Essay by Eric Worrall
Never mind that Earth has endured far more warming than today’s world without revisiting the extremes of the ancient past.
Global warming could trigger the next ice age
Earth’s climate control system may cool so hard after warming that it freezes the planet over.
Date:December 21, 2025
Source:University of California – RiversideSummary:Scientists have uncovered a missing feedback in Earth’s carbon cycle that could cause global warming to overshoot into an ice age. As the planet warms, nutrient-rich runoff fuels plankton blooms that bury huge amounts of carbon in the ocean. In low-oxygen conditions, this process can spiral out of control, cooling Earth far beyond its original state. While this won’t save us from modern climate change, it may explain Earth’s most extreme ancient ice ages.
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Why Ancient Ice Ages Were So Extreme
Geological records, however, tell a more dramatic story. Evidence shows that some of Earth’s earliest ice ages were so severe that ice and snow covered nearly the entire planet. According to the researchers, this level of freezing cannot be explained by a climate system that simply fine tunes itself.
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The Role of Oceans, Nutrients, and Plankton
The newly identified factor involves how carbon is buried in the ocean. As atmospheric CO2 rises and temperatures increase, rainfall carries larger amounts of nutrients such as phosphorus into the sea. These nutrients stimulate the growth of plankton, microscopic organisms that absorb carbon dioxide through photosynthesis.
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In warmer conditions, however, this system changes. Increased plankton growth can reduce oxygen levels in the ocean. With less oxygen available, phosphorus is more likely to be released back into the water instead of being permanently buried. This recycled phosphorus fuels even more plankton growth, whose decay further depletes oxygen and keeps nutrients circulating.
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A Climate System That Can Overshoot
Rather than gently stabilizing Earth’s temperature, this feedback can drive cooling well past its original starting point. In the team’s computer simulations, the effect was strong enough to trigger an ice age.
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As human activity continues to add CO2 to the atmosphere, the planet is expected to keep warming in the near term. The researchers’ model suggests that a cooling rebound will eventually follow. However, this future cooling is likely to be less extreme because higher oxygen levels reduce the strength of the nutrient feedback in the oceans.
Read more: https://www.sciencedaily.com/releases/2025/12/251221043231.htm
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Terrific piece of alarmist writing. After talking about snowball Earth for most of the article, they finally admit near the end that any future ice age overshoot will be less extreme because today’s world has higher oxygen levels in the atmosphere.
But if the current warming trend falters or even flips into a decline, like global temperature declined between 1940 and 1970, see they predicted it. It’s still all our fault.
The following is an episode of the wildly popular “In search of” series, featuring Leonard Nimoy, the actor who played the original Star Trek Doctor Spock.
In Search Of The Coming Ice Age features an impressive lineup of credentialed global cooling scientists, some of whom blamed global cooling on human industrial activity. One of the scientists, Stephen Schneider, who in the In Search Of episode advocated using nuclear reactors to melt the polar ice, shamelessly backflipped into warning people about global warming, which he blamed on human industrial activity. The Wikipedia article on Schneider claims Schneider backflipped in the early 1970s, but if so, why did he appear in the 1978 documentary advocating melting the polar ice caps?
I remembered watching In Search Of The Coming Ice Age as a kid in the late 70s. All the grownups were concerned, there was a lot of ice age alarmism in the media, quotes from concerned scientists, before the show was aired. The adults talked for days after the In Search Of episode aired, about how they would cope with the coming ice age, which everyone expected to happen in the next few decades. Everyone was worried about a how Australia could handle the expected flood of refugees escaping the advancing ice in the Northern Hemisphere, especially refugees from the Soviet Union.
Our memory of the global cooling consensus is likely why anyone my age and older are far more skeptical than younger people. By the 1970s the world had cooled for 30 years, and the year before the In Search Of episode was broadcast, the horror 1977 Blizzard in Buffalo NY which led to the deaths of at least 27 people received worldwide coverage. So why wouldn’t there have been widespread concern about global cooling?
Similar conditions led to the deaths of 29 people in the 2022 Buffalo blizzard.
Dubious claims there was no global cooling consensus in the 1970s naturally leads people my age to question other alarmist claims – even more so when some alarmists like the people who wrote the article above start resurrecting global cooling claims.
All still our fault of course.
The sun so hot, I froze to death….
“Increased plankton growth can reduce oxygen levels in the ocean.”
Come again?
Plankton convert water and CO2 in the presence of sunlight into O2.
How does increase plankton growth reduce oxygen levels in the ocean?
Curious minds want to know how this alchemy works.
“why did he appear in the 1978 documentary advocating melting the polar ice caps?”
He didn’t. If you listen, he was asked if nuclear energy could be used to stop advancing ice caps. He said, well you could, but you shouldn’t.
The rest was just talk about climate change. Schneider doesn’t say he expects cooling.
Learn to know when you are beaten.
Typical WUWT style arguing. Throw stuff at the wall. If that doesn’t work, let it go. Throw something else.
Looks like he threw at you and hit his mark. 🙂
The delusion is strong in you, isn’t it. What didn’t work is your feeble attempt to discredit the proven argument that more warming papers than cooling were written during that 1970s period. You remain delusional even now. The mystery is why.