Climate Models Without Pre-Industrial Volcanic Forcing Underestimate Historical Ocean Thermal Expansion

TitleClimate Models Without Pre-Industrial Volcanic Forcing Underestimate Historical Ocean Thermal Expansion
Publication TypeJournal Article
Year of Publication2013
JournalGeophysical Research Letters
Pages1600-1604
Date Published04/2013
Abstract / Summary

Explosive volcanic eruptions cause episodic negative radiative forcing of the climate system. Using coupled atmosphere–ocean general circulation models (AOGCMs) subjected to historical forcing in the late nineteenth century previous authors have shown that each large volcanic eruption is associated with a sudden drop in ocean heat content and sea‐level from which the subsequent recovery is slow. Here we show that this effect maybe an artifact of experimental design, caused by the AOGCMs not having been spun up to a steady state with volcanic forcing before the historical integrations begin. Because volcanic forcing has a long‐term negative average, a cooling tendency is thus imposed on the ocean in the historical simulation. We recommend that a next experiment be carried out in parallel to the historical simulation with constant time‐mean historical volcanic forcing, in order to correct for this effect and avoid misinterpretation of ocean heat content changes.

Journal: Geophysical Research Letters
Year of Publication: 2013
Pages: 1600-1604
Date Published: 04/2013

Explosive volcanic eruptions cause episodic negative radiative forcing of the climate system. Using coupled atmosphere–ocean general circulation models (AOGCMs) subjected to historical forcing in the late nineteenth century previous authors have shown that each large volcanic eruption is associated with a sudden drop in ocean heat content and sea‐level from which the subsequent recovery is slow. Here we show that this effect maybe an artifact of experimental design, caused by the AOGCMs not having been spun up to a steady state with volcanic forcing before the historical integrations begin. Because volcanic forcing has a long‐term negative average, a cooling tendency is thus imposed on the ocean in the historical simulation. We recommend that a next experiment be carried out in parallel to the historical simulation with constant time‐mean historical volcanic forcing, in order to correct for this effect and avoid misinterpretation of ocean heat content changes.

Citation:
Gregory, J, D Bi, M Collier, M Dix, A Hirst, A Hu, M Huber, et al.  2013.  "Climate Models Without Pre-Industrial Volcanic Forcing Underestimate Historical Ocean Thermal Expansion."  Geophysical Research Letters 1600-1604.