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

Sunday, August 4, 2019

Gaia Exists! Here is the Proof

Gaia is neither benevolent nor merciful. She is harsh and ruthless. 

Environmentalists are sometimes defined as "Gaia worshippers," a term supposed to be an insult. That's a little strange because most people on this planet openly worship non-existing entities and that doesn't normally make them targets for insults. Maybe it is because there is an important difference: Gaia exists.

But who or what is Gaia, exactly? The name belongs to an ancient Goddess but the modern version is something different. As you probably know, the term was proposed for the first time by James Lovelock in 1972 and co-developed with Lynn Margulis. As it happens for many innovative ideas, it was the result of a simple observation: if the Sun radiative intensity increases gradually over the eons, how come that the Earth's surface temperature has remained within the boundaries necessary to keep the biosphere alive? There has to be something that keeps it like that. Lovelock proposed that the mechanism was based on regulating the concentration of greenhouse gases, mainly CO2. You understand that this idea goes at the core of the current debate on climate change: it deals with the inner mechanisms that make the Earth's climate what it is and what it may become in the future.

So, Gaia is powerful but She is not supposed to be benevolent or merciful, and not even a Goddess: we could say that She is what She is. But does She really exist? Not everyone agrees on this point. The concept is often referred to as the "Gaia hypothesis" and entire books have been written to demonstrate that there is no such a thing as a control mechanism of the Earth's temperature. Indeed, in the beginning, the idea was mostly qualitative and not proven. Lovelock proposed a clever model called "Daisyworld" that showed how a simple biosphere could control the temperature of a planet. But the Earth's biosphere is not just made out of daisies and something more than that was needed. But over time proofs have accumulated to show that Gaia is much more than a qualitative hypothesis (or an object of worship by people believing in non-existing beings).

Let me show you some data from a 2017 paper by Foster, Royer, and Lunt that can be seen as proof of the existence of Gaia even though they never mention the term. It is not about new discoveries, but it uses available data to look at how the concentration of CO2 and the sun irradiation varied over the past 400 million years, most of the eon we call the "Phanerozoic." The paper is somewhat technical, but clearly written and you can follow the argument even if you are not a specialist in atmospheric physics. Here are the main results:

The top (a) figure shows the average CO2 forcing (red line), compared to the solar forcing (yellow line). "Forcing" means the thermal effect over the Earth expressed as power per square meter (W/m2). It is called forcing because it is a change of a previous condition. A positive forcing warms the Earth, a negative forcing cools it. Values of the order of a few W/m2 may seem to be small, but they may change the Earth temperature of some degrees C.

The surprising result shown in the figure is how the two forcings, sun and CO2, balance each other nearly exactly. You can see that in the bottom panel of the figure: the net forcing is the red line. This is truly impressive. Assuming a sensitivity factor of 0.3, you can calculate that the solar forcing, alone, should have increased the Earth's average temperature of about 2-3 C (nearly 5 F) over 400 million years. The increase would have been considerably larger if feedbacks (e.g. water vapor) are taken into account. But we don't see this increase, not at all. Here are some recent data by Mills et al.

Look at the gray curve: plenty of oscillations but, on the average, the temperature has remained constant over the past 400 million years. If it had increased even of just 2-3 degrees C, the effect would be clearly detectable. If we push back the boundary to more ancient times, to the origins of life on Earth, the effect should have been much larger: the ancient Earth should have been at least 20 K colder than it is today. It should have been a ball of ice. It was not: we know that there was liquid water even in those remote times.

So, the data are clear: the increasing sun irradiance over the Earth's geological history has been compensated mainly by a declining CO2 concentration. Of course, there are other factors affecting climate: other greenhouse gases, changes of albedo, ocean currents, clouds, atmospheric particulate, orbital and axial oscillations. But they seem to play a minor role at the time scale of an eon. And would you believe that this near-perfect compensation occurred by chance? Yes, sometimes things happen by chance, but can the same thing keep happening by chance for 400 million years?

