Extreme rainfall impacts China’s rice yields, study reveals

Extreme rainfall has reduced China’s rice yields by 8% over the past two decades, according to a study led by researchers from the country. The research, published in the peer-reviewed journal Nature Food, discovered that the effects of extreme rainfall on rice yields were similar to those of extreme heat. Projections show that by the end of this century, extreme rainfall could decrease rice yields by an additional 7.6% in China, on top of other climate change impacts such as global warming and increasing carbon dioxide emissions.

Jian Yiwei, the study’s lead author and a Ph.D. candidate at Peking University, emphasized that extreme weather events are likely to become more intense in the future, posing significant challenges to agricultural productivity. The study aims to help people understand the effects of extreme events on crop production, and how scientific and practical measures can be implemented to counter these occurrences.

According to the sixth Synthesis Report from the UN Intergovernmental Panel on Climate Change (IPCC) released in March, climate change is likely to have slowed agricultural productivity across the globe in the past 50 years. This has resulted in food insecurity in Africa, Asia, Central and South America, and other vulnerable regions.

China, being one of the most populous countries, is already facing the negative impacts of global warming, which include rising sea levels, harsher weather occurrences, and melting glaciers. The Ministry of Water Resources predicted in March that China’s southern region would experience frequent flooding and droughts during its annual flood season this year, with some areas encountering more severe extreme events.

Tensions and deteriorating relationships with the United States and its allies, many of which are leading agricultural suppliers, have further raised concerns about food security in China. President Xi Jinping emphasized in December that agriculture is the foundation of national security, and urgent attention must be given to addressing low productivity and other weaknesses.

Previous research primarily focused on the impacts of drought and extreme heat on crop yields. However, Jian Yiwei noted that there is limited research on the effects of extreme rainfall on yields, and their impact remains largely unclear.

The study authors used hourly rainfall data collected from nationwide observations and found that yield reductions due to extreme rainfall were comparable to those caused by extreme heat and larger than the reductions related to drought, extreme cold, or other extreme events, reports Channel News Asia.

In 64 rainfall control experiments conducted between 2018 and 2019, the researchers discovered that extreme rainfall reduced rice yields in China by diminishing available soil nitrogen and physically damaging rice plants’ panicles, hindering grain production. Wang Xuhui, the study’s lead author and a researcher at Peking University, explained that climate change is commonly associated with rising temperatures, but its effects also include the increase in frequency and intensity of extreme rainfall events.

The authors of the study concluded, “These findings demonstrate that it is critical to account for extreme rainfall in food security assessments.”