Confederate cannon balls plunged into the brick walls of Fort Sumter at the outset of the Civil War, forcing Union troops to surrender. A century and a half later, surging storm waters are now the modern threat to the South Carolina national monument. Storm-swollen seas can flood the coastal garrison, at times forcing the National Park Service to shut it down.

More than 100 National Park Service sites are located either on or near the coast. With global sea levels rising at an accelerating pace, spurred on by human-caused climate change, it's more important than ever that the service understands how storm surges and rising seas will impact historical sites like Sumter.

The conservation agency, however, lacked useful projections showing how these factors could inundate vulnerable lands, both in the near and distant future. So, when a visiting climate scientist, Maria Caffrey, proposed such a project, the Park Service accepted, and in 2013 the research began.

Five years later, the Park Service published the 90-page study to the backpages of its website with no known promotion of the work. The Union of Concerned Scientists spotted the study's publication last Friday, noting that there was "no easy way to find it unless you know where to look."

While a Park Service spokesperson explained via email that, once published, the report had been sent to park managers, it wasn't clear if the agency planned on publicizing the findings on a larger scale.

It was also unclear if the study would be published at all, and if so, in what form. After Caffrey's initial report was handed in, government officials censored out phrases relating to human-induced climate change in revisions and pushed the publication of the study back repeatedly, she said. The Center for Investigative Reporting, which acquired some 2,000 pages of revision, exposed the censored language and published the revisions on the organization's Reveal website in April.

While the Park Service finally published an uncensored version last week, the events illustrate how government interests can infringe upon the scientific integrity of new research, especially in the realm of climate change. As Caffrey notes, the removal of particular language in the study came from inside the government, not scientists outside the agency.

"The alterations came from people way beyond the coauthors," Caffrey, now a research associate at the University of Colorado Boulder, said in an interview.

What the study says about climate change

The study, "Sea Level Rise and Storm Surge Projections for the National Park Service," projects sea level rise in the years 2030, 2050, and 2100 for 118 park sites, as well as storm surge projections for 97 of them.

Simulated flooding caused by a hypothetical hurricane striking Theodore Roosevelt Island in Washington DC. Image: National Park Service

The study found that there are coastal parks — like Wright Brothers National Memorial located on a strip of sandy island off of North Carolina — that may be relatively comfortable today but are likely to become vulnerable to future sea level rise and storm surge.

"Wright Brothers might not be in serious danger right now, but when you factor in sea level rise and storm surge, it becomes a much more serious issue," said Caffrey.

During the revision process, a park official (or officials) crossed out different references to "human activities" and "anthropogenic" (meaning originating from human activity) from language discussing the influences of climate change, according to Reveal's reporting.

But in the final published version, these words were back.

"We were pleased to see it underscore that park structures were at risk from anthropogenic climate change," Sarah Barmeyer, the senior director of Conservation Programs for the National Parks Conservation Association, said in an interview.

The Park Service said that it backs the final version of the report published to the site, and that the agency often works through disagreements on recommended revisions to scientific reports.

"The National Park Service is confident in the quality and accuracy of the science behind the sea level rise and storm surge projections presented in the report," a park spokesperson said in a statement.

After seeing the report, Barmeyer called it "really significant," noting that the Park Service manages and protects 10 percent of U.S. coastlines. In 2017, three separate major hurricanes damaged and closed a variety of these coastal parks.

"National parks are on the direct front lines of sea level rise," she said. "Sea level rise and storm surges will keep happening in these places — forts, lighthouses, and historic sites."

"We’re going to be losing some of these iconic features."

Liberty Island National Monument was closed for 9 months after incurring damage from Hurricane Sandy. Image: National Park Service

The Park Service maintains the exposed Reveal documents were released as the study's authors and agency were working towards a consensus about the report's language.

Just over a week after the documents were made public, Interior Secretary Ryan Zinke, who oversees the Park Service, told a House Appropriations subcommittee in April that the Interior Department would not interfere with any scientific study.

"If it’s a scientific report, I’m not going to change a comma," Zinke said.

A pretty conservative climate report

While some government officials in either the Park Service or the Trump Administration — which is outwardly antagonistic to notions that humans have contributed to global warming — may have been displeased with aspects of Caffrey's report, Caffrey emphasized the flooding projections were actually pretty conservative.

To simulate how much sea levels might rise in the near and distant futures, Caffrey and her team used projections from the Intergovernmental Panel on Climate Change (IPCC), a United Nations organization tasked with researching the societal effects of warming temperatures and rising seas.

Their climate reports are subject to a lengthy scientific review process, though some researchers consider their climate change projections to be a bit moderate, perhaps not fully accounting for potentially momentous events like the accelerating melting of the massive West Antarctic ice sheets.

According to the report, the IPCC estimates that without reductions in greenhouse gas emissions, global average sea levels will rise between around 1.3 feet to just over 2 feet (0.4 meters to .63 meter) by 2100.

"The numbers may be conservative, but that is the bare minimum," Caffrey said.

"The IPCC is an incredible source," she added. "We wanted a source that has gone through rigorous peer review and has widespread acceptance."

NASA uses satellites to measure the average global sea level rise happening each year. Image: NASA

Caffrey's team took the IPCC's sea level rise projections and plugged them into the National Oceanic and Atmospheric Administration's SLOSH model, which the agency uses to simulate storm surges and flooding into coastlines. Caffrey and her team then created maps and simulations to give these numbers some realistic context.

"Getting a report out there is very important right now," said Barmeyer, who proceeded to list a number of park sites that were closed by storm damage in 2017. This included Everglades National Park's Gulf Coast Visitor Center, which was destroyed by Hurricane Irma, and millions in damage to the moat walls of the Civil War-era Fort Jefferson.

"National parks really are living laboratories for studying the effects of sea level rise and storm surge," said Barmeyer.

Caffrey's report may have been the first such study for the Park Service, but it's unclear whether she'll be involved in future storm projections for the conservation agency.

"The way things have gone with the reports, I don’t know how well that would be received from me," said Caffrey. "I don't know what my future will be with this right now."

"It's something I’m wrestling with."