At the water's edge, a wooden walkway leads to a small pier and boathouse. An angled sign is mounted on the railing. A measuring pole is attached to the walkway and goes into the water and into the sandy bottom.
The sign's title appears over an aerial view of Fort Jefferson, two inset photographs, and an illustration of the measuring pole.
Sign Text:
"For over 150 years, Fort Jefferson has stood fast in her sand-and-sea home. But the very waters this 'Guardian of the Gulf' once protected could take her down. Sea level rose nearly a foot in the past century and keeps rising. Earth's warming temperatures, mostly caused by human actions like burning fossil fuels, melt glaciers and make ocean water expand. Will the sea engulf this stunning piece of American history?"
In the photo of the fort, water surrounds the six-sided red brick complex. A "You Are Here" arrow points to the pier outside the entrance to the fort.
A photo shows the seawall, a brick-edged concrete wall the width of a sidewalk that defines the moat on several sides of the fort that directly border the sea. The sea wall is submerged and water comes up several feet higher on the sides of the fort.
Caption:
"Scientists predict that sea level will rise 3 feet by 2100. At that level, the fort's sea wall will no longer defend her."
A photo shows a sooty tern, a bird with a black back and cap on its head, and a white belly neck and face, sitting on an egg in the sand. The sooty tern has a black eye stripe that connects its black cap to the beak, making a white triangular patch on its forehead.
Caption:
"These islands are the only North American nesting grounds for several bird species including sooty terns. Just a small amount of sea level rise, and these birds will fly away forever."
An illustration shows rising tides along a tall pole over time. The actual pole is located just off the pier. "This pole marks current and projected sea levels, to show how rising waters would submerge this treasured fort and the islands of Dry Tortugas." From bottom to top:
A blue marker shows average sea level in 1914 as minus 10 inches.
A blue marker shows average sea level in 2000 as zero.
A yellow marker shows average elevation of Bush Key at about a foot and a half.
A red marker shows projected sea level in 2100 as 3 feet.
A red marker shows projected sea level in 2300 as 12 feet.