Coal built the modern world and still makes its lights glow, but we've reached a turning point in our love affair with this powerful and ancient fuel.
The world—with China and the U.S. in the lead—burns more coal now than ever, and our reliance on it to generate electricity keeps rising. But coal pollutes more than oil or natural gas, and scientists say that cutting its use is critical to reducing the impact of climate change.
The Obama Administration, amid objections from political foes and even some friends, is moving to push the U.S. to reduce its use of coal. The question will be how much the EPA's efforts to cut carbon emissions can do for the environment at a time when other nations, especially China and India, are escalating their burning of coal to meet a booming demand for electricity.
A Black Rock That Burns
This flammable black rock powered the steam engines and factories of the industrial revolution in England and Europe more than 200 years ago. In the United States coal powered the furnaces of iron and steel mills that built our cities, railroads, and steamships. Oil energy now turns wheels, powers ships, and keeps airplanes aloft, but the world still relies more on coal than on any other energy source to keep the lights on.
Even as cheap natural gas from hydraulic fracturing, or "fracking," has reduced the U.S.'s reliance on coal-fired power by about one-third in recent years, since 2000 coal use worldwide has gone up almost as much as the use of all other fuels—natural gas, oil, renewables, and nuclear power—combined, according to the 2011 World Energy Outlook from the International Energy Agency
Today we burn coal mostly to generate electric power. The U.S. Energy Information Agency says the U.S., with the world's largest reserves, burns about 11 percent of the world's annual coal production and gets 37 percent of its electricity from coal. But China, with reserves less than half those of the U.S., burns 49 percent of the world's coal.
Worldwide, coal consumption is projected to keep rising for decades, at least unless more countries replace coal with other energy sources or we begin to run out of coal, which is unlikely soon. Estimates vary, but the World Coal Association says we have enough recoverable coal worldwide to last more than 110 years. The U.S. Department of Energy estimates that the U.S. has slightly less than a 200-year supply.
Seeing Risks to "Our Way of Life"
Coal, as writer Michelle Nijhuis explained in the April 2014 issue of National Geographic magazine, is "fraught with 'externalities'—the heavy costs it imposes on society." Nijhuis went on, "It's the dirtiest, most lethal energy source we have. But by most measures it's also the cheapest, and we depend on it."
Coal's external costs on society include thousands of coal miner deaths annually, hundreds of flattened Appalachian mountains in the U.S., and a variety of pollutants, including carbon dioxide, sulfur dioxide, nitrogen oxide, mercury, solid ash waste, acid mine drainage, water pollution, and acid rain.
Coal produces about 39 percent of the carbon dioxide emitted from burning fossil fuels globally, and it is these carbon emissions that have come under scrutiny. Scientists for decades have pointed to cutting carbon emissions from the burning of fossil fuels as key to keeping the climate from destabilizing.
University of Chicago geophysical scientist David Archer wrote in his book The Long Thaw, "Because there is so much coal on Earth, the climate of the future ultimately will be determined by what happens to the coal."
That's one reason the U.S. government announced today that by 2030, it intends to reduce the carbon emission levels from U.S. power plants by 30 percent from their 2005 levels.
Referring to unabated carbon emissions from power plants, she said, "In our lifetimes, if we do nothing about climate change, temperatures could rise 10 degrees and seas could rise by four feet."
Those estimates are higher than the most dire scientific projections for 2100 in recent reports from the Intergovernmental Panel on Climate Change. However, like the Obama Administration, the IPCC has said that the effects of climate change can be reduced by cutting emissions.
Older than the Dinosaurs
The fuels we rely on the most—coal, oil, and natural gas—all come from ancient plants and animals that grew under the sun's heat and light hundreds of millions of years ago, long before the dinosaurs lived. Over millions of years these plants and animals were buried, compressed, and fossilized to become the carbon-rich fuels that we rely on today to power the world.
