YOUR LETTERS Ozone hole natural

Re: Todd Whitcombe column, Nov. 29.

“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary.” — H.L. Mencken

In the early 1970s, the hobgoblin du jour was ozone depletion and governments were only too happy to act on this threat. They banned chlorofluorocarbons (CFCs) and when NASA noticed the hole in the ozone over Antarctica in 1985, they panicked and worked together to enact the Montreal Protocol.

All because of a non-existent threat.

Ozone is formed in the upper atmosphere by the interaction of UV light and oxygen. The fear was that chlorides would react with ozone and deplete it to the extent that ultraviolet light would reach the surface of the Earth in such concentrations as to be disastrous. Scientists were able to demonstrate in the lab that such reactions did occur but they were not able to detect the same reaction in the stratosphere.

Natural events such as seawater evaporation and volcanic activity put hundreds of millions of tons of chlorides into the atmosphere every year. Meanwhile the human contribution peaked at 1.1 million tons per year.

How much of that human production reached the stratosphere? Very little, since CFCs are four to eight times heavier than air and most of it sinks to the ground where soil bacteria rapidly decompose them.

Evidence indicates that human CFC production has no detectable effect on the ozone layer.

Ah, but what about that hole in the Antarctic ozone that opened up in 1985? Knowing that such a hole could not have suddenly appeared out of the blue, one NASA scientist searched through the satellite archive photos and found that the hole had appeared in them for as long as satellites had been taking photos. It had not been recognized as a hole but instead had been interpreted as a refractive distortion caused by the curvature of the atmosphere around the globe.

The hole should have been no surprise to NASA. It was first noticed in 1956 (when CFCs had been developed but were not in widespread use) by Gordon Dobson of Oxford University, the inventor of the instruments and the system for measuring atmospheric ozone (called Dobson units to this day).

In 1958 two French scientists, Rigaud and Leroy, determined that the hole was a natural yearly occurrence, caused by the lack of sunlight (no ozone creating UV light) during the Antarctic winter coupled with the formation of the south Polar Vortex weather phenomenon that prevented ozone from flowing in from more northerly latitudes. When the sunlight returns and the vortex dissipates every spring, the hole disappears, only to reappear the following winter when suitable conditions return.

When the panic over the hole erupted in 1985, Rigaud and Leroy reviewed their work, found it to be correct and republished it in 1990. They were ignored.

Chicken Littles are never dissuaded by the facts.

So if all this is true, why is there not an ozone hole at the North Pole every winter? Good point. Glad you asked. There is indeed a considerable thinning of Arctic ozone due to lack of sunlight, but not nearly to the same extent, because the northern weather patterns are different, ozone is able to flow in from the south.

While NASA was a big proponent of the ozone panic, they also inadvertently disproved their own claims. On June 15, 1991, the second largest volcanic eruption of the 20th century took place when Mt. Pinatubo in the Philippines blew its top, sending more “ozone depleting chemicals” than all human production for a year combined, into the stratosphere at one time and at one location. NASA detected these chlorides drifting toward N. America and issued a warning that there would be massive depletion of ozone over Canada that summer. I can recall the scary three-inch headlines and the hysterical warnings.

It didn’t happen. Why? Because there was massively more oxygen than chlorides, and even if there had been accelerated depletion of ozone, the UV light would just make more ozone out of all that oxygen. Later that fall, in a small story in the middle of the newspaper, NASA scientists said they couldn’t understand why it hadn’t happened. They should have known.

The Antarctic ozone hole is an annual, natural occurrence. The information is widely available, yet the myth persists.

Art Betke, Prince George