Warmer temperatures, changed precipitation patterns and more CO2 in the atmosphere: Climate change affects the growth of plants in a variety of ways. Using the latest generation of climate models, researchers have now modeled how the predicted climate changes could affect the yields of maize, soy, wheat and rice. The results are more precise but also more pessimistic than previous predictions. According to this, serious yield losses are to be expected within the next twenty years, especially with maize. Wheat, on the other hand, could initially benefit from additional cultivation areas and more CO2 in the atmosphere.
Climate change is already influencing agricultural productivity today: extreme weather events such as droughts and floods are becoming more likely, rising temperatures shift the regions in which certain crops can be grown and increased CO2 concentrations in the atmosphere affect the growth of plants. On several occasions, researchers have already made various forecasts of how climate changes will affect crop yields and thus the future nutrition of the world population. However, each of the estimates was fraught with great uncertainty.
Bad outlook for corn
A team led by Jonas Jägermeyr from the NASA Goddard Institute for Space Studies in New York has now combined the latest climate models from the IPCC with simulations that show how important crops react to different climatic conditions. For corn, soy, wheat and rice, Jägermeyr and his colleagues modeled how the harvests could develop in different climate scenarios by the end of the century. Since the current climate models are much more precise than their predecessors, the statistical uncertainty in predicting future crop yields is also lower than in previous studies. To make their results as reliable as possible, the researchers performed their calculations using numerous different combinations of climate and harvest models.
“We did not expect that the predicted crop yields would change that fundamentally compared to the forecasts of the previous generation of climate and harvest models from 2014,” says Jägermeyr. While earlier, less precise models had suggested that corn yields would remain largely stable and possibly even increase slightly, the current study comes to the conclusion that, in the worst case, yields could decline by up to 24 percent by the end of the century. “That could have serious consequences worldwide,” said Jägermeyr. In terms of production volumes, maize is currently the most important grain worldwide and is crucial for food security in many regions of the world.
Wheat production could increase initially
The outlook for wheat, the world’s second most important grain, is more optimistic. The estimates assume an increase in income of up to 18 percent. “This is because wheat can benefit more than maize from a higher CO2 content in the atmosphere and that global warming is opening up new cultivation regions,” the researchers explain. It should be noted, however, that the accelerated growth of wheat plants due to more CO2 and higher temperatures is not only positive. Because if the plant grows too quickly, it can store fewer nutrients. It produces its grains faster, but they stay smaller and have less nutritional value. In addition, according to the models, wheat yields only rise until the middle of the century and then fall again, partly due to poorer water availability.
For rice and soy, the models are less clear: In some regions, yields will decrease, in others, however, increase, so that global production is likely to change only slightly over the course of the century. In the case of corn and wheat, on the other hand, changes are forecast to occur more quickly than previously thought. “The study determines the point in time when the climate impacts occur as a critical measure for risk assessment,” explains Reimund Rötter from the University of Göttingen, who was not involved in the study. “The study indicates that the ‘Time of Emergence’ (TCIE) for the global negative productivity change in maize can occur from 2032 onwards. For temperate climate zones – 81 percent of the total production – this date is calculated from 2037. This ‘worst case’ information is new from my point of view. “
Time is running out
Matin Quaim from the University of Bonn, who was also not involved in the study, emphasizes that there is little time left to meet the challenges of climate change for agriculture. “The pressure to act quickly and decisively is growing massively. Without significant changes, regional supply bottlenecks and starvation can very easily arise, ”says the agricultural economics professor. A top priority is to stop climate change as best we can. “At the same time, however, we also have to quickly develop and implement adaptation strategies for agriculture.”
Jägermeyr and his colleagues did not consider such adaptation strategies in the current study. From Quaim’s point of view, among other things, green genetic engineering could offer an opportunity to produce plants in good time that can cope with the changed climatic conditions. “New breeding methods – such as gene scissors – can help to make plants quickly and specifically more resistant to heat, drought and other climatic stress. We should quickly overcome widespread prejudices here, because these technologies offer great potential for contributing to sustainability and resilience in agriculture. “
Source: Jonas Jägermeyr (NASA Goddard Institute for Space Studies, New York) et al., Nature Food, doi: 10.1038 / s43016-021-00400-y