The forthcoming COP26 summit -- which could determine the viability of the Paris Agreement -- will "not be easy" but an outcome matching the urgency of the crisis is an "absolute necessity", the UN's climate chief said Wednesday.

As the world faces stronger and more frequent droughts, wildfires, flooding and storm surges made worse as the planet warms, the COP26 summit in Glasgow is being billed by organisers as a key milestone for keeping the Paris goals within reach.

"The point is decisions need to be taken now, that is why Glasgow is so important," UN climate chief Patricia Espinosa told AFP. 

Struck to international fanfare in 2015, the accord commits nations to limit global temperature rises to "well below" 2 degrees Celsius above those before the onset of the Industrial Revolution.

It also saw countries promise to stick to a safer warming cap of 1.5C through sweeping emissions cuts.

Yet, 6 years on, atmospheric levels of planet-warming CO2 have risen steadily and are now at their highest concentrations in roughly three million years.

The latest round of country-by-country emission-cutting pledges -- baked into the Paris deal's "rachet" mechanism of ever-increasing ambition -- put Earth on course to warm a "catastrophic" 2.7C this century.

COP26, delayed a year due to the pandemic, will provide another chance for states to agree key outstanding elements of the Paris rulebook, or how the aspirational goals outlined in the deal function in practice.

Espinosa acknowledged to AFP that the two-week negotiations, which begin in Glasgow on October 31, "will not be easy".

Speaking on the sidelines of a UN-backed gathering of some 400 youth climate activists in Milan, she said: "I think that at this moment in time it's an absolute necessity that we come out of the conference and present to the world a message of hope, a message of clarity on where we are going".

News.Az