Atmospheric Trace Gases: Trends and Distributions Over the Last Decade

Abstract

Concentrations of the halocrbons CCl₃F (F-11), CCl₂F₂ (F-12), CCl₄, and CH₃CCl₃, methane (CH₄), and nitrous oxide (N₂O) over the decade between 1975 and 1985 are reported, based on measurements taken every January at the South Pole and in the Pacific Northwest. The concentrations of F-11, F-12, and CH₃CCl₃ in both hemispheres are now more than twice their concentrations 10 years ago. However, the annual rates of increase of F-11, F-12, and CH₃CC1₃ are now considerably slower than earlier in the decade, reflecting in part the effects of a ban on their nonessential uses. Continued increases in these trace gas concentrations may warm the earth and deplete the stratospheric ozone layer, which may cause widespread climatic changes and affect global habitability.