Between 1850 and 1960, the world generally experienced a constant growth of emissions, due largely to industrialization and population growth, particularly in the United States. This development only saw some interruptions by historic events, like the Great Depression in the 1930s and the end of World War II in 1945. By the 1950s, however, China and Russia started seeing their emissions climb as their economies grew.
While the United States kept its place as the top annual emitter until 2005, when it was replaced by China. Russia experienced a significant reduction in emissions following the dissolution of the Soviet Union.