The redistribution of anthropogenic excess heat is a key driver of warming in the North Atlantic
Marie‐José Messias, Herlé Mercier
Abstract
Abstract Understanding ocean excess heat uptake is crucial for assessing climate warming, yet uncertainties remain about its history and redistribution. Here, we reconstruct ocean heat content change along the 25°N Atlantic hydrographic section and assess its spatiotemporal origin and fate. We show that the delayed response of the ocean below 700 m to sea surface temperature change contribute to 62% of full depth warming at this latitude for 1850–2018, falling to 35% for 1975–2018 when anthropogenic warming in the upper ocean accelerated. The regional climate fluctuations shape ocean heat content variability at 25°N with contributions from the Labrador Sea producing most of the decadal variability and the Nordic Seas bound to become the main contributor to deep ocean warming in the coming decades. Chiefly, the net excess heat transport across 25°N has increased recently, warming the domain north of 25°N at a rate of 0.89 ± 0.19 W m −2 during 2012–2018, revealing that excess heat redistribution is a key driver of North Atlantic heat gain.