By NANCY BENAC
Associated Press

NEW LONDON, Conn. – President Barack Obama has argued for action on climate change as a matter of health, environmental protection and international obligation. On Wednesday, he added national security.

Those who deny global warming are putting at risk the United States and the military sworn to defend it, he told cadets at the U.S. Coast Guard Academy. Failure to act would be “dereliction of duty,” their commander in chief said.

He said climate change and rising sea levels jeopardize the readiness of U.S. forces and threaten to aggravate social tensions and political instability around the globe.

The president’s message to climate change skeptics was unequivocal: “Denying it or refusing to deal with it undermines our national security.”

“Make no mistake, it will impact how our military defends our country,” Obama said on a crisp, sunny morning at Cadet Memorial Field. “We need to act and we need to act now.”

Seated before him were 218 white-uniformed graduates, pondering where military service will take them in life.

Obama drew a line from climate change to national security that had multiple strands:

-increased risk of natural disasters resulting in humanitarian crises, with the potential to increase refugee flows and worsen conflicts over food and water.

-aggravating conditions such as poverty, political instability and social tensions that can lead to terrorist activity and other violence.

-new threats to the U.S. economy from rising oceans that threaten thousands of miles of highways, roads, railways and energy facilities.

-new challenges for military bases and training areas from seas, drought and other conditions.

“Around Norfolk, high tides and storms increasingly flood parts of our Navy base and an air base,” Obama said of military facilities in Virginia. “In Alaska, thawing permafrost is damaging military facilities. Out West, deeper droughts and longer wildfires could threaten training areas our troops depend on.”

Preparing for and adapting to climate change won’t be enough, he said. “The only way the world is going to prevent the worst effects of climate change is to slow down the warming of the planet.”

He laid out his administration’s steps to reduce carbon greenhouse gas emissions, including strict limits on emissions from vehicles and power plants. The government expects those emission reductions to provide the U.S. contribution to a global climate

treaty that world leaders are expected to finalize in December. Obama said it doesn’t take a scientist to know that climate change is happening.

The evidence is “indisputable,” he said.

Without identifying the skeptics or those who resist action on climate change, Obama acknowledged the difficult terrain in Washington. “The politics will be tough, but there is no other way.” He repeated: “This will be tough.”

Obama’s climate change agenda has drawn strong political opposition from the GOP-led Congress and faces a number of legal challenges. Many Republican lawmakers either have denied the science of climate change or have distanced themselves from it, saying they lack the expertise to issue an opinion.

Some of the 2016 GOP presidential candidates have rejected unilateral moves to address the issue, saying they could hurt the U.S. economy.

The Republican chairmen of the Senate and House Armed Services Committees, meanwhile, issued derisive retorts to Obama’s address, questioning his focus on climate change when the Islamic State group is on the move in Iraq and Syria, refugees are multiplying and much in the world is amiss.

“What does the president of the United States say today? Well, its climate change we have to worry about,” said Sen. John McCain of Arizona.

“Our adversaries are not motivated by the weather; they are emboldened by America’s withdrawal from the world,” said Rep. Mac Thornberry of Texas.

Obama had a determined and hopeful response to the opposition, but one not likely to be fulfilled: “This cannot be subject to the usual politics and the usual rhetoric.”

His message was reinforced by Secretary of State John Kerry, just back from meetings in Asia. Kerry said in a statement that the idea of climate change as a national security issue “was a primary topic of discussion” throughout his conversations with Asian leaders.

Retired Rear Adm. David Titley, of the private Center for Climate and Security, said Obama’s “rhetoric is all good,” but he was waiting to see if the administration commits enough money to deal with the challenges the president identified.