When it comes to global warming, there are seven big contributors: China is obviously number one, but exempt from climate treaties, as is India and Brazil. Also leading are the United States, gradually weaning itself off of the coal increases that occurred when environmentalists drove nuclear power from the country. Russia, Germany and the United Kingdom round the list out.

A new article in Environmental Research Letters blames these countries for more than 60 percent of pre-2005 global warming. Uniquely, it also assigns a temperature change value to each country that reflects its contribution to observed global warming.


It's gotten better since 2005 in developed nations, obviously. The US is down to early 1990s levels of CO2 emissions, thanks to the inroads made by natural gas, and Germany now wants to abandon its wind and solar fiascoes and do the same thing.

The new analysis was done under the leadership of Damon Matthews, an associate professor in the Department of Geography, Planning and Environment  at Concordia. In a straight ranking, the U.S. was then the leader, responsible for a global temperature increase of 0.15 C. That's close to 20 percent of the observed warming and matches the country's reliance on coal rather than the cleaner nuclear energy used in Europe and parts of Asia. Those numbers were also before outside impartial monitoring of China, when China was providing its own numbers for emissions. 

China and Russia accounted for around 8 percent each, Brazil and India 7 percent, and Germany and the U.K. around 5 percent each. Canada uses far electricity than the U.S. per capita but is only in 10th place due to a smaller population, just after France and Indonesia. Brazil and Indonesia ranked so highly in this analysis because of carbon dioxide emissions related to deforestation.

The research team used a new methodology to calculate national contributions to global warming. They weighted 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.

Matthews and 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. Using that metric, Canada and Australia become stick thin, their geography is much larger than their share of the global warming pie.

Dividing each country's climate contribution by its population paints a different picture. Amongst the 20 largest total emitters, developed countries occupy the top seven per-capita positions, with Canada in third place behind the U.K. and the United States even though their per capita electricity usage is higher. Using that ranking, China and India drop to the bottom.

Their goal was to highlight how much individual countries have contributed to the climate problem, as well as the huge disparity between rich and poor with respect to per-person contributions to global warming. Acknowledging these disparities, and then moving to correct them, may be a fundamental requirement for success in efforts to decrease global greenhouse-gas emissions.


That's an admirable goal. Current policy efforts, mitigation and rationing, leave poor nations without a comfortable lifestyle while developed nations can simply enjoy the status quo and pay more. Cleaner energy, nuclear and some day solar when it is ready, will make clean, affordable energy attainable for all.