RUTHFULLY YOURS

If all goes according to plan, Hollywood icon Leonardo DiCaprio will blast into space aboard the maiden voyage of Richard Branson‘s Virgin Galactic spaceship sometime this year, opening up a new era of civilian space travel. This development might only be remarkable as the fulfillment of a dream long predicted by futurists and technophiles, were it not for the fact that Messrs. Branson and DiCaprio are prominent environmentalist celebrities who have warned of a coming ecological catastrophe if we fail to address our carbon problem.

Mr. Branson’s commitment to fighting climate change is praiseworthy: Over the years, he has consistently advocated for a broad mix of clean energy sources, including nuclear. He is founder and chief benefactor of the Carbon War Room, an outfit that has long advocated for carbon pricing and energy efficiency measures to help alleviate global warming. Mr. DiCaprio is on the board of trustees of the Natural Resources Defense Council and has decried overconsumption. “We are the number one leading consumers, the biggest producers of waste around the world,” the actor said in 2008.

Private space travel doesn’t seem to mesh with living green, and Mr. Branson surely anticipated that his project would raise environmentalists’ eyebrows. Perhaps that’s why he announced this past May: “We have reduced the [carbon emission] cost of somebody going into space from something like two weeks of New York’s electricity supply to less than the cost of an economy round-trip from Singapore to London.”

That would be a remarkable achievement in energy efficiency if it were true. Alas, it is not. According to the U.S. Federal Aviation Administration’s environmental assessment of the launch and re-entry of Virgin Galactic’s spacecraft, one launch-land cycle emits about 30 tons of carbon dioxide, or about five tons per passenger. That is about five times the carbon footprint of a flight from Singapore to London.

When you include the energy of the entire Virgin Galactic operation, which includes support aircraft, it is seven times more than the flight from Singapore to London. As such, a single trip on Virgin Galactic will require twice as much energy as the average American consumes each year. (These numbers were confirmed by a representative for Virgin Galactic.)

The Virgin Galactic story is familiar: Environmental celebrities and other elites often have a very hard time walking their talk. The bigger story is what Virgin Galactic tells us about the likely trajectory of future energy consumption.

Everyone from President Obama to the International Energy Agency has, in recent years, promoted energy efficiency as an easy, and often profitable, strategy to quickly reduce carbon emissions by reducing energy consumption. But even as our cars, buildings and appliances have become more efficient, we continue to find new ways to consume energy. Consumer technologies that we now consider staples, such as personal computers, flat-screen TVs, iPhones and cloud computing, have come into use in the last few decades. In addition to these everyday products, we’ve seen the rise of energy-intensive luxury goods, like private jets and yachts.

Humans have always been creative at finding new ways to use energy. Oil lamps, large ships, catapults, blast furnaces, gunpowder, fireworks, hand cannons and the printing press were all in use long before the first coal mine was dug or the first oil well was struck. But harnessing coal, and then petroleum, vastly expanded the amount of energy available for human use. Coal, first used to pump water out of mines, quickly led to the development of the railway industry and found uses in electricity, steel, transportation fuels and chemicals. Petroleum, first used in kerosene lamps beginning in the mid 19th century, soon found uses in transportation, cooking, lubrication, asphalt and myriad chemical products.

It might be that global warming will one day motivate societies to ban things like space tourism, impose stricter regulations and higher taxes on energy consumption, or voluntarily reduce their energy consumption. But it’s notable that many of the same people who express the most concern about global warming—including Messrs. Branson and DiCaprio—are the ones who are opening up new frontiers in energy consumption.

Even without restrictions, global energy consumption may peak at some point in the future, as population growth slows, poor people around the world achieve higher living standards, and our energy technologies continue to become more efficient. But for decades to come, energy use will almost certainly continue to rise around the world. Given this reality, efforts to improve energy efficiency may modestly slow the growth of energy consumption but are unlikely to halt it, much less achieve the deep declines necessary to mitigate climate change.

That Mr. Branson has developed a spacecraft that blasts humans into space more efficiently than previous vehicles is a laudable technical accomplishment. But from an environmental perspective, that accomplishment is completely overshadowed by the reality that the mogul is pioneering a new industry that involves blasting tourists into space. Should he succeed, the relative efficiency of the endeavor is almost entirely beside the point. Mr. Branson will have invented a new way for wealthy elites like Mr. DiCaprio to consume vast quantities of energy.

Weekend trips to Mars for the masses are, of course, still the stuff of science fiction. So, too, is the fantasy that climate change might be averted through deep cuts in global energy consumption.

Mr. Luke is a policy associate in the Energy and Climate Program at Breakthrough Institute in Oakland, Calif., where Ms. Mukuno is an assistant editor.