Anyone said "Gaia"? Smile! The Lady is right in front of you. She exists and we are lucky that She is what She is. Otherwise, the biosphere wouldn't have died long ago, burned or frozen.

But what mechanism causes the CO2 concentration to decline as solar irradiance increases? And where does the removed CO2 go? Lovelock had proposed that it was just the biosphere that did the job, it seems now that we need a tight coupling of biosphere and geosphere to obtain the effect we see. In part, CO2 is removed from the atmosphere by photosynthesis and then transformed into the inert substance called "kerogen" (the precursor of fossil fuels), then buried into the crust. In part, CO2 reacts with silicates in the crust to form solid carbonates. It is a long story and not everything is known, but things start to make sense. Lovelock was right.

Now, are events occurring over hundreds of millions of years relevant for us? Absolutely yes. The time scale may change, but the physics remains the same. The impressive point is that there is no fiddling, here, with mysterious models. These are experimental data coupled with simple physical principles that have been known and established for at least a century. They do show that CO2 affects climate, something that many non-worshippers of Gaia refuse to accept.

Comparing the current situation with the record of the Phanerozoic, we can see that the forcing that we are creating with our CO2 emissions (at present about 3 W/m2, and rising) is of the same order of magnitude of the past forcings that caused the Earth to reach the condition of "hothouse Earth," 10-20 degrees warmer than it is today -- and that even for a smaller sun irradiation! If it has happened in the past, it may well happen again. But it would be easier today because the sun is hotter. So, we may well be in deep, deep trouble.

How fast could the transition to hothouse Earth happen? On this point, the Phanerozoic data help us little: we don't have the resolution that would be necessary to detect rapid events such as the incredible burst in atmospheric CO2 concentrations that humans have created during the past few centuries. Some people say that humans will go exctinct in a few decades because of the triggering of the release of methane, another powerful greenhouse gas, from the permafrost. That would be consistent with the several mass extinctions that took place during the Phanerozoic: we know that Gaia is neither benevolent nor merciful.

But the extinction of humankind is not necessarily Gaia's will. The damage we made may still be reversed, especially if we manage to crash the global economic system. That would stop the burning of fossil fuels and the Earth might return to the previous conditions without the utter destruction that some scenarios foresee. Eventually, it surely will, even though that may take a few million years. Gaia may not be benevolent, but she is surely patient.

You Gotta Believe from Nina Paley on Vimeo.


A comment from my personal troll

Ancient kings hired personal advisors to remind them that they were mortal. This I know well enough by myself, but I thought I could hire a personal troll to remind me of my limits as a scientist. Here is a comment from him, Mr. Kunning-Druger). 

Glad to see this post, professor Bardi, and I see that you and your friends finally admitted what you always refused to admit: climate has always been changing. And all the data you are showing to us that humans have no effect on climate: look at all those variations in CO2 concentrations: where were the SUVs, the coal mines, the oil wells that you and the others have been telling us are the cause of "climate change"? How can that be? And the supposed "coincidence" that you are showing to us, that should "prove" that Gaia exists. Do you think we are stupid to believe that when we know that these numbers come from the same people who wrote "hide the decline" in one of their mails? And all this story of the Goddess, again, it proves what we had been saying all along: those idiotic Greens are just a bunch of adhorers of Nature, they and their little prophetess, that disturbed girl, Greta - just another scam among the many. You think you are doing science, but you do politics with just an attempt to mask it with a little New Age flavor. The reality is that the whole story is a scam to get public money for your fat research grants. We know that and I am going to write to the president of your university to tell him that you are wasting the salary that the government gives to you. You are using it to scam people and you should be fired together with all those silly scientists. (KD).


  1. Quite old now, but I liked this:

    1. Yes, I knew that one. I was uncertain about which one to use as illustration -- then I decided for Horsey's one, but the other one is very good, too!

