Bob Henson • November 29, 2012 | The incessant, inescapable dust storms of the 1930s left deep imprints on the psyches of Great Plains residents, as evidenced in the moving first-hand accounts in the Ken Burns documentary The Dust Bowl, which premiered this week on PBS. My mother grew up in western Oklahoma during the worst of the dusters. Sometimes I could see traces of their fury in the furrows of her brow, when she’d tell us about having had to walk to school clasping a wet handkerchief to her mouth.
If the United States were to experience a 1930s-style drought today, could it give us a second Dust Bowl? Some of the driest and hottest conditions on record have plagued parts of Texas, Oklahoma, Missouri, Georgia, and other states over the last two years.
A number of factors—both meteorological and societal—would need to conspire for the current event to resemble the all-out disaster of the Dust Bowl. Yet a devastating outcome could emerge with a flavor all its own.
Location. Poised between the moist East and the parched West, the Great Plains can lurch from wet to dry conditions in erratic, hard-to-predict ways. The worst of the 1930s drought involved the High Plains, the semiarid belt stretching roughly from the Black Hills to the Rio Grande. Grains such as wheat can thrive here, but a dry period can devastate crops that aren’t irrigated.
Right now, the region of most intense drought (see map) is uncomfortably similar to that of the 1930s, focused on western Nebraska, Kansas, Oklahoma, and Texas, plus parts of eastern Wyoming, Colorado, and New Mexico.
Intensity and scope. As shown in last week’s U.S. Drought Monitor, some 58% of the land area in the contiguous 48 U.S. states was in some form of drought, and 18% was within the two most dire classifications (extreme and exceptional). These numbers are down slightly from September, when the drought-covered area was at 65%.
Since the Drought Monitor didn’t exist in the 1930s, we need to use the venerable Palmer Drought Severity Index to make an apples-to-apples comparison. (The PDSI is among several factors that go into the Drought Monitor.) The highest PDSI-based extent on record occurred in 1934, when 80% of the contiguous United States was in some form of drought. Well back in second place—with PDSI-based drought coverage peaking at roughly 60%—are 1954 and 2012.
Heat. “For similarities to the 1930s, heat is the big one,” says Mark Svoboda (National Drought Mitigation Center). Svoboda has watched droughts come and go for years; he’s been of the U.S. Drought Monitor team since the weekly product began in 1999.
Svoboda notes that the Great Warm Wave of March 2012, which brought many states their toastiest early-spring weather ever observed, provided an unusually early kickoff to seasonal demand for water by fast-growing plants. Blazing temperatures across the Midwest in early summer only made things worse, pushing water stress to extreme levels as far northeast as Indiana. According to Svoboda, “The heat in June and July really exacerbated and accelerated the impacts this summer.”
Duration. The current drought doesn’t yet hold a candle to the Dust Bowl in terms of longevity. After the 1920s, a decade of ample moisture and bountiful wheat crops, the Great Plains fell into drought in 1931 and didn’t see a major recovery until 1939. The 1950s brought another intense multiyear drought that touched much of the nation.
Since then, most major U.S. droughts—including the infamous 1988 event (see PDF) that brought the Mississippi River to a virtual standstill—have only lasted a year or two. In fact, most of the last 20 years have been on the moist side across much of the central United States, with average precipitation rising in many locations for the period 1981–2010 compared to 1961–1990. (In Dallas–Fort Worth, for example, the annual values rose from 33.70” to 36.14”; in Wichita, Kansas, from 29.33” to 32.64”; and in Sioux Falls, South Dakota, from 23.86” to 26.38”.)
The current drought first gripped the Sun Belt in 2011, with Texas smashing records for summer heat and dryness. Conditions eased there only slightly this year, while drought rapidly expanded and intensified toward the north (see sidebar).
“The Southeast and Southern Plains can now consider themselves in a multiyear drought,” says Svoboda. However, he adds, “The vast majority of the areas affected this year in the West, the central and northern Great Plains, and the Corn Belt are still in multiseasonal rather than multiyear drought.”
