Killing the bear - killing hope

"The Bears' Famous Invasion of Sicily" is a story for children written by the Italian poet and novelist Dino Buzzati. It tells of how the bears came down from their mountains, defeated humans, and took over the government to create a society in which humans and bears live together in harmony. It is, of course, a fairy tale and some recent events in the Trentino region, in Italy, show how difficult it is for humans and bears to live together in harmony. And this is bad both for bears and for humans.

There have been many shocking events in this eventful 2014, but the one that shocked me most took place in the Northern Italian region of Trentino, where a wild female bear named "Daniza" was hunted and killed in the name of security for the tourists of the region. A minor story, for sure, but one that explains a lot about the behavior of humans and the problems we have when we try to manage our wold.

The story started this August in Trentino, when someone named Daniele Maturi stumbled into a wild female bear (known to humans as "Daniza") and her two cubs while searching for mushrooms in the woods. According to Mr. Maturi's own narration, he remained there to "observe the bears" instead of retreating as quickly and quietly as possible. The bear reacted attacking him, wounding him slightly, before retreating into the deep forest with her cubs. This generated a widespread public outcry, with calls for the elimination of the "dangerous animal," until Daniza was hunted down and killed by an overdose of anesthetic. Officially, it was a mistake, but more likely it was the result of the age-old attitude that says that "the only good X is dead X", where X can be Indian, bear, or anything deemed to be not human, or not human enough. In the end, Daniza's cubs may not be able to survive after the killing of their mother, but human cubs will be able to walk in a sanitized and safe forest where they won't risk to be attacked by anything larger and more dangerous than a squirrel. 

This sad story casts much light on the attitude of people in Italy about bears and about wilderness in general. It appears that in Trentino there exists a lively "anti-bear" movement - mainly organized by the Northern League -  which, among other actions, had organized a dinner based on bear meat in 2011 intended to demonstrate what, in their opinion, was to be done with the wild bears of the forest. After that the story told by Mr. Maturi appeared on newspapers, hotel owners reported that many of their customers had canceled their reservations, out of fear of the wild bears. From the debate on the press and on the web, it appears that quite a number of people were genuinely concerned that their children could be devoured by wild bears if  they were to take a walk in the parks of the Trentino region.

On the other side of the debate, Daniza was praised for her restraint in not having killed the human intruder, when she could have easily done so. Mr. Maturi, instead, was insulted and vilified in all possible ways because of his idiocy in not leaving in peace a female bear with her cubs. He was also accused of being part of a conspiracy designed to cast bears in a bad light and favor their elimination from the forests of Trentino (the latter accusation automatically implies the former).


Most of the debate seems to have missed the fundamental point of this story, which is that both humans and bears simply acted according to their genetic set-up and, probably, couldn't have behaved otherwise. We cannot exclude that Daniza the bear was intelligent enough to choose not to kill Mr. Maturi to avoid angering humans too much. But, most likely, she simply behaved according to the way female bears have always behaved: aggressively defending their cubs against all perceived. On the other side, Mr. Maturi, politicians, and most people, simply behaved according to the way human beings have always behaved; exploiting everything they perceive as a "resource" and aggressively eliminating anything they see as an obstacle. Countries other than Italy may have a less nasty attitude toward wild bears but, everywhere, if wilderness is an obstacle to profit, wilderness always loses. 


To an IQ test, most human beings (possibly including also Mr. Maturi) will score better than most bears. But, if human beings are individually smarter than bears (at least in their ability to manipulate abstract symbols), that doesn't mean that they are smarter than bears as a species. They way they behave, actually, shows no signs of intelligence as they are simply marching straight on, ruthlessly stomping over everything they see as stopping them in their path. It is our destiny as human beings to destroy what keeps us alive; but, in the end, it is unavoidable: it is what we are. Could we change for the better in the future? Probably not: killing the bear has killed the hope for that. The bell for Daniza is ringing for us.


BTW - one result of the Daniza story was a nation-wide call on boycotting the Trentino region. You might consider that: perhaps not all hope is lost.. 

