On graduation day, members of the 2015 class of the U.S. Coast Guard Academy thought they were going to pick up their diplomas and swap stories about their school days.

Instead, the boss showed up to give them an assignment likely to last their lifetimes: “You are part of the first generation of officers to begin your service in a world where the effects of climate change are so clearly upon us.”

President Obama and graduating Ensign Mary Elizabeth Hazen celebrate her diploma. (© AP Images)

President Obama spoke May 20 to more than 200 graduating ensigns, educated and trained to become officers in the U.S. Coast Guard.

The message from the commander in chief of the U.S. armed services: National security is at stake, graduates. Be prepared to respond.

“Rising seas are already swallowing low-lying lands, from Bangladesh to Pacific islands, forcing people from their homes. Caribbean islands and Central American coasts are vulnerable as well,” Obama said. “Globally, we could see a rise in climate change refugees. And I guarantee you, the Coast Guard will have to respond.”

Shrinking ice expanses on the Arctic Ocean will give the Coast Guard responsibilities to protect extended waters on the U.S. Arctic shoreline, Obama said.

The U.S. Coast Guard leads rescues of seafaring refugees and victims of marine mishaps. Climate change and extreme weather events could increase the need for rescues. (© AP Images)

“We’re witnessing the birth of a new ocean — new sea lanes, more shipping, more exploration, more competition for the vast natural resources below.”

The U.S. military services have already taken great strides toward assessing the risks climate change will create for operational readiness, Obama said, at the same time developing cleaner fuels to power equipment and facilities.

Obama makes this appeal to new Coast Guard officers about two years after he first outlined the U.S. Climate Action Plan. Key elements of the strategy are reducing carbon emissions that cause climate change and adopting cleaner energy technolgies.

In advance of an international conference on climate change action in December, the United States is making firm commitments on reducing greenhouse gas emissions. The nation has made progress in reducing its carbon footprint. By 2013 it had lowered greenhouse gas emissions 9 percent from 2005 levels.