At first the changes were barely perceptible. Gaps here and there in the supermarket shelves, the occasional hoarder filling their cart with mountains of food.

Then the fruits and vegetables disappeared. The supermarkets became crowded and hectic, and squabbles over the last of the produce occasionally turned into violent brawls.

Then the bread, meat, and milk products disappeared. Throngs of shoppers poured into the aisles in the early morning on restocking days. Fights broke out at checkout stations. One man tried to grab a shopping cart and run. He was sent to the hospital with a concussion and a broken arm.

Then the canned foods disappeared, and the processed foods with them. Rioters broke through the sliding glass doors of closed grocery stores gone out of business, often leaving with nothing to show for their efforts but bloody and tattered clothing. The president nationalized US food production and distribution, deploying the national guard to aid state and local authorities with the distribution of food rations. A Californian fringe group attempted to seize the state capitol in Sacramento to halt food “theft” and produce export to less productive states. A bomb went off at a food distribution center in Iowa, leaving half a dozen servicemembers hospitalized, and three of them dead.

And eventually, people just began to starve.

What could cause such terrible food shortages? The short answer is climate change—and the harmful farm practices and agricultural policies which exacerbate it. Ironically, federal policies intended to increase our food supply will end up undermining it. And the decline will begin within the lifetime of most people alive today.

Rising Temperatures, Falling Yields

The USDA predicts that yields of major US crops will start to decline by midcentury. By then, when temperatures have increased between 1°C to 3°C, the United States agricultural system will no longer be able to maintain current levels of food production.

If you’re under the age of 50, that means that food supplies could start to dwindle within your lifetime.

Of course, the decline will be slow at first. But even the USDA acknowledges that its estimates are conservative. Models of agricultural yields generally consider the impact of temperature and rainfall, but not biological factors like weeds, pests, and pollination. Climate change will make all of these systems more hostile to food production, so the true impacts will probably be more severe than the USDA’s projections.

Every plant’s productivity peaks at a certain temperature. Most plants are grown in places that are already tailored to their peak productivity, so rising temperatures can only decrease their yield. For staple grain crops, a 1°C temperature increase above the optimum can decrease productivity by anywhere from 10% to 15%. Consequently, yields could plummet to two-thirds or even one-half of their present levels by midcentury.

Climate change may eventually force most Americans alive today to make a difficult choice: give up meat and other grain-intensive products, or live on only one to two meals a day.

And that bleak future only considers temperature alone, not the many other challenges to agriculture that a warming world will face. Climate change increases the strength and frequency of extreme weather. That means more droughts, but also more extreme storms washing away substantial amounts of fertile soil. Pollinators will suffer under extreme temperatures, and changing seasons may throw plant and pollinator lifecycles out of sync. Weeds will proliferate as the concentration of carbon dioxide in the atmosphere increases, and pests and diseases will run rampant in our warmer, more humid world.

There would be no easy adaptations in this warmed world. If we used more pesticides, we might kill off the pollinators that make plant reproduction possible in the first place. If we cleared more land for farming, we might run the very same risk, since pollinators rely on natural ecosystems. If we developed new farmland farther north to try to replicate past conditions, we would find the soil too poor to sustain the yields we are accustomed to.

The best thing we can do to save our food production is to cut our greenhouse gas emissions. And that means changing the US agricultural policy that encourages unsustainable farming practices.

Agriculture vs. Food: Farm Practices

American industrial agriculture released around 666 million metric tons of carbon dioxide into the atmosphere in 2018 alone. That means that if American farms formed their own country, that country would be the 8th highest carbon dioxide emitter in the world, ranking just behind the Islamic Republic of Iran.

But things don’t need to be this way. One of the most important reasons why American agriculture releases so much carbon dioxide can be articulated in just one word: size.

More land gives a farmer less time to focus on each individual acre. To cover more land in the same amount of time, farmers need large, oil-guzzling machinery like tractors and combines.

Less time per acre also prevents farmers from planting a variety of crops side-by-side. Each crop needs a different kind of care, and each plant can’t get individualized attention when farmers are speeding over the land in a tractor. So, larger farms often have to be filled with a single crop, a technique known as monocropping.

Unfortunately, natural variety is precisely what keeps the soil fertile. Without variety, farmers can only keep their land fertile by smearing it with fertilizers. But the industrial process that produces artificial fertilizer is energy-intensive, and powered by fossil fuels.

So to summarize: large, monocropped farms are inherently fossil fuel-intensive. For anything to grow at all, farmers have to soak their fields with oil-based fertilizers, using oil-powered machinery. Although smaller farms are not always more sustainable, they are far more likely to be, since they tend not to run into the “less time per acre” problem that larger farms have.

But if large farms are so unsustainable, why are there so many of them?

Agriculture vs. Food: Farm Policy

American farm policy is theoretically designed to maximize food production. Instead, by driving farm consolidation and the climate change that comes with it, it has actually become a threat to the United States’ ability to produce food in the medium-to-long term.

Farm subsidies are payments that the federal government issues to farmers who grow certain kinds of crops, mainly corn and soy. In theory, subsidies encourage farmers to grow more food than they would under free market conditions, preventing food shortages. 

Unfortunately, subsidies do something else too: they underwrite the consolidation of increasingly large farms. A full 75% of subsidies end up in the pockets of those who own the very largest farms—the top 10%. And the problem is only getting worse.

That means that in the United States, the federal government is spending $20 billion in subsidies every year—more than the entire GDP of Iceland—to support the kind of agricultural practices that could lead to food shortages in only a few decades.

The reason subsidies drive consolidation is relatively simple. Subsidies make land more valuable, since it can rake in federal cash. More valuable land is more expensive. The problem is that arable land is so expensive now that only the biggest farms can afford to buy any at all. After all, the biggest farms are the richest, partly because they get more subsidies.

Eventually, smaller farms get outcompeted and the giants swallow them. Simply put, the federal government is telling farmers to go big or go home, with the perverse effect of undermining the food security of the United States.

Avoiding Climate Famine

There is no reason why Americans should starve. The worst-case scenarios for food production can still be avoided by making deep cuts in our greenhouse gas emissions. Part of that has to happen on the farm, where federal subsidies lead to farm consolidation, and consolidation leads to carbon-intensive farming practices.

The easiest first step would be to abolish the farm subsidies driving the entire process. But we can’t stop there, or we would deprive countless farmers of an economic lifeline. Instead of our current, harmful subsidies, we should offer subsidies and tax breaks to farmers engaging in sustainable practices, namely those that limit the use of large machinery and artificial fertilizers. Most importantly, we should provide financial support to farmers who own only small quantities of land. We might even consider funding the subsidies through heightened property taxes on the larger farms.

Biden is poised to act on climate change, but he isn’t going to change farm subsidies. That’s because changing farm policy is politically challenging. Big grain buyers like Cargill help write farm laws, and they love corn subsidies, because increasing the supply of corn only makes the corn cheaper for them to buy.

But the giants of the agricultural industry can only get away with jeopardizing the United States’ food supply if we keep letting them. We have to demand something better.

There are two possible futures for America. One is wracked by famine, the other is not. One is a sea of monocropped corn crawling with tractors belching carbon dioxide into the air and spraying chemicals on the ground. The other is full of small, sustainable farms, of community and connection to the land, of abundant farm jobs, and of fresh and healthy food for all. It’s up to us which one we choose.