British naturalist David Attenborough said the "moment of crisis" had come in the fight against climate change, warning that governments' targets for decades in the future were not enough to save the planet.
He called on China in particular to reduce its carbon emissions, saying that he thought other countries would follow if China set a lead.
"The moment of crisis has come - we can no longer prevaricate," said the 93-year-old, who raised public awareness around the world of the danger of plastic pollution in oceans with his television series Blue Planet II.
"We have been putting things off year after year, raising targets and saying: 'Oh well if we do it within the next 20 years...'," he told the BBC in an interview.
"This is an urgent problem that has to be solved. And what is more is that we know how to do it - that's the paradoxical thing - that we are refusing to take steps that we know have to be taken."
Noting the destruction being caused by Australia's current wave of wildfires, Attenborough criticized Canberra's approach to climate change, saying the government's support for coal mines showed the world it did not care about the environment.
Australian Prime Minister Scott Morrison said this week the country was improving its resilience and responding "to the reality of the environment in which we live".
Attenborough's interview was part of the BBC's drive to increase coverage of climate change ahead of a U.N. conference on climate change, COP 26, in Glasgow in November 2020.
Last year, Britain's Prince William launched a multi-million pound prize to find answers to Earth's biggest environmental problems, saying the planet was now at a tipping point.
(Reporting by Elizabeth Howcroft; Editing by Alison Williams)
