Pictured: The chlorofluorocarbon coolant widely used in air conditioners through the 1980s was phased out because it was damaging the Earth’s protective ozone layer, but the chemicals that replaced it are some 2,100 times stronger as greenhouse gases than carbon dioxide. We may have saved the ozone layer, but -- whoops! -- there goes the climate.
Dear EarthTalk: Has an alternative to air conditioning to keep rooms cool been invented that is significantly cheaper and/or that uses significantly less energy than traditional air conditioning? -- Ashutosh Saxena, Allahabad, India