Accompanied by drastic warnings from the scientific community of an escalating climate crisis, the UN Climate Change Conference (COP26) has kicked off in the Scottish city of Glasgow following a brief delay.
At the invitation of the United Nations, government representatives from almost 200 countries will discuss for a fortnight how humanity can still contain accelerating global warming to a tolerable level.
About 25,000 people are expected to attend, including thousands of journalists and climate protection activists.
The official opening ceremony, delayed by about one hour, began with a minute of silence in honour of the victims of the coronavirus pandemic.
COP26 president Alok Sharma, in his opening marks, underlined the importance of the conference to meet the targets set in the 2015 Paris Agreement, including limiting global warming to a maximum of 1.5C above pre-industrialisation-era levels.
"This COP is our last best hope to keep 1.5 in reach. This international conference must deliver," Mr Sharma said.
Environmental organisations and UN Secretary General Antonio Guterres had complained in advance that many countries have not sufficiently tightened their climate plans in the two years since the last UN conference in Madrid, and have delayed the necessary rapid phase-out of coal, oil and gas.
This is because man-made warming of the atmosphere with greenhouse gases is already causing extreme weather to become more frequent.
Examples include recent floods in Germany, drought in the Sahel region in Africa and devastating forest fires in the US and Russia.
The fight against the climate crisis was also a topic in Rome at the weekend at the summit of the heads of state and government of the G20 group.
British Prime Minister Boris Johnson on Sunday urged world leaders attending the UN climate change conference in Glasgow to commit to cutting carbon emissions, warning efforts to halt runaway global warming will fail if they do not.
"If Glasgow fails, then the whole thing fails," he told a news conference after a meeting of G20 leaders in Rome, where they agreed a target to limit global warming to 1.5 degrees Celsius.
Hopes for a strong signal to the climate summit were dampened, however, with activists seeing no new initiative there on new climate protection pledges.
The earth has already warmed by about 1.1C compared to pre-industrial levels.
In Paris six years ago, the international community agreed to limit global warming to a maximum of 2C, or preferably 1.5C.
So far, however, the plans submitted by countries are far from sufficient.
Other important topics in Glasgow are trade between countries with progress in climate protection and the financing of damage and losses caused by global warming, especially in poorer countries.
Thousands of climate activists have arrived in Scotland during the past days including Swedish activist Greta Thurnberg, who says she hasn't been officially invited to attend the conference and is scheduled to lead a climate rally in Glasgow.
Ms Thunberg on Sunday defended radical protests for more climate protection, saying they were sometimes necessary to garner attention.
"To make clear, as long as no one gets hurt... then I think sometimes you need to anger some people," she told the BBC.
