What would the ozone layer look like today, 11 years from now, 21 years from now and in 2060 if we hadn’t banned ozone-depleting CFCs? That’s the question NASA set out to answer, resulting in a series of images that shows ozone concentrations over the mid-latitudes of the Western Hemisphere, based on months of calculations by the Goddard Earth Observing System Chemistry-Climate Model.
From NASA:
Ozone is Earth’s natural sunscreen, absorbing most of the incoming ultraviolet (UV) radiation from the sun and protecting life from DNA-damaging radiation. Chlorofluorocarbons (CFCs for short)—invented in the early 1890s and first used in the 1930s as refrigerants and propellants for chemical sprays—are ozone destroyers.
The series of images starts with 1974, before CFCs had begun to do significant damage to the ozone layer. Concentrations of ozone in the stratosphere over the United States and Canada are high. By 1994, the model predicts that ozone concentrations over the region have fallen from highs above 500 Dobson Units to about 400. By the simulated year 2009, the ozone layer over much of the United States has thinned to only 300 Dobson Units.
By 2020, the model predicts that an ozone “hole”—concentrations below 220 Dobson Units—forms over the Arctic as well as the Antarctic. By 2040, the ozone hole is global. The UV index in mid-latitude cities reaches 15 around noon on a clear summer day (10 is considered extreme today). By the end of the model run, global ozone drops to less than 110 Dobson Units, a 67 percent drop from the 1970s.
So, what would the world be like if we hadn’t banned CFCs? NASA says the ultraviolet rays falling on mid-latitude cities like Washington, D.C. would be strong enough to cause DNA mutation with likely harmful effects on plants, animals and skin cancer rates.
193 nations agreed to ban chlorofluorocarbons (CFCs) and similar chemicals in the 1980s and 90s, and it’s clearly a very good thing that they did. Imagine how much more bleak our global climate situation would be if they hadn’t.
Link [NASA]
