[ti:Study: Planet-Warming Gasses Make Food Less Nutritious] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:01.16]A new study shows that rising levels of planet-warming gases [00:06.78]may reduce important nutrients in food crops. [00:12.12]Researchers studied the effects of one such gas -- carbon dioxide -- on rice. [00:19.65]The researchers grew rice plants in a controlled environment. [00:24.52]They set carbon dioxide levels [00:27.12]to what scientists are predicting for our planet by the end of the century. [00:32.96]They found that the resulting rice crops [00:35.84]had lower than normal levels of vitamins, minerals and protein. [00:42.17]The researchers said the effects of planet-warming gasses would be most severe [00:48.52]for the poorest citizens in some of the least developed countries. [00:54.20]These people generally eat the most rice [00:57.56]and have the least complex diets, they noted. [01:02.24]A report on the study was published in the journal Science Advances. [01:08.12]In the experiment, scientists grew 18 kinds of rice in fields in China and Japan. [01:16.36]They pumped carbon dioxide gas over the plants [01:20.16]in an effort to create the atmosphere of the future. [01:24.96]Rice grown under high carbon dioxide conditions had, on average, [01:30.64]13 to 30 percent lower levels of four B vitamins and 10 percent less protein. [01:38.80]The crops also had 8 percent less iron [01:43.16]and 5 percent less zinc than rice grown under normal conditions. [01:49.84]However, vitamin E levels increased by about 13 percent on average. [01:56.84]The results are bad news, "especially for the nutrition of the poorer population [02:03.12]in less-developed countries," said the University of Tokyo's [02:08.16]Kazuhiko Kobayashi, who helped to write the report. [02:13.08]That includes about 600 million people in Indonesia, [02:18.04]Cambodia, Myanmar, Bangladesh, [02:22.20]Laos and other nations, mainly in Southeast Asia, the report said. [02:28.92]Other studies have shown that higher temperatures from climate change [02:33.38]and weather extremes will reduce food production. [02:38.04]But scientists are finding that rising levels of carbon dioxide [02:42.88]and other planet-warming gasses threaten food quality. [02:47.60]Earlier studies showed that wheat, maize, rice, [02:52.56]field peas and soybeans grown under high carbon dioxide conditions [02:58.20]all had lower levels of protein and minerals. [03:02.76]Scientists estimated that almost 150 million people [03:08.16]might be at risk of having too little protein or zinc in their diet by 2050. [03:16.32]One of the scientists is Sam Myers of Harvard University [03:20.60]in the American state of Massachusetts. [03:24.60]He said that findings like this are an example of the surprises climate change creates. [03:32.00]"My concern is, there are many more surprises to come," he said. [03:37.64]Myers noted that pollution, loss of some species, destruction of forests, [03:44.32]and other human activities are likely to produce unexpected problems. [03:50.68]He said that you cannot completely change all the natural systems [03:55.40]that living organisms have grown to depend on over millions of years [04:00.60]without having effects come back to affect our own health. [04:05.64]The new study suggests a way to lower the nutritional harm of climate change. [04:11.92]One way, Kobayashi said, is to grow different forms of rice [04:16.93]that have shown to be more resistant to higher carbon dioxide levels. [04:22.76]I'm Phil Dierking. [04:25.24]更多听力请访问51VOA.COM