The Roman Philosopher Lucius Anneaus Seneca (4 BCE-65 CE) was perhaps the first to note the universal trend that growth is slow but ruin is rapid. I call this tendency the "Seneca Effect."
Showing posts with label Earth. Show all posts
Showing posts with label Earth. Show all posts

Thursday, February 23, 2023

Aramis: the transportation system that never was

The Aramis project was an attempt to create a sort of "micro-metro" system designed for rapid urban transportation in Paris. The cars of the Aramis system were supposed to be independent of each other and to connect and disconnect on demand to take passengers to their specific destinations. In this way, the system was supposed to replace personal cars. Starting in 1969, it failed after 17 years of attempts. Seen in retrospect, it couldn't have worked for the reason that dooms most new technologies: cost. The Aramis line started from a correct evaluation of the need to electrify the suburban transportation system, but it was doomed by the choice of an inflexible and expensive rail system. Among other things, it needed to use a dangerous "third rail" carrying a voltage of 800 V. That required the tracks to be off-limits for pedestrians, and a series of security systems that further increased the cost of the system. Today, of course, it is possible to reconsider the whole system by using more flexible battery-powered vehicles that can run on ordinary roads. We are indeed moving toward the system called TAAS (transportation as a service) that will make the current oversized cars as obsolete as steam locomotives. Unfortunately, both the industry and the public are fixed on the traditional dinosaurs on wheels (as I discussed in a recent post of mine) and the transition will take time. But never despair. The universe has ways of forcing people to learn things they don't like to learn.

Below, I reproduce a text by Bruno Grippay who takes a long-range view, starting with a discussion on Gaia and on Earth's climate, but that's just an introduction to the story of the Aramis system. (U.B.)

The philosopher Bruno Latour and Gaia Unloved
By Bruno Grippay

Latour was always fair and grateful to the other thinkers that contributed to refine his ideas and concepts. One of them is the German philosopher, Peter Sloterdijk, who deeply questioned our Western obsession to worship the form of the Globe. We always refer to it to represent our planet, and we coat it of all its virtues; however, this representation of a sphere has no meaning.

The reality is that life on Earth should rather be represented by a thin layer on the surface of the planet, between the top of the upper atmosphere and the bottom of the sedimentary rock formations. Scientists revealed that this few kilometers thickness layer, this film, this envelope, this varnish, this small membrane is an extremely sensitive “critical zone,” fragile, perishable surface that needs to be treated very carefully.

We have been misled by the image of the Earth as a beautiful globe, a ship to carry humanity within the Universe. We believed that nature was indifferent to human actions, that we could generate growth, innovations, development as we wanted, using the resources of the Earth to our human benefit without any limits. Lastly, we discovered that this "critical zone" is intensely reactive to our human activities. This is Gaia, our tangible tiny and small cockleshell trembling beneath our feet. Here is the big difference between an Earth conceived as a Globe, and an Earth conceived as Gaia. It cannot be seen from above or from below, it can only be seen laterally. We are “facing Gaia”, which is the title of a memorable series of Latour’s lectures. It is not easy to represent it: in one of his conference, Latour used a famous canvas of Caspar David Friedrich to give an image of Gaia.

When Latour talks about the concept of Gaia, he often refers to the controversial English scientist James E. Lovelock and stands up for him. He defends his views whilst at the same time he recognizes the difficulty to describe such an evolving and unpredictable system. He also refers to the work of Hans Joachim Schellnhuber, a German physicist and climatologist, and particularly his analysis of the Earth’s System. On top of that, I would recommend the two videos here and there, where Latour explains in detail why Gaia is not the Globe.

This misconception of the representation of the place we live is a major issue for our contemporary world, and Latour considers that we are in the storm of a revolution of a similar magnitude to the Copernican one. He calls it “The New Climate Regime”.

At the time of Copernicus and then Galileo, the heresy was to describe the Earth as “moving” around the sun and not being the center of the Universe. Today, heresy is to describe the Earth as “being moved” by humans’ actions (expression from Michel Serres, in the sense of manifesting an emotional reaction) and not being indifferent to us.

We know very little about the complexity of this “critical zone”. It is unstable, it is full of erratic and uncontrollable feedback loops, and it is not a unified system. This requires the associated work of all the scientific disciplines to put some light on it. It obliges us to change our perspective. Instead of looking up in the air, admiring a starry sky, imagining a beautiful globe with infinite view, and dreaming of virtual life, we are forced to look down to the ground, facing the dust, the mud, the limited view of the soil, and recognize where our real life stands.

Why is it so complicated to admit that Gaia could be a sensitive living organism? Here, we must return to the 17th century for some explanations. With his art of mixing the disciplines successfully (here with a book written by Steven Shapin and Simon Schaffer), Latour used a key moment in history to support his demonstration, which is the dispute between two inheritors of Galileo: the political philosopher Thomas Hobbes, and the natural philosopher Robert Boyle. Both thinkers had the same ambition: find a way to bring an end to the multiple civil wars. Both were rationalists, they agreed on almost everything, they wanted “a king, a Parliament, a docile and unified Church”. However, they diverged on a fundamental point that would continue to govern our behaviors from there until today: the distribution of scientific and political power.

For Hobbes, Power was Knowledge. To reach a peaceful society he wanted to establish a strict control on immaterial beliefs (spirits, phantoms, souls…), implement a sovereignty with One Power that would ensure that there is only One Knowledge. On the other hand, Boyle was searching for the peace by promoting scientific knowledge. His approach was to gather witnesses in a laboratory to attest the existence of facts, the “matter of facts”. The participants of these experiments were not supposed to give an opinion, but to observe a phenomenon in a predefined environment. Boyle “invented the empirical style that we still use today”. One of his most famous experiments was to demonstrate the possibility of producing an invisible vacuum from an air-pump.

When Hobbes heard about Boyle’s scientific experiments, and the discovery of vacuum from the air-pump, he fell from his chair. This kind of knowledge would bring disputes, arguments, immaterial beliefs, and would eventually challenge the Sovereign’s authority, so it should be eradicated. This quarrel between the two philosophers is at the source of the separation between culture and nature in the Western world, and this gap has widened since.

Still, today, we consider that humans are different, that culture has no relation with nature, that we can establish a human society to dominate nature without any impact on our life. This is one of the reasons why it has been so hard to believe that Gaia could be sensitive to human actions.

For Latour, these separated notions of culture and nature have no meaning; they should not exist, they are just the result of this initial political division. Our culture has used the concept of nature to organize its political life. But nature has no reality. We even dream about traditional societies who would live in harmony with nature, but no: “they are unacquainted with it”.

This brings us to another fascinating concept of Latour: the actor-network theory. To understand a system, we must examine the relationships between multiple entities, not only humans, but also plants, animals, objects, technical elements, artefacts, etc., because they all influence each other. Humans are just an agent like any other non-humans. All of the entities produce an impact around them; they are all actors in the overall system. Biological forms are not made of parts and holes, they are overlapping entities which cannot be well understood if you only study them one by one. We live in a collective world where humans and non-human entities are closely intertwined together.

It reminds me of a memorable night in Japan during a dramatic time. After the Fukushima catastrophe, we were walking on the beach in Kamakura when my Japanese friend told me that she had spent the last few days standing up in front of the ocean and asking for forgiveness. In her eyes, she could not help sensing the pain of what humans had done to the sea and its inhabitants. She felt a need to share her sorrow hoping that she could reconcile humans with the ocean. We spent the evening discussing the entanglement of humans and the sea and its surrounding elements. We are not above nature, we belong to it, our lives are interlaced between each other. We depend on all the entities who allow us to live.

