Holdren was asked by Alabama Republican Sen. Jeff Sessions to cite scientific data that supported claims that droughts and other weather events were being made worse by global warming. Sessions then cited contradicting evidence from climate scientists, including former NASA scientist Dr. Roy Spencer and University of Colorado climate scientist Roger Pielke, Jr. Holdren countered that the likes of Pielke and Spencer “are not representative of the mainstream scientific opinion on this point.” Pielke Jr. Responds to Holdren: 'I invite @whitehouseostp to explain where my testimony is incorrect in any way' Pielke’s research found that “extreme weather” events like hurricanes, tornadoes and wildfires have not increased in frequency or intensity, in contrast to what Democrats and environmentalists argue. “It is misleading, and just plain incorrect, to claim that disasters associated with hurricanes, tornadoes, floods or droughts have increased on climate timescales either in the United States or globally,” Pielke told the Senate last summer. “It is further incorrect to associate the increasing costs of disasters with the emission of greenhouse gases.” Holdren may disagree, but Pielke’s research mirrors the findings of the United Nations Intergovernmental Panel on Climate Change'