The speed at which drought raced across the nation this spring caught many by surprise. In Missouri, where conditions deteriorated especially quickly, the situation was labeled a “flash drought” in the media. The phrase was introduced in an interview more than a decade ago by Mark Svoboda, who frequently interacts with the media as a spokesperson for the National Drought Mitigation Center.
“We don’t have a formal definition yet,” Svoboda pointed out when I recently spoke with him. However, his center has now received funds from NASA to work on developing just such a definition.
When he first referred to flash drought, Svoboda’s goal was to raise awareness that not all droughts take years to develop. “My intent was to describe a type of drought featuring rapid onset—in a matter of weeks, not seasons—and associated with high heat, typically at a critical time for a certain crop or land cover.”
Brad Udall, who directs the Western Water Assessment project (NOAA/University of Colorado Boulder), appreciates the similarity of the “flash drought” concept to one that’s on the other side of the precipitation spectrum. “We have floods, and we have flash floods. I think there is a nice analog to drought, although the two ‘flash’ periods are obviously different in their timing.”
NOAA’s latest seasonal drought outlook, issued on November 15, doesn’t bode well. It calls for “persistence” (continued drought) through the winter across the core area now affected.
Back in March, Texas state climatologist John Nielson-Gammon highlighted the risk at hand, based in large part on multidecadal patterns in the North Atlantic and North Pacific. In a recent blog post on the situation, he warns: “The conditions that led me to say that the [Texas] drought could conceivably last for five to ten years have not changed.”
America discovered a great deal about land management during the “Dirty Thirties.” Research-based improvements were pioneered and implemented through land-grant universities and such programs as the federal Soil Conservation Service and Cooperative Extension Service. (I found an interesting discussion of the CES, including the role segregation played in its operation, here.)
Subsequent droughts—even the intensely dry 1950s—caused plenty of misery. But the Great Plains soil came through in better shape, thanks to improvements in plowing and planting techniques as well as innovations such as shelterbelts (rows of trees that serve as a shield against high winds). High Plains farmers also began irrigating their crops on a large scale, tapping into the vast Ogallala Aquifer that underlies the region. More recently, drought-resistant cultivars of many crops have come into widespread use.
All this has helped make the current drought less devastating than it might have been 80 years ago. There have been dramatic omens in the form of Thirties-style dust storms, as experienced in Lubbock, Texas, last fall and Oklahoma just last month. But there hasn’t (at least yet) been massive erosion of the sort experienced during the Dust Bowl.
To be sure, agriculture took a huge hit this summer, particularly in the Midwest. The final tally of agricultural losses is likely to top the 1988 record of around $35–40 billion, according to Svoboda. Oddly enough, even though crop yields are down—corn production is projected to drop by 13% from last year—total U.S. farm income for 2012 is expected to hit a record high. That’s because crop prices have risen (due in part to increased demand for corn as biofuel) and because many farmers will be reimbursed for their losses by crop insurance. Farmland prices are also soaring, raising concerns about a possible bubble.
Although the lessons of the Dust Bowl and the march of technology have helped boost agricultural yields across the central United States, water remains an Achilles’ heel. In the 1930s, Svoboda points out, “they had a major environmental emergency on their hands—and caused by their hands, given the disruption of the environment when they plowed under the prairie for wheat. Today, it is about more ‘straws in the drink,’ which is still a finite resource.”
The fast-diminishing Ogallala Reservoir could be virtually depleted in parts of Texas and Kansas over the next several decades, according to recent studies. And with temperatures projected to rise both globally and regionally in the coming decades, soils and plants would be expected to dry out even more for a given rainfall deficit. (There’s an interesting debate unfolding about how best to assess future drought risk in a changing climate, which we’ll get to in a future post.)
As Svoboda puts it, “I think we don’t need a Dust Bowl or a 1950s drought to have impacts that could end up being more costly.”