This interlinkage between humans and non-human entities generates a proliferation of hybrids. Latour has dedicated many pieces of work to talk about this hybrid phenomena which is essential to understand his philosophy about the operation of a complex system. Then, if we believe in this close interaction between humans and non-humans, we should challenge the concept of sovereignty from Hobbes, because it cannot work in a world where all these entities totally overlap.

In May 2015, a few months before the Paris COP agreement, Latour gathered around two hundred young people from thirty different nations for a few days to establish a parliament representing all humans and non-human entities to negotiate on the climate. Its purpose was to simulate a COP with the representation not only of nations, industries, NGOs, and unofficial lobbies and ideologies, but also of entities like land, oceans, rainforests, soil, atmosphere, oceans, and endangered species. In his Eighth Lecture of “Facing Gaia”, Latour writes: “a simulated negotiation over the climate is no more and no less enlightening than readings on political philosophy or my own very hesitant writing of these lectures.”. For the skeptical ones, he also adds: “If you are surprised to see ‘Forest’ given a voice, then you have to be just as surprised that a president speaks as the representative of ‘France’.”

This was the first experiment of what Latour called a “Parliament of Things”. The results were exceptional and should be a lesson to our real world and our repeated COP failures. All representations were inside the main negotiation room, even the strangest but influential ones like the “Stranded Petroleum Assets”, which is not the case in a real COP where all lobbyists are coming in from the outside with obscure intentions. Furthermore, scientists were simply added to the representation as normal spokespersons without any specific status. No one was there to represent nature, because, as we have seen above, it does not exist, and Gaia is not a unified system. Every representation was acting in its self-interest, which was fundamental to ensure the accuracy of the experiment. A striking result was that when you add representations for City, Land, Sahara, Amazon and so on, it completely modifies the balance of power with the old nation-states. You trace new forms of sovereignty which are no longer between nations, but between territories, and this brings us back to the land, the soil, the sea, and the water that we need to care about to protect ourselves.

I would have been so happy to join this first Parliament of Things organized by Latour with the help of a French historian of science, Frédérique Aït-Touati. I don’t know if this experience has been replicated. My wish is that the President of one of the next COPs has the ambition to organize such a Parliament of Things. This could dramatically change the way that these conferences are organized and hopefully make them more of a success!

The task that Latour gives us is to reimagine, three centuries later, what it means to reorganize the whole policy of sovereignty around the acknowledgment of Gaia and the interaction between humans and non-humans. For the young generation, Bruno Latour had an exciting and enthusiastic message. It is time for them to roll up their sleeves and undertake a similar revolution as happened in the 17th century: to completely redefine politics, get rid of traditional sovereignty, challenge private property, define new authorities, open parliaments to non-humans, foster subjectivity to compose a new good and common world. Doesn’t it sound like a plan?

2. The detective Bruno Latour and Aramis Unloved

We used to believe that a successful project is one that has been well conceived from the beginning, compared to a failed one which would have been poorly defined upfront. For Latour, it is a wrong judgment, because we forget to consider the interaction between all entities during the development phase. To illustrate his statement, Latour provides two models of the development innovation process:

  • The linear or diffusion model. Here, the project is clear, established and broadly communicated from the beginning. A key consequence is that it will generate jealousy and negative reactions from groups who are reluctant to this technological progress. Often, the project will eventually fail because of controversy and lack of wide engagement. It would require heroic and courageous people to bring it to the end with minimum adjustments.
  • The whirlwind or translation model. The project starts with a vague idea that is not well formalized. But fortunately, it progressively arouses some interest from different groups that work on it and give it more substance. The project will become consistent, and the groups will be ready to endorse it. They will eventually fully adopt the project and make it happen with major transformations. It will be recognized as a successful project.

This contradictory statement is the result of the application of the Actor-Network Theory and the fact that we are all hybrid entities. During the life of a technological project, the final product does not exist yet. It will turn into an object only when it is finished. During the development phase, it is a subjective item that can be abandoned or transformed by the influence of many entities which are interacting with each other, not only humans. An impactful report, the weather of the day, poor digestion, can change the interpretation of an engineer who would indirectly influence other people on the project. All actors must negotiate with each other to get things done. We are all hybrid entities who need to interact with each other to act and make judgments. Latour applied these principles to his analysis of the history of the Aramis project.

This investigation brought me back in time. I realized that we have been running around the same mobility issues for fifty years and maybe more. Indeed, the Aramis project started in 1970 and lasted for seventeen years until its death. The innovation was to build little automated cabins (4 seats) that would transport passengers from one point to another without intermediate stops, with close enough location points to provide a kind of on-demand “door-to-door” service. The individual cabins would run at 50 km/h on rails and could join other cabins by contactless magnetic coupling system during part of the journey, forming a train. This technology was called Personal Rapid Transit (PRT), with several similar projects in Europe, Japan, and the USA. Latour studied the one developed in the south of Paris, which was one of the most promising projects globally.

The book tells the story of a young sociologist who is the assistant of a senior inspector, depicted as a mixture of Sherlock-Columbo. In the introduction, the experimented detective, called Norbert, stated in a funny way the purpose of Aramis. You will notice that nothing has changed, and we could say the same in today’s world: “If I take my car, I’m stuck for hours in traffic jams. If I walk, I breathe carbon dioxide and get lead poisoning. If I take my bike, I get knocked down. And if I take the subway, I get crushed by three hundred people. Here, for once, we have no problem understanding the engineers. They’ve come up with a system that allows us to be all by ourselves in a quiet little car, and at the same time, we’re in a mass transit network, no worries and no traffic jams.” This was exactly the intention set for Aramis to discourage people from using their cars and shift to this on-demand, flexible transportation mode.

The hilarious tone of the investigation will continue with ups and downs all throughout the book, mixing interviews of a multitude of actors who are giving explanations all over the place about the reasons for the death of the project. These actors are ministers, directors, managers, engineers, and economists but also a motor, a chip, a chassis, and a shock absorber, which are giving their opinion about the project, applying the principle that all entities, including non-humans, are interacting between each other, and impacting any innovation project.

Many reasons for failure were given along the investigation, but none of them were strong enough to explain the abandonment of the project. Amongst the different reasons, I selected the following ones:

  • The technological complexity of doing automatic magnetic coupling and uncoupling of moving vehicles at high speed.
  • The need for each cabin to be equipped with its own computer to handle and control all operations and be able to supervise itself.
  • The design of the cabin to be created with different patterns than traditional mass transit, otherwise, the chassis would be too heavy.
  • The importance to ensure the safety of one single person getting into a cabin where there may already be passengers who look suspicious. A sarcastic observer said ironically in one of the interviews that they had “invented the rape wagon.”
  • The need to double the rail infrastructure to allow uninterrupted journeys for the individual cabins that would be too high investment.
  • The difficulty to manage the fleet of vehicles which could end up being stuck at the most popular destinations and missing at remote places, or all parked at the end of the line in the evening.
  • The complexity to handle the variation of passengers, particularly at rush hours (I learned a funny concept about the maximum number of bodies that can be fully packed in a wagon for evaluating traffic at rush hours!). Although, Aramis had too little flexibility by being limited to 4 seated passengers per cabin.
  • The concern of the Budget department regarding the high costs that could not be compensated by potential revenues. But the forecast of consumer demand and interest can be adjusted to make a project profitable or not, shaping these potential revenues constitutes an integral part of the project.
  • The big challenge of the security of the system, because every possible type of breakdown had to be studied, and it was impossible to imagine all potential failures for the software which was built with thousands of instructions.
  • The issue to protect the collective property of the cabins against vandalism.
  • The instability of the owner of the project who changed several times, with key divisions (like Bus or Subway Departments) not involved enough.
  • The overlapping with several other projects at the same time, and not enough resources (budget and engineers) to manage all of them, including Aramis.
  • The lack of flexibility of the system which did not accommodate for handicapped persons, for very tall people, or for luggage.

