Seven Growth Sectors in Green Business Instead of knocking, sometimes opportunity shows up as a crisis.

The Chinese alphabet includes a pair of characters often translated as meaning "crisis" and "opportunity." An odd combination, but no more so than those who look at tornadoes, oil spills, soaring gas prices and corn shortages and see gold. Those opportunists want to remake the carbon-challenged world, and they're backed by a growing assortment of specialized boutique firms that provide capital and support.

Southern California's Quercus Trust, for example, supports a portfolio of some 40 green schemes, while New York and Zurich-based Greentech Capital Advisors restricts itself to clients in alternative energy and cleantech sectors. And Kholsa Ventures in Menlo Park, Calif., is funding work on advanced hydrocarbons, mechanical and electrical efficiency, semiconductors and water.

Whether the aim is to seek your fortune, to improve the world or merely to engender common sense, these are top fields ripe for ecological innovation. Here's how to capitalize on crises.