WASHINGTON – Saying there's a "race against time," an advocacy group reported this week that climate change — leading to sea level rise and worsening wildfires — is putting some of the nation's most significant historical sites at risk.

Highlighting archaeological and other historical sites in several states, a report released Tuesday by the Union of Concerned Scientists said that rising waters and raging flames could endanger some of the nation's most-cherished locations.

"You can almost trace the history of the United States through these sites," Adam Markham, director of climate impacts at the Union of Concerned Scientists and a co-author of the report, said in a statement. "The imminent risks to these sites and the artifacts they contain threaten to pull apart the quilt that tells the story of the nation's heritage and history." Among the 30 sites at risk, said the report:

• The prehistoric mounds of oyster and clam shells that dot Florida's Gulf and Atlantic coasts. The report said Florida is one of the only places on Earth where coastal hunter-gatherers built shell structures as large and complicated as they are along the southwest coast. Across the state in Canaveral National Seashore, Turtle Mound is a massive shell structure that dates back at least 1,200 years. In both places, rising seas and worsening storm surge are endangering the shell structures.

• In St. Augustine, Fla., sea level rise, erosion and worsening storm surge threaten landmarks in the nation's oldest city. The city, on the Atlantic coast, was the seat of Spanish rule in North America for 200 years. Without major engineering feats, the Castillo de San Marcos fort likely will become inaccessible if sea levels rise 3 feet; a major report earlier this month about climate change projected that sea levels could rise 1 to 4 feet by 2100.

• In California, Groveland and other Gold Rush-era towns are imperiled by wildfires. The report said climate change has driven up temperatures, caused earlier melting of winter snowpack and made forests drier for longer periods — making them ripe for fire. The report singles out Groveland, a town near Yosemite National Park that was imperiled by the devastating Rim fire in 2013.

• Other locations highlighted include the Cape Hatteras Lighthouse in North Carolina; the Statue of Liberty; and the Old and Historic District of Charleston, S.C. At Cape Hatteras and the Statue of Liberty, steps already have been taken to make the sites more resilient to climate change.

The Union of Concerned Scientists, headquartered in Cambridge, Mass., is a nonprofit research and advocacy organization. The report in many ways echoes the U.S. National Climate Assessment, a major assessment released to a blizzard of attention earlier this month. That report was overseen by federal officials and represented the views of more than 300 experts and top Obama administration officials; climate change skeptics said the report was an overreach.