U.S. — The Trump administration appointed Matthew Wielicki to lead both the U.S. Global Change Research Program and the National Climate Assessment. The National Climate Assessment is a congressionally mandated report that details how climate impacts affect Americans.

Wielicki is a former geochemist without formal training in climate science. He has frequently criticized established climate science online, including in videos by PragerU. In 2023, Wielicki said people who believe in climate science are "being sold snake oil." He also argued on his blog, Irrational Fear, that increasing solar radiation has caused atmospheric warming, rather than carbon dioxide.

A White House spokesperson stated that the U.S. Global Change Research Program had "for too long, the [US Global Change Research Program] has been used as a vehicle for political agendas instead of sound science." The spokesperson added that the administration looked forward to "We look forward to restoring the USGCRP and ensuring it fulfills its legal mandate."

Carlos Martinez, a senior climate scientist at the Union of Concerned Scientists, commented on the appointment, stating, "Our country cannot afford a compromised USGCRP or NCA that peddles politically motivated disinformation echoing fossil fuel industry talking points." Martinez also said, "Reconstituting the USGCRP only to place the National Climate Assessment under the auspices of an utterly unqualified climate science denier would jeopardize the integrity of one of the nation's most important climate science resources."

Last year, the Trump administration shut down the online portal for accessing the five editions of the National Climate Assessment published since 2000. Congress passed legislation in 1990 requiring these assessments to be produced every four years. Officials dismissed all contributors to the sixth National Climate Assessment days before the American Geophysical Union and American Meteorological Society announced their plan to produce peer-reviewed research last year. The two societies stated they would produce this research to address gaps left after the Trump administration reduced the Global Change Research program.

Wielicki left his position as a geosciences professor at the University of Alabama three years ago. He has questioned climate change attribution, saying, "If every extreme weather event ends up being attributed to climate change in one way or another, is it really attribution science ... or just confirmation bias dressed up as science? A hypothesis that can explain everything risks explaining nothing."