Adam Minter

Pollution's Impact on China’s Crops Is Worse Than Imagined

China is turning back to low-cost coal to boost its ailing economy. It's an understandable reaction to the toll caused by Covid lockdowns. But it will come with a steep price for the environment and the health of its citizens.

It's also likely to worsen food insecurity in China just as the world is trying to fend off a global food crisis that's emerged as a result of the global pandemic and the war in Ukraine.

These bleak consequences were laid out in a new peer-reviewed study showing how gases associated with the burning of fossil fuels inhibit crop growth worldwide. The impact on China's crops is greater than on any other region surveyed, and could account for at least a 25% decline in winter crop yields. Adding more fossil-fuel pollution to Chinese air will only depress crop yields further, pressuring farmers, prices and — ultimately — food consumers.

For more than a century, botanists have been documenting the many ways air pollution has negative effects on plant growth. For example, nitrogen oxides, a common pollutant associated with burning fossil fuels, inhibits photosynthesis. These impacts aren't simply confined to factory landscaping. Farmers and researchers have noticed the same impacts on crops.

For example, last year, researchers examined the impacts of air pollutants on corn and soybean production in nine US states between 1999 and 2019. The results were bleak: an average loss of about 5% of corn and soybean production attributable to air pollution over two decades. Notably, yields increased with distance from power plants, many of which burned coal.

Yet there was also an important silver lining in those black clouds. Thanks to the Clean Air Act, the US experienced significant air-quality improvements during the study period. Those improvements, in turn, accounted for roughly 20% of the overall soybean and corn yield gains achieved by US farmers during those same fertile decades.

Unfortunately, pollution — and crop yields — are growing worse in many parts of the world. Emerging markets provide some of the bleakest examples.

A recent survey of Indian air quality and crop yields between 1980 and 2010 — a period of intense growth and pollution — found that wheat yields were 36% lower than they should've been without the combined effects of climate change and pollutants like ozone and particulates. In some densely populated Indian states, yield losses were as high as 50%.

China has not fared much better. As far back as the 1990s, researchers estimated that haze depressed yields for roughly 70% of the crops grown in China.

In 1999, a set of researchers went so far as to warn that ground-level ozone, the byproduct of nitrogen oxides and other pollutants, “could hinder efforts to meet increasing food demands in the coming decades.” Two decades later, researchers determined that ozone pollution caused annual yield losses of 33%, 23% and 9% for wheat, rice and corn, respectively.

That's an ominous outcome for a country in which hunger remains a living memory for older generations. Xi Jinping, among other Chinese leaders, has long been determined to prevent them from experiencing it again.

Among his first initiatives as China's leader was a campaign encouraging his compatriots to clean their plates and avoid food waste. As tensions with the US, a major food supplier to China, have escalated, Xi has prioritized food security. Late last year, for example, he told a meeting of China's top leaders that “the food of the Chinese people must be made by and remain in the hands of the Chinese.”

That's easier said than done. Among other problems, China's arable land has been shrinking for decades thanks to the growth of its cities. The authorities have worked hard to counteract these losses.

For example, Bloomberg recently reported that China is contemplating a ban on further placement of solar panels on farmland. The goal is to boost food production, even if it comes at the expense of the country's renewable-energy goals.

But that quest to boost food production is also happening just as China is boosting its fossil-fuel industry. In May, Premier Li Keqiang ordered that “China unleash domestic high-quality coal production capacity” so as to safeguard energy supplies.

Not long after, China scaled back its five-year plan for renewable energy, lowering its targets for renewable power generation. If, in fact, China does boost coal-based power production, depressed crop yields will be among the costs.

For now, it's unlikely that China or any other country will tackle air pollution for the sake of more wheat. But in the long term, the data is quite clear that pollution reductions can make a difference in feeding people. For example, Science Advances published a study a month ago suggesting that a 50% reduction in air pollution in China could lead to a 25% boost in winter crop yields, and 15% for summer ones.

As the world searches for ways to provide enough food for everyone, cutting back on coal and other fossil fuels is a natural place to start.