Read here. IPCC's Climategate scientists and big government funded alarmists have claimed that atmospheric CO2 increases and "associated" warming will cause more frequent extreme dry (drought) and wet (flood) periods. The latest research, however, clearly documents that extreme dry and wet periods have naturally occurred over thousands of years, with larger shifts starting about 1000 years ago - well before the growth of CO2 levels.
The takeaway point: the level of CO2 is completely irrelevant in terms of climate change, as the Proceedings of the National Academy of Sciences study by Nelson et al. shows. h/t WUWT (click on image to enlarge)
"The researchers analyzed a sediment core from Castor Lake in north central Washington to plot the region’s drought history since around 4,000 BCE and found that wet and dry cycles during the past millennium have grown longer. The team attributed this recent deviation to the irregular pressure and temperature changes brought on by El Niño/La Niña.....“Western states happened to build dams and water systems during a period that was unusually wet compared to the past 6,000 years,”...“Now the cycle has changed and is trending drier, which is actually normal..."...Analysis of the sediment core revealed that the climate of the Pacific Northwest fluctuated more or less evenly between wet and dry periods for thousands of years.....since around 1000 AD, these periods have become longer, shifted less frequently, and, most importantly, ushered in more extreme conditions.....The change in cycle regularity Abbott and his colleagues found correlates with documented activity of El Niño/La Niña." [Daniel B. Nelson, Mark B. Abbott, Byron Steinman, Pratigya J. Polissar, Nathan D. Stansella, Joseph D. Ortiz, Michael F. Rosenmeier, Bruce P. Finney, Jon Riedel 2010: PNAS]
Additional severe-weather, climate-history, and peer-reviewed postings. Other severe-weather charts.