Severe flooding has slashed global rice yields in recent decades, threatening food security for billions of people who depend on the grain. The losses amounted to approximately 4.3%, or 18 million tons of rice per year, between 1980 and 2015, according to research from Stanford University published November 14 in Science Advances.
Damage has accelerated since 2000 due to more frequent extreme floods across major rice-growing regions, a trend likely to be exacerbated by climate change, the researchers found.
Scientists and farmers have long understood that rice yields suffer during droughts. The new study adds to evidence of that damage, finding that droughts reduced rice yields by an average of 8.1% per year during the 35-year study period. But it also highlights a less studied threat. Although rice crops benefit from shallow flooding during early growth stages, too much water for too long can be devastating.
“While the scientific community has focused on damage to rice yield due to droughts, the impacts of floods have not received enough attention,” said Steven Gorelick, the study’s senior co-author and a professor of Earth system science in the Stanford Doerr School of Sustainability. “Our research documents not only areas where rice yields have suffered due to past flooding, but also where we can anticipate and prepare for this threat in the future.”