Dhaka, Nov. 9 -- An overarching goal for the COP26 UN 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 1.1C above pre-industrial times.

And climate scientists say they will almost inevitably "overshoot" 1.5C, the most ambitious goal set in the 2015 Paris Agreement, as planet-heating emissions rebound after a dip due to the COVID-19 pandemic.

Some nations, especially island states at risk of being swamped by rising seas, say reaching 1.5C - in any year - would be the death knell of the iconic goal, reports Reuters.

Under the 2015 Paris Agreement, countries formally aimed to limit warming to...