Rising atmospheric CO2 could widen inequalities in rice production between high- and low-income countries

Rice production is crucial to the survival of millions of people around the world, many of whom live in countries beset by severe poverty and malnutrition. A study recently published in the journal Nature Foods warns that increased concentrations of carbon dioxide (CO₂) in the atmosphere and rising temperatures are exacerbating differences between the rice yields of high- and low-income countries. Led by an international team of which CREAF and CSIC were part, the study shows that projected increases in CO₂ levels up to 2090 will lead to growth in rice production in high- and middle-income countries, such as China, Japan and Vietnam, whereas yields in countries like India, Bangladesh and Indonesia could stagnate or even decline. Furthermore, as the study points out, research has already demonstrated that climate change is reducing the nutritional quality of rice, painting an even gloomier picture for low-income countries.

Global rice production is set to rise by 7.6% by the 2050s, driven by the CO2 fertilization effect. However, there will not be a uniform increase across the planet

The study’s results are based on data from field experiments that replicated high CO₂ concentrations, and on crop model data for the 14 countries that account for 90% of all rice production. According to the research team’s analyses, global rice production is set to rise by 7.6% by the 2050s, driven by the CO₂ fertilization effect. However, there will not be a uniform increase across the planet; the scale of any improvement will depend on the rice variety grown in each region. For instance, varieties cultivated in higher-income areas of the world, such as japonica rice, which is grown at high latitudes, will benefit from the CO₂ fertilization effect. In contrast, there will be no such benefit for the indica variety, which is typically sown in low-income countries and at low latitudes, where temperatures will be even warmer and the positive impact of CO₂ fertilization will be cancelled out. 

“Low-income countries are likely to bear the brunt of climate change’s repercussions for rice production”.

JOSEP PEÑUELAS, CREAF-based CSIC research professor and one of the study’s co-authors.

"Our results are a warning that it is vital to invest in strategies to help the countries involved adapt, including developing rice varieties that are more resistant to climate change and improving agricultural practices."

Less nutritious rice

The study by no means suggests that high CO₂ concentrations are inherently good for global rice production. Other research has shown that high levels of CO₂ can diminish the nutritional quality of staple crops like rice and wheat, causing reductions in grains’ protein content, vitamins and essential minerals, a further complication in the fight against global malnutrition, especially in low-income countries.

The study’s results merely indicate that disparity in the way CO₂ fertilization affects the rice yields of low-income countries and of middle- to high-income countries could grow throughout this century, potentially intensifying such nutritional concerns. “With that in mind, we emphasize the need to undertake more research to discover how to harness CO₂ fertilization to increase rice yields while tackling the associated fall in nutritional value,” remarks Peñuelas. 

International aid and knowledge transfer 

The study proposes three actions: promoting advanced agricultural practices and developing climate-resilient crop varieties, supporting research, and promoting global cooperation.

The growing disparity identified in the study has prompted the research team to make a number of recommendations for curbing food insecurity and narrowing economic gaps worldwide. Their suggestions include three measures to be implemented in low-income countries: promoting advanced farming practices and developing crop varieties resilient to climate change; providing international capital to fund research and improve agricultural development; and fostering global cooperation by sharing knowledge and resources. 

“We hope that studies like ours will influence international efforts to combat hunger and poverty all over the planet,” states Peñuelas. “Society needs to be aware that, as the world faces up to the challenges of climate change, producing critical food sources like rice will become more and more of a problem, one that we cannot afford to ignore,” he concludes. 

Scientific article: Song, L., Tao, Y., van Groenigen, K.J. et al. Rising atmospheric carbon dioxide concentrations increase gaps of rice yields between low- and middle-to-high-income countries. Nat Food (2024). https://doi.org/10.1038/s43016-024-01021-x