The Trump administration has appointed Bruce Wielicki, a physicist who has publicly questioned the severity of human-caused climate change, to lead the next National Climate Assessment. The assessment is a federally mandated report that summarizes the state of climate science and its impacts on the United States. Wielicki, a former NASA scientist, has argued that climate models overestimate warming and has criticized the scientific consensus on climate change as exaggerated.
The appointment has drawn sharp criticism from climate scientists and environmental advocates, who warn that it could undermine the credibility of the assessment. The National Climate Assessment is a key document used by policymakers, businesses, and communities to plan for climate-related risks, including extreme weather, sea-level rise, and agricultural disruptions. Critics argue that placing a skeptic in charge of the report could lead to downplaying the risks and delaying necessary action.
Wielicki has a history of challenging mainstream climate science. He has testified before Congress that climate models are unreliable and has argued that the warming observed over the past century is within natural variability. In a 2023 paper, he claimed that the Earth's climate sensitivity is lower than the range estimated by the Intergovernmental Panel on Climate Change. His views are at odds with the overwhelming majority of climate scientists, who agree that human activities, primarily the burning of fossil fuels, are driving rapid global warming.
The last National Climate Assessment, published in 2023, found that human-caused global warming is supercharging wildfires in the West, intensifying droughts in the Great Plains, and increasing the frequency and severity of heat waves across the country. The report also highlighted the disproportionate impacts on vulnerable communities, including low-income neighborhoods and communities of color. The assessment was based on thousands of peer-reviewed studies and involved contributions from hundreds of scientists across federal agencies and universities.
The Trump administration has taken a series of actions that critics say weaken climate policy. Since returning to office in 2025, President Trump has withdrawn the United States from the Paris Agreement, rolled back regulations on greenhouse gas emissions, and promoted increased fossil fuel production. The appointment of Wielicki is seen as part of a broader effort to reshape federal climate science to align with the administration's policy goals.
Supporters of Wielicki argue that he brings a valuable perspective to the assessment process. They say that scientific debates should be open to dissenting views and that the assessment should consider a range of scientific opinions. Some conservative groups have praised the appointment as a step toward ensuring that the report is not biased toward alarmism. However, many scientists contend that Wielicki's views are outside the mainstream and that his leadership could lead to a report that misrepresents the state of climate science.
The National Climate Assessment is produced by the U.S. Global Change Research Program, a collaboration of 13 federal agencies. The report is typically updated every four years and is used to inform federal and state policies on disaster preparedness, infrastructure planning, and natural resource management. The next assessment is expected to be released in 2028. The process involves extensive peer review and public comment, but the lead author has significant influence over the report's conclusions and framing.
Several Democratic lawmakers have called for an investigation into the appointment. Senator Elizabeth Warren of Massachusetts and Representative Alexandria Ocasio-Cortez of New York have sent letters to the White House requesting documents related to Wielicki's selection. They argue that the appointment violates the scientific integrity policies of federal agencies and could violate the Federal Advisory Committee Act, which requires balanced representation on federal advisory committees.
Wielicki has defended his appointment, stating that he intends to produce a rigorous and transparent assessment. In a statement, he said that he will follow the scientific evidence wherever it leads and that he is committed to a fair process. He has also noted that he has published peer-reviewed research and has decades of experience in atmospheric science. However, his critics remain skeptical, pointing to his past statements and affiliations with organizations that have challenged climate science.
The controversy over Wielicki's appointment comes amid a broader debate about the role of science in policymaking. The Trump administration has frequently clashed with the scientific community over issues such as vaccine safety, environmental regulation, and public health. The appointment of a climate science critic to lead the National Climate Assessment is likely to intensify these tensions and could have lasting implications for how the United States addresses climate change.