Alarm sounded, nations urged to act at UN climate talks

With the direst warnings yet of impending environmental disaster still ringing in their ears, representatives from nearly 200 nations gather Sunday in Poland to firm up their plan to prevent catastrophic climate change.

The UN climate summit comes at a crucial juncture in mankind's response to planetary warming.

The smaller, poorer nations that will bare its devastating brunt are pushing for richer states to make good on the promises they made in the 2015 Paris agreement.

In Paris three years ago, countries committed to limit global temperature rises to well below two degrees Celsius (3.6 degrees Fahrenheit), and to the safer cap of 1.5C if at all possible.

But with only a single degree Celsius of warming so far, the world has already seen a crescendo of deadly wildfires, heatwaves and hurricanes made more destructive by rising seas.

Johan Rockstrom, designated director of the Potsdam Institute for Climate Impact Research, said the talks in the Silesian mining city of Katowice were crucial in nailing down how the Paris promises will work in practice.

Delegates at the COP24 talks "cannot and will not discuss if governments worldwide must achieve rapid greenhouse gas emission reductions to limit climate risks -- but how they can do this," he said.

In Katowice, nations must agree to a rulebook palatable to all 183 states who have ratified the Paris deal.

This is far from a given: the dust is still settling from US President Donald