Commentary On its first day in office, the Biden administration canceled the Keystone XL pipeline and in April hosted the “Leaders Summit on Climate,” a gathering of presidents, prime ministers, and other leaders to discuss climate policy. This is all part of a global policy agenda kickstarted by a 2018 “Special Report” issued by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The UN report, titled “Global Warming of 1.5°C,” was commissioned to study the potential benefits of limiting warming to 1.5 degrees Celsius, rather than the 2.0°C target stated in the Paris Agreement. But rather than try to justify the more aggressive target, the UN report did not conduct a cost-benefit analysis and took the 1.5°C target as externally given. For the most part, the UN report simply compared the model-projected climate impacts of 2.0°C warming versus 1.5°C, and not surprisingly concluded that the former would be larger. …