Last year, during an interview with Vaclav Smil, I asked the distinguished professor of geography at the University of Manitoba why there was such a paucity of informed discussion about energy issues. He replied “There has never been such a depth of scientific illiteracy and basic innumeracy as we see today.”

That line comes to mind amid the continuing calls for phasing out coal in the U.S. In July, Al Gore, the former vice president and recent winner of the Nobel Peace Prize, declared that the U.S. should “commit to producing 100 percent of our electricity from renewable energy and truly clean carbon-free sources within 10 years.” In November, in an op-ed in the New York Times, Gore insisted that the U.S. must replace “dangerous and expensive carbon-based fuels with 21st-century technologies that use fuel that is free forever: the sun, the wind and the natural heat of the earth.”

Gore’s calls have been seconded by groups like the Sierra Club and Greenpeace as well as by the International Energy Agency. On November 25, the I.E.A.’s executive director, Nobuo Tanaka, said that “Preventing irreversible damage to the global climate ultimately requires a major decarbonisation of world energy sources.”

While Tanaka, Gore, and others may agree on the need to phase out coal, the world is heading the other direction. On November 12, the I.E.A. released its World Energy Outlook, and the second page of the agency’s briefing slides show that coal is gaining – not losing – market share. Between 2000 and 2007, global coal use increased by 4.8 percent. That’s three times the growth rate seen in oil consumption (which grew by 1.6 percent) and nearly twice the rate in natural gas use (which climbed by 2.6 percent.) Further, the I.E.A. expects that through 2030, about 60 percent of incremental energy demand in non-O.E.C.D. countries will be met with coal. (In the O.E.C.D., coal will likely provide less than 10 percent of incremental new demand over that same time period.)

None of this is to argue that coal is good or bad. Rather, it is to provide a bit of numeracy. If the U.S. and the rest of the world really want to replace coal with some other form of energy, then it is essential to understand the size of the challenge.

Let’s look at the U.S., second only to China in terms of total coal consumption. In 2007, the U.S. used about 1.1 billion tons of coal. That’s the energy equivalent of about 4.2 billion barrels of oil per year or about 11.5 million barrels of oil per day. Here’s the key comparison: America’s daily coal ration contains more energy than Saudi Arabia’s daily oil production.

Indeed, the scale of U.S. coal consumption boggles the mind. In 2007, the amount of energy America used in the form of coal exceeded the total energy consumption – from all sources, coal, oil, natural gas, and nuclear – of all of the countries of Central and South America combined. Just as important as the scale of America’s coal consumption is this fact: U.S. coal use has increased faster in recent decades than has oil or natural gas consumption. Between 1973 and 2007, U.S. coal consumption jumped by 75.5 percent. During that same time period, U.S. oil consumption increased by 15.2 percent and natural gas consumption increased by just 5 percent.

Here’s another comparison: On a daily basis, global coal consumption is equivalent to about 63.8 million barrels of oil. Thus, replacing the world’s coal habit with something else will require finding an energy source (or sources) that can supplant the equivalent of six new Saudi Arabias. Or consider China. On an average day, its coal use provides the energy equivalent of 26.3 million barrels of oil, or about two and a half Saudi Arabias.

By any measure, those are daunting numbers. U.S. and global policymakers may not like coal, but given the enormous scale of the coal business, it’s obvious that the U.S. and the rest of the world will be relying on the black fuel for many years to come.

Robert Bryce’s latest book is Gusher of Lies: The Dangerous Delusions of “Energy Independence.”