A dust cloud approaching a ranch in Boise City, Okla., in 1935.
On a spring day in 1935, a 10,000-foot-tall dust cloud blew into Washington, D.C.—consisting, remarkably, of aerated soil from Nebraska and Oklahoma, a thousand miles away. A severe drought across the West had combined with the indiscriminate plowing of the prairie to create a new form of weather, the “black duster.” The topsoil of more than a million acres had simply blown away, a portion of it taking to the wind to begrime the nation’s capital.
The cloud arrived, obscuring the sun, as the Senate debated the federal government’s responsibility in mitigating the great Dust Bowl, which would displace some 2.5 million Americans and cause one of the largest migrations in U.S. history. There could not have been a more effective lobbying effort for national action. Congress would address grazing issues and vote to establish the Soil Conservation Service, whose measures, such as planting windbreaks and seeding grasses, did much to head off future black dusters.
Today, as we learn from two new papers in the current issue of the American Meteorological Society’s journal Earth Interactions, the arid West is again on an eastward march. In an attempt to understand the interplay of climate change and geography, the Columbia University climatologist Richard Seager and his team of researchers revisited a groundbreaking concept first put forth in 1877 by the scientist and Grand Canyon explorer John Wesley Powell, who drew a longitudinal line cleaving the U.S. into two realms, the arid West and the verdant East. Stunning in its simplicity, yet revolutionary in its implications, the idea that Powell proposed marked the first volley in the conflict over climate change. The so-called 100th Meridian would come to play a major role in how Americans saw their continent.
Powell’s line reaches from Mexico to Canada, rising up through central Texas, Oklahoma and Kansas, running through Nebraska and the Dakotas. It was, in the technical jargon, an isohyet—a line connecting areas that experience equal volumes of annual rainfall. The relatively humid lands to the east of the line get 20 or more inches of annual rainfall; the unquestionably arid lands to the west receive less, except for some narrow strips on the Pacific coast. Because conventional agriculture depends on 20 inches or more of rain unless supplemented by irrigation, Powell pointed out that this map offered valuable insight: Except for some lands offering timber or pasturage, the far greater part of the land west of the line was, on its own, essentially not farmable.
His conclusions amounted to a frontal assault on the land-grant agricultural system, still rooted in the 1862 Homestead Act’s stipulation that any American adult could receive 160 acres from the federal government, contingent on demonstrating an ability to live on the land and improve it. Though that system might work well in Wisconsin or Illinois, Powell argued, the arid West could not support traditional homesteads of that size. Those Americans flocking into the arid lands beyond the 100th Meridian would see their dreams dashed by spindly crops, heartbreak and bankruptcy. He gave fair warning for what would become a national tragedy.
The Homestead Act struck Powell as the height of folly, because it failed to take into account topography, rainfall, proximity to water, altitude and other critical factors. It was the blind, reflexive policy of a nation with outsize optimism, drunk on the seemingly infinite resources available to it. Americans, he argued, needed to listen not just to their ideals and ambitions but to what the land told them and what was sustainable in the long term. Otherwise the future would consist of shortages, endless litigation and feuds over infrastructure and water—each one a threat to a democratic society.
Powell believed as firmly as anyone that America had a shining future and that it lay in bending nature to the will of an advancing humanity. “[T]he powers of nature are his servants,” he wrote in 1883, “and the granite earth his throne.” He was a man of his times, but he understood like few others that a still-new nation would be endangered if her citizens did not pay attention to what ecology, geography and geology revealed.
The implications of the 100th Meridian challenged not only the Government Land Office, the railroads and Western senators but an overwhelming front of entrenched beliefs, myths and nation-building passion. Powell’s view was a protest against Manifest Destiny, the idea of the divinely conferred right of Americans to push across the continent to unlock unlimited wealth, and his warning prompted a furious backlash. Western senators hounded him from his job as longtime director of the United States Geological Survey. As the Dust Bowl would reveal, however, he was prescient in his call for ecological stewardship of the western lands.
The research just published by Prof. Seager and his team shows that the concept of the 100th Meridian did affect patterns of human settlement over time. In the West today, population density is much lower, farms are fewer and bigger, and water-loving corn gives way to wheat, which better withstands arid conditions.
Mr. Powell published this map in 1891 to mark out the watersheds to the west of the 100th Meridian.
But Powell did not consider one crucial factor, because he did not know about it: the effects of a warming atmosphere, caused by greenhouse gas emissions from the burning of fossil fuels. Warmer temperatures dry out soil faster, a phenomenon called evapotranspiration. Looking at data collected since 1980, the researchers found that warming conditions have pushed Powell’s line 140 miles to the east. The shift is not yet large enough to bring wholesale changes to the Midwest, but as the line continues to migrate over the course of the century, the authors anticipate that it will eventually cause significant changes in the region’s agriculture and economy.
If Powell were alive today, I suspect that he would be at the forefront of the climate-change debate, armed with reams of data—and, it would seem to some, again blocking American progress. In his own day, he found it difficult to sway hearts and minds, even with convincing evidence. Climate scientists now face a similar problem, often finding their conclusions confronted by misinformation and vested economic interests.
Let us hope that it will not take a giant dust cloud, or a catastrophic global warming event, to persuade lawmakers that our role as ecological stewards does not stand in the way of progress. As John Wesley Powell so well understood, the path toward a shining future lies in accommodation with the limits imposed by nature.