“One possible reason,” he says, “for this is that most models dont include factors such as irrigation which can influence regional climates,” meaning that the increase in large-scale irrigation during the 20th century has not been accounted for in current meteorological models. Bonfils adds that researchers have found “empirical evidence that irrigation has a large cooling effect on local summer daytime temperatures but minimal effect on nighttime temperatures.”
David Lobell, one of the authors of the study issued by Lawrence Livermore National Laboratory, declares that “If this hypothesis is verified, the acceleration of CO2 emissions combined with a leveling of irrigation may result in a rapid summertime warming in the Central Valley in the near future.” Exactly how this complex scenario will work itself out in the near future is not currently known, but as Bonfils sees it, “The 21st century may be less climatically complex than today” and that “greenhouse warming is likely to be the dominant factor over todays many climate influences.
Certainly, the on-going effects of human activity in California and in other U.S. states on our natural environment are not likely to end unless scientists and researchers can come to some solid conclusions about how to stop global warming. As Duffy sums it up, “If human-induced climate change is occurring, societal impacts… cannot be far behind” which shows that global warming is indeed a very serious problem.
Human Activities Contribute to Californias Global Warming.” Science Daily. Internet. January 18, 2008. Retrieved at http://www.sciencedaily.com/releases/2008/01/080118093350.htm..