Sep 19, 2006

Forced and unforced ocean temperature changes in Atlantic and Pacific tropical cyclogenesis regions

by
B. D. Santer, T. M. L. Wigley, P. J. Gleckler, C. Bonfils, M. F. Wehner, K. AchutaRao, T. P. Barnett, J. S. Boyle, W. Brüggemann, M. Fiorino, N. Gillett, J. E. Hansen, P. D. Jones, S. A. Klein, G. A. Meehl, S. C. B. Raper, R. W. Reynolds et al
,
Proceedings of the National Academy of Sciences
  • States that previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity
  • Uses climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions
  • States that the observed SST increases in these regions range from 0.32°C to 0.67°C over the 20th century
  • Examines 22 climate models, and these suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system
  • Employs model simulations of natural internal variability to make probabilistic estimates of the contribution of external forcing to observed SST changes
  • Finds an 84% chance that external forcing explains at least 67% of observed SST increased in the two cyclogenesis regions for the period 1906–2005
  • States that model “20th-century” simulations, with external forcing by combined anthropogenic and natural factors, are generally capable of replicating observed SST increases
  • Finds that, in experiments in which forcing factors are varied individually rather than jointly, human-caused changes in greenhouse gases are the main driver of the 20th-century SST increases in both tropical cyclogenesis regions