Figure 7. The CO2 global growth rate (expressed here as 1015 g/yr of carbon accumulating in the atmosphere since the start of direct CO2 monitoring) is compared to fossil fuel emissions over 4 decades. On average, 55% of the anthropogenic carbon is retained in the atmosphere, but with large interannual variability related to the southern oscillation index (SOI). (The very low growth following the Pinatubo volcanic explosion in 1991 is an exception). All CO2 data are deseasonalised and smoothed over 650 days. The records collected by SIO/NOAA from Mauna Loa, by NOAA from 50 global sites, or by CSIRO from Cape Grim all closely track the global growth rates (Source: R J Francey, presented at the EC-IGBP-GTOS Terrestrial Carbon Meeting, 22–26 May 2000, Costa da Caparica, Portugal).