Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Saturday, February 8, 2020

What is in a Carbon Sink? Why Can't Mother Gaia use it to Save us from Disaster?

Can the ecosystem remove the CO2 we dumped into the atmosphere? 
One of the reasons for the popularity of Gaia, the Earth Goddess, is the hope that She'll save us from our own reckless behavior. Maybe she'll absorb the CO2 we emitted into the atmosphere? Doesn't the planet have "natural" sinks? Why worry, then? Well, I am afraid that Gaia will react just as shown in the figure above

Roy Spencer is one of the few critics of the current interpretation of climate change who can produce reasonably good scientific credentials. And, indeed, his criticism is often valuable, although -- unfortunately -- sometimes marred by political elements. But that's normal, we are all political animals.

So, Spencer made an interesting observation in a post of a few days ago. He says (boldface mine):

For many years I have seen reference to the average equivalent fraction of excess CO2 that is removed by nature, and I have often (incorrectly) said something similar to this: “about 50% of yearly anthropogenic CO2 emissions do not show up in the atmosphere, because they are absorbed.” I believe this was discussed in the very first IPCC report, FAR. I’ve used that 50% removal fraction myself, many times, to describe how nature removes excess CO2 from the atmosphere.
Recently I realized this is not a very useful metric, and as phrased above is factually incorrect and misleading. In fact, it’s not 50% of the yearly anthropogenic emissions that is absorbed; it’s an amount that is equivalent to 50% of emissions. You see, Mother Nature does not know how much CO2 humanity produces every year; all she knows is the total amount in the atmosphere, and that’s what the biosphere and various geochemical processes respond to.

And that's perfectly correct. I have to admit that I myself made the same mistake more than once. Of course, Mother Gaia doesn't know where the CO2 in the atmosphere comes from. The ecosystem just absorbs part of it.

Then, Spencer went on to claim that the IPCC scenarios were wrong of a factor of 4 with respect to the fraction of CO2 absorbed by the sinks. That was a mistake that he himself corrected later on. That's normal: a good scientist is never afraid of admitting a mistake. Apart from that, Spencer's observation changes nothing of our interpretation of climate change, but it has the merit of focusing on a fundamental point: the interplay of sources and sinks.

Eventually, Spencer presented the following (corrected) model:

Note how the models presented by the IPCC assume that the fraction of CO2 that will be absorbed by the sinks will go down as more CO2 is present in the atmosphere. Spencer's model ("CO2 Budget Model") assumes instead that the ratio will remain constant. If the latter is the case, when we stop burning fossil fuels (and we will, sooner or later), then the CO2 concentration will go down faster and -- hopefully -- we may go back to temperatures comparable to those of the Earth we used to know up to not long ago.

I wish that Spencer were right but, unfortunately, that can't be the case. What he has been doing, in practice, is returning to a criticism that had been already used against Swante Arrhenius when he developed the first version of the greenhouse gas warming theory -- more than a century ago. The criticism was, "but the oceans will absorb the excess CO2!" and it took decades to overcome it. Eventually, a picture emerged in which the sinks of the ecosystem absorb most of the human-generated CO2, but not all of it. In addition, the fraction absorbed will go down as the sinks are gradually filled.

As you may imagine, it is a complex matter. There are all sorts of sinks: the biosphere, the oceans, the weathering reaction, carbon burial, and probably more. You may take a look at the latest IPCC report, or at this recent paper by Walsh. The sinks behave in a complex way and they may still surprise us. But, so far, the experimental data show a small but measurable decline in the absorption rate. I don't have to tell you that this is bad, very bad, extremely bad.

Instead, Spencer assumes that the sinks will continue absorbing at a rate proportional to the difference between the current CO2 concentration and the "reference" value of 295 ppm. In practice, he assumes that the sink is infinite. That's a little too much: nothing on this planet is infinite. Even though we see Gaia as a Goddess, She is not all-powerful. And She is not even benevolent and merciful. She won't save us from ourselves.

