Speaking as the talks enter their second week, he said not enough has been done to combat climate change and called for united action.
Mr Obama, who arrived in Glasgow on Sunday night, said larger nations should shoulder more of the burden of fixing the climate crisis – as a theme of the talks on Monday is support for poorer countries to cope with the problem.
A veteran of the failed UN climate summit in Copenhagen and the successful meeting in Paris which secured the world’s first comprehensive climate treaty, Mr Obama was speaking at an event by COP26 organisers the UNFCCC on island resilience.
1. Barack Obama at COP26
Former US president Barack Obama gives a speech during the Cop26 summit at the Scottish Event Campus (SEC) in Glasgow. Photo: Jane Barlow
2. The former US president arriving at the summit
Barack Obama (right) attending the Cop26 summit in Glasgow. Picture date: Monday November 8, 2021. Photo: Andrew Milligan
3. Former US president Barack Obama walking through ahead of his speech
Former US president Barack Obama waved to those waiting on his arrival. Photo: Jane Barlow
4. Former US president Barack Obama (left) and US Special Presidential Envoy for Climate, John Kerry
Former US president Barack Obama (left) and US Special Presidential Envoy for Climate, John Kerry, attending the Cop26 summit at the Scottish Event Campus (SEC) in Glasgow. Photo: Andrew Milligan