Questioning the basic foundations of climate science and policy
As an isotope geochemist, I spent years researching the subtle signatures that uncovered the Earth’s hidden stories. Isotopes, variants of elements such as carbon, act as chemical fingerprints, tracking the movement, age and source of the material. [emphasis, links added]
They don't lie, nor succumb to the narrative.
Early in my career, I was shocked by the Suess effect, which seemed to fix the rise in CO2 to fossil fuel combustion.
The evidence is convincing: burning ancient coal and oil, without radiocarbon (C), and depleting in μC, is diluting the isotope ratio of the atmosphere. This doesn’t scare me of catastrophic climate change, but it makes me believe that humanity is reshaping the atmosphere.
Now, I'm not sure.
Recent discoveries and lingering contradictions suggest that the story is not as clear as we have been told.
At the heart of climate science is a key assumption: we fully understand the complex dance of carbon circulation, carbon passing through air, oceans, plants, soil and rocks.
This assumption is the basis for every climate model, policy and trillion-dollar investment. But what if the foundation is more shaken than we thought? What if nature plays a greater role in rising carbon dioxide than we do?
Let’s explore the cracks in this narrative and ask a key question: Are we really responsible for the carbon in the atmosphere?
The cracks of the foundation
The carbon cycle is the earth's grand accounting system that tracks how carbon moves between huge reservoirs: the atmosphere (850 carbon, PGC), the ocean (38,000 pgc), soil, vegetation and fossil fuels.
According to the IPCC's Sixth Assessment Report (AR6, Working Group Chapter 1, Chapter 5), natural processes such as photosynthesis, breathing and ocean-atmosphere exchange will bring hundreds of gigabits of carbon each year, higher than the number of human activities, adding approximately 9.5 pgc each year through fossil fuel combustion and land combustion and land combustion and land combustion and land combustion and land combustion and land combustion and land combustion and land combustion.
Figure 5.12 illustrates this in the IPCC report, with yellow arrows showing natural flux and pink arrows marking human contributions. Only the deep sea has 40 times the carbon that is the atmosphere, and natural flux dwarfs our emissions.
This is not to say that human emissions are insignificant. Even a slight imbalance can gradually increase the scales, thereby gradually increasing the carbon dioxide in the atmosphere. However, the enormous scale of natural processes raises a question: How do we understand these fluxes accurately?
If our model missed even a part of nature’s contribution, then the entire carbon budget, our estimates of the source and sink could disappear. Therefore, our confidence in ascribed CO2 to human activities.
Isotope fingerprint…and its stain
The Suess effect has long been the trump card of climate science in the cave.
As fossil fuels burn, they release CO2 without C (millions of years due to radioactive attenuation) and less CO2 compared to atmospheric.
This dilutes the isotope ratio of the atmosphere, a pattern observed since the Industrial Revolution. The IPCC believes this is clear evidence that fossil fuels drive CO2 increase, and I once agreed. Isotope mathematics seems to be sealed.
But this is wrinkle: other natural sources can mimic this signature. The melting permafrost in the Arctic releases ancient organic carbon, low in c and¹. The same is true for particle carbon from weathered sedimentary rocks.
Deep-sea carbon dioxide is rising in waters over hundreds of years and has similar isotope characteristics. These sources are not new, but they contribute very little. If they are larger than the assumptions, they may blur the line between “human” and “natural” carbon dioxide.
The Suess effect is still strong evidence, but it is not the impeccable fingerprint we once thought about. Can we be overconfident? (I discussed this in more detail in my article on the Suess effect.)
Nature's lung capacity is greater than we imagined
Recent research deepens these questions. A 2024 natural geoscience study uses chemical carbonyl sulfides (COS) absorbed by plants to estimate global photosynthesis. (You can learn more about this in my criticism.)
result? Terrestrial ecosystems absorb 31% more carbon dioxide than previously modeled. This suggests that land plants are more powerful than we realize, which may narrow down human contributions to atmospheric carbon dioxide.
If our model underestimates this sink, what else do we miss?
Irrational Fear is written by climatologist Dr. Matthew Wielicki and has been supported by readers. If you value what you read here, consider subscribing to and supporting the work there.
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