How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Century-Scale Drought
Yu, Z. and Ito, E.  1999.  Possible solar forcing of century-scale drought frequency in the northern Great Plains.  Geology 27: 263-266.

What was done
The authors examined a sediment core from a closed-basin lake in the northern Great Plains of North America, producing a 2100-year decadal-scale resolution proxy record of drought.

What was learned
Spectral analysis of the data revealed four dominant periodicities of drought in the record, occurring at intervals of approximately 400, 200, 130 and 100 years.  These data were then compared with various solar indices, which, according to the authors, match "in surprising detail, so this spectral similarity forces us to consider solar variability as the major cause of century-scale drought frequency in the northern Great Plains."  An additional phase correlation was noted in the proxy drought record when compared with oxygen isotope data from a Greenland ice core, indicating "a possible teleconnection of century-scale global climate fluctuations through common solar forcing."

What it means
This study demonstrates that drought is a recurring feature of the climate of the northern Great Plains of North America.  In addition to previously reported solar-induced drought cycles of 11, 22 and 90 years, there is now evidence of much longer periods of moisture variability.  As a result, solar variability has emerged as the leading candidate for inducing drought, leaving even less of a possibility of attributing recent drought to CO2-induced global warming.  As for the future of drought in North America's interior, Yu and Ito's data indicate that this area is currently in the midst of a dry period that may persist for about another century and may be followed by a 130-year period of relatively wet climate.

Reviewed 15 May 1999