This article in the FT is a year old but a very concerning read.
After decades of rapid growth thanks to the development of new varieties, yields are stagnating in four big rice-producing countries in south-east Asia, according to a recent study in Nature Food, an academic journal. Globally, on average yields increased 0.9 per cent a year between 2011 and 2021, a slowdown from 1.2 per cent a year between 2001 and 2011, according to data from the UN.
The chief reason for this setback is climate change. Because rice grows in hot climates — 90 per cent of the world’s rice is produced in Asia — it is often assumed that a few extra degrees will not matter, says Bjoern Ole Sander, a climate scientist based in Thailand. This is not the case. Above certain temperatures, rice yields drop, explains Sander, adding that the grain is particularly sensitive to night-time heat.
A 2017 study found that a global increase in temperature of 1C was likely to reduce rice yield by an average of 3.3 per cent. Temperatures have already risen by at least 1.1C since pre-industrial times.
Modelling by commodity data group Gro Intelligence forecasts that by 2100, Asia’s top rice exporters will all experience a sharp increase in the number of days above 35C, with Thailand potentially seeing an 188 additional days above this threshold in a worst-case scenario.
For Asia’s rice-producing deltas, from the Mekong to Ganges, climate change could present other complications. As temperatures increase, sea levels rise and salty water flows into fresh water rivers, irrigation channels and the soil, reducing yields or making growing impossible.