A Drought of Truth


Make no mistake about it: It is very dry in the Mid-Atlantic region. Farmers in Virginia's Shenandoah Valley and much of Maryland are coping with a very difficult situation; residents of highly populated Northern Virginia are nearly as dry but suffer few effects, thanks to upstream reservoirs and the very wide Potomac River. Some might be happy to not have to water the lawn.

The real story of the drought of 1999 is the phenomenal level of distortionthat has been heaped on by the White House and by the large number ofreporters who care more for sensation than truth. President Clinton wantsto mix the drought up with global warming and food scares. After callingthe situation the "worst agricultural drought this century," he added onAugust 7: "As weather disruptions become even more common, and they will,they will demand a more coordinated response by the national government."

Those who know Clinton/Gore may suspect a little bit of exaggeration here.So how bad is it?In terms of severity and extent, this drought is nothing special.Climatologists measure drought with something called the Palmer DroughtSeverity Index, a clunky mathematical beast that attempts to account forall of the variables that define moisture status: rainfall, evaporation,runoff (into streams) and ground storage.

It has some quirks, including the debatable notion that drought is measuredprimarily by the departure from average moisture at any spot. In otherwords, if a place like Washington, D.C., receives 60 percent of its averagerainfall for a year -- which is the current situation -- it's likely to bein a big time drought, even though it still gets 13 times the averagerainfall of Death Valley, which is not in a drought as long as it staysnear its annual average rainfall of 1.89 inches.

There's a certain sort of liberal logic around this. The implication isthat the natural vegetation as well as the human infrastructure put in itsplace are adapted to "normal" conditions for that spot, and the moreabnormal things become, the more they fall apart. In other words, DeathValley Scotty is adapted to Death Valley and Al Gore is adapted toWashington, but if either experiences below normal rainfall, he'll beunhappy.

To make everyone's moisture shortages equivalent, the Palmer Index isstatistically adjusted to give uniform values between places. It isassigned an average value of zero and a "standard deviation" of 2.0. Thisis a measure of the scatter of month-to-month readings about the arbitraryaverage of zero. Statistically speaking, one-sixth of the time we are morethan one standard deviation below the average. Federal climatologists givethis zone a name: All values between -2 and -3 in the Palmer Index arecalled "Moderate Drought."

Think about it. On average, any given place has a "moderate drought"one-sixth of the time. Flipping the data around, this statisticaltechnique also means that, on average, one-sixth (17 percent) of the nationis in "Moderate Drought."

That makes for some pretty snappy electioneering and porking. It getspretty easy for some climate demagogue to stand in front of voters instates with a lot of electoral votes, claiming that this is what you getfrom mean ole Republicans who don't want to stop global warming. That'spretty much what Al Gore pulled last week, in a lecture along with BillNye, the public broadcasting (surprised?) science guy.

But in fairness, Northern Virginia, where this spectacle unfolded, is in"Extreme Drought." That occurs when the Palmer Index is more than twostandard deviations away from its mean; that is, has a value below -4.0.

Statistically speaking, this occurs on average 2.5 percent of the time atyour house, or in an average year over 2.5 percent of the nation. That'sright -- thanks to the wonders of statistical fiddling, an area the size ofseveral small states is normally in "Extreme Drought." To me, the notionof "extreme drought" conjures up visions of cattle skulls and dust storms,something I can't seem to find outside my Shenandoah Valley window.Perhaps the rhetoric is a bit hot.

The most recent Palmer Index figures, from August 7, are very interesting.It's below -4.0 in Northern Virginia, much of Maryland and Delaware, theMohawk Valley in New York, a little spot in Central Florida and two placesin the desert region of the Northwest that probably can't tell thedifference between hardly any average rain and a bit less.

Together, these regions comprise 1.98 percent of this fair country. But,on average, 2.5 percent of the nation has "Extreme Drought." That's right. For all of the lead stories, for all of the hype and demagoguery, less ofthe nation than average is currently experiencing a major drought. It alsohasn't hurt the hype machine that the epicenter of dryness just happens tobe Washington, D.C. That makes this more important than any moistureshortage in the world.

The same thing happens when there's a big snowstorm here. Twenty-fourinches of snow in D.C. in January 1996 prompted a Newsweek cover articlewith the headline, "Blizzards, floods and hurricanes: blame globalwarming." The red band said "Hillary's Damage Control," doubly emphasizingthe apparently limited number of constantly recycled news stories.

The current situation doesn't mean that conditions aren't pretty bad downon the Mid-Atlantic farm. Those people need a hand. But it also meansthat any attempt to hype this thing into something that it isn't -- sometype of national or global catastrophe -- is a clear and cynical attempt atdistortion.