evidence: Already, the IPCC’s synthesis report shows, humanity has fundamentally and irreversibly transformed the Earth system. Emissions from burning fossil fuels and other planet-warming activities have increased global average temperatures by at least 1.1 degrees Celsius (2 degrees Fahrenheit) since the start of the industrial era. The amount of carbon dioxide in the atmosphere hasn’t been this high since archaic humans carved the first stone tools. [...] Though much of the synthesis report echoes warnings scientists have issued for decades, the assessment is notable for the blunt certainty of its rhetoric. The phrase "high confidence" appears nearly 200 times in the 36-page summary chapter. Humanity’s responsibility for all of the warming of the global climate system is described as an unassailable "fact." [...] Yet even as environmental ministers met in Switzerland last week to finalize the text of the IPCC report, the U.S. government approved a new Arctic drilling project that is expected to produce oil for the next 30 years, noted Hans-Otto Pörtner, a climatologist at Germany’s Alfred Wegener Institute and a co-author of a dozen IPCC reports, including the latest one.