Deep Future: the ultimate destiny of humankind

In the 1950s, we knew what the future would be: an age of prosperity and unprecedented wonders. Energy too cheap to meter, flying cars, vacations on the moon, and the conquest of space. Then, space heroes would return to Earth to relax on the edge of their swimming pool while the robot-butler would bring them their margaritas. To be sure, the future had a dark side: that of the nuclear holocaust. But it was still a future where human ingenuity would trump everything else. 

The future today is completely different. The way we see the destiny of humankind is inextricably linked to the great "pulse" of carbon burning that has been ongoing for a couple of centuries and which is now reaching its peak. Fossil carbon has taken us to where we are now, creating the prosperity of our industrial civilization. But fossil fuels are rapidly running out and that creates a number of consequences; one is the impossibility of running an industrial society without abundant and cheap energy, the other is global warming which is transforming the earth into a completely new planet. These effects will shape the future of humankind in ways that can't be exactly predicted, but that we can imagine in the form of "scenarios" - futures that could happen. So, here are some possible futures of humankind, arranged from the least exciting one (near term extinction) to highly exciting ones, involving expansion over the whole galaxy.



1. Extinction.

Extinction is a simple scenario to describe: humankind goes extinct and that's it. The time scale of extinction may be millennia, centuries or, perhaps, just decades (in the last case, it may go under the name of "Near Term Extinction," a term popularized by Guy McPherson). In any case, extinction would be very rapid in comparison to the time span of existence of homo sapiens, at least two hundred thousand years.

Extinction is a perfectly possible scenario if we assume the playing out of some of the most dire effects of the human impact on the ecosphere, in particular the emissions of greenhouse gases. The great "methane burp" that could result from the thawing of the Earth's permafrost could raise temperatures up to 6-8 degrees C and even more in times of the order of a few centuries or even much faster. In its extreme version, global warming could evolve into the "Venus catastrophe", where the whole biosphere could be sterilized by extremely high temperatures. To be sure, this scenario seems to be ruled out by the results of the current climate models, but we don't need the Venus catastrophe to unbalance the ecosystem to such a degree that the resources humans need in order to survive would be destroyed. At that point, the outcome could be only one: extinction. 

This is a scenario that leaves little to discuss about the destiny of humankind. But, assuming that the biosphere is not completely destroyed, could the planet recover afterward? Perhaps it could, but not necessarily. Nowadays, the Earth is perilously close to the inner edge of the habitable zone in the Solar system and it is being pushed out of it by the gradual increase of solar radiation. It is a very slow process by human standards, but it is estimated that vertebrates have no more than some 100-150 million years to go before the Earth becomes too hot for them to survive. A major disaster such as the one we are contemplating in this scenario could kick the Earth out of the vertebrate habitable zone. In this case, the Earth's biosphere might revert to a world of unicellular creatures such as it was during the Archean or the Proterozoic eons. In such case, it is possible, and perhaps likely, that vertebrates would never re-evolve and that the planet would remain dominated by unicellular life forms until it gets sterilized by further increases in solar radiation, about one billion years from now.

But let's assume that the ecosystem can recover without major losses of phyla. In times of the order of hundreds of thousands of years, the excess CO2 in the atmosphere would be removed and transformed into solid carbonates. That would slowly cool down the planet and the ecosystem would gradually recover its former productivity. At that point, vertebrates could become again abundant and the Earth would look very much like it looked millions of years ago, when the ancestors of human beings didn't seem to be destined to the great explosion of numbers that was to take place with the Anthropocene.

Is there a chance that the Earth would evolve again a species of sentient beings? It is not impossible. If some species of primates could survive the great carbon pulse, they might re-develop tool making abilities and, in time, human-like intelligence. That would take time, considering that it took some 50 million years to arrive to homo sapiens from the earliest primates, but it would still be possible within the remaining lifetime of the biosphere for vertebrates. If all primates go extinct, then the task becomes more difficult considering that it took more than 400 million years for primates to appear after the evolution of vertebrates. But, again, it would not be impossible and, anyway, perhaps sentient beings don't need to be primates. So, there might be a second (and probably last) chance for intelligent creatures to do better than we did. Good luck to them!


