Chemical and Engineering News: PEOPLE CAN’T walk on water, but scientists say the carbon dioxide emitted by humans into the atmosphere has started to leave noticeable footprints on the ocean. Scientists have been concerned for years that lower ocean pH caused by absorption of CO2 emissions could decrease calcification processes underlying the growth of shells and corals’ hard exteriors. Besides studying that phenomenon, they are investigating how acidification alters the concentration and behavior of the ocean’s …