Rice paddies’ climate footprint has nearly doubled since the 1960s, researchers say
A new study says greenhouse gas emissions from rice paddies have nearly doubled since the 1960s. The findings underscore how critical it is to cut emissions without undermining yields from one of the world’s main staple crops.
Rice feeds more than half of the world, but a new research-based article in The Conversation argues that the crop’s climate cost is rising sharply. According to the study cited by the authors, greenhouse gas emissions from rice paddies have nearly doubled globally since the 1960s. In the 2010s, average emissions were estimated at about 1.1 billion tonnes of CO2-equivalent a year, which the article compares with the annual emissions of 239 million cars.
The researchers say rice growing has become the largest source of agricultural emissions outside livestock. The basic problem is that flooded soils create ideal conditions for microbes that release methane and other climate-warming gases. Demand for rice is still expected to increase, so the crop remains essential to food security even as its environmental footprint becomes harder to ignore.
The article identifies two main drivers behind the rise in emissions. The first is the expansion of rice area itself: the authors say just over half of the global increase came from bringing more land into rice production. In Africa, for example, rice area has roughly doubled since the 1960s, helping to drive a twofold increase in methane emissions. The second driver is intensification, with more fertiliser and organic amendments, more productive varieties and denser planting systems raising both output and emissions.
One practice highlighted in particular is leaving rice stalks in the field after harvest and ploughing them back into the soil. That improves soil fertility, but the article says it was responsible for about 18% of the increase in overall net emissions from rice production since the 1960s. Rising use of synthetic nitrogen has also added pressure: after 2000, nitrogen use increased by about 76%, lifting nitrous oxide emissions. Even intermittent flooding, while helpful for methane reduction, can slightly increase nitrogen oxide emissions as soils cycle between wet and dry conditions.
The authors argue that growers already have some room to improve. If the best currently available climate-smart practices were adopted widely, global rice emissions could be reduced by about 10% by mid-century. Even so, they say much deeper progress will require new and more effective tools so that rice producers can protect yields, save water and curb emissions at the same time.