by reports from the U.S. Geological Survey and other independent researchers, who concluded that man-made climate change was likely to devastate polar-bear populations by 2050. The paper was also criticized by an expert at the National Snow and Ice Data Center, who wrote that it "doesn't measure up scientifically." A subsequent in depth international independent study, Re-Assessment of the Baffin Bay and Kane Basin Polar Bear Subpopulations: Final Report to the Canada-Greenland Joint Commission on Polar Bear determined that while polar bear populations are not declining overall and are increasing significantly in some areas, "If the current trends in sea ice continue it is reasonable to predict further changes in [the Baffin Bay] subpopulation including, ultimately, declines in abundance and vital rates. This warrants caution in both future monitoring and management." Books disputing climate change Tim Ball wrote several books positing a false notion that carbon dioxide is not a greenhouse gas causing warming and advancing a false climate change conspiracy theory. In his 2016 book Human Caused Global Warming : the Biggest Deception in History Ball tells "the story of how and why the global warming deception was achieved. The world has not warmed for over 20 years, yet carbon dioxide (CO2) levels continue to rise in complete contradiction to what all governments are saying". Ball writes: Ball introduces his book as "presented in the form of a journalistic investigation answering basic questions, Why, Who, What, Where, When, and How." Ball's 2014 book The Deliberate Corruption of Climate Science was along the same lines. Ball was one of several authors of the 2011 book Slaying the Sky Dragon: Death of the Greenhouse Gas Theory. Climate change-related activism Ball worked with Friends of Science and Natural Resources Stewardship Project, which oppose the scientific consensus of significant anthropogenic global warming, and is a former research fellow at the Frontier Centre for Public Policy. Ball also rejected the scientific consensus on climate change, claiming that "CO2 is not a greenhouse gas that raises global temperature." Ball rejected the scientific consensus on climate change and stated that he believed global warming is occurring but that human production of carbon dioxide is not the cause. Ball rejected not only greenhouse gas–induced climate change but the existence of the greenhouse effect itself. Ball told National Geographic that carbon dioxide causing warming was just a hypothesis, but had been treated as fact because it fit a