Global warming’s biggest offenders

Posted on January 15, 2014|By: Cléa Desjardins *
* Parts of this text appear courtesy of New Scientist magazine.

When it comes to global warming, there are seven big contributors: the United States, China, Russia, Brazil, India, Germany and the United Kingdom. A new study published in Environmental Research Letters reveals that these countries were collectively responsible for more than 60 per cent of pre-2005 global warming. Uniquely, it also assigns a temperature-change value to each country that reflects its contribution to observed global warming.

The study was conducted at Concordia under the leadership of Damon Matthews, an associate professor in the Department of Geography, Planning and Environment. In a straight ranking, the U.S. is an unambiguous leader, responsible for a global temperature increase of 0.15 C. That’s close to 20 per cent of the observed warming.

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Matthews and his colleagues also experimented with scaling the emissions to the size of the corresponding area (see graphic above). 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 proportionate to the countries’ land masses. Canada and Australia become stick thin as their land mass is much larger than their share of the global-warming pie.

Meanwhile, dividing each country’s climate contribution by its population paints a different picture. Amongst the 20 largest total emitters, the top seven per capita positions are occupied by developed countries, with Canada falling in third place behind the U.K. and the U.S. In this ranking, China and India drop to the bottom of the list.

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