As world leaders converge in Glasgow to chart a new course of action to prevent the world from catastrophic climate change, the effects could be aggravated sooner than we anticipated. As extreme weather events become common across the world, climate change is set to hit the production of food crops by as early as 2030.

Production of maize (corn) and wheat could be affected by climate change as early as 2030 under a high greenhouse gas emissions scenario. The projected increases in temperature, shifts in rainfall patterns, and elevated surface carbon dioxide concentrations from human-caused greenhouse gas emissions will lead to a major change in crop yields.

Maize crop yields are projected to decline 24 per cent, while wheat could potentially see a growth of about 17 per cent.

In a study published in the journal Nature Food, scientists gave the new 21st century projections using ensembles of latest-generation crop and climate models. “The emergence of climate impacts consistently occurs earlier in the new projections-before 2040 for several main producing regions. While future yield estimates remain uncertain, these results suggest that major breadbasket regions will face distinct anthropogenic climatic risks sooner than previously anticipated,” the paper said.

Designing climate models

Scientists used two climate models to reach the conclusion. The first was climate model simulations from the international Climate Model Intercomparison Project-Phase 6 with their unique response of Earth’s atmosphere to greenhouse gas emission scenarios through 2100

The second was climate model simulations as inputs for 12 state-of-the-art global crop models that are part of the Agricultural Model Intercomparison and Improvement Project. The model simulates how crops grow and respond to environmental conditions such as temperature, rainfall and atmospheric carbon dioxide, which are provided by the climate models.

Researchers in all created 240 global climate-crop model simulations for each crop. “What we’re doing is driving crop simulations that are effectively growing virtual crops day-by-day, powered by a supercomputer, and then looking at the year-by-year and decade-by-decade change in each location of the world,” said Alex Ruane, co-author of the study.

Maize, wheat to be affected

Corn is grown across the world and large quantities are produced in countries close to the equator. North and Central America, West Africa, Central Asia, Brazil, and China will potentially see their maize (corn) yields decline in the coming years and beyond as average temperatures rise across these breadbasket regions, putting more stress on the plants.

Nasa, which provides the satellite observations of the planet, reported that temperature is not the only factor the models consider when simulating future crop yields. Higher levels of carbon dioxide in the atmosphere have a positive effect on photosynthesis and water retention, increasing crop yields, though often at a cost to nutrition. This effect happens more so for wheat than maize, which is more accurately captured in the current generation of models.

Meanwhile, wheat, which is grown in a temperate climate, may see a broader area where it can be grown as temperatures rise, including the Northern United States and Canada, North China Plains, Central Asia, Southern Australia, and East Africa, but these gains may level off mid-century.

“We did not expect to see such a fundamental shift, as compared to crop yield projections from the previous generation of climate and crop models conducted in 2014. A 20 per cent decrease from current production levels could have severe implications worldwide,” said Nasa’s Jonas Jagermeyr, a crop modeler and climate scientist who led the study.