2. The Olduvai Scenario. 

The "Return to Olduvai" was proposed by Richard Duncan in 1996 to describe the effect of the gradual depletion of fossil fuels; taking the name "Olduvai" from the name of a region in Tanzania, Africa, where our remote ancestors lived. The idea is that, without fossil fuels, humans would lose their principal source of energy and would be forced to return to their oldest survival lifestyle: hunting and gathering.

The Olduvai scenario could play out as the result of a combination of factors. First of all, fossil fuels would gradually become so expensive to make an industrial economy impossible. In parallel, global warming would raise temperatures so much that tropical and temperate latitudes would become impossible to inhabit year round for human beings. At this point, humans would be forced to retreat to extreme northern and southern regions, where it is not obvious that agriculture is possible. As we move away from the equator, a strong limiting factor is the low level of solar irradiation. Crops can grow nicely at high latitudes, but the problem is the slow rate of the reforming of fertile soil and the consequent erosion. It is a problem already evident today in regions such as in Iceland and Greenland and which might make agriculture impossible to maintain for long times.

So, humans living in high latitude regions could find that the best survival strategy for them is to adopt a lifestyle similar to that of modern Inuit, even though at much higher temperatures. They would live mainly by fishing and hunting marine mammals in the warm season - retreating in their shelters during the long polar night. In the Northern Hemisphere, this lifestyle would be possible in the ring of land around the North Pole, part of Eurasia and of the American Continent. In the Southern Hemisphere, it would mean the tip of the South American continent, Tierra Del Fuego, and perhaps an ice-free Antarctica, where humans could live for the first time in their history.

Modern humans have been hunters and gatherers for at least two hundred thousand years. Their hominid ancestors have been using this strategy for a couple of million years, at least. So, hunting and gathering is a stable and successful way of living that humans could adopt for a long time, at least as long as the planetary ecosystem would be able to maintain a sufficient biological productivity. In time, the ecosystem could stabilize and return the planet to the conditions of the past ten million years or so. In this case, the high latitude regions would probably freeze again and become covered by ice. Humans could then move back to lower latitudes. At this point, they would probably rediscover agriculture and restart with agricultural civilizations, as they had done tens or hundreds of thousands of years before. And so, we move to the next scenario; the return to agriculture. 


3. The return to agriculture.

Suppose that we run out of cheap fossil fuels, that is, fuels as cheap enough to sustain an industrial society. And suppose that we haven't used the energy we had - while we had it - to build up an alternative. Then, we will be forced to return to the world as it was before we started burning fossil fuels: an economy wholly based on biological resources; that is on agriculture.

This is a straightforward scenario that doesn't imply special events other than assuming that the effects of climate change would not be so drastic and ruinous as some scenarios describe them. Not that the transition won't be traumatic for humans. The world without fossil fuels and without alternatives to them won't be able to support, not even remotely, the same population that the fossil-powered agriculture had supported. And it is not just the lack of fossil fuels that will reduce agricultural productivity, it is the fact that centuries of intensive agriculture have destroyed a large fraction of the fertile soil that had created the human civilization. That would necessarily bring a drastic reduction in human population. In such a scenario, "traumatic" is surely an understatement. But humankind would survive.
 
In this farming future, there would hardly be a chance for a new industrial revolution. The fossil fuels that created the present one will be gone and will need millions of years to reform, if they ever will. Metal ores would also be scarce, although our farming descendants would do well by scavenging the ruins of our cities for metals. They would have plenty of iron and copper and they could even use aluminum for their cooking pans by melting down the zillions of beverage cans that we left behind. But their technological level would be severely limited by the lack of fuels: they would have only wood charcoal for their metallurgy. So, our descendants could still work iron and they could still kill each other with swords and spears (and, maybe, even with occasional muskets and cannons). But we know of no society in the past that could develop an industrial revolution without a cheap and abundant source of energy.

