This article has been jointly published by NBCNews.com and InsideClimate News, a nonprofit, independent news outlet that covers climate, energy and the environment.

PORTSMOUTH, Va. — At the foot of the Chesapeake Bay in southeast Virginia lies a Naval shipyard older than the nation itself. One of the country’s first warships was built here in 1799. So was the first battleship, and decades later the first aircraft carrier.

Over the past three centuries, Norfolk Naval Shipyard has been blockaded and burned to the ground, only to be rebuilt again and again. Today, it’s one of four Navy shipyards that maintain the nation’s nuclear-powered submarines and aircraft carriers, which enable the Pentagon to respond quickly to military and humanitarian crises across the globe.

But the shipyard now faces its greatest existential threat: rising seas and extreme weather driven by climate change.

In the past 10 years, Norfolk Naval Shipyard has suffered nine major floods that have damaged equipment used to repair ships, and the flooding is worsening, according to the Navy. In 2016, rain from Hurricane Matthew left 2 feet of water in one building, requiring nearly $1.2 million in repairs.

The Norfolk Naval Shipyard lies at the foot of Chesapeake Bay.

And that wasn’t even a direct hit — the most immediate worry, former military leaders say, is a strong storm that blows right through the area.

“It would have the potential for serious, if not catastrophic damage, and it would certainly put the shipyard out of business for some amount of time,” said Ray Mabus, who was the Navy secretary under President Barack Obama. “That has implications not just for the shipyard, but for us, for the Navy.”

Among the shipyard’s greatest vulnerabilities are its five dry docks, which are waterside basins that can be sealed and pumped dry to expose a ship’s hull for repairs. Once inside, vessels are often cut open, leaving expensive mechanical systems vulnerable to damage from storms and flooding.

Dry Dock 12 in Newport News, Virginia, is flooded to float the aircraft carrier Gerald R. Ford before its commissioning in 2013. Joshua J. Wahl / U.S. Navy

The dry docks “were not designed to accommodate the threats” of rising seas and stronger storms, according to a 2017 report by the Government Accountability Office. Navy officials warned the government watchdog agency that flooding in a dry dock could cause “catastrophic damage to the ships.”

Already, high-tide flooding is contributing to extensive delays in ship repairs, the GAO said, disrupting maintenance schedules throughout the Navy’s fleet. Sea level in Norfolk has risen 1.5 feet in the past century, twice the global average, in part because the coastline is sinking.

The Navy has erected temporary flood walls and uses thousands of sandbags to protect the dry docks at Norfolk Naval Shipyard. The Navy has also begun elevating some equipment, but the facility remains vulnerable, according to a Defense Department survey on the effects of extreme weather on military bases, obtained through a public records request. In response, the Navy proposed a more permanent barrier estimated to cost more than $30 million, part of a 20-year, $21 billion plan submitted to Congress this year to modernize Norfolk as well as Navy shipyards in Maine, Washington and Hawaii.

But the new projects have yet to be approved.

The Navy said it takes extensive measures to limit damage from flooding. “These requirements ensure the safety of our personnel, our ships (nuclear and non-nuclear), and shipyard infrastructure," William M. Couch, a Navy spokesman, said in an email.