Rising temperature may bring down rice production

Data collected from 227 irrigated rice farms in six Asian countries

Carefully analysing the pattern of increase in the maximum and minimum temperature, an international team of scientists and economists found that even a modest increase in minimum daily temperature could decrease rice production in the decades to come.

The researchers analysed data collected during 1994 to 1999 from 227 irrigated rice farms in six Asian countries – India, China, Thailand, Indonesia, Vietnam and Philippines – together which account for 70 per cent of the global rice supply and feed almost 40 per cent of Asia. Each country was represented by one location in the study.

The analysis may be crucial for India and China where not only the increase in minimum temperature is more than the maximum temperature, but the trend is likely to continue in the future.  

The researchers claim that the net effect of modest warming will be to decrease future rice yields, because climate projections indicate that minimum daily temperatures are likely to increase more rapidly than daily maximums.

The team comprising economists, farm scientists and environmentalists from both sides of the Atlantic note that the marginal beneficial effect of a higher maximum temperature would surely be offset by the rise in minimum temperature adversely impacting rice production.

Studies conducted so far did not take the difference in maximum and minimum temperature into account. They use average daily temperature to figure out the impact of global warming on climate change.

“Disentangling (the max-min temperature trend) is important, because temperature has been rising faster at night than during the day in much of Asia, and climate models indicate that this difference in trend is likely to continue,” lead author Jerry Vincent from Duke University, North Carolina, told Deccan Herald.

Higher maximum daily temperature may have boosted rice yields somewhat, but higher minimum daily temperature have had a stronger and opposite effect. However, the researchers conceded that conclusion drawn from the studies of irrigated rice fields may not be relevant for the country as a whole, which depend on monsoon for paddy cultivation.

“Rice production is not solely dependent on temperature. There are other factors. At the all-India level there is no comprehensive study showing the adverse impacts of the rise in average minimum temperature,” said an Indian weather scientist, who is not a part of the research team.

Another team member Jarrod Welch from the University of California, San Diego, said though the harmful effects of higher night time temperature was anticipated, their conclusion is on the basis of real-time data coming from farmer’s fields.