IT'S HAPPENING AGAIN. In the 1970s, when oil prices soared, Americans started pursuing alternative energy technologies. But when prices subsequently dropped, so did the promising projects. As recently as six months ago consumers, CEOs and politicians were hell-bent for green technologies, but then the recession worsened, oil prices plummeted and calls rose to postpone clean tech options.

Begging off now would be a terrible waste. In an incredibly short time, impressive business, technological and political gains have been made. Venture capital investment in clean tech hit an all-time high in 2008 (page 15). Airlines are making test flights powered by biofuels (page 68). And President Barack Obama—exploiting unprecedented political will to clean up the planet—has promptly set the federal government on a course to confront climate change (page 24).

The U.S. and the rest of the world cannot cave in to a temporary dip in energy prices and the economy. Rest assured, both will rise again. Fossil-fuel dependence remains a grave problem: production cutbacks by the Organization of the Petroleum Exporting Countries were already pushing oil prices back up in January. Global warming still looms as highly dangerous, in part because China has announced it will increase coal production by 30 percent by 2015 to meet its energy needs.

Clearly, we should continue to pursue clean technology aggressively, if for no other reasons than to create millions of jobs and to put the country in a strong competitive position. Even venture capitalists, whose sole metric is profit, say we must stay on the offense. As John Doerr, partner at Kleiner Perkins Caufield & Byers, writes on page 16, the best response to our concurrent economic, climate and energy security crises “is a bold, coordinated campaign of investment and incentives to accelerate green innovation.” Let’s press on toward solutions for sustainable progress.