What I found interesting in this non-exhaustive list is that many of the reasons given are not technological. Latour expresses it very well by saying: “The more a technological project progresses, the more the role of technology decreases, in relative terms: such is the paradox of development.”

Towards the end of the inquiry, after many twists and turns, our two detectives realized (here the young sociologist imagined himself as Hercule Poirot) that the project remained identical after these seventeen years. A lot of discussions happened, but eventually no transformation, no negotiation was done to modify and improve the project. Aramis remained exactly the same in 1987 as it was at the beginning in 1970. It turned out that there was no intention or willingness to compromise and make this project happen. The explanation finally dawned on our both inspectors that the project was missing something crucial for its success, something that nobody during the interviews and no other entity had raised as a concern, something untouchable but essential for any project: the love for the technological innovation.

The final sequence of the book is the traditional restitution of the investigation, like in a detective novel. But Latour added a gothic touch, as in the “Frankenstein” story from Mary Shelley, by giving the voice to Aramis itself who expressed its frustration for not being alive: “No, no, you didn’t love me. You loved me as an idea (...) If you cannot reach agreement on my behalf, if you refuse to negotiate with one another over what I am supposed to be, it’s because you want me to stay in limbo forever (...) I’m just something to talk about. A pretext-object. (...) You hid from one another in order not to admit that you didn’t want me. (...) What horrible hypocrisy!”

In the epilogue, there is an effect of mise-en-abyme when Norbert says that he would like to publish the story of Aramis, which was the intention of Latour in writing the book. His argument is that “it would be good for educating the public, for getting people to understand, getting them to love technologies. I’d like to turn the failure of Aramis into a success, so it won’t have died in vain.” This book gave a new life to Aramis thanks to the interest of the readers who can continue to talk about this project (like me) and get it out of the limbo. This book demonstrated also, by its simple existence, the influence of a non-human object on a human life.

Related articles:

Future of Mobility #13: The need for collaborative leadership.
Future of Mobility #11: when Nature becomes a legal person...
Future of Mobility #3: Future Design in Yahaba, Japan.
Future of Mobility #2: What automakers need to do in making Vehicle-to-Everything a reality.

Passionate about Sustainable and Smart Mobility. Expert in Procurement and Project Management.

“Au revoir” dear professor Latour, we will miss you! I will keep reading your books shaped by your dense and multifaceted thoughts, and I will continue to watch your conferences always enlightened by your unique sense of humor. In the domain of mobility, you wrote an iconoclast sociological detective story about the death of Aramis, an ambitious on-demand public transport project that would have transformed our lives with a system combining the benefits of private cars and the affordability of collective trams.

During my lecture of this whodunit, dear professor, I could not help thinking of you being mystified in Columbo, the waggish inspector with his legendary raincoat and his falling-apart old Peugeot 403 convertible.

I hope you will not mind me spoiling the end of the investigation later on in my article. It is a fascinating explanation given for the failure of this technological project, which could be applied to any major innovative program. To start, I will provide a few elements of your philosophy, such as the second Copernican revolution, the parliament of things, the actor-network theory, the figure of Gaia, and other powerful ideas. These are necessary concepts to figure out what happened eventually to this unfortunate Aramis project.

Sunday, April 24, 2022

Earth's Past and Future: a Long-Term View


For the Orthodox Easter day of 2022, I thought to abandon the daily noise of the news and take a long-term view. So, here is a post, republished from "The Proud Holobionts," that presents the history of our planet during the past 400 million years and some hypotheses on what could happen in the next billion years or so. Easter is a time of rebirth and of hope, so let's hope for a future of peace for these poor savanna monkeys, so noisy and so unruly. 

Gaia and the Savanna Monkeys. 

The Great Cycle of Earth's Forests

 Forests appeared on Earth some 400 million years ago, and they have been thriving over that long period. But, during the past 150 million years, they started to show signs of distress, reacting to the decline in atmospheric CO2 concentrations and to the competition with grasslands. As Earth changes, will forests be able to cope and survive? It is an extremely slow trend, but we cannot rule out that forests will conclude their cycle and disappear in a geologically short time. This text is an attempt to reconstruct the story of forests, and not just of foreste, and to imagine what their future could be in deep time. (image courtesy of Chuck Pezeshky

A forest is a magnificent, structured, and functional entity where the individual elements -- trees -- work together to ensure the survival of the ensemble. Each tree pumps water and nutrients all the way to the crown by the mechanism called evapotranspiration. The condensation of the evaporated water triggers the phenomenon called the "biotic pump" that benefits all the trees by pumping water from the sea. Each tree cycles down the carbohydrates it manufactures using photosynthesis to its mycorrhizal space, the underground system of roots and fungi that extracts mineral nutrients for the tree. The whole "rhizosphere" -- the root space -- forms a giant brain-like network that connects the trees to each other, sometimes termed "the Wood Wide Web." It is an optimized environment where almost everything is recycled. We can see it as similar to the concept of "just in time manufacturing" in the human economy. 

Forests are wonderful biological machines, but they are also easily destroyed by fires and attacks by parasites. And forests have a competitor: grass, a plant that tends to replace them whenever it has a chance to. Areas called savannas are mainly grass, although they host some trees. But they don't have a closed canopy, they don't evapotranspirate so much as forests, and they tend to exist in much drier climate conditions. Forests and grasslands are engaged in a struggle that may have started about 150 million years ago when grass appeared for the first time. During the past few million years, grasses seem to have gained an edge in the competition, in large part exploiting their higher efficiency in photosynthesis (the "C4" pathway) in a system where plants are starved for CO2.

Another competitor of forests is a primate that left its ancestral forest home just a couple of million years ago to become a savanna dweller -- we may call it the "savanna monkey," although it is also known as "Homo," or "Homo sapiens." These monkeys are clever creatures that seem to be engaged mainly in razing forests to the ground. Yet, in the long run, they may be doing forests a favor by returning the atmospheric CO2 concentration to values more congenial to the old "C3" photosynthetic mechanism still used by trees. 

Seen along the eons, we have an extremely complex and fascinating story. If forests have dominated Earth's landscape for hundreds of millions of years, one day they may disappear as Gaia gets old. In this post, I am describing this story from a "systemic" viewpoint -- that is, emphasizing the interactions of the elements of the system in a long-term view (it is called also "deep time"). The post is written in a light mood, as I hope to be able to convey the fascination of the story also to people who are not scientists. I tried to do my best to interpret the current knowledge, I apologize in advance for the unavoidable omissions and mistakes in such a complex matter, and I hope you'll enjoy this post. 

The Origin of Forests: 400 million years ago

Life on Earth may be almost 4 billion years old but, since we are multicellular animals, we pay special attention to multicellular life. So, we tend to focus on the Cambrian period (542-488 million years ago), when multicellular creatures became common. But that spectacular explosion of life was all about marine animals. Vascular plants started colonizing the land only during the period that followed the Cambrian, the Ordovician, (485 - 443 million years ago)

To be sure, the Ordovician flora on land was far from impressive. As far as we know, it was formed mainly by moss and lichens, although lichens may be much older and precede the Cambrian. Algae may have eked a precarious life on rocks even much earlier. Mosses, just like lichens, are humble plants: they are not vascularized, they don't grow tall, and they surely can't compare with trees. Nevertheless, they could change the planetary albedo and perhaps contribute to the fertilization of the marine biota -- something that may be related to the spectacular ice ages of the Ordovician. It is a characteristic of the Earth system that the temperature of the atmosphere is related to the abundance of life. More life draws down atmospheric CO2, and that cools the planet. The Ordovician saw one of these periodic episodes of cooling with the start of the colonization of the land. (image from Wikipedia)

There followed another long period called the "Silurian" (444 – 419 My ago) when plants kept evolving but still remained of the size of small shrubs at most. Then, during the Devonian (419 -359 million years ago) we have evidence of the existence of wood. And not only that, the fossil record shows the kind of channels called "Xylem" that connect the roots to the leaves in a tree. These plants were already tall and had a crown, a trunk, and roots. By the following geological period, the Carboniferous (359 - 299 My ago), forests seem to have been widespread.  

