Global Surface Temperatures Are Rising Faster Now Than At Any Time In The Past 485 Million Years

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The headline pretty much says it all. A team of climate researchers led by Emily Judd at the University of Arizona and The Smithsonian have combined more than 150,000 pieces of fossil evidence with state of the art climate models to determine the Earth’s average global surface temperatures during the past 480 million years, a timeline that begins with with the emergence of multi-cellular, non-microscopic organisms at the beginning of the time period known as the Phanerozoic Eon. The results show that the Earth has been hotter — much hotter, actually — during most of that time and humans first appeared during one of the coolest periods. It also shows that over the past 480 million years, temperatures have never risen as quickly as they are doing today.

Take a moment to let that sink in. This has never happened before — ever — in almost a half a billion years!

What The Global Surface Temperatures Study Reveals

Assuming we have your full attention now, here is an excerpt from the report published by the journal Science on September 20, 2024. Jesse Smith, who edited the report, says, “Understanding how global mean surface temperature (GMST) has varied over the past half-billion years, a time in which evolutionary patterns of flora and fauna have had such an important influence on the evolution of climate, is essential for understanding the processes driving climate over that interval. Judd et al. present a record of GMST over the past 485 million years that they constructed by combining proxy data with climate modeling. They found that GMST varied over a range from 11° to 36°C, with an ‘apparent’ climate sensitivity of ∼8°C, about two to three times what it is today.” In the introduction to the study, Judd and her colleagues wrote:

“A long term geological record of global mean surface temperature (GMST) is important for understanding the history of our planet and putting present day climate change into context. Such a record is necessary for constraining the relationship between climate and other aspects of the Earth system, including the evolution and extinction of life, and the chemistry of the atmosphere and oceans. Further, quantifying the relationship between GMST and atmospheric carbon dioxide concentrations can refine our understanding of Earth’s climate sensitivity and improve future predictions under anthropogenic warming.

“Although several Phanerozoic (the last 539 million years) temperature reconstructions exist, during the intensively studied Cenozoic Era (the last 66 million years), they are colder and less variable than individual estimates from key time periods, particularly during ice free (greenhouse) intervals. This discrepancy suggests that existing Phanerozoic temperature records may underestimate past temperature change, and merits further investigation using a new approach.

“Here, we present PhanDA, a reconstruction of GMST spanning most of the Phanerozoic Eon. PhanDA was created using data assimilation, a method that statistically integrates geological data with climate model simulations. PhanDA indicates that Earth’s temperature has varied between 11° and 36°C over the past 485 million years. This range is larger than previous reconstructions; however PhanDA agrees well with independent GMST estimates from the Cenozoic, providing confidence in its larger dynamical range.

“PhanDA reveals key features in the relationship between GMST and the pole-to-equator temperature gradient, including polar amplification (i.e., larger temperature changes at high latitudes) and a shallowing of the gradient with increasing GMST. Tropical temperatures range between 22° and 42°C, refuting the idea of a fixed upper limit on tropical warmth and suggesting that ancient life must have evolved to endure extreme heat. We parse PhanDA into five climate states and find that overall, Earth has spent more time in warmer climate states than cold ones during the Phanerozoic.

“There is a strong relationship between PhanDA GMST and CO2, indicating that CO2 is the dominant control on Phanerozoic climate. The consistency of this relationship is surprising because on this timescale, we expect solar luminosity to influence climate. We hypothesize that changes in planetary albedo and other greenhouse gases (e.g., methane) helped compensate for the increasing solar luminosity through time. The GMST-CO2 relationship indicates a notably constant ‘apparent’ Earth system sensitivity (i.e., the temperature response to a doubling of CO2, including fast and slow feedbacks) of ∼8°C, with no detectable dependence on whether the climate is warm or cold.

“In the conclusion to the study, the authors say, ‘The PhanDA provides a statistically robust estimate of GMST through the Phanerozoic. We find that Earth’s temperature has varied more dynamically than previously thought and that greenhouse climates were very warm. CO2 is the dominant driver of Phanerozoic climate, emphasizing the importance of this greenhouse gas in shaping Earth history. The consistency of apparent Earth system sensitivity (∼8°C) is surprising and deserves further investigation. More broadly, PhanDA provides critical context for the evolution of life on Earth, as well as present and future climate changes.’”

