istock green collar roofAccording to a study released today by the US Conference of Mayors, green jobs “could be the fastest-growing segment of the United States economy over the next several decades and dramatically increase its share of total employment.”

As the Seattle P-I reports, Miami Mayor Manny Diaz, the conference’s president, said the report makes “a very compelling economic argument for investing in the green economy and that we’re going to get a huge return for it.”

Indeed. The study cautions that these numbers won’t be realized without “an aggressive shift away from traditional fossil fuels toward alternative energy and a significant improvement in energy efficiency.” From the P-I:

For example, it assumes that by 2038 alternative energy will account for 40 percent of electricity production with half of that coming from wind and solar; widespread retrofitting of buildings to achieve a 35 percent reduction in electricity use; and 30 percent of motor fuels coming from ethanol or biodiesel.

“These are things we have to do,” Mayor Diaz told an AP reporter over the phone, adding that “Washington [DC] needs to get on the train.”