字幕列表 影片播放 列印英文字幕 In developing countries alone, more than 3.5 billion people depend on rice for more than 20 per cent of their calories. But traditional rice farming uses up to a third of the world's freshwater supplies and produces harmful greenhouse gases – as much as the entire aviation industry before the pandemic. A key problem is methane production, due to the custom of keeping fields flooded during the growing season. The gas is a significant contributor to global warming, with rice cultivation the second biggest agricultural source after livestock. Researchers are currently working to generate new, high-yield varieties that can be seeded directly into dry ground. A new farming method for paddy fields could also reduce both water use and greenhouse gas emissions. It alternates wetting and drying, rather than always keeping paddies flooded. Far less methane is produced when fields are drained and organic matter isn't left to rot under water. Farmers are also being encouraged in the use of practices such as laser land levelling, which produces flatter paddies. These in turn allow farmers to reduce their use of both water and fertiliser. Aid group the Sustainable Rice Platform, which promotes the wetting and drying method, started in 2015 and has grown to 500,000 farmers across 21 countries today. It says pilot projects have on average reduced water use by 20 per cent, and greenhouse gas emissions by 50 percent. But these projects cover less than one percent of rice production worldwide and persuading significant numbers of farmers and governments to commit to environmental and cost efficiencies will take time. Rice is not internationally traded to the same extent as other food products. As a result, it has attracted less attention from pressure groups concerned with workers' rights and the environment. But as demand for rice grows, along with the world's population, and with sustainability rising up companies' and governments' agendas, the commodity's carbon footprint is gradually coming into focus.