Good news for greenhouse worriers.Good news for greenhouse worriers In the 1970s, consumers in the United States and other countries unwittingly took a major step toward reducing the threat of future global warming. Fear of another environmental catastrophe -- a vanishing ozone layer -- drove many people to stop using aerosol spray cans containing chlorofluorocarbons chlorofluorocarbons (klōr'əfl  r`əkär'bənz, klôr'–) (CFCs), organic compounds that contain carbon, chlorine, and fluorine atoms. (CFCs). Yet aside from harming ozone, CFCs acts as "greenhouse gases" that warm the Earth by absorbing infrared radiation. If consumers had continued to spray with abandon, CFCs would have surpassed carbon dioxide carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. by now in terms of current human contributions to the greenhouse effect, according to James Hansen, Andrew Lacis and Michael Prather at NASA's Goddard Institute for Space Studies The NASA Goddard Institute for Space Studies (GISS), at Columbia University in New York City, is a component laboratory of NASA's Goddard Space Flight Center Earth-Sun Exploration Division and a unit of The Earth Institute at Columbia University. in New York City New York City: see New York, city. New York City City (pop., 2000: 8,008,278), southeastern New York, at the mouth of the Hudson River. The largest city in the U.S. . In the Nov. 20 JOURNAL OF GEOPHYSICAL RESEARCH Journal of Geophysical Research is a publication of the American Geophysical Union. JGR was formerly titled Terrestrial Magnetism from its founding by the AGU's president Louis A. , the NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. scientists report that CFCs now constitute 25 percent of the annual human additions to the greenhouse effect. Reflecting industrial emissions and the continued sale of CFC-containing aerosol sprays in many countries, this percentage represents an increase over the past -- but without the 1970s cutbacks, it would have been much greater, Hansen says. In comparison, carbon dioxide today accounts for 57 percent, methane for 12 percent and nitrous oxide for 6 percent. Many policy experts believe it will be easier to eliminate CFCs than to drastically cut emissions of carbon dioxide, and most countries are currently reducing their use of CFCs as part of an international agreement (SN 6/10/89, p.367). "We can make an enormous contribution toward decreasing the current contributions by phasing out the CFC CFC See: Controlled foreign corporation part," Hansen says. He warns, however, that while proposed substitute chemicals should not harm the ozone layer as much as CFCs do, several of them would contribute to the greenhouse effect. Hansen says the NASA study shows that moderate CFC decreases that slow an exponential increase in emissions can make a big difference after a while. "This is an example which I think provides some optimism about the possibility of influencing what's going to happen," he says. |
|
||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion