Climate change lowers global crop yields, even with adaptations

Science Editorial, June 18 (EFE).- Rising global temperatures will reduce the world's capacity to produce food from most staple crops, even after taking into account economic development and farmers' adaptation to the new circumstances.

A study published in Nature and led by Stanford University (USA) estimates that each additional degree Celsius of global warming will, on average, reduce the world's capacity to produce food by 120 calories per person per day, or 4.4% of current daily consumption.

“If the climate warms 3 degrees, it’s basically as if everyone on the planet gives up breakfast,” a high cost for a world where more than 800 million people sometimes go a day or more without food due to lack of access, said Solomon Hsiang, one of the authors of the article, quoted by Stanford University.

The study modeled the yield of six staple crops—wheat, maize, rice, soybeans, barley, and cassava—under various warming and adaptation scenarios.

By 2050, climate change will reduce crop yields by 8%, regardless of whether carbon dioxide emissions increase or decrease in the coming decades. Carbon dioxide emissions remain in the atmosphere, trapping heat and causing damage for hundreds of years.

By 2100, the authors estimate that global crop yields will decline by 11% if emissions rapidly fall to net zero and by 24% if they continue to rise unchecked. The study is based on observations from 12,658 regions in 55 countries and analyzes the adaptation costs and yields of the six crops that provide two-thirds of humanity's calories.

Models suggest a 50% chance that global rice yields alone will increase on a warmer planet, largely because the crop benefits from warmer nights.

However, the chances of yield declines by the end of the century range from 70% to 90% for each of the other staple crops.

Under a high-emissions scenario, corn production could decline by up to 40% by the end of the century in the US, East China, Central Asia, Southern Africa, and the Middle East, while wheat losses range from 15% to 25% in Europe, Africa, and South America, and 30% to 40% in China, Russia, the US, and Canada.

As a novelty, this study takes into account farmers' realistic adaptation to changing conditions, assuming either "perfect" adaptation or none at all.

Thus, in many regions, for example, crop varieties are changing, sowing and harvesting dates are changing, or fertilizer use is changing.

The team estimates that these adjustments offset about one-third of climate-related losses in 2100 if emissions continue to rise, but the remainder remains unchanged. Any level of warming, “even accounting for adaptation, leads to losses in global agricultural production,” said Andrew Hultgren of the University of Illinois (USA).

The steepest losses are occurring at the extremes of the agricultural economy: in modern breadbaskets that now enjoy some of the best growing conditions in the world, and in subsistence farming communities that depend on small cassava crops.

A favorable climate, he added, goes a long way toward keeping farmland productive from generation to generation, “but if you let the climate depreciate, the rest is a waste. The land you leave your children will be good for something, but not for farming,” Hsiang said.