forcing scenarios, indicating a nonlinear dependence of the regional TC genesis environment during CDR on the magnitude of the CO 2 overshoot.
Source: Environmental Research Letters
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $3,045
OpenAlex ID: W7216590937