An overarching goal for the COP26 U.N. summit of "keeping alive” a 1.5-degree Celsius limit on global warming is in jeopardy, with deep splits about what would signal its demise.
Global average surface temperatures are already up about 1.1 C above pre-industrial times.
And climate scientists say they will almost inevitably "overshoot” 1.5 C, the most ambitious goal set in the 2015 Paris Agreement, as planet-heating emissions rebound after a dip due to the COVID-19 pandemic.