By looking here (you might need to click over to the Feb 2010 listings):
http://www.worldclimatereport.com/index.php/2010/ 02/24/update-on-global-drought-patterns-ipcc-take- note/
and using this paper:
Sheffield, J., K.M. Andreadis, E.F. Wood, and D.P. Lettenmaier. 2009. Global and Continental Drought in the Second Half of the Twentieth Century: Severity–Area–Duration Analysis and Temporal Variability of Large-Scale Events. Journal of Climate, 22, 1962-1981
you'll see a group of scientists looking into the theory that you would see a pattern of increased drought.
Naturally, with several drought indexes to choose from, they had to come up with a way to see GLOBAL coverage.
They picked this:
"...Soil moisture is a useful indicator of drought because it provides an aggregate estimate of available water from the balance of precipitation, evaporation, and runoff fluxes..."
So, they used a popular hydrologic simulation model to estimate soil moisture levels at the 1º latitude by 1º longitude resolution for land areas of the globe for the period 1950 to 2000.
What they found was simply amazing.
Sheffield et al. note with respect to global and continental droughts" "...The longest duration drought was 49 months (4 yr) in Asia from 1984 to 1988, closely followed by the 1950–53 North American drought (44 months)..."
Now, here's where the counters jump in. They'll find a drought index somewhere that negates the findings, or they'll claim cherry-picking (only used the period from 1950 to 2000) and missed the dust bowl era and the recent Texas and Mexico droughts.
Still, they managed to find a drought back in 84-88, when the CO2 levels ranged from 344.24 - 351.47. You'll see that we crossed the deadly upper limit of CO2 (350ppm) during this time.
http://data.giss.nasa.gov/modelforce/ghgases/Fig1 A.ext.txt
"...The most spatially extensive was the African drought of the early 1980s, which reached its peak extent in April 1983 when it covered over 11 million square kilometers..."
Again, this extreme drought occurred when the CO2 was BELOW the magic 350ppm level (342.53).
The telling parts of their research, their time series plot for the globe and for various continents shows no upward trend whatsoever.
Using their data, "...The mean number of global droughts > 500,000 km2 occurring in any month is about 4.5 (or 55 yr-1) with a standard deviation of 1.6. This time series is quite variable and indicates several periods of increased global drought activity: the mid-1950s, 1960s, late 1980s to early 1990s, and late 1990s. The mid-1970s to mid-1980s are characterized by the lowest number of droughts, apart from a short burst of activity around 1976–77. The year with most drought months is 1992..".
In other words, Sheffield et al. analyzed drought patterns at the global scale for the period 1950 to 2000, and found no evidence to support claims of increasing drought activity.
So, next post goes into the third item on The List: new pandemics.