What The Global Surface Temperature Study Means

The timeline illustrates how swift and dramatic temperature shifts are associated with global surface temperatures and many of the world’s worst moments — including a mass extinction that wiped out roughly 90 percent of all species and the asteroid strike that killed the dinosaurs. The largest mass extinction happened 250 million years ago, when gases from volcanic eruptions — including carbon dioxide — raised the temperature of the Earth by more than 18°F (10°C) in the span of about 50,000 years. “We know that these catastrophic events … shift the landscape of what life looks like,” Judd told the Washington Post. “When the environment warms that fast, animals and plants can’t keep pace with it.”

At no point in the nearly half billion years that Judd and her colleagues analyzed global surface temperatures did the Earth change as fast as it is changing now, she added.

For most of the Phanerozoic Eon, the research suggests average temperatures exceeded 71.6°F (22°C), with little or no ice at the poles. Coldhouse climates — including our current one — were prevalent just 13 percent of the time. That is one of the more sobering revelations of the research, Judd said. Life on Earth has endured climates far hotter than the one people are now creating through planet-warming emissions, but humans evolved during the coldest epoch of the Phanerozoic, when global average temperatures were as low as 51.8°F (11°C). Without rapid action to curb greenhouse gas emissions, global temperatures could reach nearly 62.6°F (17°C) by the end of this century — a level not seen in the timeline since the Miocene epoch more than 5 million years ago.

“We built our civilization around those geologic landscapes of an icehouse,” Judd said. “So even though climate has been warmer, humans haven’t lived in a warmer climate and there are a lot of consequences that humans face during this time.” She added that the study should serve as a wake-up call. Even under the worst case scenarios, human caused warming will not push the Earth beyond the bounds of habitability. But it will create conditions unlike anything seen in the 300,000 years our species has existed — conditions that could wreak havoc through ecosystems and communities. “As long as one or two organisms survive, there will always be life. I’m not concerned about that,” Judd said. “My concern is what human life looks like. What it means to survive.” (Emphasis added.)

The Takeaway

In an email about the new research, Bill McKibben said, “Our only hope of avoiding utter ruin — our only hope that our western world, in the blink of an eye, won’t produce catastrophe on this geologic scale — is … replacing coal and gas and oil with something else. The only something else on offer right now, scalable in the few years we still have to work with, is the rays of the sun, and the wind that sun produces, and the batteries that can store its power for use at night.”

I actually saw this story about global surface temperatures late yesterday and have been thinking about it all day. We have been saying what Emily Judd and Bill McKibben have been saying for years. We have covered every COP conference and faithfully reported the words of António Guterres, the secretary general of the United Nations. We have shared the thinking of Michael Mann and James Hansen and Mark Jacobson, and none of it has made a damn bit of difference. There is always some short-term reason why we cannot pursue a long-term solution.

Bill McKibben reports that, according to Bloomberg, a new paper from the Institute of International Finance indicates the money required to green the economy is ready to flow, but leaders of the financial industry say their first priority is delivering financial returns for clients, which means energy transition investments will only be undertaken if they’re considered profitable. “Expecting banks collectively to rapidly reallocate their portfolios may not be compatible with maintaining a profitable, diversified business model,” the IIF said. “It also neglects the reality of a bank’s commercial relationships, considering that banks can’t force clients or counter-parties to take finance for certain activities.”

If you look at the bottom of this story, you will see that I have penned nearly 6000 articles for CleanTechnica. None is as important as this one. What this study tells me is that unless we try something different, we are going to make the Earth incapable of supporting human life, and probably within the lifetime of our great-grandchildren if not before. There is only one solution I can think of — a world government focused on policies that prioritize a sustainable environment for humans and the immediate elimination of fossil fuels, with enough military might to back up its dictates.

Does this make me demented or a fool? It may be that both are true, yet nothing else has worked and we are running out of time. To paraphrase Barry Goldwater, “Extremism in defense of humanity is no vice.” I know putting this in writing will lead some (many?) of you to characterize me as a lunatic, but honestly, I see no other path that stands any chance of success, and look forward to reading your comments.