It seems just yesterday that the world was debating whether we humans are causing global warming. That debate, not yet over, looks like child’s play compared with the one that’s coming: what we should do about it.

A preview of the choice President-elect Barack Obama is likely to confront came in a pair of dueling essays in Saturday’s Journal.

One camp, which includes most environmentalists, says the solution is more caps on emissions – ones that get tougher over time. The other camp, which includes many corporate leaders, says the better answer is to invest in developing breakthrough technologies – ones that could, if they pan out, achieve deeper emission cuts at lower cost.

Mr. Obama has endorsed both approaches. He supports the notion of a U.S. cap-and-trade program to curb greenhouse-gas emissions. And he has proposed the U.S. spend $150 billion over a decade to develop new-energy technologies.