China, India and Brazil — three of the largest developing nations— joined the U.S. in a list of the biggest historical contributors to global warming, according to a study by researchers in Canada.
Seven nations between them accounted for more than 60 percent of all heat-trapping gas emissions between 1750 and 2005, researchers at Concordia University, Montreal, said today in a statement. Russia, the U.K. and Germany rounded out the list.
The findings are important for diplomats trying to broker a new deal by 2015 to limit fossil fuel emissions. The question of historical responsibility caused friction at talks in Warsaw in November, when richer nations blocked a Brazilian proposal that would use pollution levels dating back to the industrial revolution to help set limits on future emissions.
“A clear understanding of national contributions to climate warming provides important information with which to determine national responsibility for global warming, and can therefore be used as a framework to allocate future emissions,” the researchers said in their paper, to be published in the journal Environmental Research Letters. “Our analysis has the potential to contribute to this discussion.”
The U.S. is the “unambiguous leader,” responsible for about 20 percent of total warming since industrialization. That’s equivalent to about 0.15 degree Celsius (0.27 degree Fahrenheit), according to the researchers. The group was led by Damon Matthews, an associate professor in Concordia’s Department of Geography, Planning and Environment.
China and Russia each accounted for about 8 percent of total emissions. Brazil and India each had 7 percent apiece, and the U.K. and Germany each were responsible for 5 percent.
The researchers took account of the atmospheric lifetime of the different greenhouse gases when making their calculations. They also included the effects of deforestation and land-use change since the industrial revolution in the 18th century, though not before. They only used data through 2005 to ensure consistency between the different countries.
When the top 20 biggest historical emitters are re-ranked to give per-capita responsibility for causing climate change, the U.K. ranks first, followed by the U.S., Canada, Russia, Germany, the Netherlands and Australia. Brazil in eighth is the highest ranked developing nation, with China and India in 19th and 20th due to their large populations.
–Editors: Reed Landberg, Amanda Jordan