Cooling after net zero

Nathaniel Tarshish, Nadir Jeevanjee, Inez Fung

Climate policy aims to limit global warming by achieving net-zero greenhouse gas emissions. Climate models indicate that achieving net-zero emissions yields a nearly constant global temperature over the following decades. However, whether temperatures remain stable in the centuries after net-zero emissions is uncertain, as models produce conflicting results. Here, we explain how this disagreement arises from differing estimates of two key climate metrics, which govern the carbon system’s disequilibrium and the ocean’s thermodynamic disequilibrium, respectively. By constraining these metrics using multiple lines of evidence, we demonstrate—with greater than 95% confidence—that global temperature anomalies decline after net-zero. In the centuries that follow net-zero, the global-mean temperature anomaly is projected to decrease by 40% (median estimate). Consequently, achieving net-zero emissions very likely halts further temperature rise, even on multi-century timescales.