Why it is important to read scientific papers beyond their abstracts

especially when it is about the role of CO2 in climate

I was overwhelmed by Neal Spackman’s post “The False Promise of Blue Carbon”, in which he laid out how the carbon credit system locks investors’ money away from ecological restoration projects. You won’t get paid to restore a mangrove forest because, unlike tree plantations, it doesn’t store carbon fast enough. The multiple benefits to fisheries, communities, and coastline ecosystems don’t count. Neal’s post received a comment from Tom Goreau, President of the Global Coral Reef Alliance, whose experience is similar: carbon credits are of no help for nature restoration and protection. There is no protection against the dredgers in the Maldives, which, as I write this, are working non-stop creating sandbanks for luxury beach resorts, killing coral reefs.

In my perception, the narrow and simplistic focus on carbon that dominates the “green talk” today is extremely harmful to the biosphere and hence to our long-term persistence as a species. Our thinking is organized in such a manner that we tend to see what we expect to see. The information that we are offered has been filtered, consciously or unconsciously, through the dominant narrative. As I read scientific papers, I try to decipher what the authors could say and discuss in a less rigidly morphed intellectual landscape. Below I describe one of such experiences.

A few days ago, a highly interesting study led by researchers from the University of St. Andrews, UK reported a unique and novel reconstruction of atmospheric CO₂ concentration for 80 million years based on the isotope ratios of boron in the shells of extinct brachiopods that lived between 340 and 260 million years ago (Ma).

Jurikova, H., Garbelli, C., Whiteford, R., Reeves, T., Laker, G.M., Liebetrau, V., Gutjahr, M., Eisenhauer, A., Savickaite, K., Leng, M. J., Iurino, D. A., Viaretti, M., Tomašových, A., Zhang, Y., Wang, W.-Q., Shi, G. R., Shen, S.-Z., Rae, J. W. B. & Angiolini, L. Rapid rise in atmospheric CO₂ marked the end of the Late Palaeozoic Ice Age. Nature Geoscience (2025).

How one of the biggest ever existed brachiopods, Gigantoproductus giganteus, could have looked like (Reconstruction by Joschua Knüppe)

Here is the abstract with my emphasis.

Atmospheric CO₂ is thought to play a fundamental role in Earth’s climate regulation. Yet, for much of Earth’s geological past, atmospheric CO₂ has been poorly constrained, hindering our understanding of transitions between cool and warm climates. Beginning ~370 million years ago in the Late Devonian and ending ~260 million years ago in the Permian, the Late Palaeozoic Ice Age was the last major glaciation preceding the current Late Cenozoic Ice Age and possibly the most intense glaciation witnessed by complex lifeforms. From the onset of the main phase of the Late Palaeozoic Ice Age in the mid-Mississippian ~330 million years ago, the Earth is thought to have sustained glacial conditions, with continental ice accumulating in high to mid-latitudes. Here we present an 80-million-year-long boron isotope record within a proxy framework for robust quantification of CO₂. Our record reveals that the main phase of the Late Palaeozoic Ice Age glaciation was maintained by prolonged low CO₂, unprecedented in Earth’s history. About 294 million years ago, atmospheric CO₂ rose abruptly (4-fold), releasing the Earth from its penultimate ice age and transforming the Early Permian into a warmer world.

If one does not read the paper further, one goes away with the familiar message: when the atmospheric concentration of CO₂ was low, it was cold; as the atmospheric concentration of CO₂ increased, it got warmer and the ice shields melted.

Reading the paper further reveals a more complicated picture. Below is the main result of the paper (Figure 2f) showing the time evolution of the atmospheric CO₂ concentration. I added the horizontal line at 300 ppm to facilitate comparison between early and late values.

One can see that during the studied period, besides an abrupt rise of CO₂ there was an equally abrupt decline back to the same or lower values than during the Ice Age.

The CO₂ concentrations were reconstructed from boron isotopic ratios using additional information about the isotopic composition of oxygen that relates to temperature which in turn determines CO₂ solubility. The authors made two different assumptions. The solid curves in the graph (the mean (red) and the confidence intervals (blue)) indicate CO₂ concentrations inferred assuming constant temperature. This assumption gives a conservative estimate of the maximum CO₂ concentration. The dashed curves indicate CO₂ concentrations inferred assuming a 9 K temperature rise in the early Permian, an assumption that is based on another very interesting study of Grossman, E. L. & Joakimski, M. M. (2022).