A major feature of these ancient trees was the development of an association with fungi. Their roots formed what we call a "mycorrhizal" symbiotic system. The fungi receive carbohydrates that the tree manufactures using photosynthesis, while the tree receives from the fungi essential minerals, including nitrogen and phosphorous. We don't know the details of how this symbiotic relationship evolved over hundreds of millions of years but, below, you can see a hypothesis of how it could have happened. (Source) (in the figure, "AM" stands for "arbuscular mycorrhiza" - the oldest form of symbiotic fungi).

Another major evolutionary innovation that may have been already operating in the Paleozoic forests is the "biotic pump." As an effect of the pressure drop created by the condensation of evapotranspirated water, forests can create pump water vapor from the ocean and create the "atmospheric rivers" that bring water inland. That, in turn, creates the land rivers that bring that water back to the sea. As forests create their own climate, they can expand nearly everywhere. The image shows clouds created by condensation over the modern Amazon rainforest (source).  

If we could walk in one of those ancient forests, we would find the place familiar, but also a little dreary. No birds and not even flying insects, they evolved only tens of million years later. No tree-climbing animals: no monkeys, no squirrels, nothing like that. Even in terms of herbivores, we have no evidence of the kind of creatures we are used to, nowadays. Grass didn't exist, so herbivores may have subsisted on decaying plant matter, or perhaps on ferns. Lots of greenery but no flowers, they had not evolved yet. You see in the image (source) an impression of what an ancient forest of Cladoxylopsida could have looked like during the Paleozoic era.

The Paleozoic forests already had one of the characteristics of modern forests: fires. There had never been fires on Earth before for at least two good reasons: one was that there was not enough oxygen, and the other was that there was nothing flammable. But now, with the oxygen concentration increasing and plants colonizing the land, fires appeared, lighting up the night. They would remain a characteristic of the land biosphere for hundreds of millions of years.

Image Source. The "fire window" is the region of concentrations in atmospheric oxygen in which fires can occur. Note how during the Paleozoic, the concentration could be considerably larger than it is now. Fireworks aplenty, probably. Note also how there exist traces of fires even before the development of full-fledge trees, in the Devonian. Wood didn't exist at that time, but the concentration of oxygen may have been high enough to set dry organic matter on fire. 

Wildfires are a classic case of a self-regulating system. The oxygen stock in the atmosphere is replenished by plant photosynthesis but is removed by burning wood. So, fires tend to reduce the oxygen concentration and that makes fires more difficult. But the story is more complicated than that. Fires also tend to create "recalcitrant" carbon compounds, charcoal for instance, that are not recycled by the biosphere and tend to remain buried for long times -- almost forever. So, over very long periods, fires tend to increase the oxygen concentration in the atmosphere by removing CO2 from it. The conclusion is that fires both decrease and increase the oxygen concentration. How about that for a taste of how complicated the biosphere processes are? 

 The Mesozoic: Forests and Dinosaurs

At the end of the Paleozoic, some 252 million years ago, there came the great destruction. A gigantic volcanic eruption of the kind we call "large igneous province" (sometimes affectionately "LIP") took place in the region we call Siberia today. It was huge beyond imagination: think of an area as large as modern Europe becoming a lake of molten lava. (image source)

It spewed enormous amounts of carbon into the atmosphere in the form of greenhouse gases. That warmed the planet, so much that it almost sterilized the biosphere. It was not the first, but it was the largest mass extinction of the Phanerozoic age. Gaia is normally busy keeping Earth's climate stable, but sometimes she seems to be sleeping at the wheel -- or maybe she gets drunk or stoned. The result is one of these disasters.  

Yet, the ecosystem survived the great extinction and rebounded. It was now the turn of the Mesozoic era, with forests re-colonizing the land. Over time, the angiosperms ("flowering plants") become dominant over the earlier conifers. With flowers, forests may have been much noisier than before, with bees and all kinds of insects. Avian dinosaurs also appeared. They seem to have been living mostly on trees, just like modern birds. 

For a long period during the Mesozoic, the landscape must have been mainly forested. No evidence of grass being common, although smaller plants, ferns, for instance, were abundant. Nevertheless, the great evolution machine kept moving. During the Jurassic, a new kind of mycorrhiza system evolved, the "Ectomycorrhizae" which allowed better control of the mineral nutrients in the rhizosphere, avoiding losses when the plants were not active. This mechanism was typical of conifers that could colonize cold regions of the supercontinent of the time, the "Pangea."  

During the Mesozoic, the dinosaurs appeared and diffused all over the planet. You surely noted how the Jurassic dinosaurs were often bipedal (See the illustration showing an early form of Iguanodon). They are also called "ornithopods," it is a body plan that allows herbivorous creatures to eat leaves on the high branches of trees. A bipedal stance makes the creature able to stand up, balancing on its tail. Some dinosaurs chose a different strategy, developing very long necks for the same purpose: the brontosaurus is iconic in this sense even though, traditionally, it was shown half-submerged in swamps (the illustration is from the New York Tribune of 1919). That's a bit silly, if you think about that. Why should a semiaquatic creature need a long neck? Think of a hippo with the neck of a giraffe: it wouldn't work so well. 

A much better representation of long-necked dinosaurs came with the first episode of the "Jurassic Park" (1993) movie series, when a gigantic diplodocus eats leaves. At some moment, the beast rises on its hind legs, using the tail as further support. 

If you are a dinosaur lover (and you probably are if you are reading this post) seeing this scene must have been a special moment in your life. And, after having seen it maybe a hundred times, it still moves me. But note how the diplodocus is shown in a grassy environment with sparse trees: that's not realistic because grass didn't exist yet when the creature went extinct at the end of the Jurassic period, about 145 million years ago. 

To see grass and animals specialized in eating it, we need to wait for the Cretaceous (145-66 million years ago). Evidence that some dinosaurs had started eating grass comes from the poop of long-necked dinosaurs. That's a little strange because, if you are a grazer, the last thing you need is a long neck. But new body plants rapidly evolved during the Cretaceous.  The Ceratopsia were the first true grazers, also called "mega-herbivores". Heavy, four-legged beasts that lived their life keeping their head close to the ground. The Triceratopses gained a space in human fantasy as prototypical dinosaurs, and they are often shown in movies while fighting tyrannosauruses. You see that in Walt Disney's movie "Fantasia" (1940). It may have happened for real.

Note the heavy bone shield over the head. With so much weight on board, Trixie couldn't possibly rise on its hind legs to munch on leaves on tree branches. Note also the beak, it looks perfectly adapted for collecting grass. It means that the Cretaceous landscape was probably similar to our world. We don't know if there existed the kind of biome we call today "savanna" -- a mix of grass and trees, but surely the land was shared by forests and grass, each biome with its typical fauna. 

The Great Cooling and the Rise of C4 Grass

At the end of the Cretaceous period, 66 million years ago, a new large igneous province appeared in the Deccan region, in India. It generated another climate disaster with the associated mass extinction. Most dinosaurs were wiped out, except those we call "birds" today. A large meteorite also hit Earth at that time. It caused only minor damage but, millions of years later, it gave human filmmakers a subject to explore in many dramatic movies. 

