Hemispheric asymmetry of surface temperature anomalies

Abstract

In recent months there has been some controversy concerning the possible effect of suspended sulfate aerosols on warming trends predicted to occur in response to steadily increasing greenhouse gas concentrations in the troposphere. Evidence in the recent literature both supporting and doubting the theory that aerosols have suppressed warming in the Northern Hemisphere more than in the Southern Hemisphere has relied on analyses of radiosonde observations covering various periods between 1958 and 1995. In this letter the UK Met Office/University of East Anglia Climatic Research Unit (Parker/Jones) data sets of mean surface temperature anomalies over land and sea for the past 140 years serve as an independent data base to test earlier reported results obtained from radiosonde observations. The results suggest that there is no evidence of any systematic differences in temperature trends between the two hemispheres.