Agriculture’s ‘Green Revolution’ is now turning to climate change

A sweltering heat wave decimated Pritam Singh’s wheat crop in 2022.

That year, temperatures reached a record-breaking 127 degrees Fahrenheit in Haryana, India, where Singh operates a 35-acre farm. The scorching heat shrivelled the wheat and forced it to mature faster, he recalled, leading to just half of his usual harvest. Across India, the heat wave caused wheat production to plummet by 3 million metric tons, and the states of Punjab and Haryana reported stunted grain yields as well. This led the government to halt wheat exports to manage domestic food security. 

But two years later, even though temperatures were the highest they’d been in more than a decade, Singh was much more optimistic when he planted his seeds. That’s because the Mexico-based International Maize and Wheat Improvement Centre, known by its Spanish initials CIMMYT, had worked with local partner organizations to distribute cost-free buckets of climate-resilient seeds to Singh and millions of farmers like him across the country. The hardier seeds, currently sown across 40 million hectares, had been crossbred to survive harsh heat and minimal rainfall, ensuring that Singh wouldn’t suffer the devastating loss of 2022.

“The per-acre wheat production in 2024 exceeded all expectations,” he told Grist, attributing his success to the new seeds, which he received ahead of the sowing season in October.

The project was a continuation of long-running efforts by CIMMYT, which has been developing high-yield crop varieties using conventional breeding techniques since 1943. Here’s how it works: Researchers at the organization select wheat varieties with genes known to weather pest attacks and fare well in extreme climates. These varieties then become the “parent crops” that are bred together to create more resilient strains. Plants with desirable genetic traits are intercrossed and planted for several cycles before the best specimen is selected among hundreds of thousands of plants. (This is distinct from genetic modification, which involves editing or injecting DNA into the genome of an organism; CIMMYT does use some genome editing techniques in some of its other efforts, mainly to improve the resilience of maize.)

The organization was founded by Norman Borlaug, a Nobel Prize-winning agronomist whose work launched the so-called Green Revolution, which dramatically increased crop yields around the world. Their initial trials — funded by the Mexican government and the U.S.-based Rockefeller Foundation — helped Mexico become self-sufficient in its wheat production by the 1950s. 

Since then, the organization has been shipping conventionally-bred grains to developing countries through nonprofit organizations, agricultural universities, and other regional partners in 88 countries. It manages one of the world’s largest collections of maize and wheat genetic resources. Through its breeding program, it has developed about two-thirds of the wheat varieties and a third of the maize varieties grown worldwide.

Now, the same techniques that fed the exploding global population of the twentieth century are being used to adapt agriculture to one of the most serious threats of the twenty-first. Since 2011, the organization has turned toward developing maize and wheat strains that can withstand the erratic weather and higher temperatures unleashed by climate change. CIMMYT-India works in tandem with institutions such as the Indian Institute of Wheat and Barley Research, the International Rice Research Institute, and the Indian Council of Agricultural Research, says Ravi Singh, a retired scientist associated with CIMMYT. Its roster also includes provincial government institutions and private companies working on wheat breeding.

Such efforts are becoming increasingly important as heat waves become longer and more persistent in certain parts of the world. In India, temperatures that usually rise at the end of May have begun soaring weeks earlier. Northwestern Indian states like Punjab and Haryana typically experience five to six heat wave days per year, but the country’s meteorological department has forecast roughly twice that number this year.  

The higher temperatures are likely to stymie wheat growth in the region. Today, the area’s wheat meets the nutritional needs of 35 percent of the world’s population. A recently published study has estimated that, for every additional degree Celsius increase in average global surface temperature, the world’s farms will produce 120 fewer calories per person per day due to lower yields of staple crops. This projected loss is particularly severe for wheat-producing regions in northern India. As the world’s second-largest wheat producer, India’s threatened yields could have far-reaching economic as well as nutritional consequences. 

A critical concern is protecting the “grain-filling” phase, when a wheat plant moves nutrients from its leaves to the husk as it prepares to germinate. But grain-filling stops when temperatures get too high, yielding grains smaller than those grown in cooler conditions, according to experiments conducted by the University of Adelaide’s Scott Boden, who studies flowering times and grain quality in Asian wheat. 

