Aggressive optimism. Those two words capture the spirit of Earth 3.0 and, we hope, the spirit that Washington, D.C., will bring to urgent energy, environment and sustainability issues. Right now a new president is calculating his administration’s first steps. If he is serious about ending U.S. dependence on oil, stopping climate change and reversing destruction of land and sea, he has to take strong actions in his first 100 days. Shirley Ann Jackson, president of Rensselaer Polytechnic Institute, talks straight about what those actions should be.

One big decision will be how to limit carbon dioxide emissions. Everyone has been calling for a cap-and-trade system, but as entrepreneur Peter Barnes of the Tomales Bay Institute explains, such an approach has a tragic flaw: it will cost average citizens money. Barnes has a better plan, called cap and dividend, that actually pays you and me.

Like it or not, money is at the nexus of energy and emissions decisions. History shows that as soon as high fossil-fuel prices drop, so does investment in alternative energy. Economist Steven Kyle of Cornell University argues that there is only one way to prevent a backslide: a tax on oil. If you think altruism or fear is enough to support clean energy, talk to venture capitalists. I recently asked three of them whether, knowing the national security and environmental value of weaning society off oil, they would continue to fund alternative energy start-ups if oil prices sagged. All three said no.

Given that, the government has to step in. It needs to stop subsidizing fossil industries and start funding renewable ones, even if standard economic models question such spending. A century ago the federal government backed a struggling electric grid and a fledgling automobile industry, despite models that indicated a poor probability of payback. Of course, those bold actions fueled American prosperity for decades. The lever then, as now, was neither a cost-benefit analysis nor hand-wringing but the political will to embrace aggressive optimism and lead.

Note: This article was originally printed with the title, "Editor's Letter".