This story was originally published by Reveal from The Center for Investigative Reporting, a nonprofit news organization based in the San Francisco Bay Area. Learn more at revealnews.org and subscribe to the Reveal podcast, produced with PRX, at revealnews.org/podcast.

House Democrats grilled Interior Secretary Ryan Zinke this week about National Park Service officials deleting all references to the human cause of climate change in drafts of a long-awaited report.

Zinke told a House Appropriations subcommittee on Wednesday that he and other political appointees at the Interior Department, which oversees the Park Service, have not seen the draft. And he repeated a vow that he will not censor scientific reports.

Reveal from The Center for Investigative Reporting last week reported that Park Service officials had edited the scientific report, which outlines the risks of sea level rise and storm surge at 118 coastal national parks. Groups of Senate and House Democrats on Friday requested an investigation by the Interior’s inspector general.

At the hearing, Zinke said the drafts were obtained through a public records request to a university and that he wants an investigation into how the media reviewed the drafts before he did.

Rep. Chellie Pingree told Zinke she is concerned about sea level rise at Acadia National Park in her home state of Maine.

“When that report comes out, I personally don’t want to see it edited to remove any reference,” she said.

Zinke responded, “If it’s a scientific report, I’m not going to change a comma.”

Earlier in the hearing, Rep. Betty McCollum, a Democrat from Minnesota, referred to a similar vow Zinke made last month at a Senate hearing.

“You even challenged any member to find an altered document and now we have that proof,” she said. “This clear interference of political leadership is forcing employees to violate their scientific integrity policies and it must stop.”

More editing underway

Reveal has obtained new drafts of the report that show a higher-ranking National Park Service official deleted references to the human cause of climate change.

In a draft dated March 21, the lead author, University of Colorado researcher Maria Caffrey, rejected the deletions of “anthropogenic” and “human activities” and restored the earlier version of her report, according to a draft obtained through a Colorado open records request. Caffrey confirmed that she had restored all the deleted references to the human’s role in climate change.

But a subsequent draft, dated April 1, shows that the head of the National Park Service climate change response program, Cat Hawkins Hoffman, re-deleted references to “anthropogenic” and “human activities.” Hoffman, a career Park Service manager, is listed as an author of the report.

For example, in the executive summary, Hoffman removed a phrase that explains that humans are causing the sea level rise and storm surge that imperils parks.

Apparently compromising with Caffrey, Hoffman allowed some references to the human role in climate change farther down in the report, but in a watered-down way.

Caffrey’s version stated that “[A]nthropogenic climate change has significantly increased the rate of global sea level rise.” Hoffman deleted that statement. Her version blurs the connection between human emissions and sea level rise:

“[R]ecent analyses reveal that the rate of sea level rise in the last century was greater than during any preceding century in at least 2,800 years, with rates almost doubling since 1993. Human activities continue to release carbon dioxide (CO2) into the atmosphere, causing the Earth’s atmosphere to warm.” (Note: Scientific references removed by Reveal.)

Caffrey told Hoffman that the university advised her not to accept any changes, and that her contract with the Park Service establishes that the report is her intellectual property.

Neither Hoffman nor the media contact for her unit responded to requests for interviews.

Some veterans of the National Park Service were disappointed to hear about the edits.

Mike Soukup was a scientist at the National Park Service for three decades and rose to be the associate director with responsibility for science and natural resources from 1995 to 2007. He recalled having to stand up to political appointees who wanted to change scientific reports.

“Washington is a place of compromise. Sometimes you have to go along with political appointees,” Soukup said. “But changing scientific reports to get along with an administration, that’s uncalled for and unethical and shouldn’t happen.”

Elizabeth Shogren can be reached at [email protected]. Follow her on Twitter: @ShogrenE.