Researchers write papers, which “Public Relations” department use to write “Press Releases.” phys.org (and other sites) use the “Press Releases” to write articles. They make little changes, sometimes simply for “style.” Occasionally, meanings are changed, or an attempt to “clarify” clouds the waters.
In this case, the “Public Relations” department at Columbia took their hand at things, but at least one of the authors was at their campus. Let’s just look at the evolution of a headline. First the paper:
https://doi.org/10.1073/pnas.2514628122
Overestimated natural biological nitrogen fixation translates to an exaggerated CO2 fertilization effect in Earth system models
Now, the first university press release:
https://www.uni-graz.at/en/news/stickstoff-als-schluessel-ueberschaetzter-effekt-von-co2-als-duenger-von-pflanzen/
Nitrogen as the key: the overestimated effect of CO2 as a plant fertiliser
Now, Columbia’s reworking:
https://news.columbia.edu/news/scientific-models-overestimate-natural-processes-mitigate-climate-change
Scientific Models Overestimate Natural Processes That Mitigate Climate Change
Finally, phys.org:
https://phys.org/news/2025-11-earth-overstate-carbon-nitrogen-fixation.html
Earth system models overstate carbon removal: New findings suggest nitrogen fixation is 50% lower than thought
OK, was the headline clarified in the editorial process? Where did that 50% lower figure come from anyway?
In the paper’s abstract, we find:
https://www.pnas.org/doi/10.1073/pnas.2514628122
… We find that compared to observations, ESMs underestimate agricultural BNF but overestimate natural BNF in the present day by over 50%. Natural BNF is overestimated in the most productive ecosystems that contribute most to the terrestrial carbon sink (forests and grasslands). …
Well, that’s
different, now isn't it? (A 50%
overestimation does not mean that the real number is 50%
lower.) Also, the paper differentiates between two different types of biological nitrogen fixation - “BNF” (agricultural BNF -vs-
natural BNF.)
Did the press releases make this basic mistake in handling percentages? The original press release quoted a researcher:
https://www.uni-graz.at/en/news/stickstoff-als-schluessel-ueberschaetzter-effekt-von-co2-als-duenger-von-pflanzen/
“We compared different Earth System models with current nitrogen fixation values and found that they overestimate the nitrogen fixation rate on natural surfaces by about 50 per cent,” Weber explains. Overall, this overestimation of biological nitrogen fixation leads to a reduction in the CO2 fertilisation effect of about 11 per cent.
OK, how about the folks at Columbia?
https://news.columbia.edu/news/scientific-models-overestimate-natural-processes-mitigate-climate-change
The researchers compared different Earth system models with current nitrogen fixation values and found that they have been overestimating the nitrogen fixation rate on natural land by about 50 percent. Consequently, this overestimation of nitrogen fixation means that Earth system models have been overestimating the carbon dioxide fertilization effect by about 11 percent. …
This is why I am wary of phys.org. If you can’t do simple math, you shouldn’t be rewriting press releases/
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