Climate change will pose major new hurdles for U.S. naval forces, forcing the military to grapple with an emerging Arctic frontier, increasing demand for humanitarian aid and creating rising seas that could threaten low-lying bases, the National Academy of Sciences said yesterday.

"Even the most moderate current trends in climate, if continued, will present new national security challenges for the the U.S. Navy, Marine Corps and Coast Guard," concludes a new academy report. "While the timing, degree and consequence of future climate change impacts remain uncertain, many changes are already underway in regions around the world ... and call for action by U.S. naval leadership in response."