The explanation to the media comes before Monday evening's deadline to deliver the original testimony and an explanation to the House Science Committee, which is investigating examples of scientists being censored.
White House Office of Science and Technology Policy Director John Marburger said he decided to explain changes to the testimony of CDC Director Julie Gerberding because of recent "reports and press statements that have alleged or insinuated that OSTP acted inappropriately."
"The OSTP comments did not seek to redact sections of the report, but instead made a number of substantive and constructive comments and suggestions to ensure the testimony accurately represented the state of climate science," Marburger said. He added that his office takes its role in evaluating the scientific accuracy of administration documents seriously.
Gerberding was supposed to testify on the impact that climate change could have on human health. Marburger said the OSTP climate science experts who reviewed the draft testimony thought "there was an overall lack of precision" in details about "the specific nature of some climate change impacts on human health."
Marburger said that based on a report by the U.N. Intergovernmental Panel on Climate Change, his scientists felt it was not possible to offer testimony on some points because those studies were global rather than on the specific geographic area of the United States.
A spokeswoman for the House Science Committee, Alisha Prather, declined to say how investigators learned the testimony underwent some heavy editing. But she said scientific integrity has been an issue that House Science and Technology Committee Chairman Bart Gordon, D-Tenn., has been investigating for several years now.
Sen. Barbara Boxer, D-Calif., who chairs the Senate Environment and Public Works Committee, said OSTP cut the testimony from 12 to six pages, and examples of climate change impacts on health were mostly deleted.
Marburger acknowledged that references to food-supply shortages, mental health challenges, and frequent hurricanes and other weather extremes as a result of climate change were altered. He said the U.N. report just links global warming to more severe hurricanes, not more frequent ones.
"When Congress calls a witness to testify, we expect the witness to testify based on the truth as the witness knows it, not what a higher-up tells the witness is true," said North Carolina Democrat Brad Miller, who chairs the House Science Investigations and Oversight Subcommittee "My advice to any administration witness is if you're convicted of contempt of Congress, obstruction of justice or perjury, Dr. Marburger will not serve your sentence for you."
Gordon said what he is seeing makes him inclined to reintroduce his legislation aimed at ensuring scientific integrity.
Rep. James Sensenbrenner of Wisconsin, the top Republican on Miller's subcommittee, criticized Miller and Gordon for investigating the matter, saying Gerberding was happy with the testimony.