(RICE)Environmental impacts

Environmental impacts

In many countries where rice is the main cereal crop, rice cultivation is responsible for most of the methane emissions.^[48] Rice requires slightly more water to produce than other grains.^[49]
As sea levels rise, rice will become more inclined to remain flooded for longer periods of time. The longer it stays in water, it cuts the soil off from atmospheric oxygen and causes fermentation of organic matter in the soil. During the wet season, rice cannot hold the carbon in anaerobic conditions. The microbes in the soil convert the carbon into methane which is then released through the respiration of the rice plant or through diffusion of water. Current contributions of methane from agriculture is ~15% of anthropogenic greenhouse gases, as estimated by the IPCC. A further rise in sea level of 10-85 centimeters would then stimulate the release of more methane into the air by rice plants. Methane is twenty times more potent a greenhouse gas than carbon dioxide.^[50]
A 2010 study found that, as a result of rising temperatures and decreasing solar radiation during the later years of the 20th century, the rice yield growth rate has decreased in many parts of Asia, compared to what would have been observed had the temperature and solar radiation trends not occurred.^[51][52] The yield growth rate had fallen 10-20% at some locations. The study was based on records from 227 farms in Thailand, Vietnam, India, China, Bangladesh and Pakistan. The mechanism of this falling yield was not clear but might involve increased respiration during warm nights, so expending energy without being able to photosynthesise.