Droughting the forecast

Droughting the forecast
July 1, 2000

As we headed through spring, concern was growing that the Midwest was sitting on the brink of a major drought.

An overflight of the region found it to be greening up nicely, but the amount of stored soil moisture just below the surface was in fact getting pretty low. Farmers hoped for spring rains to remedy the situation, knowing all the while that this summer could be a difficult one for the nation’s breadbasket.

However, while some climatologists were starting to worry, apparently commodities traders didn’t share their concern. Futures prices for soybeans and corn, adjusted for inflation, fell near all-time lows.

High crop yields last year led to a large stock going into this year’s season, and an increase in planted acreage was forecast. That led traders to think that supplies would be high come harvest. And they know that during the past 50 years, corn and soybean yields (bushels per acre) have increased by about 300 percent. The same land is now producing more crops than ever before.

Improved technology is the major cause of that dramatic increase, but the enhanced level of carbon dioxide in the atmosphere has undoubtedly contributed as well.

The current conditions in the Midwest may be tied to La Niña in the tropical Pacific Ocean. The last time there was a strong La Niña, 1987-1988, the middle part of the country experienced a drought rivaling those observed in the 1930s and 1950s.

Those major droughts covered as much as 70 percent of the United States’ major crop-growing regions. (It’s worthwhile to compare that number with the one that somehow inspired last summer’s media circus, in which the entire percentage of the our prime agricultural land affected by severe drought was a grand total of zero.)

Recall that the hot, dry conditions during the spring and summer of 1988 were the spark that NASA’s James Hansen used to start the apocalyptic greenhouse fires burning. Hansen proclaimed to Congress that summer that he had a “high degree of confidence” that those drought conditions were related to changes in the greenhouse effect.

Ironically, federal climatologist Kevin Trenberth—one of the leaders of a small band of vocal scientists advocating the notion of drastic climate change—has published a series of papers that pointed to La Niña, not the greenhouse effect, as the cause of breadbasket dryness.

Both scientists and the enviromedia know full well that natural causes can and do lead to droughts in the United States and that a precursor to drought—La Niña conditions—is now prevailing in the tropics. So it will be interesting to see how an extreme drought this summer will be handled by the fourth estate and its favorite scientists.

In any event, Environment and Climate News will be here to set the record straight—whether our scientific contributors make their short list or not.


Paul C. Knappenberger is technical supervisor at New Hope Environmental Services, a scientific consulting firm in Charlottesville, Virginia. His research appears frequently in the refereed scientific journals.


References

Trenberth, K.E., et al., 1988. Origins of the 1988 North American drought. Science, 242, 1640-1645.

Trenberth, K.E., and C.J. Guillemot, 1996. Physical processes involved in the 1988 drought and 1993 floods in North America. Journal of Climate, 9, 1288-1298.