Of all the projected impacts of climate change, the scariest one in a world is the effect warming could have on our ability to feed ourselves. Scientists have looked at the impact of major heat waves in the past, and have found that such abnormally hot weather tends to hurt agriculture, with maize productivity levels falling by more than 30% in Italy during the blistering summer of 2003. A study from last year predicted that there was more than a 90% chance that average growing-season temperatures by the end of the century would be hotter than the most extreme levels seen in the past—and that such hot weather could wilt out crops. Given that the Intergovernmental Panel on Climate Change is projecting that temperatures in major grain-growing regions of North America could increase by 3 to 4 C by the end of the century, that’s a scary thought.
But while unchecked global warming is likely to alter the climate at a rate faster than anything we’ve experienced in recorded history, it’s important to remember that we have one big advantage on our side: human ingenuity. As a new paper published today in the Proceedings of the National Academy of Science (PNAS) shows, farmers in North America have proven able to grow crops in climates that were initially considered too harsh and too dry. (Download a PDF here.) Thanks to mechanization, improving infrastructure and plant breeding—before the age of genomics—farmers managed to turn the Plains state of the Midwest from the Great American Desert to the Great American Breadbasket. The paper shows that climate, while a vital factor in agriculture, is far from the only one, and provides a little hope for a hotter future.
In the PNAS paper, economists Alan Olmstead of University of California-Davis and Paul Rhode of University of Michigan, chart the amazing history of North American wheat farmers as they spread out across the continent, moving from the wetter, warmer climates in the East to the far harsher Midwest. Olmstead and Rhode found that between 1839 and 2007, wheat output increased 26-fold in the U.S. and more than 270-fold in Canada—even though the median annual precipitation norm for wheat-growing areas in 2007 was half what it was in 1839, while the average temperature in 2007 was 3.7 C lower. As farmers pushed from eastern Ohio to west-central South Dakota, they encountered drier land and colder temperatures, yet over time they were able to keep on growing more and more wheat. And it’s important to note that most of this geographical shift and agricultural adaptation was already finished by 1929—well before Norman Borlaug’s Green Revolution in the 1950s, which saw an explosion in global farming productivity.
Adapting to a colder, harsher land wasn’t easy, as Olstead and Rhode write:
The experiences of the Selkirk colonists who settled near Lake Winnipeg offer an example. The winter wheat, first tried in 1811–1812, failed. Successive crops of spring wheat also succumbed to drought, freezing, and insects. To obtain sufficient seed for the 1820 crop, a band of Selkirk settlers had to trek more than 2,000 km (round trip) to Prairie du Chien on the upper Mississippi River during the dead of winter. After about a decade of hungry times, the colony began to sustain itself (12). The prolonged troubles of the Selkirk colonists represented a clear case of settlers leapfrogging beyond the limits of their climatic knowledge. However, even when settlers inched west in a more orderly fashion, the challenge of adapting was daunting. In the 1840s, attempts to grow soft winter wheat on the Wisconsin Prairie failed repeatedly, and wheat culture succeeded only after farmers switched to a new hard spring wheat cultivar (13).
While the spread of railroads and mechanized equipment helped farmers get more per acre—producing a unit of wheat took half the labor in 1913 as it did in 1840—adaptation was only successful thanks to the laborious work of breeding hardier seeds, with both private and public funding. German Mennonites—who immigrated from (cold and dry) southern Russia to Kansas in the late 19th century—introduced Turkey wheat in 1873, which thrived in the tougher climates the new farmers had been accustomed to back home. By 1919 Turkey seeds provided more than 80% of the wheat acerage in Nebraska and Kansas, and nearly 70% of the average in Colorado and Nebraska. The authors quote a government plant breeder who said that without the Turkey strain:
The wheat crop of Kansas today would be no more than half what it is, and the farmers of Nebraska, Montana and Iowa would have no choice but to grow spring wheat.
The introduction and breeding of those strains wasn’t accidental, either. Railroad companies—who wanted people to move west—encouraged the immigrants from cold-weather regions who might be able to make the Midwest bloom, and the government invested in plant breeding research. By 1919, 27% of the wheat acerage in the U.S. was planted with cultivars bred by the public sector. Today in the U.S. and Canada 84% of wheat acerage is planted with cultivars bred by the public sector. That’s worth remembering as a fiscally conservative Congress debates cutting basic research spending.
Of course, farmers in a warmer world will need to deal with higher temperatures, not lower ones. But the PNAS paper notes that farmers in Mexico have been successful over time breeding more wheat in hot and dry areas. In all likelihood, farmers will need to respond to warmer temperatures over time by shifting agriculture further north into Canada and even Alaska—but Olmstead and Rhode note that even with the predicted high temperatures of 2100, farmers near Edmonton, Alberta and Dickerson, South Dakota will still be dealing with temperatures that will be colder than those faced by eastern wheat growers back in 1839. Adapting to climate change won’t be easy—especially because we don’t know whether there will be larger changes on a regional or local basis that could upset our best efforts. But we’ve done it before—and we’ll need to do it again.
