Even half degree of extra warming will affect hundreds of millions of people, decimate corals and intensify heat extremes, report shows

World leaders have been told they have moral obligation to ramp up their action on the climate crisis in the wake of a new UN report that shows even half a degree of extra warming will affect hundreds of millions of people, decimate corals and intensify heat extremes.

But the muted response by Britain, Australia and other governments highlights the immense political challenges facing adoption of pathways to the relatively safe limit of 1.5C above pre-industrial temperatures outlined on Monday by the Intergovernmental Panel on Climate Change (IPCC).

With the report set to be presented at a major climate summit in Poland in December, known as COP24, there is little time for squabbles. The report noted that emissions need to be cut by 45% by 2030 in order to keep warming within 1.5C. That means decisions have to be taken in the next two years to decommission coal power plants and replace them with renewables, because major investments usually have a lifecycle of at least a decade.

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Mary Robinson, a UN special envoy on climate, said Europe should set an example by adopting a target of zero-carbon emissions by 2050. “Before this, people talked vaguely about staying at or below 2C – we now know that 2C is dangerous,” she said. “So it is really important that governments take the responsibility, but we must all do what we can.”

The UK, which has gone further than most nations by cutting its annual emissions by 40% since 1990, will need to step up if the more ambitious goal is to be reached.

Quick guide What difference would restricting warming to 1.5C make? Show Hide A key finding of the new IPCC report is the dramatic difference that restricting warming to 1.5C above pre industrial levels would have on the global environment. The scientists found: • By 2100, global sea level rise would be 10cm lower with global warming of 1.5C compared with 2C. • Extreme heatwaves will be experienced by 14% of the world's population at least once every five years at 1.5C. But that figure rises to more than a third of the planet if temperatures rise to 2C • Arctic sea ice would remain during most summers if warming is kept to 1.5C. But at 2C, ice free summers are 10 times more likely, leading to greater habitat losses for polar bears, whales, seals and sea birds.

• If warming is kept to 1.5C, coral reefs will still decline by 70-90% but if temperatures rise to 2C virtually all of the world's reefs would be lost



Claire Perry, minister for energy, said the government would outline its next steps in the next few days: “I welcome the strong scientific analysis behind today’s IPCC report and its conclusions are stark and sober. As policymakers we need to work together to accelerate the low-carbon transition to minimise the costs and misery of a rapidly warming world.”

But her failure to spell out how this would be achieved was criticised by Green party MP Caroline Lucas, who said the UK government has slashed support for renewables, pushed ahead with fracking and airport expansion, and continues to subsidise fossil fuels.

“If ministers are serious about taking the action they admit is needed,” Lucas said, “the government would commit today to reversing the freeze on fuel duty announced last week and lifting the ban on onshore wind turbines. And crucially, Claire Perry must stop forcing fracking on communities who’ve rejected it.”

Bob Ward, of the Grantham Institute for Climate Change, said the UK had a good track record but needed to be more ambitious, which would require action across a wider area of government: “More effort is needed from other departments. For instance, the Ministry of Housing, Communities and Local Government needs to be more proactive in ensuring that buildings become zero-carbon as soon as possible. And the Department for Transport must be more ambitious on developing electric vehicles.”

Politicians, scientists and climate activists will hold a meeting chaired by Lord Krebs, former member of the Committee on Climate Change, in parliament on Wednesday to discuss the new 1.5C report and consider policy options.

Among those attending will be Jim Skea, a co-chair of the IPCC working group on mitigation. “My biggest hope is that they [political leaders] take this seriously,” Skea said. “We can’t carry on with business as usual or minor changes.”

But there is increasing pushback by the world’s powerful fossil fuel and agribusiness interests, who are supporting politicians who are apathetic or hostile to climate action. The new IPCC report stressed the urgent need for reforestation and greater forest protection, but within hours of its release the first round of the Brazilian presidential election ended with a huge lead for Jair Bolsonaro, who has promised to quit the Paris accord and open up the Amazon rainforest to farmers and miners.

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Donald Trump has also announced that the US will pull out of the climate deal. And in Australia, the prime minister, Scott Morrison, said there was no money for “global climate conferences and all that nonsense”.

So far, however, no government has actually dropped out and civil society groups say the new report by scientists will help them put pressure on leaders to aim for the safer, lower level of warming.

“Any administration, and it would appear especially the US and Australia, that pushes damaging domestic policies and picks apart science consensus is a dangerous outlier by ignoring the deadly impacts now due to climate chaos,” said Rachel Kennerley of Friends of the Earth.

“International cooperation is manifestly preferable but the rest of the world will have to double down on efforts – it’s a shortsighted block to the global efforts needed that this report sets out, but it’s not insurmountable either.”

Andrew Steer, president of the World Resources Institute, said the urgent message of the report “must be carried into the halls of power and the negotiation rooms at COP24. This should be a moral imperative for all leaders around the world.”