Present-day North Atlantic salinity constrains future warming of the Northern Hemisphere

Earth system models show varying projections of Atlantic Meridional Overturning Circulation (AMOC) intensity and carbon uptake, leading to uncertainty in future climate predictions. This study demonstrates that present-day North Atlantic subpolar sea surface salinity (SSS) influences anthropogenic carbon uptake and thus constrains future warming. Models with higher present-day SSS in this region exhibit greater future carbon uptake, suppressing warming, and vice versa. Using observed SSS as an emergent constraint significantly reduces uncertainty in Northern Hemisphere surface temperature warming and cumulative carbon uptake by approximately 30% and 53%, respectively, by the end of the 21st century under the SSP5-8.5 scenario.

In-Hong Park, Sang-Wook Yeh, Wenju Cai, Guojian Wang, Seung-Ki Min, Sang-Ki Lee