Source: Adapted from National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Global Monitoring Division.
Note: The Land-Ocean Temperature Index considers the deviation in degrees Celsius from the 1951-1980 temperature average.
In the 19th century, the Industrial Revolution saw a gradual increase in CO2 emissions resulting from the combustion of a growing quantity of fossil fuels, particularly coal. However, it is not until the second half of the 20th century that CO2 emissions increased sharply, followed by an increase in average global temperatures. The fact that rising carbon emissions up to the mid-1970s did not appear to have been associated with global temperature changes underlines the potential existence of a threshold, after which additional emissions can trigger noticeable temperature variations. This threshold may have been reached in the early 1980s went global temperature averages started to increase above long-term averages. The growth in carbon emissions continued in the early 21st century as global CO2 emissions continued to rise in relation to the fast growth taking place in economies such as China and India, which have become the world’s largest carbon emitters.