The Science™ Now Uses Dinosaur Teeth to Learn About CO2 Emissions

It's in the peer-reviewed literature, hence it's as good a moment to revisit the climate change debate

If you’re into dinosaurs, you’ll like this one ^-^.

Translation, emphases, and [snark] mine.

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‘Milestone’: Climate Researchers Use Dinosaur Teeth

Researchers from Göttingen, Mainz, and Bochum have succeeded in making statements about the climate of more than 150 million years ago by examining fossilised dinosaur teeth.

Via Norddeutscher Rundfunk, 8 Aug. 2025 [source]

A research team from the universities of Göttingen, Mainz, and Bochum used a new method to examine dinosaur tooth enamel. According to the university, the fossilised teeth date from the Late Jurassic and Late Cretaceous periods. The tooth enamel contains various forms of oxygen, which the dinosaurs inhaled. The study [not linked or named in the news item, but do see below] shows that the air already contained a lot of carbon dioxide (CO2) [what a science-ey comment: congrats] around 150 million years ago. According to the scientists, it even contained four times as much as in the pre-industrial era [huhum, more evidence, then, that the hypothesis of anthropogenic climate change may be…well, problematic™]—that is, before humans released large amounts of the greenhouse gas into the atmosphere.

New Perspective on Climate History

According to the researchers, the high CO2 content could be linked to volcanic eruptions at that time, explains author Dingsu Feng from the Department of Geochemistry and Isotope Geology at the University of Göttingen [strangely, her faculty page returns a 404 message; check out her LinkedIn profile, though (which, strangely, seems very…well, shall we say none-too-professional, esp. if compared to her apparent current position as a post-doc at the Ruhr University Bochum]. For the researchers, the results represent a milestone in the reconstruction of the climate at that time. The newly developed method is the first to allow conclusions about the Earth’s past using vertebrates on land. This makes it possible to reconstruct not only the composition of the air, but also the plants that grew during the dinosaurs' lifetime.

More Active Plants in the Time of the Dinosaurs

The higher CO2 content in the air and the higher average annual temperature led to the plants at that time performing more photosynthesis [totally unexpected™, if you’ve ever looked inside a commercial greenhouse], the researchers continue. Dinosaur tooth enamel is very reliable because the substances it contains are not as easily destroyed as in other samples taken from the soil, for example. Dinosaur teeth ‘recorded the climate 150 million years ago—now we're finally listening’, says Feng. The researchers now want to conduct further measurements.

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‘More’ About the Paper and the Researchers

That’s quite unexpectedly interesting, right?

As regards that news item’s conclusion, I hope that these intrepid researchers are now going to test human teeth from, say, around 1750 to the present. There’s plenty of those to go around, and I’m pretty convinced that we’ll be able to learn a lot in terms of CO2 concentrations in the atmosphere, which, at some point, may have been different (higher) than climate science™ asserts:

180 Years of CO2 Analysis by Chemical Methods

Yet, I promised ‘more’ about the paper, so let’s go down that rabbit-hole.

Here’s the paper—entitled, ‘Mesozoic atmospheric CO₂ concentrations reconstructed from dinosaur tooth enamel’, it just appeared in PNAS, vol. 122, no. 33 (doi: 10.1073/pnas.2504324122). Here’s from the paper’s abstract:

Air-breathing vertebrates incorporate a fraction of isotopically anomalous air O₂ in their body water…we demonstrate the potential of respective reconstructions of atmospheric pCO₂ or GPP from the triple oxygen isotope composition of fossil dinosaur tooth enamel. The data from unaltered enamel samples, along with an assumed modern GPP_t/GPP₀ ratio of 1 for the Mesozoic, suggest a mean Late Jurassic pCO₂ = 1,200 ± 150 ppmv and Late Cretaceous pCO₂ = 750 ± 200 ppmv. These estimates are in good agreement with other pCO₂ proxy data for the same time intervals…Using published pCO₂ data, we reconstructed GPP_t/GPP₀ ratios with 1.20 ± 0.17 for the Late Jurassic and 2.24 ± 0.96 for the Late Cretaceous, which would imply a 20 to 120% higher GPP in the Mesozoic than today. Overall, triple oxygen isotope analysis of fossil teeth of terrestrial amniotes can provide insights into past atmospheric greenhouse gas content and global primary productivity [that would be plants].

And here’s a word or two from the section ‘significance’ of the findings:

We reconstruct Mesozoic paleo-pCO₂ levels from the triple oxygen isotope composition of dinosaur teeth and obtain paleo-pCO₂ levels 2.5 to 4 times higher than preindustrial values. In addition, changes in the ¹⁷O-anomaly could also point to substantial fluctuations in GPP of the biosphere.

To translate from the academese, note that the pre-industrial consensus CO2 concentration is around 280ppm in the mid-eighteenth century. According to the de facto official™ count at the Mauna Loa observatory, we’re at around 428ppm in July 2025, which is about 52-53% higher than the 280ppm.

When dinosaurs roamed the world, CO2 levels were ‘2.5 to 4 times higher’.

