COPENHAGEN – One of the stranger spectacles of the climate change debate was the sight, earlier this month, of NASA climate scientist Jim Hansen marching hand-in-hand with Hollywood actress Darryl Hannah outside the Capitol Coal Power Plant in Washington, DC.

Hansen promised to brave arrest at what was billed as the world’s largest direct-action climate change protest. Instead, the worst snowstorm in three years reduced the size of the crowd, prevented special guests from arriving, and hindered efforts to use a solar panel to light up a protest billboard.

The police reportedly told the crowd that they didn’t want to arrest anybody who didn’t want to be arrested, and nobody was. That didn’t stop the protesters from proclaiming the event a success.

"VICTORY: THIS IS HOW TO STOP GLOBAL WARMING,” declared the Web site of Capitol Climate Action.

And, indeed, the US House Speaker and Senate Majority Leader called on the Architect of the Capitol to stop using coal for the Capitol Power Plant (albeit days before the rally).

But if stopping global warming were this easy, I – and everybody I know – would be painting placards for the next round of direct action.

Hansen condemns coal-fired power plants as "death factories,” and his belief that coal is evil is widely shared. It is also obviously wrong. If we were to stop using coal tomorrow, we would discover that it remains a vital source of life.

Coal accounts for almost half of the planet’s electricity supply, including half the power consumed in the United States.

Coal keeps hospitals and core infrastructure running, provides warmth and light in winter, and makes life-saving air conditioning available in summer.

In China and India, where coal accounts for about 80% of power generation, it has helped to lift hundreds of millions of people out of poverty.

It is little wonder, then, that US Energy Secretary Steven Chu, who two years ago described the expansion of coal-fired power plants as his "worst nightmare,” now calls coal a "great natural resource.”

The vital question is what would replace coal if were to stop using it. Judging from their chant – "No coal, no gas, no nukes, no kidding” and "Biofuels - hell no!” – the protesters in Washington would rule out many plausible alternatives.

Solar and wind power appear to be acceptable, but both are much less reliable than coal, and much more expensive. Only about 0.5% of the world’s energy comes from these renewable sources.

Even with optimistic assumptions, the International Energy Agency estimates that their share will rise to just 2.8% by 2030.

One reason is that we don’t know how to store the energy from these sources: when the wind doesn’t blow and the sun doesn’t shine, what powers your computer or the hospital’s operating room?

Moreover, renewables are still costly. Recently, former US Vice President Al Gore and United Nations Secretary General Ban Ki-moon claimed that, "in the US, there are now more jobs in the wind industry than in the entire coal industry.”

Never mind that the numbers were massaged, because they still hold a valuable lesson. The US gets 50% of its electricity from coal but less than 0.5% from wind. If it takes about the same manpower to produce both, wind power is phenomenally more expensive.   

The equivalent of more than 60 million barrels of oil is consumed in coal every day, and there is no affordable "green” alternative. There is an ample and cheap supply of coal for several centuries.

We need to accept that much of the world’s cheap coal will be burned – but we should focus on capturing the CO2. In agreements announced by the Obama administration, the US is working with China and Canada on projects to develop this technology.

The end of fossil fuel’s stronghold will come when we have cheap alternatives, especially in developing countries. That day will arrive sooner if governments spend a lot more money on low-carbon energy research, which is woefully inadequate.

Every nation should ideally commit to spending 0.05% of GDP exploring non-carbon-emitting energy technologies. This would cost $25 billion per year – a 10-fold increase in global financing – and create momentum to recapture the vision of delivering a low-carbon, high-income world.

Coal contributes strongly to global warming, but no amount of political theater can alter the inescapable fact that it also provides benefits that we cannot yet replicate with renewable energy. Braving arrest with Hollywood stars is a diversion.

Declaring true victory over global warming will take a lot more pragmatism, and a lot more work.

Bjorn Lomborg, the director of the Copenhagen Consensus Center, is an adjunct professor at the Copenhagen Business School, and author of The Skeptical Environmentalist and Cool It: The Skeptical Environmentalist’s Guide to Global Warming.