From Watts Up With That?
Essay by Eric Worrall
Please, please, let’s cross one of these imaginary tipping points.
Point of no return: a hellish ‘hothouse Earth’ getting closer, scientists say
Continued global heating could set irreversible course by triggering climate tipping points, but most people unaware
Damian Carrington
Environment editor Thu 12 Feb 2026 03.00 AEDT
The world is closer than thought to a “point of no return” after which runaway global heating cannot be stopped, scientists have said.
Continued global heating could trigger climate tipping points, leading to a cascade of further tipping points and feedback loops, they said. This would lock the world into a new and hellish “hothouse Earth” climate far worse than the 2-3C temperature rise the world is on track to reach. The climate would also be very different to the benign conditions of the past 11,000 years, during which the whole of human civilisation developed.
At just 1.3C of global heating in recent years, extreme weather is already taking lives and destroying livelihoods across the globe. At 3-4C, “the economy and society will cease to function as we know it”, scientists said last week, but a hothouse Earth would be even more fiery.
The public and politicians were largely unaware of the risk of passing the point of no return, the researchers said. The group said they were issuing their warning because while rapid and immediate cuts to fossil fuel burning were challenging, reversing course was likely to be impossible once on the path to a hothouse Earth, even if emissions were eventually slashed.
This is nonsense. We already know with absolute certainty from paleo evidence that 3-4C global warming does not represent the end of economic activity.
That evidence is the PETM. CO2 levels during the PETM may have been as high as 2520ppm – 6x higher than today. There is no evidence life suffered during the PETM, quite the opposite. The Palaeocene-Eocene Thermal Maximum, 5-8C hotter than today, was the age of monkeys. Our mostly fruit eating monkey ancestors thrived on the abundance of the hothouse PETM, and colonised much of the world, only retreating when the cold returned.
If a bunch of monkey ancestors with brains the size of match boxes prospered in such conditions, then we could definitely cope.
Fish also did well during the PETM.
With abundance on the land, and a sea teaming with fish, and proof that our monkey ancestors did really well during previous periods of extreme warmth, how could a few degrees of warming possibly mean “the economy and society will cease to function as we know it “?
The answer is it can’t. Even if such extreme warming were to occur, our society and economy would do just fine.
And there is no possibility anthropogenic CO2 emissions could cause anything like PETM levels of global warming. The world today is very different from the world of the PETM, powerful geological forcings which appeared after the PETM have kept our world locked in the Late Cenzoic Ice Age for the last 34 million years.
The truth is, our world is not too hot, our world is dangerously cold. During the last glacial maximum, CO2 levels dropped so low it was almost an extinction event.
We are currently in one of the coldest periods of the Late Cenzoic Ice Age. We are also in the cooling phase of the Holocene, our current interglacial, which is a serious concern. Sea level today is around 3ft lower than 6000 years ago, during the warm phase, the Holocene Optimum.
The truth is we need all the warming and CO2 emissions we can produce, to try to hold back the next 100,000-year ice age. Because when the next glacial maximum strikes, next time ice age conditions cause CO2 levels plummet, our species might not get so lucky as we were last time glacial maximum conditions brought our species to the brink of extinction.
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