The UN said per-capita emissions from burning fossil fuels needs to fall to 1.6 tons in 2050 from 5.4 tons now across the 15 nations in order to stand even half a chance of capping the global average temperature rise at a safe level.
It tasked research teams in each of the countries, including the U.S., India, Germany and Japan, to devise “deep decarbonization pathways” through to 2050. The Chinese team produced one that leads to 3.5 tons per capita, and the sum total of the 15 nations’ efforts totaled 2.4 tons, according to the study by the UN’s Sustainable Development Solutions Network.
The potential for China to cut its harmful emissions matter because the country is the world’s biggest emitter, after overtaking the U.S. in 2006. The two nations combined account for more than two-fifths of global emissions.
“We know that we are not on track, and time is not on our side,” UN Secretary-General Ban Ki-moon said in a statement on July 8, when the report was released. “I expect countries to adopt different combinations according to their needs, resources and priorities. But all countries need to embark on the same journey.”
The pathways outlined by the 15 research teams involved ramping up technologies such as nuclear and renewable power, carbon capture and storage, and electric vehicles. They led to an aggregate cut in annual emissions from energy of 45 percent, falling to 12.3 gigatons (12.3 billion tons) in 2050 from 22.3 gigatons in 2010.
Even so, that’s not enough to keep the Earth on a pathway to cap the temperature rise since industrialization began to 2 degrees Celsius (3.6 degrees Fahrenheit), according to the study. That threshold has been agreed as a target by 194 nations involved in climate treaty talks and compares with the current trajectory which the UN predicts will lead to warming of at least 3.7 degrees Celsius.
The 15 countries account for 70 percent of total global greenhouse gas emissions. Cutting per-capita emissions to 1.6 tons by 2050 would yield a 50-percent chance of capping the temperature rise at 2 degrees, according to the UN.
The U.S. team charted four potential pathways, leading to emissions totaling 1.6 tons to 1.7 tons per capita in 2050. That compares with 17.7 tons in 2010. The researchers said it’s “technically feasible” to cut U.S. emissions by 85 percent between 1990 and 2050, while still growing the economy.
In the Chinese scenario, coal use declined to 5 percent of the energy mix in 2050 from 39 percent in 2010, while hydro, renewables and nuclear increase their share of power generation to 41 percent. China’s industrial base, which manufactures goods for much of the world, was picked out as a challenge.
“Currently, 25 percent of energy is used for the production of export products in China,” the researchers wrote. “Given that adjustments of the structure of exports is not an easy task, manufacturing exports (and associated emissions) are expected to remain important in the long run.”
The U.K. pathway would drive emissions per capita down to 1.1 ton in 2050 from 7.9 tons in 2010, while the Japanese one would see greenhouse gas output fall to 1.9 ton from 8.8 tons. Chapters covering Germany, India and Brazil weren’t yet available. The other countries covered are Australia, Canada, France, Indonesia, Mexico, Russia, South Africa and South Korea.
The study set the per-capita emissions number as a “benchmark but not as a target in a strict sense.” That’s because 194 nations locked in global climate treaty talks for two decades have squabbled over the fairest way to split the burden of cutting emissions.
Industrialized nations have benefited from decades of higher emissions that helped them modernize -- something developing nations including China and India say they should be allowed to do too. The countries aim to write a new global deal on climate change at a UN meeting in Paris in December 2015.
The UN said its analysis of the pathways remains “preliminary and incomplete.” It plans to issue a complete report before Ban hosts a climate change summit of world leaders in September in New York. It then plans to further refine its analysis and broaden the study to cover what is not yet technically feasible, preparing a wider report in 2015 for the French government, which will host the treaty talks.
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