In time, the Deccan LIP faded away, and the era that followed is called the "Cenozoic." The ecosystem recovered, forests re-colonized the land, and mammals and birds (the only survivors of the Dinosauria clade) fought to occupy the ecological niches left free by their old masters. The early Cenozoic was a warm period of lush forests that offered refuge to a variety of animals: birds made their nests in branches, while squirrels and other small mammals jumped from branch to branch, or lived at the bottom. It is during this period that primates evolved: the huge forests of those times offered refuge for a variety of species that had probably already developed sophisticated social behaviors.  

Grass also survived the end-Cretaceous catastrophe. As a result, some mammals evolved into new "megaherbivores" or "megafauna" that occupied the same ecological niche that the triceratopsides had colonized long before.  Here is a brontotherium, a large herbivorous mammal that lived some 37-35 million years ago, during the late Eocene period (image from BBC).

The megabeasts of the Cenozoic do not have the same fascination of the giant dinosaurs, but this creature has a nice-sounding name, and it looks like Shrek, the ogre of Spielberg's movie. Note how the beast is correctly shown walking on a grassy plain. The Eocene is supposed to have been mostly forested, but grass existed, too. The brontotherium was an opportunistic herbivore, apparently able to subsist on various kinds of food, not just grass. 

During the warm phase of the Cenozoic, Earth reached a maximum temperature around 55 million years ago, some 8-12 deg C higher than today. The concentration of CO2, too, was large. That is called the "early Eocene climatic optimum". It doesn't mean that this period was better than other periods in terms of climate, but it seems that Earth was mainly covered with lush forests and that the biosphere thrived.  

Then, the atmosphere started cooling. It was a descent that culminated at the Eocene-Oligocene boundary, about 34 million years ago, with a new mass extinction. It was a relatively small event in comparison to other, more famous, mass extinctions, but still noticeable enough that the Swiss paleontologist Hans Georg Stehlin gave it the name of the "Grande Coupure" (the big break) in 1910. One of the victims was the brontotherium -- too bad!

Unlike other cases, the extinction at the Grande Coupure was not correlated to the warming created by a LIP, but to rapid cooling. You see the "step" in temperature decline in the figure. 

Why the big cooling? The answer is not completely known. Surely, the cooling was correlated to a decline in the CO2 content in the atmosphere and that, in turn, may have been generated by the collision of the Indian plate with Eurasia. It was a gigantic geological event that generated the Himalayan mountain belt. It exposed huge amounts of fresh rock to the atmosphere, and the result was the removal of CO2 because of silicate erosion and weathering. The Himalaya hypothesis is one of those explanations that seem to make a lot of sense, but it has big problems

Another possible explanation is that Earth just outgassed less CO2 than before. The CO2 that plants need for their photosynthesis is generated mainly at the mid-oceanic ridges where the hot mantle (the molten rock layer below Earth's crust) outgasses it, as it has been doing for billions of years. It may well be that the mantle is getting a little colder over the eons, so it outgasses less CO2 than before. It may be true, but it seems to be a weak effect -- not enough to explain the CO2 decline of the Cenozoic.

In my opinion, the most likely hypothesis is that the CO2 concentration declined because of higher biological productivity not just on land, but also in the sea (as it seems to be implied in a recent study)
In other words, the early Cenozoic may have been so booming with life of all kinds that it absorbed more CO2 from the atmosphere than the mantle could replace by outgassing. The result was the cooling phase. The abrupt step at "Grande Coupure" may be related to the evolution of a specific life form: baleen whales, which changed the equilibria of the whole marine ecosystem, drawing down even more CO2 from the atmosphere.

This interpretation agrees with the fact that ice ages are often observed after LIPs. It may be one of the many cycles of the ecosphere. So, when a major LIP appears, the rise of CO2 is disastrous at the beginning but, in the long run, it gives the biosphere a chance to rebound and expand in a CO2 rich system.  Then, the rebound generates its own doom: the abundant biological productivity draws down CO2 from the atmosphere, cools the planet, and the system finds itself CO2-starved again. In this interpretation, the Eocene cooling and the Grande Coupure were long-term consequences of the Deccan LIP that had destroyed the dinosaurs, millions of years before. I hasten to note that this is just one of the several possible interpretations but, in my opinion, it makes a lot of sense.    

The Eocene cooling had profound effects on forests. First, the CO2 decline gave an advantage to those plants which utilized a more efficient photosynthesis mechanism called the "C4" pathway. Earlier on, the standard photosynthesis mechanism (called "C3") had evolved in an atmosphere rich in CO2. The C3 mechanism is efficient in processing carbon dioxide, but it is hampered by the opposite process called "photorespiration," which becomes important when the CO2 concentration is low. Using the C4 mechanism, plants can concentrate CO2 in the cells where photosynthesis occurs and avoid the losses by photorespiration. 

C4 plants appeared shortly after the Grande Coupure and diffused mainly in grasses, Trees, instead, didn't adopt the new mechanism. The explanation is subtle: photosynthesis needs water, and the process that goes on in leaves is strongly connected to the evapotranspiration mechanism. The C4 mechanism needs less water than the C3 one, so evapotranspiration is hampered. The result is that C4 trees could not be as tall as the ordinary C3 ones, and so they are not favored by natural selection in forests. In an atmosphere of very low CO2, forests are disadvantaged because of the higher photosynthesis efficiency of grasses. 

During the period that followed the Grande Coupure, temperatures and CO2 concentrations remained stable, but at relatively low levels. The result was that many forests disappeared, replaced by grasslands and savannas. Herbivorous species evolved teeth more specialized for grazing and became "mega-herbivorous" species. The landscape must have become similar to the modern one, with patches of forests alternating with savannas. 

A typical savanna ecosystem: the Tarangire national park in Tanzania. (Image From Wikipedia). Compare with the forest image at the beginning of this post. 

Despite the expansion of savannas, rainforests continued to exist in the tropical regions. Conifer forests kept a foothold in the Northern regions, helped by their Ectomycorrhiza system that avoided the runoff of nutrients in winter. The boreal forest is also called "Taiga." 

Then, a new cooling phase started, apparently a continuation of the previous trend: cooling begets more cooling. It was the beginning of the "Pleistocene," a period of unstable climate with ice ages and interglacials following each other, triggered by small oscillations in solar irradiation caused by the characteristics of Earth's orbit. These oscillations are called "Milankovich Cycles" -- they are not the cause of the ice ages, just triggers. (Image Source).

The oscillations are caused by ice having a built-in albedo feedback so that the more ice expands, the more sunlight is directly reflected into space. That causes the temperature to decline and ice to expand even more. Taken to its extreme consequences, this mechanism may lead to the "Snowball Earth" condition, with ice covering the whole planet's surface. It may have happened for real during the "Cryogenian" period, some 600 million years ago. Fortunately, there were mechanisms able to re-heat Earth and return it to the conditions we consider "normal." 

During the Pleistocene, the CO2 concentration in Earth's atmosphere plunged to very low levels, especially during the glacial periods, when it reached levels as low as around 150 parts per million (ppm). Earth may have inched close to a new snowball Earth but, fortunately, that didn't happen. In part, it may be because the sun, today, is about 5% hotter than it was during the Cryogenian. But we will never know how close Gaia got to freezing to death. 

During the Pleistocene, the advancing ice sheets swept away all plants, but even in non-glaciated areas, forests suffered badly.  Tropical rainforests didn't disappear, but they were much reduced in extension. In the North, most of the Eurasian boreal forests were replaced by the "mammoth steppe," a huge area that went from Spain to Kamchatka. where mammoths and other mega-herbivores roamed. 

It is not impossible that an ice age colder than the Pleistocene average could have led to the eventual extinction of the forests, completely replaced by grasses. But that didn't happen, and things were going to change again. 

