Global warming is “more likely than not” in the near-term to reach a 1.5C rise since pre-industrial times, the world’s top scientists said, and climate change already taking place will continue across the lifespan of three generations born in 1950, 1970 and 2020,
The summary of the most advanced climate science by hundreds of scientists as part of the UN Intergovernmental Panel on Climate Change found the risks of warming were greater than was thought at the time of the last assessment in 2014. Some regions had already reached the “limits” of what they could adapt to.
But the report, signed off by governments worldwide, also concluded that humanity had the tools to curb and adapt to climate change, and a lack of political “commitment” was a key barrier to progress in what was a “rapidly closing window”.
“The climate time-bomb is ticking,” but the IPCC report was a “survival guide for humanity,” said UN secretary-general António Guterres. “The 1.5C limit is achievable. But it will take a quantum leap in climate action.”
Guterres also urged richer countries to significantly enhance their net zero greenhouse gas emissions targets, and strive to achieve the goal by as close to 2040 as possible, rather than by 2050.
The report draws together six landmark scientific assessments published since 2018, and comes just months ahead of the UN COP28 climate summit to be held in the United Arab Emirates that will feature the so-called global stock take.
Carbon emissions continued to rise relentlessly last year but they must fall by almost half by 2030 for the world to have any hope of limiting global warming to 1.5C, previous IPCC reports have said.
The latest report included the year 2035 in its assessment, in an effort to bridge previous warming timelines pegged to 2030 and 2050.
The sequence of devastating extreme weather events in the past year is expected to continue, including floods, fires and droughts that the scientists said would become more frequent and intense with every fraction of a degree of warming.
Researchers and policymakers signed off the report after a week of discussions, including a frantic 24-hours of final nonstop negotiations as government representatives from fossil fuel producing nations clashed on issues including finance, carbon capture technology and fossil fuel subsidies.
Detlef van Vuuren, a report author from the Netherlands, said the research showed “deep, rapid, fair, sustained and immediate action” was needed.
“This report is about urgency. It is crunch time for every one of us. We are so close to [reaching] 1.5C [that] things need to happen now,” he said.
Reiterating the findings of the 2021 IPCC report, the researchers said it was “unequivocal” that humans had caused global warming.
Temperatures had risen faster since 1970 than “in any other 50-year period over at least the last 2,000 years”.
Global surface temperatures are now 1.1C higher than during the preindustrial era.
To limit warming to 1.5C, a key threshold committed to by governments in the Paris accord and at which irreversible “tipping points” occur in nature, greenhouse gas emissions would need to peak before 2025, the report said. By 2035, greenhouse gas emissions would need to fall by 60 per cent.
Yet governments’ national emissions reductions plans are already falling short and set the world on track for warming of about 2.8C by 2100.
While the report could be seen as “a final warning” on 1.5C, said Francis Johnson, a report author, this was “not a magic number . . . 1.6C is still better than 1.7C”.
Achieving net zero emissions would require a “substantial reduction” in the use of coal, oil and gas, yet public and private financial flows for fossil fuels were still greater than for climate, the researchers said.
The projected carbon emissions from existing fossil fuel infrastructure that was not retrofitted with carbon capture technology would blow through the emissions limit for achieving 1.5C, they said.
Saudi Arabian representatives had pushed for the emphasis on carbon capture to deal with emissions, people familiar with the talks said. But the report cautioned that such technologies came with “feasibility and sustainability concerns”.
The need to phase out fossil fuels would be a “key battleground for COP28,” said Lili Fuhr, from the Center for International Environmental Law, adding that the promotion of carbon capture technology at the summit was something “we’re quite worried will be high on the agenda”.
The report said “limits to adaptation” had been reached in some tropical, coastal, polar and mountain ecosystems. Climate extremes were “increasingly driving displacement”, and “maladaptation” was happening in some regions.
Mark Howden, a report editor from Australia, said the research showed a “significant step-up” in confidence about the effects of climate change, especially at different temperatures. For example, it found that the economic and social benefits of limiting warming to 2C exceeded the costs of mitigation.
It also focused more on sustainable development and economics, looking at the financial and social “cost of action versus the cost of inaction”.
Solutions existed, the scientists said, stressing that “the choices and actions implemented in this decade will have impacts now and for thousands of years”.
These include renewable energy and electric vehicles, as well as regulatory changes, such as new carbon taxes and the removal of fossil fuel subsidies.
Frank Jotzo, a report author, said mitigation policies had already helped avoid several gigatonnes of carbon dioxide emissions each year.
The report, signed off in Interlaken, came as government leaders met in Copenhagen on Monday to discuss the agenda for this year’s COP28. Danish climate minister Dan Jørgensen said the IPCC report, which would be a key topic of discussion in Copenhagen, showed “just how much of a climate crisis we are in”.