On March 21, 2019, the National Park Service (NPS) sent a "cease-and-desist" letter to its principal climate scientist, Dr. Patrick Gonzalez, after he testified before Congress about the impacts of climate change on U.S. national parks and as he was working with the Intergovernmental Panel on Climate Change (IPPC) on a report on synthesizing climate science in his capacity as an Associate Adjunct Professor at the University of California, Berkeley. The letter warned Dr. Gonzales that his Berkeley affiliation was not separate from his government work and that his actions violated NPS policy. Dr. Gonzales told reporters that he viewed the letter "as attempted intimidation" and believed it was intended to prevent him continuing his research. However, Dr. Gonzales continued working on the IPCC report, and accepted a second invitation to testify before Congress in June 2019.