Rice yields to plummet and arsenic to spread due to climate crisis, study says

1 Nov 2019

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A new study suggests that changes in soil as a result of the climate crisis could lead to worrying news for future rice yields.

Yields of the world’s largest staple crop could plummet by almost half as a result of soil drastically changed by the onset of the climate crisis.

That was the finding of a new study published in Nature Communications by a team of Stanford University researchers that wanted to see how rice would grow in scenarios where soil would change based on future climate predictions.

The experiments showed that rice yields could drop about 40pc by 2100, which would not only devastate parts of the world reliant on the crop, but also suggested the rice that does manage to grow would have twice the amount of toxic arsenic than today.

“By the time we get to 2100, we’re estimated to have approximately 10bn people, so that would mean we have 5bn people dependent on rice, and 2bn who would not have access to the calories they would normally need,” said co-author Scott Fendorf.

“We have to be aware of these challenges that are coming so we can be ready to adapt.”

While many food crops today contain small amounts of arsenic, some growing regions are more susceptible than others. Rice was the focus of this study because, as it is grown in flooded paddies, it is more susceptible to loosening arsenic in the soil making its way into the grains.

A shocking discovery

In the experiments, the team based its ‘future’ soil on estimates of a five degrees Celsius global increase and twice the amount of atmospheric CO2 as predicted by 2100. This was the first study to account for soil conditions in a changing climate, rather than just an increase in temperature.

Medium-grain rice was grown in soil obtained from California within greenhouses tuned to the possible future scenario, including increased arsenic. This is due to its build-up in soils from irrigating crops with arsenic-contaminated water, a problem that is worsened by over-pumping groundwater. This revealed the 40pc decrease in yield, something Fendorf admitted came as a shock.

“I just didn’t expect the magnitude of impact on rice yield we observed,” he said.

“What I missed was how much the soil biogeochemistry would respond to increased temperature, how that would amplify plant-available arsenic, and then – coupled with the temperature stress – how that would really impact the plant.”

Despite serious concern for future yields, Fendorf said he was optimistic that in addition to this research shining a light on the massive issue at hand, there is hope rice varieties could be bred capable of withstanding these changes.

Last month, researchers announced the creation of a new super hormone that could offer hope for drought-proof crops.

Colm Gorey was a senior journalist with Silicon Republic