From an overall standpoint, the amount of carbon emissions by both middle- and low-income groups saw an upward trend, though the pace of growth varied significantly, whereas carbon emissions from the high-income category revealed a slight downward trend. It is also important to note that high-income groups accounted for the largest share of the total world population, while low-income groups had the smallest share.
Looking closely at the bar chart first, high income groups emitted 13 metric tons of carbon in 1990, a figure that then fell negligibly to 12 metric tons in 2000. The figure for middle income groups, by contrast, indicated an opposite trend, increasing dramatically from 15 to 22 metric tons between 1990 and 2000. A somewhat similar upward pattern was recorded in the amount of carbon released into the atmosphere by low-income groups, with its number rising marginally from 1 to 2 metric tons throughout the given period.
According to the pie chart, it is evident that high-income groups made up the highest share of the total world population, with 48%, followed by middle-income cohorts, at 34%. Conversely, the figure for low-income groups in this category lagged considerably behind, at a mere 18%.