Data measuring wheat growth in northern India shows that the crop is particularly sensitive to climate change; temperatures above 30 degrees Celsius (86 degrees Fahrenheit) are expected to slow the grain-filling phase. This has prompted hot-weather countries like India to increasingly turn to crop varieties bred especially to withstand such uncertainties. Last August, the Indian government introduced 109 climate-resilient, nutritionally rich crop varieties, which Velu Govindan, a senior wheat breeding scientist at CIMMYT, said were developed by the organization. 

Those breeds were only the latest in a long line of innovations. As of October 2024, nearly 2,600 varieties had been released over the past decade by The Indian Council of Agricultural Research, an autonomous body under the Ministry of Agriculture that CIMMYT works closely with.  More than 80 percent of them were found to fare well against climate stressors. 

Since the 1960s, CIMMYT has been working to identify genes that determine how crops — principally wheat and maize — react to heat and drought stress. At its facility in Mexico, CIMMYT tests thousands of crossbred varieties under conditions designed to replicate heat waves and drought, Govindan said. 

“We look for the genes constructing the stress factors [and] use that information to carefully decide on which parents to cross,” he said. 

In developing the resilient varieties, the organization first conducts trials in the labs and then in the fields, where checks for disease resistance, heat, and tolerance are carried out — some spanning two or three years. After the varieties are shared with regional partners, they carry out additional testing at multiple field sites, which can sometimes take another couple of years. 

Despite these efforts, there are some factors that even CIMMYT cannot control, which might impede the success of these varieties. These can range from a new pathogen that can overcome the deployed resistance genes — or even farmers refusing to shift away from a well-known crop variety, said Ravi Singh, the retired scientist. 

The 400-plus varieties that perform best are shipped to partner organizations in South Asia and Africa, who then disseminate buckets of seeds to farmers like Pritam Singh for free. For his part, Singh takes a hybrid approach. The farmer has been experimenting with various wheat varieties for nearly two decades, relying on advice and seeds from academic experts, but also on his knowledge of local conditions. 

In the 1960s, under the guidance of the geneticist M.S. Swaminathan, India welcomed the Green Revolution to increase agricultural production by using high-yielding crop varieties to alleviate malnutrition in the country. While it achieved its goals of heightened grain production and lower food costs, the Revolution has been criticized for encouraging monocropping and high pesticide consumption, which left a lasting impact on the soil. It also excluded large numbers of smallholder farmers who could not afford new seed varieties or pesticides.

This is a gap that CIMMYT hopes to address, and the organization says it intends to help small-scale farmers such as Pritam, who otherwise would not have access to hardier seeds engineered for climate resilience. 

But the region remains plagued by myriad issues that CIMMYT seeds alone cannot fix. Parched soil is contributing to crop loss, as droughts have reduced water retention in topsoil and made it harder for essential nutrients to reach the grains, according to Gurpreet Dabrikhana, a Punjab-based advocate for organic farming. Dabrikhana worries that CIMMYT’s approach doesn’t adequately consider variations in local soil conditions and could ultimately speed degradation of topsoil. “These approaches are very crop-centric, and not soil-centric,” he said.

More than 5,000 miles away in South Africa, the plant pathologist Norman Muzhinji, who teaches at the University of Free State, told Grist that the country’s institutions have collaborated with CIMMYT “in adopting and adapting conventionally bred, high-yielding, and climate-resilient crop varieties to meet food security and smallholder farmer needs.”

This year, even temperatures at 46 degree Celsius did not derail Pritam Singh’s crop — a welcome departure from the calamity of 2022, when temperatures spiked up to 50 degree Celsius. But he is quick to acknowledge that luck is also a factor in his recent success: Intermittent rain spells offered a much-needed respite.

In some recent years, even the crossbred seeds he’s planted have been unsuccessful, costing him thousands of rupees in crop losses. This makes Singh skeptical: “The breeder varieties [from CIMMYT] can withstand two or three degrees more heat than the regular strains, but what if the temperature grows higher?”