Countering climate catastrophe

NEARLY 200 nations started online negotiations yesterday to validate a UN science report that will anchor autumn summits charged with preventing climate catastrophe on a planetary scale.

“The report to be finalised is going to be very important worldwide,” World Meteorological Organization head Petteri Taalas told 700 delegates by Zoom. The Intergovernmental Panel on Climate Change (IPCC) assessment “is critical for the success of the Glasgow climate conference in November”, he said.

Record-smashing heatwaves, floods and drought across three continents in recent weeks – all amplified by global warming – have added pressure for decisive action.

“For years we warned that all of this was possible, that all of this was coming,” the UN’s climate chief, Patricia Espinosa, said in a statement.

A key G20 summit with climate on the agenda is scheduled for late October.

The world is a different place since the IPCC’s last comprehensive overview in 2014 of global heating. Lingering doubts that warming was gathering pace or almost entirely human in origin, along with the falsely reassuring notion that climate impacts are tomorrow’s problem, have since evaporated amid deadly heatwaves and fires.

Another milestone since the last IPCC tome: the Paris Agreement has been adopted, with a collective promise to cap the planet’s rising surface temperature at “well below” 2°C above late-19th century levels. Carbon pollution from burning fossil fuels, methane leaks and agriculture has driven up the thermometer 1.1°C so far.

The 2015 treaty also features an aspirational limit on warming of 1.5°C, with many parties assuming this goal could be safely ignored. But an IPCC special report in 2018 showed how much more devastating an extra 2°C would be, for humanity and the planet.

“1.5°C became the de facto target” – and proof of the IPCC’s influence in shaping global policy, said IPCC lead author and Maynooth University professor Peter Thorne.

Scientists have calculated that greenhouse gas emissions must decline 50% by 2030, and be phased out entirely by 2050 to stay within range of 1.5°C. “The reality is that we are not on track to achieve the Paris Agreement goals of limiting climate change to 1.5°C by the end of the century,” said Espinosa.

On current trends, she noted, the world will warm more than twice that much. A third sea change over the past seven years is in the science itself.

“Today we have better climate projection models, and longer observations with a much clearer signal of climate change,” said climatologist Robert Vautard, also an IPCC lead author and director of France’s Pierre-Simon Laplace Institute.

Arguably the biggest breakthrough are so-called attribution studies, which for the first time allow scientists to rapidly quantify the extent to which climate change has boosted an extreme weather event’s intensity or likelihood.

For example, within days of the deadly “heat dome” that scorched Canada and the western US last month, the World Weather Attribution consortium calculated that the heatwave would have been virtually impossible without manmade warming.

From yesterday, representatives from 195 nations, with lead scientists, will vet a “summary for policymakers”.

A leaked draft warns that climate change will fundamentally reshape life on Earth in the coming decades even if planet-warming carbon pollution is tamed, and calls for “transformational change” lest future generations face far worse.

Part of it examines solutions for reducing emissions.

Based almost entirely on published research, the report under review this week will likely forecast, even under optimistic scenarios, a temporary “overshoot” of the 1.5°C target.

There will also be a new focus on so-called “low-probability, high-risk” events, such as the irreversible melting of ice sheets that could lift sea levels by metres, and the decay of permafrost laded with greenhouse gases.

“We may be approaching some tipping points,” said Tim Lenton, director of the University of Exeter’s Global Systems Institute.