Britain should commit to a net zero greenhouse gas emissions target by 2050, government climate advisers said, a goal that could require phasing out new petrol and diesel cars by at least 2035
In a strong message for action on climate change, Guterres said international political resolve was fading and it was the small island nations that were "really in the front line" and would suffer most.
India warned of severe heat in northern and central areas on Monday, following similar extreme weather on Sunday.
Under sunny skies, activists sang songs or held signs that read "There is no Planet B" and "Extinction is forever" at some of the capital's most iconic locations.
Anchorage, Alaska's largest city, recorded a 90 degrees Fahrenheit (32 centigrade) as heat takes over the US state.
Consumers worried about the environment are cutting their spending on meat and bottled drinks and trying to reduce plastic waste, and this trend is set to accelerate as climate concerns mount.
Fires burning in Brazil and the broader Amazon basin are shining a spotlight on the role of forests and land use in the climate change challenge. Next week, the California Air Resources Board will hold a hearing that could have a direct impact on such fires.
Two C-130 Hercules aircraft carrying thousands of liters of water on Sunday began dousing fires devouring chunks of the world's largest rainforest.
Bolsonaro responded on Sunday to a Facebook post that compared the looks of his wife Michelle, 37, with Macron's 66-year-old wife Brigitte. "Do not humiliate the man hahahah," Bolsonaro wrote, in a comment widely criticised as sexist.
The eyes of those who care about the environment are on the burning Amazon rainforests. But also the eyes of the greedy land mongers and oil thirsty mongers are also gleefully on the Amazon fires. The sufferers in the long run are all the inhabitants of planet Earth but right now, the saddest part is the loss of life of the forest and the creatures