Year: 2026
Type: article
Abstract: The Arctic is warming more than three times faster than the global average – driven by increasing CO2 emissions – yet its response to the cessation of these emissions remains uncertain. We analyze 6-member ensembles of an Earth system model in which CO2 emissions are set instantaneously to zero at cumulative emission totals ranging from 800 to 2000 PgC. While global mean temperature stabilizes after CO2 emissions cessation, we find that the Arctic exhibits nonlinear and bifurcating behavior: either continued warming and sea-ice loss (below 1700 PgC), or abrupt cooling and sea-ice expansion (above 1700 PgC). The cooling results from a near-collapse of the Atlantic Meridional Overturning Circulation, causing reduced poleward ocean heat transport and amplifying lapse-rate and surface-albedo feedbacks. This collapse occurs when CO2 emission mitigation is delayed and global-mean temperature exceeds the 2∘C Paris Agreement target. Our results suggest stochastic tipping behavior modulated by the increased greenhouse gas forcing, triggering an abrupt transition to an alternative Arctic climate state. Collapse of the Atlantic Meridional Overturning Circulation and abrupt Arctic cooling only occur when a delayed CO2 emission cessation happens after the exceedance of the 2∘C global mean temperature target, while in other scenarios the Arctic maintains warming trend, as suggested by idealized zero-emission model experiments.
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $3,490
OpenAlex ID: W7126032472
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