YEAR-TO-YEAR CHANGES IN ATMOSPHERIC CO2

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 accu mulation 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 in crease rate. A comparison between both hemispheres shows that the decr ease of the increase rate was smaller, and lagged by about one year, i n the southern hemisphere relative to the northern. This enables one t o attribute these particularly low accumulation rates to the explosion of the mount Pinatubo in June 1991.