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Research reveals that seasonal drought could reduce yields of three major grains — rice, wheat and corn - with corn suffering the most
Food production systems are particularly vulnerable to adverse impact of climate change, and it is one of the key factors affecting food security in China. Rising temperature reduces the growth period of grains leading to yield reduction on an average, while frequent seasonal drought places stress on water supply for irrigation. Safeguarding food security, particularly the food production systems, from the adverse impacts of climate change is a fundamental priority under the 2015 Paris Agreement.
In the case of China, seasonal drought could lead to substantial losses. Our research reveals in the worst scenario seasonal drought could result in losses of nearly 8 percent by 2030, in yields of three major grains —rice, wheat and corn. Corn yields are likely to suffer the most, estimated to drop by nearly one-fifth of total production, followed by wheat at 4 percent and rice at 1.5 per cent.
We obtain these results by assessing the impact of climate change on grain production and total land area sown in China by applying the Chinese Agricultural Policy Analysis model, in combination with agricultural census data.
Studies have shown climate warming can shorten the growth period of local crops through early flowering and fruit-bearing, leading to a reduction in dry matter accumulation, seeds’ weight, and the crop yields. Typically, a one degree Celsius increase in temperature in the full growth cycle can reduce the growth period of rice by nearly 4 days, wheat by 10 days and corn by 7 days.
The climate warming, though, has mixed results on grain production. On one hand, it shortens crop growth duration and causes yield decline, on the other hand, it generates abundant heat resources. China has developed several strategies to adapt to climate change, including adjusting cropping pattern, strengthening agricultural infrastructure, deferring sowing time to avoid high-temperatures or drought, water-saving techniques to increase the efficiency of water, and adopting mulching technology to prevent frost in late spring, but they aren’t enough to mitigate the adverse impact.
Our second scenario projecting the impact solely of climate warming reveals a drop in the yields of wheat, corn and rice by nearly 4, 3, and 2 per cent respectively.
The third scenario, modeling the adaptation technique of water-saving irrigation, reveals an increase in yields of corn, wheat and rice by nearly 10, 2 and 1 percent respectively. The fourth scenario, examines the impact of adoption of new crop varieties, and indicates a significant increase in corn, wheat and rice yields by nearly 12, 3 and 15 percent.
However, the fifth integrated scenario that combines both water-saving techniques and adoption of new crop varieties can offset reductions due to climate warming and seasonal drought, and even lead to higher yields. This integrated scenario considers both the negative impact of climate change as well as adaptation strategies; and is closer to what is likely to happen in the future, and thus holds significance for policymakers. In the integrated approach, grain production is likely to increase by one-fifth, with the biggest yield increase in rice by nearly 30 percent, corn 19 percent, and wheat 1.6 percent.
Research has shown adaptation practices are remunerative enough for farmers to adopt voluntarily. But, urgent steps need to be taken to upgrade China’s rural water infrastructure and promote breeding new varieties through research and agriculture extension services. Additionally, local governments should provide technical support to farmers to adjust crop selections from water intensive crops to drought-tolerant crops, especially in seasonal drought regions.
Man Li is a research fellow at the Environmental and Production Technology division at the International Food Policy Research Institute (IFPRI), based in Washington, DC.