The Coastal Post - September, 1995

Ozone Hole Tourism

The Coastal Post first sent Jim Scanlon to Tierra del Fuego in 1990, and he has subsequently visited Bolivia, Peru and Argentinean Patagonia reporting on ozone.

This year, Jim will spend two months in the "Southern Cone" of South America, but will take along this time two small, sophisticated instruments, one for directly measuring ultra-violet radiation and the other for measuring ozone, water vapor and sulfur dioxide.

These instruments are manufactured by the Solar Light Company of Philadelphia, and cost a tiny fraction of the instruments used by the National Science Foundation and the World Meteorological Organization. Anyone can afford them.

Jim intends to freeze his butt for a few weeks on Isla Navarino, between Tierra del Fuego and Cape Horn, then go to Puerto Natales where he suffered snow blindness without any snow in 1990. Finally, he will go on to El Calafate on Lake Argentina in the rain shadow of the Torres de Paine range of the southern Andres, which is relatively sunny for that part of the world.

His reports for October and November will be via modem.

Ultraviolet Menace Looms (Or Does It?)

BY JIM SCANLON

Although stratospheric ozone has been regularly measured since the 1930s, it has been measured with great accuracy only since the discovery of the springtime ozone hole over Antarctica. In contrast, virtually nothing is known about natural levels of ultraviolet radiation (UV), which are expected to rise dangerously as ozone continues to decline.

Whereas billions are spent for satellite and space shuttle sensors to measure ozone, virtually nothing is spent on ground-based instruments to verify the high tech UV predictions. So far, the only ground-based survey of ultraviolet radiation (Scotto et al Science #239), published in 1988, failed to show an increase on the surface of the earth.

Last month Nature (August 3) reported on the continued, frightening deterioration of the ozone layer over Antarctica: the downward trend continues to deepen, with the minimum measurements going down along with the mean. The temperature is also going down. The springtime ozone loss now extends into the summer when the sun is higher and shines continuously.

There are indications that other substances (mostly acids) may form hydrates that make chlorine activation and ozone destruction possible at warmer temperatures. What this means for populated areas of the Southern Hemisphere (South America, New Zealand and South Africa) is not clear just yet.

A report appeared in Science (July 28, #269) of a NASA study of satellite data which suggested that "...increasing amounts of UV [were] leaking through the damaged ozone shield and actually reaching the surface."

This report, presented to the International Union of Geodesy and Geophysics, estimated that at 40 degrees latitude (Japan, Central California, the New York area, Southern Europe, etc.), ultraviolet light at DNA-damaging wavelengths "must have increased at a rate of eight percent per decade in the spring, summer and autumn."

There is no way to verify these estimates, since there is no ground-based measuring network. The network that was responsible for the Science #239 report was defunded. This is akin to killing the messengers before they even get a chance to deliver the message.

But the most startling news of all was buried in a report in Geophysical Research Letters (July 15), which was blandly entitled "Geographical Differences in the UV Measured by Intercompared Spectroradiometers."

While this article was presumably about the reliability of the few different instruments scattered around the globe which measure ultraviolet radiation, it presented very frightening numbers which are actually measurements and not estimates based on tweaking satellite data or computer models and simulations!

Not only are ultraviolet doses systematically larger in the Southern Hemisphere than those measured in the Northern, but in summertime "...daily doses at the South Pole exceed those at mid-latitudes in the Northern Hemisphere."

While Geophysical Research Letters is not the "last word" in scientific publications and is intended as a forum for new, interesting developments, it is strictly professional and reviewed by experts. It states, "Erethemally-weighted UV irradiances [those that cause sunburn and damage skin] at mid-southern latitudes appear to be approximately 40 percent greater than at corresponding northern latitudes. Differences in DNA-weighted UV irradiances are even higher."

In the summer, sun burning rays are worse at high southern latitudes than at mid-latitudes in the northern hemisphere.

What this means for our neighbors to the south, and the plants and animals that sustain them, is completely unknown and will remain unknown until scientists and naturalists begin to look. One scientist, commenting on the NASA study, managed to put a positive spin on the news that UV was actually reaching the surface of the earth. He was quoted: "It should open the way to seeing UV slow its increase as restrictions on the release of ozone-destroying chemicals take effect." This is a very nice, hopeful way of looking at it.

On the other hand...