  2. Not sure that we can extrapolate the last 400 million years and make the conclusions that you do Prof. I believe the rate at which we are forcing via CO2 and Ch4 is happening faster than ever before making it harder for Gaia to balance the books and triggering multiple additional positive forcings all at once unlike anything Earth has experienced.

    1. Yes, you are right. I didn't mention this point, it is important. I modified the text a little to take it into account.

  3. I guess your troll has no comprehension of time scale.

    1. He is a nice fellow, a little fixated on some ideas of his.....

  4. You forget to mention the reefs release a gigaton of CO2 a year and they get shut down by ocean acidification when atmospheric CO2 gets too high. Just one more knob.

  5. Carlos Castenada was taught by Juan Matus that the Earth is a living being that should be loved. But her Arctic methane deposits were put in place to assure that no greedy,selfish, sociopathic naked ape would be allowed to strip her majesty and go unpunished.

    1. You know that Juan Matus is not a real person? Just as Lovelocks gaia, hi is personification invented by an author to illustrate complex cocepts.

    2. (sorry, broke my hand, even more typos than usual)

  6. US Sen. Tulsi Gabbard is calling to take the US Off Fossil Fuels (OFF).

    I am confident Gabbard genuinely believes it is an option, among few others, to take her country to.

    But it is not.

    OFF is the coming reality forced on humans everywhere by Physics, as gold-grade, finite, once-only fossil fuels reserves are severely depleting overtime.

    "the term[, Gaia] was proposed for the first time by James Lovelock in 1972 and co-developed with Lynn Margulis".

    This is about the same time the Limit of Growth has been released.

    Its authors should have thought of it differently - authoring it in the context of Physics and Energy, rather than Economics, titling it: The Limit of Physics.

    The Limit of Growth has actually indirectly inspired the rapid industrialization of China, with Kessigner's historic visit to Mao, in the 1970's, too.

    Fast forward and China now is having much less of its own fossil fuels reserves, its environment in tatters - CO2 will be no more, as fossil fuels reserves are vanishing by the minute.

    Iraq, Syria, Libya, Yemen, Nigeria, Venzuela are already and officially OFF, some of them now for decades.

    Sen. Tulsi Gabbard call to put the US OFF, too - is a screaming evidence that Physics what rules humans first of all, rather than Economics, Politics or Growth!

  7. Gaia is the same reality that you find in traditional religions, good and bad, yin and yang, both are intrinsic to the existence of the Universe and life. You find it in the 99 Beautiful Names of God of the Islamic tradition which comprises the following opposite descriptors of God: The Giver of Life/The Bringer of Death, The Avenger/ The Most Kind, The Enricher/The Distresser, The Bestower/The Reducer.

  8. Excellent well-written post :-)
    Which reminded me of this too:
    See BTW his last/7Aug2019 post, I am curious if you share his view whether we will see such an global opinion shift in that direction (which would go against the idea that a seneca effect in the next decade would shape the view of the world).

  9. Great insight and paper adding to the discussion. I wonder how many folks noted your little play on words about the Dunning -Kruger effect which of course illustrated how dummies over estimate their competence. We have vast hordes of these cognitively challenged individuals often in positions of power and influence spouting nonsense. My six year old grandson whispered to me a secret this morning when I was reading your blog. He whispered:Pappy, the Internet doesn't tell the truth."

    1. My little troll is smart, but your grandson is surely much smarter!

  10. Just spent 3 days with friends and family gathering. Only one person out of the 20 or so I talked to had even heard of IPCC.

  11. I wondered why nobody here mentioned Bruno Latour's "Facing Gaia" (

    Latour, (as author of the actor network theory), is (imo) the most influencial living social philospher. His work signaled a comeback of "materialism" in social theory. (also helped by Jared Diamonds "Collaps").

    In the 10 years since, Latour released many additional papers concerning Gaia.
    Him starting this rebirth of Gaia theory is really a big thing. Check it out. '



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)