A comment from my personal troll, Mr. Kunning Druger

"Now, now, Mr. Bardi. I see that you finally came out for what you are: one of those silly Greenies who are Gaia worshippers. Actually, I think it is worse than that: you just pretend to be a worshipper of Gaia, but under that green skin you are all red: really, you are one of those communists who would use the excuse of a non-existing climate change to impose on us such ugly ideas as free health care and social security for everybody and that would destroy the American way of life. Anyway, about this silly rant of yours, let me first note how it shows your deep elitism: why should those so-called "scientific credentials" be needed to express an opinion? A citizen's opinion is worth another citizen's opinion: that's good, old American democracy. Then, you'll tell us that we need a Ph.D. to vote in our elections, wouldn't you? It is all because you foreigners are envious of our freedom and our democracy that works so well. And all this criticizing Dr. Spencer is only because you are envious of him: he works at a proper American University, in Alabama, whereas you work at a silly, little, provincial university in Europe where people can't even speak proper English. So, keep going like this, the more you disinform us, the more we know who you are."



  1. The weather is becoming wilder, feels like we are entering the bust part of a boom-bust population cycle, hold on tight, may the force be with us.

  2. P.S. Here is a lullaby written for our times:

    1. Thank you. Glad I didn't miss that. Paul Kelly and Pub Choir. It's beautiful.

  3. O Great Mother! Who makes all things to grow. And all things to rot.

  4. Carboniferous had quite a hi CO2 levels and hotter climate, fantastic conditions for plant growth and carbon capture. Sinking is surely a matter in this big game and water vapor too, hotter climate is needed for more evaporation and rain, most of complex systems are quite resilient to shocks, Jurassic mass extinction was a mere blip on earth history. Anthropocene is influencing the last 100 years of history in a measurable way, to our planet this is about the same timescale of the meteor impact but quite less severe, so we can suppose that the percentage of removal is about constant at 50% yearly for a wild range of possible incomes.
    As human I am more interested in OUR survival to our doing, we have to brace for declining energy at our disposal (EROEI) and the depletion of easy access concentrated resources, ecological thinking and steady state real economy are needed for ourselves, the planet is more than enough ready for consequences as ever.

  5. Thank Gaia for your articles Ugo, great reading.

    About your troll, whilst he sounds like a wannabe satarist, actually has the same talking point as our gov/murdoch empire in Australia - that science is merely one of many opinions. Facts = opinions is the pivot. The hypocricity of course is they then treat their opinions as if they were facts.

    Australian Liberal Party Senator Jim Molan on ABC on 2 Feb 2020

    “I accept the climate is changing,” Molan said. “It has changed and it will change. What it’s producing is hotter and drier weather and a hotter and drier country.

    “As to whether it is human-induced climate change … my mind is open.”

    “And I respect very much scientific opinion but every day across my desk comes enough information for me to say that there are other opinions.”

    Macdonald asked him once again “what is the evidence you are relying on?” to which the Senator responded, “I’m not relying on evidence, Hamish”.

    (apologies for the repost)

  6. Instead, Spencer assumes that the sinks will continue absorbing at a constant rate for the foreseeable future -- in practice, he assumes that the sink is infinite.

    Spencer's assertion is stronger and more dubious than that. What he's calling a constant removal rate is defined as

    removal_rate = outflow / (co2_concentration – 295 ppm)

    "Outflow" is the portion of CO2 leaving the atmosphere annually and the constant "295 ppm" is apparently Gaia's preferred atmospheric CO2 fraction. An alternate explanation is that 295 ppm is the constant required to get a reasonable curve fit to the Mauna Loa data (since 1959) ignoring (despite it being pointed out repeatedly) that atmospheric CO2 was below 295 ppm for several hundred thousand years prior to the mid-1920s.

