Which countries are responsible for climate-warming greenhouse gas emissions to date? In light of the release of the working group I (WGI) contribution for the IPCC fifth assessment for climate change, and the U.S. Environmental Protection Agency’s September 20th announcement of new limits to carbon emissions from coal and gas power plants (details here), this post aims to put into perspective the cumulative carbon emissions emitted to date by the U.S. and other countries.
More than 200 lead authors and 600 contributing authors from all over the world prepared the WGI contribution, and reported “it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century”. Particularly, anthropogenic CO2 emissions that have concentrated in the atmosphere are the largest contributor to total radiative forcing, which is leading to surface warming. Cumulative CO2 has increased by 40% since pre-industrial times –reaching unprecedented levels in at least the last 800,000 years, and the ocean has absorbed 30% of all emitted anthropogenic CO2, causing ocean acidification. Given the climate dynamics and the persistent effects of past emissions in the atmosphere, limiting climate change will require substantial and sustained reductions of green house gases.
How responsible is the U.S. for climate change?
In 1960 the U.S. had been the biggest contributor to the cumulative amount of carbon emitted globally, representing almost 40% of the world cumulative carbon emissions from fossil fuels and cement production. The second largest contributor by 1960 was the U.K., which had emitted approximately 15%, followed by Germany and France, with 11% and 5% of the total cumulative world carbon emissions, respectively.
Today, total global cumulative carbon emissions have quadrupled from 1960’s levels to about 335 billion metric tons. The U.S. has slightly reduced its global share, but is still the largest contributor of cumulative emissions (by 2010), accounting for a not-so-modest 27% of the total. Moreover, it is still the second largest contributor of annual global emissions. In fact, the reduction in its global share is due to the changes in the global scenario, as big developing economies emerge. Today’s Russia’s share in cumulative emissions is 11%, followed by China with 10%. The next largest contributors are the U.K. and France, each representing about 6%, and Germany with 5%.
Recently, some developing countries are beginning to contribute annually as much as developed countries. In 2010, of the roughly 8.6 billion tons emitted globally (Gt), the top annual emitters included China, India and Russia. Specifically, the largest contributors were China (26%), U.S. (17%), India (6%), Russia (6%) and Japan (4%). These five countries account together for 60% of all annual global emissions. U.S. and Japan annual emissions represent a third of the emissions of this group, while the developing economies of China, Russia and India represent two thirds.
On the other hand, while the U.S. has almost doubled its annual emissions since 1960, other developed economies have made more progress in limiting their emissions. For example, the U.K. is the only country that has decreased its annual emissions since 1960, from 159 to 135 million tons in 2010, and Germany presents a modest increase, from 148 to 203 million.
Power plant emissions standards are a step toward taking responsibility.
EPA’s proposed regulations would now limit emissions from coal and natural gas-fired power plants to 1,100 pounds and 1,000 pounds of CO2 per MWh –about 0.14 and 0.12 tons of carbon per MWh. The new rules are another strategic part of President’s Obama Climate Action Plan, which “aims to reduce greenhouse gas emissions levels in the range of 17 percent below 2005 levels if all other major economies agreed to limit their emissions as well” (Editor’s note: check out this video for the ins and outs of Obama’s climate plan).
Since power plants are the largest concentrated source of emissions in the United States, this first federal standard for carbon emissions for new power plants is a powerful step in achieving Obama’s goal. Americans should be proud of U.S. efforts to take responsibility for its past and to begin cleaning up the future.