In a March 28 letter addressed to NASA Administrator Charles Bolden, the group of 49 former employees ask NASA and the Goddard Institute for Space Studies to “refrain from including unproven remarks in public releases and websites” because “it is clear that the science is NOT settled.”

“As former NASA employees, we feel that NASA’s advocacy of an extreme position, prior to a thorough study of the possible overwhelming impact of natural climate drivers is inappropriate,” the letter reads.

The group said that the statements that “man-made carbon dioxide is having a catastrophic impact on global climate change are not substantiated.”

“The unbridled advocacy of CO2 being the major cause of climate change is unbecoming of NASA’s history of making an objective assessment of all available scientific data prior to making decisions or public statements,” the letter reads.