The Rise of the Savanna Monkeys  

Primates are arboreal creatures that evolved in the warm environment of the Eocene forests. They used tree branches as a refuge, and they could adapt to various kinds of food. From the viewpoint of these ancient primates, the shrinking of the area occupied by tropical forests was a disaster. They were not equipped to live in savannas: slow on the ground, they would be just an easy lunch for the powerful predators of the time. Primates also never colonized the northern taiga. It was probably not because they couldn't live in cold environments (some modern monkeys can do that), but because they couldn't cross the "mammoth steppe" that separated Tropical forests from the Northern forests. So, "boreal monkeys" do not exist (actually, there is one, but it is not exactly a monkey!).  

Yet, during the Pleistocene, the shrinking of the tropical forests forced some monkeys to move into the savanna, leaving their comfortable living on tree branches. The Australopythecines, (image source) appeared about 4 million years ago. We may call them the first "savanna monkeys." The first creatures that we classify as belonging to the genus Homo, the homo habilis, appeared some 2.8 million years ago. They were also savanna dwellers. 

The savanna monkeys won the game of survival by means of a series of evolutionary innovations. They increased their body size for better defense, they developed an erect stance to have a longer field of view, they super-charged their metabolism by getting rid of their body hair and using profuse sweating for cooling, they developed complex languages to create social groups for collective defense, and they learned how to make stone tools adaptable to different situations. Finally, they developed a tool that no animal on Earth had mastered before: fire. Over a few hundred thousand years, they spread all over the world from their initial base in a small area of Central Africa. The savanna monkeys, now called "Homo sapiens," were a stunning evolutionary success. The consequences on the ecosystem were enormous.

First, the savanna monkeys exterminated most of the megafauna. The only large mammals that survived the onslaught were those living in Africa, where they had the time to adapt to the new predator as it evolved. For instance, the large ears of the African elephant are a cooling system destined to make elephants able to cope with the incredible stamina of human hunters. But in Eurasia, North America, and Australia, the arrival of the newcomers was so fast and so unexpected that most of the large animals were wiped out. 

By eliminating the megaherbivores, the monkeys had, theoretically, given a hand to the competitors of grass, forests, which now had an easier time encroaching on grassland without seeing their saplings trampled. But the savanna monkeys had also taken the role of megaherbivores. They used fires with great efficiency to clear forests to make space for the game they hunted. In the book "1491" Charles Mann reports (. p 286) how "rather than domesticating animals for meat, Indians retooled ecosystems to encourage elk, deer, and bear. Constant burning of undergrowth increased the number of herbivores, the predators that fed on them, and the people who ate them both."  Later, as they developed metallurgy, the monkeys were able to cut down entire forests to make space for the cultivation of the grass species that they had domesticated meanwhile: wheat, rice, maize, oath, and many others. 

But the savanna monkeys were not necessarily enemies of the forests. In parallel to agriculture, they also managed entire forests as food sources. The story of the chestnut forests of North America is nearly forgotten today but, about one century ago, the forests of the region were largely formed of chestnut trees planted by Native Americans as a source of food (image source). By the start of the 20th century, the forest was devastated by the "chestnut blight," a fungal disease that came from China. It is said that some 3-4 billion chestnut trees were destroyed and, now, the chestnut forest doesn't exist anymore. The American chestnut forest is not the only example of a forest managed, or even created, by humans. Even the Amazon rainforest, sometimes considered an example of a "natural" forest, shows evidence of having been managed by the Amazonian Natives in the past as a source of food and other products. 

The action of the savanna monkeys was always massive and, in most cases, it ended in disaster. Even the oceans were not safe from the monkeys: they nearly managed to exterminate the baleen whales, turning large areas of the oceans into deserts. On land, entire forests were razed to the ground. Desertification ensued, brought upon by "megadroughts" when the rain cycle was no more controlled by the forests. Even when the monkeys spared a forest, they often turned it into a monoculture, subjected to be destroyed by pests, as the case of the American chestnuts shows. Yet, in a certain sense, the monkeys were making a favor to forests. Despite the huge losses to saws and hatchets, they never succeeded in completely exterminating a tree species, although some are critically endangered nowadays. 

The most important action of the monkeys was their habit of burning sedimented carbon species that had been removed from the ecosphere long before. The monkeys call these carbon species "fossil fuels" and they have been going on an incredible burning bonanza using the energy stored in this ancient carbon without the need of going through the need of the slow and laborious photosynthesis process. In so doing, they raised the concentration of CO2 in the atmosphere to levels that had not been seen for tens of millions of years before. That was welcome food for the trees, which are now rebounding from their former distress during the Pleistocene and reconquering the lands they had lost to grass. In the North of Eurasia, the Taiga is expanding and gradually eliminating the old mammoth steppe. Areas that today are deserts are likely to become green. We are already seeing the trend in the Sahara desert. 

What the savanna monkeys could do was probably a surprise for Gaia herself, who must be now scratching her head and wondering what has happened to her beloved Earth. And what's going to happen now?  

The New Large Igneous Province made by Monkeys

The giant volcanic eruptions called LIPs tend to appear with periodicities of the order of tens or hundreds of million years. But nobody can predict a LIP and, instead, the savanna monkeys engaged in the remarkable feat of creating a LIP-equivalent by burning huge amounts of organic ("fossil") carbon that had sedimented underground over tens or hundreds of millions of years of biological activity. 

It is remarkable how rapid the monkey LIP (MLIP) has been. Geological LIPS typically span millions of years. The MLIP went through its cycle in a few hundreds of years. It will be over when the concentration of fossil carbon stored in the crust will become too low to self-sustain the combustion with atmospheric oxygen. Just like all fires, the great fire of fossil carbon will end when it runs out of fuel, probably in less than a century from now. Even in such a short time, the concentration of CO2 is likely to reach, and perhaps exceed, levels never seen after the Eocene, some 50 million years ago.  

There is always the possibility that such a high carbon concentration in the atmosphere will push Earth over the edge of stability and kill Gaia by overheating the planet. But that's not a very interesting scenario, so let's examine the possibility that the biosphere will survive the carbon pulse. What's going to happen to the ecosphere?

The savanna monkeys are likely to be the first victims of the CO2 pulse that they themselves generated. Without the fossil fuels they had come to rely on, their numbers are going to decline very rapidly. From the incredible number of 8 billion individuals, they may return to levels typical of their early savanna ancestors: maybe just a few tens of thousands. Quite possibly, they'll go extinct. In any case, they will hardly be able to keep their habit of razing down entire forests. Without monkeys engaged in the cutting business and with high concentrations of CO2, forests are advantaged over savannas, and they are likely to recolonize the land. We are going to see again a lush, forested planet where arboreal monkeys will probably survive and thrive. Nevertheless, savannas will not disappear. They are part of the ecosystem, and new megaherbivores will evolve in a few hundreds of thousands of years. 

Over deep time, the great cycle of warming and cooling may restart after the monkey LIP, just as it does for geological LIPs. In a few million years, Earth may be seeing a new cooling cycle that will lead again to a Pleistocene-like series of ice ages. At that point, new savanna monkeys may evolve. They may restart their habit of exterminating the megafauna, burning forests, and building things in stone. But they won't have the same abundance of fossil fuel that the monkeys called "Homo sapiens" found when they emerged into the savannas. So, their impact on the ecosystem will be smaller, and they won't be able to create a new monkey-LIP. 

And then what? In deep time, the destiny of Earth is determined by the slowly increasing solar irradiation that is going, eventually, to eliminate the oxygen from the atmosphere and sterilize the biosphere, maybe in less than a billion years from now. So, we may be seeing more cycles of warming and cooling before Earth's ecosystem collapses. At that point, there will be no more forests, no more animals, and only single-celled life may persist. It has to be. Gaia, poor lady, is doing what she can to keep the biosphere alive, but she is not all-powerful. And not immortal, either. 

