China needs to tackle climate change - Attenborough
"The moment of crisis has come" in efforts to tackle climate change, Sir David Attenborough has warned.
According to the renowned naturalist and broadcaster, "we have been putting things off for year after year".
"As I speak, south east Australia is on fire. Why? Because the temperatures of the Earth are increasing," he said.
Sir David's comments came in a BBC News interview to launch a year of special coverage on the subject of climate change.
He told me it was "palpable nonsense" for some politicians and commentators to suggest that the Australian fires were nothing to do with the world becoming warmer.
"We know perfectly well," he said, that human activity is behind the heating of the planet.
What does Sir David mean by 'the moment of crisis'?
He's highlighting the fact that while climate scientists are becoming clearer about the need for a rapid response, the pace of international negotiations is grindingly slow.
The most recent talks - in Madrid last month - .
Assuming they are delivered as promised (and there's no guarantee of that), there could still be a rise in the global average temperature of more than 3C by the end of the century, compared to pre-industrial levels.
The latest assessment by the UN's Intergovernmental Panel on Climate Change (IPCC) lays bare the dangers of that.
It suggests that a rise of anything above 1.5C would mean that coastal flooding, heatwaves and damage to coral reefs would become more severe.
And the latest figures show that the world has already warmed by just over 1C.
What happens next?
As things stand, further heating looks inevitable.
"We're already living in a changed world," according to Professor Ed Hawkins of the University of Reading, a scientist whose depictions of global warming have often gone viral on social media.
He uses bold coloured stripes to show how much each year's temperature is above or below average - different shades of red for warmer and blue for colder.
Our Planet Matters: Climate change explained
The designs now adorn T-shirts, scarves and even a tram in Germany.
At the moment, Prof Hawkins uses dark red to denote the highest level of warming, but regions such as the Arctic Ocean have seen that maximum level year after year.
Such is the scale of change that he's having to search for new colours.
"I'm thinking about adding dark purple or even black", he told me, to convey future increases in temperature.
"People might think climate change is a distant prospect but we're seeing so many examples around the world, like in Australia, of new records and new extremes."
What else is on the environmental agenda this year?
The natural world, and whether we can stop harming it.
While most political attention will be on climate change, 2020 is also seen as potentially important for halting the damage human activity is having on ecosystems.
Sir David has a blunt explanation for why this matters: "We actually depend upon the natural world for every breath of air we take and every mouthful of food that we eat."
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