WASHINGTON - In what could be an encouraging sign of change in the longstanding shortage of American students preparing for high-tech careers, the hottest subject on college campuses across the nation seems to be renewable energy - a surge of interest largely stimulated by the specter of global warming.

Concern about climate change is apparently galvanizing more undergraduate students to turn toward a subject involving science and engineering, some educators suggest, in much the same way that Moscow's launching of the Sputnik space satellite jolted baby boomers to turn their eyes to the stars.

What remains uncertain is whether enthusiasm for the science and technology of renewable energy sources will carry over into graduate school and swell the ranks of Americans with advanced degrees in such subjects.

"We have a shortfall of people to do cutting-edge research and do the innovations we need," said Vijay K. Dhir, dean of the engineering school at the University of California, Los Angeles. But, he added, "the potential is there."

The rising interest in renewable energy is so new that it's not clearly reflected in the latest enrollment figures, educators say. But leaders from a range of schools - including Arizona State University, Indiana University, and the University of Colorado - say energy and sustainability are the hottest topics for their students.

President Obama is mounting a multibillion-dollar push to boost "clean energy," in hopes of creating millions of domestic jobs. The effort includes stepped-up support for graduate students doing research in the area.

At the White House last week, he told a group of academics and energy entrepreneurs that "innovators like you are creating the jobs that will foster our recovery."

The United States has struggled in the past two decades, however, to produce enough homegrown scientists and engineers to meet demand.

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