Sea ice and climate in 20th- and 21st-century simulations with a global atmosphere-ocean-ice model

Abstract

A global atmosphere-ocean-sea-ice general circulation model (GCM) is used in simulations of climate with greenhouse gas concentrations and sulfate aerosols prescribed from observational data (1870-1995) and future projections (1995-2100). Simulations that include the variability in solar flux from 1870 through 1995 are also performed. The variation in solar flux of ± 2 W m-2 produces a global temperature change of ± 0.2°C in the model. The more recent simulated warming trend produced by increasing greenhouse gases exceeds this solar-flux warming, although the solar flux contributes to some of the simulated present-day warm temperatures. The future increases in greenhouse gases produce an increase in global temperature of 1.2°C over 70 years, with significant decreases in Arctic ice thickness and area. The model exhibits an atmospheric pressure mode similar to the Arctic Oscillation, with different correlation indices between the North Atlantic and North Pacific pressure anomalies.