WASHINGTON, D.C., FEBRUARY 19, 1992---The announcement on Feb. 3 that NASA researchers had observed a peak concentration of reactive chlorine in the northern stratosphere--and the subsequent move by the White House, just a few days later, to accelerate the phaseout of CFCs--has raised a number of concerns and questions among atmospheric scientists.
The phrasing of the NASA press statement led many journalists to report ozone depletion or an ozone "hole" over the Arctic. In fact, no such claim was made; the statement only suggests the possibility, which is dependent upon unique meteorological conditions. Chlorine atoms cycle back and forth between reactive and inactive forms, depending on the presence of stratospheric ice particles, which in turn depend upon temperature.
Principal project scientist James Anderson (in Science News, 2/8/92) could only vaguely predict the development of a "hole" during some year in the near future, perhaps in the "decade to come."
The chlorine peak was observed on Jan. 20; presumably readings both before and after that date were lower. Without additional information, it is impossible to assess the significance of the peak nor to explain its occurrence. The announcement came well before the completion of the October to March suite of measurements.
NASA reported similar high chlorine values in its last Arctic experiment in 1989. No polar ozone thinning developed at that time.
It is impossible to tell the source of a chlorine atom; one looks pretty much like another. The NASA press release claimed that the chlorine came mainly from CFCs. No estimate was given of the contribution from Mount Pinatubo's volcanic eruptions, now producing a temporary ozone depletion over the tropics.
For the past four years, the U.N. Ozone Trends Panel has been reporting a global depletion of ozone, with each report announcing a depletion that is more rapid and larger than expected. But natural variations of ozone are many times larger than the reported trends. In addition, two Belgian scientists, de Muer and de Bakker, have just published a startling paper in The Journal of Geophysical Research, pointing out that sulfur dioxide pollution interferes with ozone measurements. Correcting for changes in SO2 cancels the reported ozone depletion trend.
If claims of ozone depletion over North America were correct, scientists should have seen an increase in ultraviolet radiation at ground level. However, measurements to date show just the opposite, a decrease in ground level UV.
Claims of huge increases in skin cancer, cataracts, or plankton death appear unsubstantiated. A 5 percent decrease in ozone, causing (theoretically) a 10 percent increase in surface UV, would be equivalent to moving 60 miles closer to the equator, roughly the distance from Washington to Richmond.
Overlooked by the press was the fact that the research was partly supported by the chemical industry's Alternate Fluorocarbon Environmental Acceptability Study. These chemical companies produce and hope to sell CFC substitutes, as CFCs are phased out. According to Tony Vogelsberg of DuPont (as quoted in the Wall Street Journal, 2113/92): "The customers haven't been buying the alternatives because they haven't felt pressured."
Many scientists have noted a disturbing trend in ozone research in recent years: for example, announcements of depletion trends are being made by press release, without the publication of peer-reviewed data and analyses.
In March 1988, NASA announced that global ozone depletion had been observed for the first time (quite apart from the temporary annual thinning observed over the Antarctic). The announcement was made at a press conference with a press release. To date the full study has yet to be published in a peer-reviewed scientific journal.
On October 23, 1991, the United Nations Environmental Program, based in Nairobi, claimed that an unnamed panel of "80 of the world's foremost atmospheric scientists" had concluded that the ozone layer was thinning even faster than predicted. Again, a press release, followed by an executive summary. Despite references in the press release, and in subsequent news accounts, to a"just-released 300-page report," the report has yet to be published.
The Feb. 3, 1992, NASA announcement was yet another instance of a press statement without full publication of data.
NWF Correction: In a Feb. 3 "Action Alert" to members of the National Wildlife Federation, NWF President Jay D. Hair refers to the "emissions of carbon dioxide and other ozone destroying gases." To avoid confusing ozone depletion with greenhouse warming, it must be noted that carbon dioxide, while a greenhouse gas, does not destroy ozone.