Life as we know it will have to change radically to stop the worst effects of climate change.
The cars we drive, the food we eat, even the pets we keep now need careful consideration if the global temperature rise is to be kept below 1.5C.
And there are just 11 years to overhaul our lifestyles before the world reaches a tipping point.
Already the Earth's average temperature has increased by 1C since pre-industrial times. Under current projections we are set to soar past 1.5C in 2040, heading towards 3C later in the century.
Three years ago world leaders met in Paris and agreed to keep the global temperature rise below 2C. But the clear conclusion of the Intergovernmental Panel on Climate Change (IPCC) is that isn't good enough – 1.5C is a much safer target.
It holds back sea level rises by 10cm, reducing by 10 million the number of people affected on low-lying coastlines and islands.
And lowering the target by just 0.5C also reduces the amount of energy in the atmosphere. It cuts the likelihood of heatwaves and severe droughts in some parts of the world, and serious flooding in others.
To keep the planet on track for a 1.5C rise means cutting human-caused emissions of carbon dioxide by 45% compared to 2010 levels, and reducing them to net zero by 2050.
And that's a massive challenge.
The UK is one of the leaders on climate change. But we would need to rapidly accelerate our switch away from fossil fuels.
Half of our electricity still comes from fossil fuel power plants and most homes are heated by gas.
Plug-in cars account for just 2.9% of total UK registrations and there has been little effort to set up a hydrogen fuel infrastructure for heavy goods vehicles.
Some of the changes needed will have to be driven by the government.
Power generation and transport are by far the biggest sources of emissions. Yet the ban on petrol and gas vehicles doesn't kick in until 2040 – and hybrids will still be allowed.
But we can make a difference at home, too.
The average meat-based diet results in 7.2kg of carbon being released every day. Compare that to just 3.8kg for a vegetarian or fish-based diet.
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And a medium-sized dog has a bigger ecological footprint than a family SUV. Perhaps our pets – or at least pet food – need to change.
This is a rallying cry – a final call – from the scientists. And we don't have much time to act.