GLASGOW - World leaders from US President Joe Biden to Indian Prime Minister Narendra Modi gather in Glasgow, Scotland, on Monday (Nov 1) to push for faster progress in tackling climate change, regarded as one of the greatest threats to humanity.
More than 100 leaders are expected to address the COP26 UN climate talks on Monday and Tuesday as the negotiations get fully under way.
This is the most important climate gathering in years and is being held against a backdrop of increasingly severe weather disasters and rising emissions from burning fossil fuels, the main driver of global warming.
Delegates from nearly 200 nations are attending the two-week conference with the aim of ending with a deal that will ultimately put the world on a safer path and speed up the transition to a greener and cleaner future.
That means keeping global warming to within 1.5 degrees Celsius above pre-industrial levels. This is a key temperature threshold enshrined in the 2015 Paris climate agreement.
Exceeding this threshold will bring a world increasingly alien to humans, the United Nations' top climate science panel says, as storms, floods and droughts become ever more severe and sea levels rise faster, placing more and more people's lives and livelihoods at risk.
"COP26 is our last best hope to keep 1.5 (degrees Celsius) in reach," COP26 president Alok Sharma, from host nation Britain, told delegates at Sunday's opening ceremony.
"In each of our countries we are seeing the devastating impact of a changing climate. And we know that our shared planet is changing for the worse."
Putting the world on a safer path will not be easy. The planet has already warmed 1.2 deg C, so there is little time left to act. Reducing the risks from increasingly severe and costly weather extremes means nations must step up their plans to cut greenhouse gas emissions.
Current national climate plans pledged under the Paris Agreement put the world on a path to warm a dangerous 2.7 deg C by 2100, the UN says.
It also means mobilising huge amounts of money to switch to renewable energy, electrified transport, more efficient ways of growing food and ending deforestation. Crucially, it means coming up with cash to help poorer nations make the switch and adapt to damaging climate impacts, and rich countries finally making good on a long promised US$100 billion in annual climate finance for developing nations.
But while investment in renewable energy and electric vehicles has been increasing, it is a fraction of what is needed.
"This is not only about the 100 billion," said UN climate chief Ms Patricia Espinosa on Sunday. "We need to mobilise the trillions.
To reach net zero emissions by 2050, annual clean energy investment worldwide will need to more than triple by 2030 to around US$4 trillion, the International Energy Agency said recently.
The talks also need to settle unresolved issues, such as the complex regulations around the use of carbon markets to help nations meet part of their emissions reduction pledges. These outstanding issues are part of the rulebook for the Paris Agreement, which are needed to put the Paris pact into full operation.
Some, though, are doubtful the leaders' summit will achieve much.
"The world leaders coming to Glasgow tomorrow are not coming for a 'summit' meeting but rather for a photo opportunity with Prime Minister Boris Johnson," Dr Saleemul Huq, London-based director of the International Centre for Climate Change and Development (ICCCAD) in Bangladesh, and a UN climate talks veteran, said on Sunday.
"I expect each leader to provide concrete actions in line with staying below 1.5 deg C. But I don't have much hope they will deliver."