Without global pact, ultraviolet radiation would have singed us by 2065

March 20th, 2009 - 1:29 pm ICT by IANS  

Washington, March 20 (IANS) What would happen if the planet’s upper atmosphere were to be stripped of two-thirds of its ozone layer by 2065, not just over the poles, but everywhere?
Intense DNA-mutating ultraviolet (UV) radiation, up by 650 percent, falling on mid-latitude cities like Washington, would singe your skin in just five minutes, besides damaging plants, animals and aggravating skin cancer rates.

Such is the world we would have if 193 nations had not agreed to ban ozone-depleting substances, according to atmospheric chemists at NASA’s Goddard Space Flight Centre, Greenbelt, Johns Hopkins University, Baltimore, and the Netherlands Environmental Assessment Agency, Bilthoven.

Led by Goddard scientist Paul Newman, the team simulated “what might have been” if chlorofluorocarbons (CFCs) and similar chemicals were not banned through the treaty known as the Montreal Protocol.

In the new analysis, Newman and colleagues “set out to predict ozone losses as if nothing had been done to stop them”. Their “world avoided” simulation took months of computer time to process.

Ozone is Earth’s natural sunscreen, absorbing and blocking most of the incoming UV radiation from the sun and protecting life from DNA-damaging radiation.

The gas is naturally created and replenished by a photochemical reaction in the upper atmosphere where UV rays break oxygen molecules (O2) into individual atoms that then recombine into three-part molecules (O3).

As it is moved around the globe by upper level winds, ozone is slowly depleted by naturally occurring atmospheric gases. It is a system in natural balance.

But chlorofluorocarbons (CFCs), invented in 1928 as refrigerants and as inert carriers for chemical sprays, upset that balance.

Researchers discovered in the seventies and the eighties that while CFCs are inert at Earth’s surface, they are quite reactive in the stratosphere (10 to 50 km high), where roughly 90 percent of the planet’s ozone accumulates.

“Ozone science and monitoring has improved over the past two decades, and we have moved to a phase where we need to be accountable,” said Newman, who is co-chair of the United Nations Environment Programme’s Scientific Assessment Panel to review the state of the ozone layer and the environmental impact of ozone regulation.

“We are at the point where we have to ask: Were we right about ozone? Did the Montreal Protocol work? What kind of world was avoided by phasing out ozone-depleting substances?”

UV radiation causes CFCs and similar bromine compounds in the stratosphere to break up into elemental chlorine and bromine that readily destroy ozone molecules. Worst of all, such ozone depleting substances can reside for several decades in the stratosphere before breaking down.

In the 1980s, ozone-depleting substances opened a wintertime “hole” over Antarctica and opened the eyes of the world to the effects of human activity on the atmosphere.

By 1987, the World Meteorological Organisation and United Nations Environment Programme had brought together scientists, diplomats, environmental advocates, governments, industry representatives, and non-governmental organisations to forge an agreement to phase out the chemicals.

In January 1989, the Montreal Protocol went into force, the first-ever international agreement on regulation of chemical pollutants, said a Goddard release.

The analysis was published online in Atmospheric Chemistry and Physics.

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