阅读填空 (2019 年 省实初三一模 ) ★★★ Climate change could make food less healthy As levels of carbon dioxide — CO2 — in the atmosphere have been rising in recent years , the Earth has been warming. 1 That warming is one sign of climate change. And it has the possibility to influence food in many ways. Rising temperatures and the changes in rainfall that it will bring should make an effect on how much and where crops grow. Facts now show that rising levels of CO2 can also influence how healthy a crop will be. Some of those facts were reported last year in Annual Review of Public Health. Indeed, it showed that several studies have come to this conclusion. 2 He was part of a team that has studied the p ossible effects of climate change on food ’ s health . In one 2014 study, his group looked at six major food crops: wheat, rice, field peas, soybeans, cor n and sorghum (高粱) . They provided plants with different amounts of CO2. Some got levels of between 363 and 386 parts per million (ppm). 3 Such levels are expected to develop within the next 50 years or so. After harvesting the plants, the researchers measured their levels of vitamins, minerals and other healthy chemicals . And plants grown with more CO2 were less healthy . For example , wheat and rice had lower protein levels. They also had less zinc (锌) and iron, as did the peas and soybeans. Some two billion people worldwide already don’t get enough of these healthy chemicals . ___ __4 _ If crop levels of such healthy chemicals fall, people may face an even greater risk of falling ill. People who replace sugars for protein face a greater risk of high blood pressure and heart disease, U.S. studies have shown. Scientists don’t yet know why CO2 i nfluences levels of these healthy chemicals . But the new findings suggest scientists may want to try growing new types of crops that are less influenced by CO2. 5 A. Other plants were given more of that greenhouse gas as they grew — 546 to 586 ppm. B. Samuel Myers is an environmental health scientist at Harvard University in Cambridge, Mass. C. In t hat way people will still get the most benefits from their greens and grains. D. That’s because as a greenhouse gas, CO2 keep s in heat in the Earth’s atmosphere. E. Most people depend on cereal crops, such as wheat and rice, to meet their needs for both zinc and iron.