Higher temperatures, more frequent and longer droughts, catastrophic rainfall events and rising atmospheric carbon dioxide levels all influence the growth, development and reproductive viability of crop plants, he writes. While some plants and regions may benefit from some aspects of climate change, without prolonged and costly intervention, many more will suffer potentially catastrophic declines.
"By 2050-60, crops will experience a significantly different environment from today," Long writes. From its pre-industrial level of about 200 parts per million, "atmospheric CO2 reached 427 ppm in 2024 and is projected to be about 600 ppm by 2050."
Extreme heat, droughts, floods and other climate-related events are already disrupting agricultural systems. Projected temperature extremes and climate instability will further reduce crop yields, increasing starvation, political unrest and mass migration, he writes.
There is some hope, however. It may be possible to alter crops in ways that allow them to persist and perhaps even increase yields despite the challenges, Long said. While the process takes time and can be costly, the work has already begun.
For example, researchers are evaluating the heat-, drought- and flood-tolerance of different varieties of specific crop plants, identifying those with potentially beneficial attributes. Discovering the genetic traits that confer these benefits will allow scientists to develop crops - through plant breeding and/or genetic engineering - that can better withstand the extremes.
Through painstaking work, scientists have discovered that some rice varieties can survive up to two weeks of submergence during periods of intense flooding, while other varieties are more heat tolerant than others. The findings offer opportunities to develop hardier cultivars.
Plants must withstand an array of challenges as temperatures rise. The drying capacity of the atmosphere, which increases with temperature, draws moisture out of plant leaves through tiny pores called stomata. This reduces plant water-use efficiency, Long said, straining already scarce water resources in many parts of the globe.
"A plant may partially close its stomata to retain moisture, but this can interfere with its ability to draw carbon dioxide from the atmosphere, a key step in photosynthesis," Long said.
In laboratory and field experiments, researchers found that increasing the expression of the gene for a sensor protein found in plants reduced water loss through stomata without interfering with photosynthesis.
"The result was a 15% improvement in leaf-level water-use efficiency in field-grown tobacco and a 30% decrease in whole plant water use," Long wrote. Because of the high speed with which it can be genetically modified, tobacco is often used as a "test-bed" for studying alterations that can be used in a variety of other plants.
Researchers also have found ways to reduce the density of stomata on the leaves of rice and wheat, improving water-use efficiency by 15-20% with no decrease in yield.
High carbon dioxide on its own alters plant physiology, sometimes in beneficial ways by boosting photosynthesis, but also in detrimental ways, Long said. High CO2 can change plant metabolic control by altering levels of key enzymes. Scientists have found that adjusting the levels of proteins that regulate rubisco, a key photosynthetic enzyme, can boost photosynthetic efficiency in the presence of high CO2.
To demonstrate what kinds of gains are possible in food crops, Long points to the remarkable progress made in research on maize, nearly 80% of which is used in ethanol production and to feed animals, not humans.
"Between 1980 and 2024, U.S. maize yields doubled while sorghum improved just 12%," he said. The success in maize is the result of massive investments from large multinational companies. The same investments are not yet being made on the public domain side of the equation.
Without similar investment, "it is hard to see how the opportunities ... for future-proofing our crops can be implemented at the scale that is necessary," he writes.
Long also is a professor in the Carl R. Woese Institute for Genomic Biology at the U. of I. He is supported by Gates Agricultural Innovations and the Department of Energy Center for Advanced Bioenergy and Bioproducts Innovation.
Research Report:Needs and opportunities to future-proof crops and the use of crop systems to mitigate atmospheric change
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