Despite gains in developing renewable energy sources, China will remain the world's biggest producer and consumer of coal for the next 25 years, international experts say.
Renewables like solar, wind and nuclear energy will provide nearly a third of China's power by 2040, the Paris- based International Energy Agency (IEA) said in an annual report.
But although China's coal consumption may be nearing a plateau, it will stay at high levels over a prolonged period, leaving it as the world's largest single source of energy-related greenhouse gas (GHG), according to IEA data released earlier this month.
The influence of China's emissions on global warming will peak and start to fade gradually over the forecast period as it reduces coal use and pursues its transition to a service- led economy with slower growth rates.
The IEA's 700-page World Energy Outlook report has shifted its focus away from China and onto India for the first time, noting the impact of factors like industrial development and the needs of an estimated 240 million people who still lack access to electricity.
The numbers are a measure of the challenges that government leaders face as they gather at the United Nations climate change summit in Paris next week to reach an agreement on limiting global warming effects.
India will take over from China as the largest source of growth in world coal use, nearly doubling its consumption from 2020 to 2040, the report said.
That will make it a major source of carbon dioxide (CO2), surpassing the United States by 2035, according to the forecast.
In 2013, coal accounted for 29 percent of world energy but 46 percent of carbon dioxide (CO2) emissions, the agency said in an earlier report.
As in China previously, developing India has argued that its emissions are proportionally far less than those of industrialized nations. On a per capita basis, India emits about one-tenth as much as the United States, the report said.
But coal use is expected to climb as India narrows the gap.
"All the numbers are indicating that India will be the number one country in terms of coal consumption worldwide," the Washington Post quoted IEA executive director Fatih Birol as saying.
But the forecast data in the back of the IEA's book suggests that displacing China as the top coal consumer and CO2 emitter will take a long time.
In 2040, China will still be burning twice as much coal as India and seven times more than the United States, according to the projections.
China's share of world CO2 emissions will decline from 27.4 percent in 2020 to 24.9 percent in 2040, but it will dwarf the 14-percent portion of India and the U.S. share of 10.9 percent.
The numbers suggest that the shift of focus from China to India may be premature, said David Fridley, staff scientist at the China Energy Group of the U.S. Department of Energy's Lawrence Berkeley National Laboratory in California.
"The fact that Chinese coal demand has nearly tripled in 15 years to me continues to be the story, since it's the single largest source from a single country of global emissions," Fridley said in an email message.
Half the coal consumed in the world
Coal consumption and energy-related CO2 emissions are both expected to peak in China around 2030 in keeping with a landmark agreement reached with the United States last year.
China's coal use in 2035 will be the same as in 2013, the report said. The country now accounts for about half the coal consumed in the world.
Despite the improvement, the long duration of China's coal consumption at world-leading levels ensures that its emissions will remain a primary cause of global warming for the foreseeable future, since GHG effects on climate change are cumulative.
In 2040, China will burn 4.8 percent less coal than in 2030, while its CO2 emissions will be 3.3 percent less, according to IEA estimates.
Over the same period, coal use will rise 35 percent in India and fall 8.9 percent in the United States.
But even in 2040, China will still be using 63 percent more coal than the United States and India combined.
The projections are based on the IEA's "new policies scenario," which includes firm climate change commitments from countries, as well as announced intentions like carbon emissions trading that may not have implementation plans in place.
Based on those policies, the IEA estimates that global temperatures since the start of the industrial era will rise 2.7 degrees Centigrade (4.8 degrees Fahrenheit) by the end of the century, exceeding the United Nations' danger limit of 2 degrees Centigrade (3.6 degrees Fahrenheit).
Greater efforts are possible under the IEA's more ambitious scenario, which is designed to meet the 2-degree goal. But that would require China to reduce coal burning by over 20 percent in 2020-2030 with another 20-percent cut by 2040, based on the forecast data.
Barring a major policy change at the Paris summit, that seems unlikely to happen.
A separate report this month by the environmental group Greenpeace East Asia said that China is continuing to approve and build new coal-fired power plants with a 40-year lifespan at a rapid rate, although existing generators are severely underutilized.
The policy, driven in part by cheap coal prices and profits at the provincial level, could lock in patterns of coal consumption and emissions for decades to come.
There are also concerns that long-range emissions forecasts based on projections of declining economic growth in China could go widely off the mark if the government steps in with stimulus policies to stop the slide.
Fridley compared the uncertainty to forecasts of peak gasoline use in the United States several years ago during the recession. The predictions turned out to be wrong when the economy recovered and growth in fuel consumption resumed.
China's slowdown could also be cyclical, particularly if the government decides to stem industrial losses with supplies of cheaper coal-fired power.
"I think in both cases, we're seeing an inflection point, though not necessarily a continued decline," Fridley said. "The China coal story isn't over."
China may have created even greater uncertainty about the forecasts of its emissions with a recent data revision showing that coal consumption for some years was understated by as much as 17 percent.
Fridley said the new census accounting for 2013, reported in a recent front page story by The New York Times, was known to his research team as far back as February, but the new figures imply the release of about 1 billion tons of additional CO2.
It is unclear whether more revisions are in the offing, but the inaccuracies may further cloud confidence in China's official data and its emissions pledges for the Paris climate conference.
In a late amendment to its annual report, the IEA said the revised accounting from the National Bureau of Statistics (NBS) would increase its estimate of China's energy-related CO2 in 2040 by 1.7 percent.