Picture an ideal dinner plate. If you’re like most Americans, it features a hearty portion of meat, from animals fattened on midwestern corn and soybeans, and a helping of vegetables, largely trucked in from California. The unique landscapes we rely on to deliver this bounty – the twin jewels of the US food system – are locked in a state of slow-motion ecological unravelling.
California’s agricultural sector has flourished from decades of easy access to water in one of the globe’s biggest swaths of Mediterranean climate. The Sierra Nevada, the spine of mountains that runs along California’s eastern flank, captures an annual cache of snow that, when it melts, cascades into a network of government-built dams, canals and aqueducts that deliver irrigation water to farmers in the adjoining Central Valley. In light-snow years, farmers could tap aquifers that had built up over millennia to offset the shortfall.
But the Sierra snowpack has shown an overall declining trend for decades – most dramatically during the great California drought of 2012-2016 – and it will dwindle further over the next several decades as the climate warms, a growing body of research suggests. A 2018 paper by Lawrence Berkeley National Laboratory researchers articulates the alarming consensus: a “future of consistent low-to-no snowpack” for the Sierra Nevada, the irrigation jewel of our vegetable patch.
Even as snowmelt gushing from the mountains dwindles, the Central Valley farming behemoth gets ever more ravenous for irrigation water, switching from annual crops that can be fallowed in dry years to almond and pistachio groves, which require huge upfront investments and need to be watered every year. As a result, farm operations are increasingly resorting to tapping the water beneath them. Between 2002 and 2017, a period including two massive droughts, farmers siphoned enough water from the valley’s aquifers to fill Louisiana’s Lake Pontchartrain three times.
As the water vanishes, the ground settles and sinks in uneven and unpredictable ways, a phenomenon known as subsidence. By 2017, large sections of the Central Valley were sinking by as much as 2ft a year. In addition to damaging roads, bridges, houses, sewage pipes and pretty much all built infrastructure, subsidence snarls up the canals that carry snowmelt from the Sierra Nevada. Thus we have a vicious circle: reduced snowmelt means less water flowing through government-run irrigation channels, which pushes farmers to pump more water from underground, causing more subsidence that damages those channels and reduces their flow capacity, pushing farmers to accelerate the cycle by pumping more water from underground.
There’s no great mystery about how to halt the withering away of California’s water or Iowa’s soil
Seventeen hundred miles to the east, the prevailing agriculture system consumes a different but equally precious resource: soil. When white settlers seized what we now call the corn belt from indigenous inhabitants in the 19th century, they found thousands of miles of prairies and marshlands, with hundreds of species of perennial wild grasses, legumes and flowers that towered over their heads, with roots plunging just as deep into the earth, burying carbon from the atmosphere and feeding a teeming web of micro-organisms that break down and cycle nutrients. Aboveground, vast herds of bison ate their way through fields, stimulating new plant growth and recycling nutrients through their manure.
Interactions between Native Americans, plants, animals, microbes and climate left behind a majestic store of fertile topsoil that scientists call mollisol. Even today, the US midwest boasts the largest of four major mollisol stores on the planet. Mollisols develop over millennia yet can be squandered in decades. US colonial-settler agriculture transformed this ecological niche, a land mass 1.5 times the size of California, into a factory churning out just two crops – corn and soybeans.
This kind of agriculture fouls water as a matter of course. Since corn and soybeans are planted in the spring and harvested in the fall, the vast majority of corn-belt farmland lies bare for the winter months, leaving the ground naked when storms hit. These deluges pummel bare topsoil and send it – and the agrochemicals and manure farmers apply to it – cascading off farms and into streams and creeks that flow into rivers, lakes and ultimately the Gulf of Mexico. But there’s another problem with subjecting the land to the same two crops every year: loss of the region’s precious black topsoil. According to research by the soil scientist Rick Cruse, Iowa – and much of the surrounding corn belt – is losing soil at a rate 16 times the pace of natural replenishment.
Again, climate change is a driver. Today’s farmers encounter a weather regime radically different from that of their grandparents: more intense off-season storms, and thus ever-heavier pressure on the soil. If global greenhouse gases continue rising, the region faces a 40% increase in precipitation by the late 21st century, according to the Fourth National Climate Assessment. The soil that makes one of the globe’s most important growing regions so productive is vanishing before our eyes, degrading a crucial food production region at the very time when climate change and global population growth call for building resilience.
Our food supply comes from an environmentally unsustainable system that is going to unravel
There’s no great mystery about how to halt the withering away of California’s water or Iowa’s soil. California needs to shrink its agricultural footprint to match the scale of its water resources, which means other regions of the US should ramp up their own fruit and vegetable production to make up the difference. In the corn belt, US federal farm policy should stop paying farmers to overproduce corn and soybeans, and instead push them to diversify their plantings and keep their land covered all winter – practices known to maintain high levels of production while also preserving soil, decreasing water pollution and slashing the need for pesticides and fertilizers.
Reduced demand for agrichemicals, however, pinches the bottom line of the agrichemical behemoths, and a turn from corn-and-soybean dominance will dent profits for the meat companies that rely on cheap, overproduced feed. These companies divert a share of their income into lobbying and campaign finance, and their interests shape US farm policy. But it doesn’t have to be that way. Just as creating a sane climate policy requires the rise of a social movement to negate the power of the fossil fuel lobby, a better agricultural regime will require a direct political challenge to big agribusiness.
Climate justice and food justice are, in fact, the same fight – the struggle to beat back corporate dominance and make the world livable for everyone.