Seven Nations Contributed to 60 Percent of Global Warming: Study

New research done at Concordia University suggests that more than 60 percent of the anthropogenic global warming that occurred before 2005 was generated by just seven countries.

That the study names United States, China, Russia, Brazil, India, Germany and the United Kingdom as the biggest contributors to man-made global warming is nothing new; the research is unique in that it assigns a value to each country that reflects its contribution to observed global warming during the study period.

The US, the researchers report, is the uncontested leader in contributing to global warming. The researchers calculated that the US alone is responsible for a global temperature increase of 0.15 degrees Celsius, a change that amounts to 20 percent of observable global warming.

China and Russia contributed 8 percent each, India and Brazil provided 7 percent and the UK and Germany contributed around 5 percent each.

Other nations made up the remaining 40 percent. France, Indonesia and Canada rounded out the top 10 largest contributors to global warming, the researchers said in a statement.

To calculate the national contributions to global warming, the researchers, led by Damon Matthews an associate professor in Concordia University's Department of Geography, Planning and Environment, used the novel approach of weighing each type of emission according to the atmospheric lifetime of the temperature change it caused.

"Using data from 1750 onward, the team accounted for carbon dioxide contributions from fossil fuel burning and land-use change, along with methane, nitrous oxide and sulphate aerosol emissions," Concordia University said in a statement.

"Matthews and his colleagues also experimented with scaling the emissions to the size of the corresponding area. Western Europe, the U.S., Japan and India are hugely expanded, reflecting emissions much greater than would be expected based on their geographic area. Russia, China and Brazil stay the same. Taken in this light, the climate contributions of Brazil and China don't seem so out of line - they are perfectly in proportion with the countries' landmasses," the statement continued. "Of course, Canada and Australia become stick thin, being countries whose geography is much larger than their share of the global warming pie."

The data Matthews and his team gathered can be interpreted a number of ways, however.

By taking each country's climate contribution and dividing it by its population, a markedly different picture emerges.

Developed nations occupy the top seven positions in per-capita emissions, so by looking at the climate change contribution data in terms of population, a place like Canada ranks much higher, and China and India rank much lower.