    The essence of his most recent posts is that mainstream carbon cycle models are suspect because they don't agree with his model, despite that model's obvious shortcoming outside of its training interval. The mainstream models may be suspect, but not for this reason.

    1. Right, I was unclear in my statement. Let me modify the text, and thanks for the comment.

  7. but this so called carbon removal does not let humans off the hook so easily. it could be a trap. maybe gaia is not saving us from ourselves, it is making things look better than they are so we have the excuse to continue BAU and destroy ourselves. oops, my bad. i must not suppose any purpose to mindless complex adaptive systems lol. but that the carbon is going away somewhere (there is no away), is not good, and it is highly ominous. where is all the c02 pumped out from billions of cars going. not sucked back into the forests surely; we are cutting them down as fast as we can. not into soil or permafrost. soils are dying due to industrial agriculture and permafrost is melting and releasing carbon. correct me if im wrong, but isnt most of the carbon going into the oceans. and wont this cause the mass extinction event (ultimately the only thing that matters) that is the humans greatest fear (sarcasm), and at least as severe as superficially more alarming atmospheric warming would cause. and if there is a mass extinction event in the oceans, it certainly wont stop there. i might be an ignorant alarmist, weirdly obsessed with the future of all life on earth generally rather than just human surival, but i have a gut feeling that 50% of the c02 'going somewhere' is not a good thing.

  8. I think that this attitude is not helping us. While extinction of humans is possible, I would assume that at least some humans will survive any collapse. We are very adaptable. We found suitable environments for human life from the arctic to the sahara.

    It is not because we will all die that we need to change the way we do things, but because we might survive. It is in our hands to decide in what world the survivors will live in. Will there be Tigers and Whales? Will there be Woods full of wildlife? Will there be peacefull summer days, clean rivers, humming bees in blooming gardens, children playing in the park? Will we have culture, books, science, social justice, democracy? Will we be inclusive or fascist?

    If we all die anyway, why bother about each other? Will empathy and solidarity survive when we fight each other for the last remaining resources?

    What if humanity dies but man survives? Wouldn't that be much worse?

    1. You just had to spoil it by mentioning 'Fascism' didn't you?

      An ideology pertaining only to the early 20th century in Europe, and as dead as a doornail except for the puerile fantasies of a handful of nutters - and kept alive only by Lefties who love frightening themselves to death over it and ignoring the horrendous crimes of the Utopian Left.

    2. The Antarctic is looking good with a balmy 18 degrees Celsius the other day.

    3. About fascism

      I know its a futile effort to educate the (Anonymous) clueless by posts in a forum, but I cant help myself:

      Lets take a look into Roger Griffin "The Nature of Fascism"
      He famously says about fascism as an ideology:
      "Fascism is a genus of political ideology whose mythic core in its various permutations is a palingenetic form of populist ultra-nationalism."

      Meaning fascists are radical nationalists that pursue a revolutionary and possibly violent grab for power over an ostensibly "corrupted" society that they say is "infected/soiled" by (mostly outside) "evil" forces and must therefore be changed / saved.

      Griffin basically says fascism is the (marginally more?) radical form of "Making america great again".

      I also want to link Umberto Ecos definition of the 14 most common features of fascism:

      end of lesson

  9. Rising CO2 levels aren't good for Human Habitat & custom.


    Rise in Radiation - from Chernobyl Accident isn't good for Human Habitat & custom - Accepted -

    OK - Except: For a long time, scientists have known that certain types of fungi are attracted to radiation, and can actually help to break down and neutralize radiation in certain environments.

    So the Earth and Environment are being prepared - via current Human activity - for an environment which does not allow for the propagation of creatures with 23 genes dependent upon reaping Plants and Animals for it's sustenance.

  10. Hey gang! Sorry to be so long between Comments, but things are really BIZZY on the Diner. We are celebrating our 8th Anniversary chronicling COLLAPSE on the internet.

    Here is our latest Interview with John Lounsbury, Managing Editor of



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)