The influence of volcanic, solar and CO2 forcing on the temperatures in the Dalton Minimum (1790-1830): a model study

Abstract

The Dalton Minimum (1790-1830) was a period with reduced solar irradiance and strong volcanic eruptions. Additionally, the atmospheric CO concentrations started to rise markedly from the background level of previous centuries. In this period most empirical climate reconstructions indicate a minimum in global or hemispheric temperatures. Here, we analyze several simulations starting in 1755 with the coupled atmosphere-ocean model ECHO-G driven by different forcing combinations to investigate which external forcing could have contributed more strongly to the cold temperatures during the Dalton Minimum. Results indicate that on global and hemispheric scales, the volcanic forcing seems to be largely responsible for the temperature drop in this period, especially during its second half, whereas changes in solar forcing and the increasing atmospheric CO concentrations were of minor importance. At regional scales, the impact of volcanic forcing is much less discernible due to the large regional variability, a finding that agrees with empirical temperature reconstructions.