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The United States is the largest national contributor to global climate warming, followed by China, Russia, Brazil and India.

Damon Matthews and his colleagues at Concordia University in Montreal, Canada, analysed the national emissions of greenhouse gases and aerosols, including those from land use, between 1800 and 2005. They calculated that a total warming of 0.7 °C occurred during this period, and that more than 21% of this total is linked to the United States. China and Brazil exceed the United States slightly in terms of their contributions from land-use activities, such as deforestation and agriculture, but the high level of cumulative US fossil-fuel use makes the country the biggest contributor overall.

Among the major emitters, the United Kingdom and the United States top the rankings on a per capita basis, with contributions that are more than ten times higher than those of either China or India.

Environ. Res. Lett. 9, 014010 (2014)