No Evidence for Strongly Enhanced Northern Hemisphere Cooling From Extratropical Versus Tropical Eruptions

Abstract Volcanic eruptions in the Northern Hemisphere extratropics have been reported to produce several times greater cooling in that region than tropical eruptions of similar magnitude. Using a large ensemble of simulations spanning the eruption size range from 5 to 40 Tg of stratospheric sulfur, we find that the extratropical‐to‐tropical cooling ratio is consistently within a factor of two, indicating no enhancement beyond the effect of aerosols being confined to a single hemisphere. We further show that paleoclimate evidence suggests similarly unexceptional cooling, and also reconcile why earlier analyses yielded unreliable estimates. Moreover, owing to their rarity, we argue that extratropical eruptions exert a smaller overall influence on Northern Hemisphere extratropical temperatures than tropical eruptions. These findings question the notion that extratropical eruptions are of outsized importance for the climate of the Northern Hemisphere.