Ozone Layer Article Summary
Ozone
Our Global Sunscreen
By Mike Carlowicz t’s not often that scientists get to conduct experiments that seem like they come out of a science fiction novel or a video game. Yet, that is what some researchers at NASA did a few years ago. Atmospheric physicists Paul Newman and Luke Oman built a simulation of the Earth’s atmosphere and then proceeded to strip away our protective ozone layer. Their computer model reproduced the chemistry and circulation of the air; natural variations in temperatures and winds; and minor changes in the energy received from the sun. Newman and Oman then added ozone-destroying chemicals to the atmosphere at a rate of 3% more per year—on top of what was already in our 1970s atmosphere. For several months, they ran their model on a supercomputer and reproduced about 80 years of simulated Earth time. They called their experiment “The World Avoided.” By the year 2020 in the simulation, 17% of the Earth’s protective ozone layer vanished. Holes in the ozone layer formed not just over Antarctica—as they currently do each spring—but over the Arctic, too. By 2040, the ultraviolet (UV) index, the measure of the sunburn-causing radiation reaching the Earth’s surface, rose as high as 15 on summer days in mid-latitude cities such as Washington, D.C. (A UV index of 10 is considered very high today and quickly leads to sunburn if you don’t wear sunscreen.) In the simulated future, two-thirds of the planet’s ozone layer disappeared by 2065. Ozone holes swirled over both poles all year long, and most ozone disappeared from the tropics, too. The intensity of UV radiation reaching the Earth’s surface doubled—levels that would increase DNA mutations in human and animal cells, suppress our immune systems, and increase the incidence of cataracts and skin cancer. In another demonstration of the effects of a world without an ozone layer, Newman’s group exposed a basil plant to intense UV radiation. In a lab at NASA’s Goddard Space Flight Center, they set up
Our Global Sunscreen
By Mike Carlowicz t’s not often that scientists get to conduct experiments that seem like they come out of a science fiction novel or a video game. Yet, that is what some researchers at NASA did a few years ago. Atmospheric physicists Paul Newman and Luke Oman built a simulation of the Earth’s atmosphere and then proceeded to strip away our protective ozone layer. Their computer model reproduced the chemistry and circulation of the air; natural variations in temperatures and winds; and minor changes in the energy received from the sun. Newman and Oman then added ozone-destroying chemicals to the atmosphere at a rate of 3% more per year—on top of what was already in our 1970s atmosphere. For several months, they ran their model on a supercomputer and reproduced about 80 years of simulated Earth time. They called their experiment “The World Avoided.” By the year 2020 in the simulation, 17% of the Earth’s protective ozone layer vanished. Holes in the ozone layer formed not just over Antarctica—as they currently do each spring—but over the Arctic, too. By 2040, the ultraviolet (UV) index, the measure of the sunburn-causing radiation reaching the Earth’s surface, rose as high as 15 on summer days in mid-latitude cities such as Washington, D.C. (A UV index of 10 is considered very high today and quickly leads to sunburn if you don’t wear sunscreen.) In the simulated future, two-thirds of the planet’s ozone layer disappeared by 2065. Ozone holes swirled over both poles all year long, and most ozone disappeared from the tropics, too. The intensity of UV radiation reaching the Earth’s surface doubled—levels that would increase DNA mutations in human and animal cells, suppress our immune systems, and increase the incidence of cataracts and skin cancer. In another demonstration of the effects of a world without an ozone layer, Newman’s group exposed a basil plant to intense UV radiation. In a lab at NASA’s Goddard Space Flight Center, they set up
References: Carlowicz, M.; Lindsey, R. Earth Observatory: The World We Avoided by Protecting the Ozone Layer, Earth Observatory, Goddard Space Flight Center, NASA, May 13, 2009: http://earthobservatory.nasa.gov/Features/WorldWithoutOzone/ page1.php [accessed Feb 2013]. Wiscombe, W. Aura: A Mission Dedicated to the Health of the Earth’s Atmosphere, Earth Observatory, Goddard Space Flight Center, NASA: http://earthobservatory.nasa.gov/ Features/Aura/ [accessed Feb 2013]. Allen, J. Chemicals in the Air: Latest Results from NASA’s Aura Satellite, ChemMatters, April 2008, 26 (2), pp 15–17. The ozone hole is shown in purple above the Antarctic on Sept. 16 in the years 1979, 1987, 2006, and 2011. The Sept. 16 date was chosen because it is the International Day for the Preservation of the Ozone Layer. The maps were produced with data collected by statellite istruments, including the Ozone Monitoring Instrument on the Aura Satellite. They show that the ozone hole kept increasing from 1979 to 2011, although to a lesser degree between 2006 and 2011. 14 ChemMatters, APRIL 2013 www.acs.org/chemmatters Mike Carlowicz is a science writer from Massachusetts and the author of three books on the sun, moon, and space weather. He is the editor of the NASA Earth Observatory.