The Marine Corps training grounds on Parris Island will need a sea wall.

That's what Assistant Commandant Glenn Walters told a congressional committee earlier this year, calling the rising seas and repeated flooding of the base a critical vulnerability.

And it's not just Parris Island. A runway for the Marine Corp Air Station nearby in Beaufort is only a few feet from the Mulligan Creek marsh and has been rip-rapped to protect it.

In Charleston, the roads near the Coast Guard stations on the Ashley and Cooper rivers get swamped with a heavy rain during high tides.

The base continually reviews their status, said Matt Bournonville, the base commander. 

While Congress and the administration waffle on the climate change issue, the military is preparing for the reality, said John Conger, the Center for Climate and Security director and a former Department of Defense comptroller.

Service budgets for the Pentagon now include funding for proposed mitigation projects, he said, and projects already are underway.

A number of former military leaders will speak Tuesday at the conference "Sea Level Rise & Security in South Carolina: Implications for Military & Civilian Communities." The gathering is sponsored by the center partnering with the Charleston Resilience Network. It will be at The Citadel.

Registration has been closed. But some limited seating is available on request, particularly for the Tidewater documentary screening at 5:30 p.m. Contact the center online.

Parris Island now floods about 10 times per year. By 2050 it could be flooded one-third of the year, according to the Climate and Security center.

"Seventeen of the 18 hottest years on record have occurred since 2000," said retired Marine Brig. Gen. Stephen Cheney of the American Security Project. He formerly commanded the Parris Island Recruit Depots and will speak at the conference.

The loss of space is bigger than an inconvenience, he said.

"That turns into a security issue. It turns into a tactical issue," he said, because the ability to move troops or armament, train troops or even staff the bases all get impacted.

Naval Station Norfolk might be the prime example on the East Coast. Because of persistent northeast winds and the ocean exposure of the lower Chesapeake Bay, sea level at the base has risen more than 14 inches since it was built in World War I, according to National Geographic. 

In a 2015 Department of Defense study on the situation, "the project team found sea level rise to be a significant and pervasive threat multiplier to mission sustainability," including infrastructure, capabilities and provisioning, the report said.

Roads to and through the base now flood nearly every time there's an unusually high tide, or what is popularly called a king tide.

Estimates suggest that by the end of the century the base will be flooded for two-thirds of the year. The electrical system at the docks has been compromised, Cheney said.

Tidal flooding also is accelerating along the South Carolina coast, including Charleston, federal researchers say. The coast might flood nearly every day by the turn of the century.

The Coast Guard is making improvements as its funding allows, Bournonville said.

"In terms of actual impacts of sea level rise-related high tide flooding, I think Charleston and Norfolk are in similar situations due to their exposure to tides," said William Sweet, a National Oceanic and Atmospheric Administration oceanographer. 

"I would say that sea level rise flooding at these locations, with their regionally distinctions, are a telling tale of what’s coming to many other communities around the country in the coming decades," he said.

Historic bases such as Fort Sumter, now a federal historic site, that have stood for centuries also are in jeopardy, as well.

A $5.4 million project is in planning to build a "living shoreline" breakwater around Sumter at the mouth of Charleston Harbor to protect it from wave damage partly from rising seas and storms, National Park Service spokeswoman Paula Ogden-Muse said.

Reach Bo Petersen Reporter at Facebook, @bopete on Twitter or 1-843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.