The president of the COP26 climate summit called on countries to work together to avert the most devastating impacts of global warming as he opened the meeting on Sunday.
The Glasgow gathering, which runs to November 12, will be the "last, best hope to keep 1.5C in reach", said Alok Sharma, referring to the temperature aspiration of the landmark Paris deal.
Sharma said the impacts of climate change were already being felt across the world in the form of "floods, cyclones, wildfires, record temperatures".
"We know that our shared planet is changing for the worse," he said at the opening ceremony, adding that climate change had not paused for the Covid-19 pandemic, which caused the meeting to be delayed by one year.
"If we act now and we act together we can protect our precious planet," he said.
Experts warn that only transformative action in the next ten years will help stave off far more devastating impacts.
COP26 inherits its central goal from the landmark 2015 Paris Agreement, which saw countries agree to cap global warming at "well below" 2C above pre-industrial levels, and 1.5C if possible.
That deal left many of crucial details to be worked out, however, while emissions reductions remain woefully insufficient to avert devastating global warming.
Last week a UN report said even the latest, most ambitious carbon cutting commitments would still lead to "catastrophic" warming of 2.7C.
But nations continue to subsidise fossil fuels, while the Covid-19 pandemic has piled on the economic pressure.
UN climate chief Patricia Espinosa told the Glasgow opening ceremony that nations must turn away from business as usual or accept that "we are investing in our own extinction".