THINK OF THESE: Saving our shield

These days, people are talking more about climate change and disasters (floods, earthquakes, and volcano eruptions).  It seems no one pays attention anymore to ozone layer depletion.

But thirty years ago, the international community gathered together in Canada and came up with what is now known as Montreal Protocol to save the ozone layer, a minor constituent of the atmosphere, comprising only a few millionths of its total volume.  Today, 197 countries have participated in the treaty and resulted in the phase-out of 99% of nearly 100 ozone-depleting chemicals.

“Thirty years ago, the world proved it can come together and tackle a global problem with global resolve,” said Erik Solheim, head of the Nairobi-based United Nations Environment Program (UNEP), of what is touted as the most successful international environmental treaty in history.

The Philippines is among those that signed the treaty.  “The Montreal Protocol is clear proof that despite formidable odds, transformative results can be achieved through concerted global efforts,” said Senator Loren Legarda, the UN Global Champion for Resilience.

The earth’s atmosphere is divided into several layers.  According to science, the lower region – called troposphere – extends from the planet’s surface up to about 10 kilometers in altitude.  (For the uninformed, Mount Everest, the tallest mountain on the planet, is only about 9 kilometers high.)  All human activities occur in this layer.

Ozone at the ground level, at the bottom of the troposphere is a harmful pollutant.  One of the greenhouse gases, it is actually a result from the exhausts of automobiles and other vehicles and other sources.

After troposphere comes stratosphere, which continues from 10 kilometers to about 50 kilometers.  Most commercial airline traffic occurs in the lower part of the stratosphere.  It is in this layer where the ozone shield is found.

“If all the ozone contained in the atmosphere from ground level to a height of some 50 kilometers could be assembled at the earth’s surface, it would comprise a layer of gas only about three millimeters thick, weighing some 3,000 million tons,” a science scribe wrote.

Why is there so much ado about ozone layer?  Nothing except that existence of humans and other terrestrial being depends on the presence of ozone.  Studies have shown that depletion of the ozone layer would allow more ultraviolet radiation to reach the earth’s surface.

“Protecting the ozone is crucial since it is the only gas in the atmosphere that limits the amount of harmful solar ultraviolet radiation reaching the earth,” points out Cynthia Pollack Shea, a senior researcher at the Washington, D.C.-based Worldwatch Institute. “Without ozone, life on earth would be impossible.”

In 1974, two American scientists – Drs. Mario Molina and F. Sherwood Rowland from the Jet Propulsion Institute of Pasadena and the University of Southern California in Irvine, respectively – hypothesized that man-made chlorofluorocarbons (CFCs) were escaping into the atmosphere and “eating” the ozone layer.

In 1976, it was found that the concentration of chlorine in the atmosphere – which were released from CFCs – was 1.25 parts per billion (ppb).  The number doubled in 1989.  “Although the figures may sound like a ridiculously small amount, CFCs are about 15,000 times more efficient at producing greenhouse effect.  So, a little means a lot.  About 20% of global warming is attributed to CFCs,” wrote H. Steven Dashfhersky, author of “Environmental Literacy.”

It was then that scientists became alarmed as the effects could be lethal. UVB (the higher energy ultraviolet radiation absorbed by ozone) is generally accepted to be a contributory factor to skin cancer and to produce Vitamin D. In addition, increased surface ultraviolet leads to increased tropospheric ozone, which is a health risk to humans.

Another form of skin cancer – malignant melanoma – is much less common but far more dangerous, being lethal in about 15–20% of the cases diagnosed. The relationship between malignant melanoma and ultraviolet exposure is not yet well understood, but it appears that both UVB and UVA are involved.

There are also studies suggesting the association between ocular cortical cataracts and UVB exposure.  In the Philippines, 400,000 Filipinos get blind because of cataract, whose global cost of blindness is approximately 25 billion dollars annually in lost productivity.

“When a cataract happens, the amount of light that can enter the eye is reduced and the patient complains of blurring of vision especially in bright sunlight when the pupil gets constricted and also glare at night when driving,” says Dr. Manuel Agulto, chair of the Department of Ophthalmology at the University of the Philippines College of Medicine. “These complaints are progressive and by the time the cataract has become matured (noticeable by its white color) the patient is already blind.”

Ozone depletion can also have devastating effects on the environment. According to the US Environmental Protection Agency (EPA), depletion of the ozone layer could reduce crop yields and seriously disturb the balance of the ecosystems of the oceans.

Had the depletion of ozone layer continued, the world would be at least 25% hotter today.  “That additional heat energy would have provided ‘fuel’ for today’s extreme weather events like typhoons, floods and droughts,” said Dr. Rolando Garcia, a senior scientist at the US National Center for Atmospheric Research.