Many of Earth’s “vital signs” have hit record extremes, indicating that “the future of humanity hangs in the balance”, a group of the world’s most senior climate experts have said.
More and more scientists are now looking into the possibility of societal collapse, says the report, which assessed 35 vital signs in 2023 and found that 25 were worse than ever recorded, including carbon dioxide levels and human population. This indicates a “critical and unpredictable new phase of the climate crisis”, it says.
The temperature of Earth’s surface and oceans hit an all-time high, driven by record burning of fossil fuels, the report found. Human population is increasing at a rate of approximately 200,000 people a day and the number of cattle and sheep by 170,000 a day, all adding to record greenhouse gas emissions.
The scientists identified 28 feedback loops, including increasing emissions from melting permafrost, which could help trigger multiple tipping points, such as the collapse of the massive Greenland icecap.
Global heating is driving increasingly deadly extreme weather across the world, they said, including hurricanes in the US and 50C heatwaves in India, with billions of people now exposed to extreme heat.
The scientists said their goal was “to provide clear, evidence-based insights that inspire informed and bold responses from citizens to researchers and world leaders – we just want to act truthfully and tell it like it is.” Decisive, fast action was imperative to limit human suffering, they said, including reducing fossil fuel burning and methane emissions, cutting overconsumption and waste by the rich, and encouraging a switch towards plant-based foods.
“We’re already in the midst of abrupt climate upheaval, which jeopardises life on Earth like nothing humans have ever seen,” said Prof William Ripple, of Oregon State University (OSU), who co-led the group. “Ecological overshoot – taking more than the Earth can safely give – has pushed the planet into climatic conditions more threatening than anything witnessed even by our prehistoric relatives.
“Climate change has already displaced millions of people, with the potential to displace hundreds of millions or even billions. That would likely lead to greater geopolitical instability, possibly even partial societal collapse.”
The assessment, published in the journal Bioscience, says the concentrations of CO2 and methane in the atmosphere are at record levels. Methane is a potent greenhouse gas, 80 times more powerful than CO2 over 20 years, and is emitted by fossil fuel operations, waste dumps, cattle and rice fields.
“The growth rate of methane emissions has been accelerating, which is extremely troubling,” said Dr Christopher Wolf, formerly of OSU, who co-led the team.
While wind and solar energy grew by 15% in 2023, the researchers said, coal, oil and gas still dominated. They said there was “stiff resistance from those benefiting financially from the current fossil-fuel based system”.
The report includes the results of a Guardian survey of hundreds of senior climate experts in May, which found that only 6% believed that the internationally agreed limit of 1.5C of warming would be adhered to. “The fact is that avoiding every tenth of a degree of warming is critically important,” the researchers said. “Each tenth places an extra 100 million people into unprecedented hot average temperatures.”
The researchers said global heating was part of a wider crisis that included pollution, the destruction of nature and rising economic inequality. “Climate change is a glaring symptom of a deeper systemic issue: ecological overshoot, [which] is an inherently unstable state that cannot persist indefinitely. As the risk of Earth’s climate system switching to a catastrophic state rises, more and more scientists have begun to research the possibility of societal collapse. Even in the absence of global collapse, climate change could cause many millions of additional deaths by 2050. We need bold, transformative change.”
Among the policies the scientists recommend for rapid adoption are gradually reducing the human population through empowering education and rights for girls and women; protecting, restoring or rewilding ecosystems; and integrating climate change education into global curriculums to boost awareness and action.
The assessment concludes: “Only through decisive action can we safeguard the natural world, avert profound human suffering and ensure that future generations inherit the livable world they deserve. The future of humanity hangs in the balance.”
The world’s nations will meet at the UN’s Cop29 climate summit in Azerbaijan in November. Ripple said: “It’s imperative that huge progress is made.”