Nevertheless, the future is always full of surprises, and you should never underestimate how clever and resourceful Gaia is. Think of how she reacted to the CO2 starvation of the past few tens of millions of years. She came up with not just one, but two brand-new photosynthesis mechanisms designed to operate at low CO2 concentrations: the C4 mechanism typical of grasses, and another one called crassulacean acid metabolism (CAM). To say nothing about how the fungal-plant symbiosis in the rhizosphere has been evolving with new tricks and new mechanisms. You can't imagine what the old lady may concoct in her garage together with her Elf scientists (those who also work part-time for Santa Claus). 

Now, what if Gaia invents something even more radical in terms of photosynthesis? One possibility would be for trees to adopt the C4 mechanism and create new forests that would be more resilient against low CO2 concentrations. But we may think of even more radical innovations. How about a light fixation pathway that doesn't just work with less CO2, but that doesn't even need CO2? That would be nearly miraculous but, remarkably, that pathway exists. And it has been developed exactly by those savanna monkeys who have been tinkering -- and mainly ruining -- the ecosphere. 

The new photosynthetic pathway doesn't even use carbon molecules but does the trick with solid silicon (the monkeys call it "photovoltaics"). It stores solar energy as excited electrons that can be kept for a long time in the form of reduced metals or other chemical species. The creatures using this mechanism don't need carbon dioxide in the atmosphere, don't need water, they may get along even without oxygen. What the new creatures can do is hard to imagine for us (although we may try). In any case, Gaia is a tough lady, and she may survive much longer than we may imagine, even to a sun hot enough to torch the biosphere to cinders. Forests, too, are Gaia's creatures, and she is benevolent and merciful (not always, though), so she may keep them with her for a long, long time. (and, who knows, she may even spare the Savanna Monkeys from her wrath!). 

We may be savanna monkeys, but we remain awed by the majesty of forests. The image of a fantasy forest from Hayao Miyazaki's movie, "Mononoke no Hime" resonates a lot with us. But can you see the mistake in this image? What makes this forest not a real forest? 


Note: You always write what you would like to read, and that's why I wrote this post. But, of course, this is a work in progress. I am tackling a subject so vast that I can't possibly hope to be sufficiently expert in all its facets to avoid errors, omissions, and wrong interpretations. Corrections from readers who are more expert than me are welcome! I would also like to thank Anastassia Makarieva for all she taught me about the biotic pump and about forests in general, and Mihail Voytehov for his comments about the rhizosphere. Of course, all mistakes in this text here are mine, not theirs.

Thursday, July 29, 2021

We are not in the Holocene Anymore: A World Without Permanent Ice.

The post below is reproduced from my blog "The Proud Holobionts," but I think the subject is compatible with the vision of the "Seneca Effect" blog. Indeed, everything is related on this planet and the concept of "holobiont" can be seen as strictly connected to the concept of "Seneca Cliff." Complex systems, both virtual and real, are networks that can be almost always seen as holobionts in their structure. A collapse, then, is when the network undergoes a chain of link breaking in a process known as the "Griffith fracture mechanism" in engineering (you see that everything is correlated!)
This post is also part of the material that myself and Chuck Pezeshki are assembling for a new book that will be titled (provisionally) "Holobiont: the new Science of Collaboration," where we plan to explore how new concepts in biology and network science can combine to give us the key to managing highly complex system: human societies, large and small. And the overarching concept that links all this is one: empathy.



When the Ice Will be Gone: The Greatest Change Seen on Earth in 30 Million Years.

From: "The Proud Holobionts," July 27, 2021


An image from the 2006 movie "The Meltdown," the second of the "Ice Ages" series. These movies attempted to present a picture of Earth during the Pleistocene. Of course, they were not supposed to be paleontology lessons, but they did show the megafauna of the time (mammoths, sabertooth tigers, and others) and the persistent ice, as you see in the figure. The plot of "The Meltdown" was based on a real event: the breakdown of the ice dam that kept the Lake Agassiz bonded inside the great glaciers of the Laurentide, in the North American continent. When the dam broke, some 15,000 years ago, the lake flowed into the sea in a giant flood that changed Earth's climate for more than a thousand years. So, the concept of ice ages as related to climate change is penetrating the human memesphere. It is strange that it is happening just when the human activity is pushing the ecosystem back to a pre-glacial period. If it happens, it will be the greatest change seen on Earth in 30 million years. And we won't be in the Holocene anymore.


We all know that there is permanent ice at Earth's poles: it forms glaciers and it covers huge areas of the sea. But is it there by chance, or is it functional in some way to Earth's ecosphere? 

Perhaps the first to ask this question was James Lovelock, the proposer (together with Lynn Margulis) of the concept of "Gaia" -- the name for the great holobiont that regulates the planetary ecosystem. Lovelock has always been a creative person and in his book "Gaia: A New Look at Life on Earth" (1979) he reversed the conventional view of ice as a negative entity. Instead, he proposed that the permanent ice at the poles was part of the planetary homeostasis, actually optimizing the functioning of the ecosphere. 

Lovelock was perhaps influenced by the idea that the efficiency of a thermal engine is directly proportional to the temperature differences that a circulating fluid encounters. It may make sense: permanent ice creates large temperature difference between the poles and the equator and, as a consequence, winds and ocean currents are stronger, and the "pumps" that bring nutrients everywhere sustain more life. Unfortunately, this idea is probably wrong, but Lovelock has the merit to have opened the lid on a set of deep questions on the role of permanent ice in the ecosystem. What do we know about this matter?

It took some time for our ancestors to realize that permanent ice existed in large amounts in the high latitude regions. The first who saw the ice sheet of Greenland was probably Eric the Red, the Norwegian adventurer, when he traveled there around the year 1000. But he had no way to know the true extent of the inland ice, and he didn't report about them.

The first report I could find on Greenland's ice sheet is the 1820 "History Of Greenland", a translation of an earlier report (1757) in German by David Crantz, where you can find descriptions of the ice-covered inland mountains. By the early 20th century, the maps clearly showed Greenland as fully ice-covered. About Antarctica, by the end of the 19th century, it was known that it was also fully covered with a thick ice sheet. 

Earlier on, in the mid 19th century, Louis Agassiz had proposed a truly revolutionary idea: that of the ice age. According to Agassiz, in ancient times, much of Northern Europe and North America were covered with thick ice sheets. Gradually, it became clear that there had not been just one ice age, but several, coming and going in cycles. In 1930, Milutin Milankovich proposed that these cycles were linked to periodic variations in the insulation of the Northern Hemisphere, in turn caused by cycles in Earth's motion. For nearly a million years, Earth was a sort of giant pendulum in terms of the extent of the ice sheet. 

The 2006 movie "An inconvenient truth" was the first time when these discoveries were presented to the general public. Here we see Al Gore showing the temperature data of the past half million years.

An even more radical idea about ice ages appeared in 1992, when Joseph Kirkschvink proposed the concept of "Snowball Earth." The idea is that Earth was fully covered by ice at some moment around 700-600 million years ago, the period appropriately called "Cryogenian."

This super-ice age is still controversial: it will never be possible to prove that every square kilometer of the planet was under ice and there is some evidence that it was not the case. But, surely, we are dealing with a cooling phase much heavier than anything seen during relatively recent geological times.

While more ice ages were discovered, it was also clear that Earth had been ice-free for most of its long existence. Our times, with permanent ice at the poles, are rather exceptional. Let's take a look at the temperatures of the past 65 million years (the "Cenozoic"). See this remarkable image (click to see it in high resolution)

At the beginning of the Cenozoic, Earth was still reeling after the great disaster of the end of the Mesozoic, the one that led to the disappearance of the dinosaurs (by the way, almost certainly not caused by an asteroidal impact). But, from 50 million years ago onward, the trend has been constant: cooling. 

