That's not a lot of bang for the buck. Indeed, the projected costs of this approach - some $5 trillion annually by mid-century - are so much greater than its likely benefits that it makes no sense to call it a solution at all.

Fortunately, there is a better, smarter way to deal with global warming. What if, instead of spending trillions of dollars trying to build an impossible number of power plants - or, more likely, condemning billions of people around the world to continued poverty by trying to make carbon-emitting fuels too expensive to use - we devoted ourselves to making green energy cheaper?

Right now, solar panels are so expensive - about 10 times more than fossil fuels in terms of cost per unit of energy output - that only well-heeled, well-meaning (and, usually, well-subsidized) Westerners can afford to install them. But think where we'd be if we could improve the efficiency of solar cells by a factor of 10 - in other words, if we could make them cheaper than fossil fuels.

We wouldn't have to force (or subsidize) anyone to stop burning coal and oil. Everyone, including the Chinese and the Indians, would shift to the cheaper and cleaner alternatives - and global emission targets would automatically be met.

Can we achieve this technological miracle over the next 20 to 40 years? In a word, yes. The price of solar energy has been dropping steadily for 30 years - by about 50 percent every decade - and we could accelerate that decline further with sufficiently large investments in research and development.

How large? If we were willing to devote just 0.2 percent of global GDP (roughly $100 billion a year) to green-energy R&D, I believe that we could bring about game-changing breakthroughs not just for solar power, but also for a wide variety of other alternative-energy technologies.

This belief in the potential of technological progress strikes some climate activists as naive or even delusional. But is it really? Consider one of the miracles of the modern age - the personal computer. These devices didn't become household items because governments subsidized purchases or forced up the price of typewriters and slide rules.

No, what happened is that, largely as a result of the space race, the United States government poured lots of money into R&D for solid-state physics and electronics engineering. The resulting breakthroughs not only got Neil Armstrong to the moon in 1969, but also made it possible for Apple to introduce the first Mac in 1976 and IBM to debut the first PC five years later.

We can do the same for clean energy. Forget about subsidizing inefficient technologies or making fossil fuels too expensive to use. Instead, let's fund the basic research that will make green energy too cheap and easy to resist.

The author is head of the Copenhagen Consensus Center and adjunct professor at Copenhagen Business School.

Project Syndicate