Frequency and Severity of Extreme Weather

In 1981, Dr. James Hansen published a paper in Science that warming over the past century had been consistent with the effects of anthropogenic CO2 release. He also predicted that the signal (i.e. climate change appearing in the data) would rise above the noise (i.e. background natural variability in the climate) by the end of the century, which happened.

The last sentence in Dr. Hansen’s abstract is:


  • “Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage” [1].


Sound familiar? In addition to these effects predicted 32 years ago, we know that because warm air holds more moisture than cold air, and moisture in the air generates weather related events,we have created the conditions for greater severity and frequency of weather related events [2].



  1. 1. Hansen, J., D. Johnson, A. Lacis, S. Lebedeff, P. Lee, D. Rind, and G. Russell. “Climate impact of increasing atmospheric carbon dioxide”. 1981. Science, 213, 957-966, doi:10.1126/science.213.4511.957.
  2. Kevin E. Trenberth. “Framing the way to relate climate extremes to climate change”. 2012. Climatic Change (2012) 115:283–290. DOI 10.1007/s10584-012-0441-5.