The Earth is now some 12 degrees centigrade colder than it was during the "warmhouse" of the Eocene. It was still ice-free up to about 35 million years ago but, gradually, permanent ice started accumulating, first in the Southern hemisphere, then in the Northern one. During the Cenozoic, Earth never was so cold as it is now.

The reasons for the gradual cooling are being debated, but the simplest explanation is that it is due to the decline of CO2 concentrations in the atmosphere. That, in turn, may be caused to a slowdown of the outgassing of carbon from Earth's interior. Maybe Earth is just becoming a little older and colder, and so less active in terms of volcanoes and similar phenomena. There are other explanations, including the collision of India with Central Asia and the rise of the Himalaya that caused a drawdown of CO2 generated by the erosion of silicates. But it is a hugely complicated story and let's not go into the details.

Let's go back to our times. Probably you heard how, just a few decades ago, those silly scientists were predicting that we would go back to an ice age. That's an exaggeration -- there never was such a claim in the scientific literature. But it is true that the idea of a new ice age was floating in the memesphere, and for good reasons: if the Earth had seen ice ages in the past, why not a new one? Look at these data:

These are temperatures and CO2 concentrations from the Vostok ice cores, in Antarctica (you may have seen these data in Al Gore's movie). They describe the glacial cycles of the past 400,000 years. Without going into the details of what causes the cycles (solar irradiation cycles trigger them, but do not cause them), you may note how low we went in both temperatures and CO2 concentrations at the coldest moments of the past ice ages. The latest ice age was especially cold and associated with very low CO2 concentrations. 

Was Earth poised to slide down to another "snowball" condition? It cannot be excluded. What we know for sure is that during the past million years, the Earth tethered close to the snowball catastrophe every 100,000 years or so. What saved it from sliding all the way into an icy death?

There are several factors that may have stopped the ice from expanding all the way to the equator. For one thing, the sun irradiation is today about 7% larger than it was at the time of the last snowball episode, during the Cryogenian. But that may not enough as an explanation. Another factor is that the cold and the low CO2 concentrations may have led to a weakening -- or even to a stop -- of the biological pump in the oceans and of the biotic pump on land. Both these pumps cycle water and nutrients, keeping the biosphere alive and well. Their near disappearance may have caused a general loss of activity of the biosphere and, hence, the loss of one of the mechanisms that removes CO2 from the atmosphere. So, CO2 concentrations increased as a result of the continuing geological emissions, unaffected by changes of the biosphere. Note how, in the figure, the CO2 concentration and temperatures are perfectly superimposable during the warming phases: the reaction of the temperature to the CO2 increase was instantaneous on a geological time scale. Another factor may have been the desertification of the land that led to an increase in atmospheric dust that landed on the top of the glaciers. That lowered the albedo (the reflected fraction of light) of the system and led to a new warming phase. A very complicated story that is still being unraveled.  

But how close was the biosphere to total disaster? We will never know. What we know is that, 20 thousand years ago, the atmosphere contained just 180 parts per million (ppm) of CO2 (today, we are at 410 ppm). That was close to the survival limit of green plants and there is evidence of extensive desertification during these periods. Life was hard for the biosphere during the recent ice ages, although not so bad as in the Cryogenian. Lovelock's idea that permanent ice at the poles is good for life just doesn't seem to be right.

Of course, the idea that we could go back to a new ice age was legitimate in the 1950s, not anymore as we understand the role of human activities on climate. Some people maintain that it was a good thing that humans started burning fossil hydrocarbons since that "saved us from a new ice age." Maybe, but this is a classic case of too much of a good thing. We are pumping so much CO2 into the atmosphere that our problem is now the opposite: we are not facing an "icehouse Earth" but a "warmhouse" or even a "hothouse" Earth. 

A "hothouse Earth" would be a true disaster since it was the main cause of the mass extinctions that took place in the remote past of our planet. Mainly, the hothouse episodes were the result of outbursts of CO2 generated by the enormous volcanic eruptions called "large igneous provinces." In principle, human emissions can't even remotely match these events. According to some calculations, we would need to keep burning fossil fuels for 500 years at the current rates to create a hothouse like the one that killed the dinosaurs (but, there is always that detail that non linear systems always surprise you . . .)

Still, considering feedback effects such as the release of methane buried in the permafrost, it is perfectly possible that human emissions could bring CO2 concentrations in the atmosphere at levels of the order of 600-800 ppm, or even more, comparable to those of the Eocene, when temperatures were 12 degrees higher than they are now. We may reach the condition called, sometimes, "warmhouse Earth."

From the human viewpoint, it would be a disaster. If the change were to occur in a relatively short time, say, of the order of a few centuries, the human civilization is probably toast. We are not equipped to cope with this kind of change. Just think of what happened some 14,500 years ago, when the great Laurentide ice sheet in North America fragmented and collapsed. (image source) (the 2006 movie "Meltdown" was inspired exactly by this event). Earth's climate went through a series of cold and warm spells that is hard to think we could survive. 


Human survival concerns are legitimate, but probably irrelevant in the greater scheme of things. If we go back to the Eocene, the ecosystem would take a big hit during the transition, but it would survive and then adapt to the new conditions. In terms of life, the Eocene has been described as "luxuriant." With plenty of CO2 in the atmosphere, forests were thriving and, probably, the biotic pump provided abundant water everywhere inland, even though the temperatures were relatively uniform at different latitudes. A possible mental model for that period is the modern tropical forests of Central Africa or Indonesia. We don't have data that would allow us to compare Earth's productivity today with that of the Eocene, but we can't exclude that the Eocene was more productive in terms of life. Humans might well adapt to this new world, although their survival during the transition is by no means guaranteed. 

Again, it seems that Lovelock was wrong when he said that ice ages optimize the functioning of the biosphere. But maybe there is more to this idea. At least for one thing, ice ages have a good effect on life. Take a look at this image that summarizes the main ice ages of Earth's long history

 (image source)

The interesting point is that ice ages seem to occur just before major transitions in the evolutionary history of Earth. We don't know much about the Huronian ice age, but it occurred just at the boundary of the Archean and the Proterozoic, at the time of the appearance of the Eucaryotes. Then, the Cryogenian preceded the Ediacaran period and the appearance of multicellular life that colonized the land. Finally, even the evolution of the Homo Sapiens species may be related to the most recent ice age cycle. With the cooling of the planet and the reduction of the extent of forested areas, our ancestors were forced to leave the comfortable forests where they had lived up to then and take up a more dangerous lifestyle in the savannas. And you know what it led to!

So, maybe there is something good in ice ages and, after all, James Lovelock's intuition may have hinted at an important insight in how evolution works. Then, there remains the question of how exactly ice ages drive evolution. Maybe they have an active role, or maybe they are simply a parallel effect of the real cause that drives evolution, quite possibly the increasing concentration of atmospheric oxygen that has accompanied the biosphere over the past 2.7 billion years. Oxygen is the magic pill that boosts the metabolism of aerobic creatures -- what makes possible creatures like us. 

In any case, it is likely that ice ages will soon be a thing of the past on planet Earth. The effect of the human perturbation may be moderate and, when humans will stop burning fossil hydrocarbons (they have to, one day or another) the system may reabsorb the excess CO2 and gradually return to the ice age cycles of the past. That may occur in times of the order of at least several thousand years, possibly several tens of thousands. But the climate is a non-linear system and it may react by reinforcing the perturbation -- the results are unknowable. 

What we know for sure is that the cycle of Earth's ecosystem (Gaia) is limited. We still have about 600 million years before the sun's increasing brightness takes Earth to a different condition: that of "wet greenhouse" that will bring the oceans to boil and extinguish all life on the planet. And so it will be what it will have to be. Gaia is long-lived, but not eternal.