Dear Tom,
The burning of fossil fuels is causing an increase in carbon dioxide in the atmosphere, but burning also uses up oxygen. Is the oxygen level decreasing?
William Forsythe
Dear William,
Indeed it is, but the decrease is miniscule because the reservoir of atmospheric oxygen is massive. Oxygen comprises 21 percent (or 209,500 parts per million (ppm)) of the mixture of gases that we call air, and the annual depletion of oxygen is a tiny 3.5 ppm. Moreover, the depletion process is complex.
Combustion (burning) uses up oxygen, but other processes reduce oxygen replenishment.
Worldwide deforestation limits oxygen production, as does ozone depletion. Ozone blocks harmful ultraviolet light, and as more UV shines in, marine phytoplankton (important contributors to the atmosphereM-9s oxygen content) produce less oxygen.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
