Published date September 19, 2006

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

  • 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