UK Prime Minister Boris Johnson said that the world can take hope from what has already been agreed at COP26, with the negotiations set to last two weeks.
He said that the UK has asked the world for action on coal, cars, cash and trees, with progress being made on three of those in Glasgow, report Skynews.
The prime minister said that the negotiations have a long way to go and said far more must be done.
"Whether we can summon the collective wisdom and will to save ourselves from an avoidable disaster still hangs in the balance," he said, vowing to "press on with the hard work" until the last moment.
Boris Johnson said that after "all the targets and promises" and warnings from scientists, "we now come to the reckoning".
The prime minister said that "in the end it is a question of will", saying that the technology to reduce emissions is there.
He argues that there does appear to be that will - and goes through a list of the agreements made by G20 countries in Rome at the weekend.
But he adds "far more needs to be done" to prevent the catastrophe of global warming.
Boris Johnson said over 130 countries have agreed to a global tax initiative to ensure companies pay the right tax.
And he said the G20 resolved to work together to ease supply chain disruptions.
Boris Johnson also paid tribute to Italian PM Mario Draghi for hosting the G20 summit but said more needs to be done to tackle climate change.
He said COP26 is going on in the hope of keeping the aspiration of 1.5C alive.
And he said for some countries the negotiations are a point of national survival.
Boris Johnson said the US and over 100 other countries agreed to cut their methane emissions by 30% by 2030 while 122 countries agreed to end and reverse deforestation by 2030, backed by the greatest ever amount of funds.
India has promised to produce half its energy consumption through renewables.
And he said the UK has asked for action on coal, cars, cash and trees.
"We have begun to make progress on three out of the four but negotiations in Glasgow have a long way to go and far more must be done," he said.
Whether we can save ourselves from disaster still hangs in the balance, he adds.