Year-to-year changes in atmospheric CO₂

Abstract

The atmospheric CO₂ increase rate has decreased from figures generally between 1 and 2 ppmv per year, typical of the years 1982 to 1990, to less than 1 ppmv per year in 1992-1993. This corresponds to a CO₂ accumulation in the whole atmosphere, from mid-1991 to December 1992, of 2.6 Gt C instead of 4.8 Gt C, as expected from the preceding average increase rate. A comparison between both hemispheres shows that the decrease of the increase rate was smaller, and lagged by about one year, in the southern hemisphere relative to the northern. This enables one to attribute these particularly low accumulation rates to the explosion of the mount Pinatubo in June 1991.