Here’s a bit more from a press release by the universities of Mainz and Göttingen:

A previously unexploited source of information is now throwing new light on the Earth's climate during the age of dinosaurs. Fossilized dinosaur teeth show that concentrations of carbon dioxide in the atmosphere during the Mesozoic Era, i.e., 252 to 66 million years ago, were far higher than they are today…

During the Late Jurassic, roughly 150 million years ago, the atmosphere contained a concentration of carbon dioxide (CO₂) four times that in the period before industrialization commenced, i.e., before human activity resulted in the release of large quantities of greenhouse gases into the air. Some 73 to 66 million years ago, in the Late Cretaceous, the corresponding concentration of CO₂ was three times higher than the preindustrial level…This might be evidence of peaks of CO₂ levels in the air that could be attributable to volcanic activity [or dinosaurs breathing heavily under the strains of heat-waves], such as the massive eruptions that occurred in what is now India in the flood basalt region of the Deccan Traps at the end of the Cretaceous period. That the land and aquatic vegetation was more photosynthetically active in global terms can also probably be ascribed to the levels of CO₂ and the higher average annual temperatures.

Once again, consider commercial greenhouses and their average CO2 concentration of ‘800 to 1,200 parts per million (ppm) when CO2 enrichment is used to optimize plant growth’, as Grok maintains, which is that ‘some operations may target up to 1,500 ppm for maximum yield, depending on light, temperature, and crop type’.

What’s the significance of the paper? Well, here’s that press release again:

Results represent a breakthrough in paleoclimatology. To date, researchers have mainly used soil carbonates and so-called marine proxies to reconstruct the climate of the past. Marine proxies are indirect indicators present in marine environments that correlate so closely with the parameters under investigation that they represent surrogates for these. Unfortunately, the results obtained are subject to uncertainty…

‘We now have the possibility to use fossilized tooth enamel to study the composition of the atmosphere of the early Earth and the productivity of terrestrial and marine vegetation back then. This is crucial for our understanding of long-term climate dynamics’. As Feng points out, dinosaurs are becoming climate experts: ‘Their teeth have recorded the climate more than 150 million years ago—and at last we are able to read that record.’

‘The information obtained through our study on the global primary production provides important evidence of both marine and terrestrial food webs that would be otherwise difficult to obtain, as the available plant biomass limits the abundance and number of species and the length of food chains in the ecosystem’, emphasized co-author Professor Dr. Eva M. Griebeler of the JGU Institute of Organismic and Molecular Evolution.

There’s also a write-up by Michelle Starr in Nature, via Science Alerts, and another English press release from the Ruhr University Bochum, for those so inclined.

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Bottom Lines

Surely, these dinosaur teeth have caught the attention of various people.

Let’s note that a look beyond the headlines suggests that Earth and the biosphere are capable of adapting to (much) higher CO2 concentrations, if given enough time.

What’s unmentioned here so far are the dangers of habitat loss and human activities that are actively endangering many of Earth’s remaining natural wonders.

Human activities have certainly increased CO2 emissions from around 9Gt in 1958 (the year of the Keeling curve’s start) to around 40Gt by 2025.

Yet, emissions as recorded at Mauna Loa have increased relatively consistently by about 2ppm/year.

I’ve have a weird exchange with Grok about this (read it here), and the weirdest aspect is that while I do get the part about the more rapid growth of emissions since esp. the mid-20th century (which are accompanied—compounded—by habitat loss, population growth, etc.), I’m unsure what to make of Grok’s conclusions:

a) Higher Efficiency in 1958: Sinks were more efficient (55–65% absorbed) due to lower atmospheric CO₂ (315 ppm), less ocean acidification, cooler temperatures, and reduced human impact (population 2.9 billion, less deforestation), allowing oceans and land to absorb a higher proportion of lower emissions (9 Gt/yr).

b) Scaling with Emissions: Sinks scale via concentration-dependent uptake (ocean dissolution, CO₂ fertilization), absorbing ~5–6 Gt/yr in 1958 to ~20–24 Gt/yr in 2025, maintaining a ~40–50% atmospheric fraction. This mirrors the PNAS paper’s implied Mesozoic sink response but under faster, sustained pressure.

c) Stable ~2 ppm/yr Rate: The stable rate results from sinks scaling absolute uptake with emissions, despite a slight efficiency drop (65% to 50–60%). Quantitative checks confirm 80% of emissions are absorbed, and the Mesozoic analogy suggests sinks can handle high CO₂ long-term, but rapid anthropogenic emissions (20 ppm/decade vs. ~0.5–5 ppm/decade volcanic) stress sinks, risking saturation. The equilibrium is temporary, as declining efficiency and tipping points could increase the atmospheric CO₂ rate, unlike the episodic volcanic pulses in the paper.

In the end, I pushed a bit further and this is what I got:

Anthropogenic emissions exceed volcanic pulses in rate and continuity, forcing sinks to scale via CO₂ concentration but under greater stress, leading to swings. Volcanic pulses caused swings due to lags, not sink failure—sinks mitigated post-pulse via lulls. Modern sinks don't "outperform" paleoclimate ones; they respond to different conditions, with data showing stable but declining efficiency.

And when I asked if comparisons were possible, I was told the following:

Comparison of historical (paleoclimatic) and modern carbon sinks, emission rates, and their effects is possible, though it requires careful consideration of differences in timescales, environmental conditions, and data availability.

I.e., leave it to the experts™.

Look, I’m all for making sure our children and grand-children have a world in which they can thrive.

But what these experts™ are doing, and what Grok summarises, reads more like a comparison of apples (different methods) and oranges (very different data sets).

I suppose I’ll ask Grok next about chemical CO2 measurements from before the Keeling curve.

In the meantime, here’s something for you to ponder:

The Quite Unknown Story of CO2 Measurements--in the 1820s