Fossil fuels originated in a geological period called the Carboniferous, which lasted from about 300 million to 360 million years ago. Dinosaurs appeared millions of years later. The world was much warmer during the time when fossil fuels were created, and coal formed in regions across portions of North America, England, Europe, and China that were covered by vast tropical forests.
Fossil fuels were created over millions of years as these ancient forests died out and eventually were covered by layers of mud, rock, and sand as seas rose and fell. These ancient layers of carbon-rich plant and animal sediments built up over millions of years. It's only in the past few hundred years that we've discovered, dug up, and drilled for these rich stores of coal, oil, and gas.
MIT (now Harvard) chemist Daniel Nocera told the New Yorker in May 2012, "Every year, by burning fossil fuels, we release a million years of photosynthesis." In other words, it took a million years of plant growth powered by the sun to create the coal, oil, and gas that we burn each year.
By burning these fossil carbon fuels, each year we release back into the atmosphere the plant carbon that was stored up gradually over that million years. This helps explain why we see dramatically rising levels of carbon dioxide in the atmosphere: Levels are now almost 400 parts per million, about one-third higher now than before we began burning coal at the start of the industrial revolution, around 1800. (Related: "Northern Hemisphere Cracks 400 ppm CO₂ for Whole Month for First Time")
Like a Global Blanket
Like a greenhouse, the Earth is warmer than outer space because carbon dioxide in our atmosphere holds heat near the Earth's surface. Carbon dioxide in our atmosphere acts in much the same way as blankets on a bed: If we have too few blankets we get cold, too many blankets and we get hot.
If we had no carbon dioxide in the atmosphere, the Earth would be an ice-covered ball. Carbon dioxide is radiative—it absorbs solar heat reflected off Earth's surface and holds that heat in the atmosphere near the Earth. Hold your hand near a hot iron or hot stove and you will feel the heat; it is this radiative (or reflected) heat that CO₂ absorbs.
Add too much carbon dioxide, and it's like adding too many blankets to your bed: You get warm. Now the Earth is warming. Arrhenius pointed out that too much carbon dioxide would cause the Earth to warm up. He was not alone.
In the late 1950s, Charles David Keeling of the California Institute of Technology began tracking carbon dioxide levels at the Mauna Loa Observatory in Hawaii. Carbon dioxide levels in the atmosphere were about 315 parts per million when he began his work in 1959, and they've been continuously measured since then by the Scripps Institution of Oceanography.
Now CO₂ levels regularly exceed 400 ppm. Studies of ice cores from Antarctica indicate that current CO₂ levels are higher now than they've been in the past 800,000 years. Before we began burning fossil fuels, levels of carbon dioxide in the atmosphere averaged no higher than about 280 ppm.
Scientific studies have indicated a link between rising levels of atmospheric carbon dioxide and rising seas. In many studies scientists have documented other impacts as temperatures rise: melting glaciers and ice caps, loss of snowpack, shifting seasons, more frequent extreme precipitation, and more heat waves and droughts that will damage crop yields.
A Benchmark Moment?
All things considered, the proposed carbon emissions ruling from the Obama Administration could reduce global carbon emissions by a small amount. Since the 600 existing coal power plants in the U.S. burn about 11 percent of the world's coal, the proposed 30 percent emissions cut would, in the years ahead, result in slightly more than a 3 percent reduction worldwide.
The question remains whether other nations such as China and India will also move to reduce emissions. In absolute numbers the Obama Administration's effort is small, but it does begin to slowly move the country away from carbon-intensive fuels for electric power and toward less polluting energy sources such as wind, solar, and nuclear power.
U.S. carbon emissions have fallen in recent years, but they're beginning to rise again. And since global emissions keep rising too, this move to cut power plant emissions looks to get swamped unless China and India begin to move away from coal.
Still, little things can add up.
If the Obama Administration's move against carbon pollution inspires other nations to follow—and the eventual result is a meaningful reduction in such emissions worldwide—the people of low-lying coastal cities, all of us who rely on crop harvests to eat, and the children of future generations may be able to mark this as the moment we truly began to turn toward alternative ways of powering the planet.