This study deserves a special mention. In the paper titled “Ocean temperatures through the Phanerozoic reassessed“ the last phrase of the abstract is “Correlations between atmospheric CO₂ forcing and paleotemperature support CO₂’s role as a climate driver in the Paleozoic.“ Again, if you do not read more than the abstract, you go away with your trust in the carbon dominance in climate reinforced. Meanwhile, in the paper it is also shown that unlike in the Paleozoic (541-252 Ma), there is no correlation between atmospheric CO₂ forcing and paleotemperature in the Mesozoic (252-66 Ma) and the Cenozoic (66-0 Ma), as their Figure 6 below shows. Why was it not mentioned in the abstract?

Returning to the results of Jurikova et al. 2025, since the mean global surface temperature depends on the logarithm of the CO₂ concentration, I took the base-2 logarithm of the CO₂ concentration in ppm and multiplied it by three, where the factor three is chosen to represent the sensitivity of temperature to a doubling of CO₂. In this form, the curve can be understood as describing changes in temperature (but not absolute temperature) in a climate where the sensitivity to a doubling of CO₂ is 3 K. The reconstructed fourfold increase in CO₂ concentration would then correspond then to a temperature increase of 6 K.

If we equipped an unprejudiced person with the qualitative knowledge that more CO₂ leads to warming and asked this person to imagine the temperature evolution that accompanied these CO₂ changes, a plausible guess would be that there was a temperature increase to a maximum somewhere around 290 million years ago, followed by a decrease.

Below is the graph showing the estimated global mean surface temperature where I highlighted the period studied by Jurikova et al. 2025. The graph comes from the review of Scotese, C. R., Song, H., Mills, B. J. W., & van der Meer, D. G. (2021) “Phanerozoic paleotemperatures: The earth’s changing climate during the last 540 million years“, which I highly recommend.

One can see that between 360 and 300 Ma when the boron-derived CO₂ on average increased or at least did not change much, there was a significant decline in the planetary temperature. At around 300 Ma the temperature began to increase in phase with CO₂. However, this increase in temperature continued almost monotonically until 260 Ma and beyond, while CO₂ peaked at 290 Ma and dropped back to near the Ice Age concentration already by 280 Ma.

Apparently as CO₂ was dropping, something was preventing the Earth from getting colder. Is not this interesting? Why is it not discussed in the paper? Could it be that if the authors did emphasize this pattern, the paper would not have been published?

Someone could say, "Anastassia, you're being pesky." A couple of sentences or paragraphs displaced or missing in a couple of articles, what larger difference can it make? But imagine if this is ubiquitous and continues for years. It is not an information Matrix around us, but a caricature world where some important pieces of information and thoughts that we do not know about have been erased while others are arbitrarily highlighted. And this caricature reinforces itself, because those who do not fit in, have no voice.

And it’s not innocent. Human long-term memory can only store one bit per second. If all the incoming bits are about carbon, there’s no computing power left to think about other, more complex things. For example, I’m willing to bet that most readers have never considered that, according to current climate models, changing Earth’s atmospheric circulation by transporting more heat to the poles could lower global average surface temperatures by more than ten degrees Kelvin. At constant CO₂. Have you ever heard of that?

With regard to the exciting new boron-derived CO₂ reconstructions, I believe that one of the most interesting questions is as follows. What kept the Earth’s temperature increasing while CO₂ was decreasing back to the Ice Age levels? Was it the disappearance of wetland forests (see Fig. 5 of Jurikova et al. 2025 below), similar to what we witness today in the Amazon, Congo, the Maritime Continent and the boreal zone, and which our leading climate scientists refrain from even remotely considering?

Can it be that protecting these forests now we will restore the climate more than we destabilize it by chopping down trees for pellets as dictated by the carbon-focused narrative? Whoever is overseeing these processes, if there is indeed some money set aside to improve the climate, let us consider allowing it to be routed to ecosystem protection and recovery.