Since 1958, the yearly accumulation rate of atmospheric carbon dioxide has grown, on average, from about 1 Pg C/yr to about 3.0 Pg C/yr (light blue area). Over the same period, fossil-fuel emissions¹⁷ (red line) have grown from about 2.5 Pg C/yr to about 6.5 Pg C/yr. Net uptake by the ocean or terrestrial biosphere (green region) must account for the difference. Note the large interannual variation in the annual atmospheric CO₂ growth rate.² Higher growth rates generally appear to be associated with El Niño episodes (orange arrows), the exception being the period following the eruption of Mt. Pinatubo in the early 1990s.