Graduate Robert McConnel asks US President Barack Obama to strike a "James Bond" pose during the 134th Commencement Exercises of the United States Coast Guard Academy in New London, Connecticut, May 20, 2015. [Photo/Agencies]

NEW LONDON, Conn., - Rising seas and thawing permafrost caused by warmer global temperatures threaten US military bases and will change the way the US armed services defend the country, US President Barack Obama said on Wednesday.

In a commencement address at the United States Coast Guard Academy, Obama underscored the risks to national security posed by climate change, one of his top priorities for action in his remaining 19 months in office.

"The threat of a changing climate cuts to the very core of your service," Obama told the 224 graduating cadets, who studied the impacts of global warming as part of their curriculum.

"It will affect everything that you do in your careers," Obama added, noting that sea levels were expected to rise by 1 to 4 feet (30-120 cm) in the coming century.

The Pentagon is assessing the vulnerability to climate change of its 7,000 bases, installations and facilities, many of which are on the coast, the White House said.

Obama highlighted damage to the navy and air bases at Norfolk, Virginia, from increasing floods.

Coast guard operations in Alaska have already begun dealing with changes, Admiral Paul Zukunft, commandant of the Coast Guard, told cadets.