May 1, 2005

Trends in Intense Precipitation in the Climate Record

Pavel Ya Groisman
AMS Journal of Climate
  • Analyzes observed changes in intense precipitation (e.g., the frequency of very heavy precipitation or the upper 0.3% of daily precipitation events) for over half of the land area of the globe
  • States that these changes have been linked to changes in intense precipitation for three transient climate model simulations, all with greenhouse gas concentrations increasing during the twentieth and twenty-first centuries and doubling in the later part of the twenty-first century
  • Finds that both the empirical evidence from the period of instrumental observations and model projections of a greenhouse-enriched atmosphere indicate an increasing probability of intense precipitation events for many extratropical regions including the United States
  • Documents statistically significant (at the 0.01 level) increasing trends in very heavy precipitation in three large neighboring regions in the central United State for the period 1893–2002
  • Finds the frequency of very heavy precipitation increased by 20% and that all of the increase has occurred during the last third of the century
  • States that changes in global mean annual precipitation from an ensemble of coupled model simulations driven by both natural (changes in volcanism and solar forcing) and anthropogenic forcing closely follow the observed trajectory; however, this similarity is caused only by the effect of volcanic eruptions on global precipitation and the anthropogenic signal cannot presently be detected