PUNTA ARENAS, Chile – The worst of the ozone hole has pulled back once more to Antarctica this southern spring, leaving behind a shadow of uncertainty for the people living at the bottom of the Americas.
How many will develop skin cancer in years to come? How many more decades must their children live with dangerous ultraviolet rays? Will the global treaty to save the ozone survive until then?
The people of windblown Punta Arenas, like the local evergreens forever bent eastward from westerly gusts, are adjusting to the intense radiation that pours each year through the gap in the ozone layer. At least that’s what some say.
“People are better informed. They’re buying more sun-block and putting it on their children,” said pharmacist Gerardo Leal. “They’ve gotten used to it,” taxi driver Rene Bahamonde said.
But on a “red alert” day when UV rays could damage eyes, Bahamonde’s dark glasses sat unused by his side. And local health chief Dr. Lidia Amarales said many of the 150,000 Punta Arenas inhabitants take few precautions against the damaging sun as they go about their business on the quiet streets that slope downward to the chill waters of the Strait of Magellan.
The reason is simple: It’s cool here.
This is a gray, drizzly corner of South America where it rarely exceeds 70 degrees. But clouds are no protection against UV. “Without the heat, they don’t feel the radiation,” Amarales said. “We need to change habits.”
The stratosphere’s layer of ozone, a form of oxygen, for countless millennia has filtered out almost all of the sun’s cancer-causing ultraviolet-B rays. But in the 1970s scientists warned that manmade chemicals such as chlorofluorocarbons, or CFCs, used in aerosol sprays and refrigerants, were destroying ozone through chain reactions high in the skies. By the 1980s, satellite images showed an “ozone hole” had formed over Antarctica.
The world’s nations took action in 1987, signing the Montreal Protocol, phasing out some CFCs and some other ozone-damaging compounds. As a result, chlorine has declined in the lower atmosphere since the mid-1990s, while the rate of growth of bromine, another targeted chemical, has slowed.
It will take decades to purge the atmosphere. Experts watch year by year for positive signs, and in fact this September’s maximum ozone hole, at 8 million square miles, was markedly smaller than last year’s huge 11million-square-mile hole, though similar in size to the one in 2002.
Dutch climatologist Henk Eskes, a leading ozone analyst, cautioned that climatic changes make it hard to draw conclusions.
“It’s still very difficult to say that it’s really at a turning point. There’s a lot of variability from one year to the next because of wind patterns and dynamic situations,” he said from De Bilt, Netherlands.
Punta Arenas’ own expert, Claudio Casiccia, is equally noncommittal.
“If this trend continues for four, five, six years, then I think that’s a sign the ozone is recovering,” said the Chilean, who monitors the skies with sophisticated instruments on the roof of his ozone laboratory at the University of Magallanes.
Computer models suggest ozone should recover globally by 2040 to 2050, Casiccia pointed out. “But global ozone is one situation” – it was depleted by 6 percent over the United States, for example – “and Antarctica is another situation.”
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