Curiously, however, there is a possibility for a new burst of industrialization in this remote future. It would be the result of mining Antarctica and, in minor measure, Greenland and other high latitude northern regions. Because of the ice cover, so far these regions have been scarcely exploited for minerals (or not at all, in the case of Antarctica). But the great carbon pulse could heat the planet enough that the world's glaciers would melt completely and open up these lands to mining. In this case, our ancestors could have a second (and likely last) chance to develop a new coal based industrial revolution. That would bring back everything to square one: with the new industrial society threatened by the deadly combination of depletion and climate change. Would our descendants be able to do better than us? Considering that they are - indeed - our descendants, probably not. Hence, this second cycle of industrialization might truly be the last one on the planet.

Apart from Antarctic coal, our descendants could remain farmers for a long, long time. It is said that agricultural societies of the past could be described as "peasants ruled by brigands", but this is an over-simplification for an integrated social structure where different layers perform highly specialized tasks: peasants, warriors, priests, artisans, and more. In time, agricultural societies could evolve converging to the social structure typical of other species which practice agriculture: mainly ants and termites. These species are "eusocial" (or "ultrasocial", according to some definitions) and practice extreme specialization, for instance with "queens" taking care of reproduction, while the other members of society are sterile female workers and warriors. Could future human agricultural society become something similar? Why not? At least one other species of mammals has developed full eusociality (the naked mole rat).

Eusocial species are highly resilient and tend to dominate the ecosystem, as ants and termites do and have been successfully doing for at least 50 million years. In principle, eusocial humans could also maintain their dominance of the ecosystem and continue in this role for tens or hundreds of millions of years, until they gradually disappear in a remote future as the earth becomes too hot for vertebrates to survive. If that happens, they would have been the most successful vertebrate species of earth's history; a species that even briefly dreamed of conquering space.



4. The great metabolic revolution

In more than four billion years of existence, the Earth never stood still. Powerful forces have shaped it in a continuous series of revolutions which have seen the development of more and more complex life forms, increasingly able to exploit the thermodynamic gradient created by sunlight. During this long time span, we have seen several metabolic revolutions; of which two have been the most important ones. The first was photosynthesis, some 4 billion years ago. The second is the aerobic metabolism, about 2.5 billion years ago. It is the latter revolution which, eventually, generated vertebrates and us.

Today, we seem to have reached an impasse in this ever increasing growth of biological complexity. Actually, we may be heading for an inversion of tendency created by long term changes of the ecosphere. The planetary thermostat which stabilizes the Earth's temperature works by regulating the concentration of CO2 in the atmosphere. But with the gradually increasing solar radiation, these concentrations are already near the lower limits necessary for photosynthesis. So, the present ecosystem is in a no-win situation: in the long run, either it will be destroyed by the lack of CO2 or by high temperatures. So, in order for a complex ecosystem to survive, we need a truly drastic metabolic revolution. Organic photosynthesis has reached its limits: we need to move to a completely different kind of substrates.

What is in photosynthesis, after all? It is a way to transform solar energy into excited electrons and use them to create chemical compounds which can give back this energy on demand. The efficiency of photosynthesis in this process is reported to arrive to about 13% in ideal conditions - in practice it is of the order of 8%. Note also that plants can't function as photosynthetic machines outside a narrow range of temperatures and without of nutrients and chemicals which are not always available.

So, if we want another metabolic revolution, we need something that can be both more efficient and less demanding in terms of environmental conditions. A possibility is the photovoltaic (PV) cell. The efficiency of a modern silicon PV cell can be higher than 20% in creating excited electrons. By themselves, the cells do not store energy, but can be coupled to energy storage devices and used to power a variety of processes and reactions for an overall efficiency that is comparable (and arguably higher) to that of photosynthesis. Silicon PV cells function using abundant elements: mainly silicon and aluminum, plus traces of nitrogen, boron, an phosphorous. The present generation uses also silver, but that's not a crucial. But the great advantage of "silicon photosynthesis" is that solid state PV cells do not need water or gaseous oxygen, and can operate in freezing temperatures or at high temperatures, up to a few hundred degrees centigrade. The "habitable zone" for PV cells is not a narrow shell around the sun: it spans a huge volume that includes all the major planets and probably extends even closer and farther from the sun. The quantity of solar energy that can be gathered in this volume is incredibly larger than the tiny amount intercepted by the Earth.

Of course, solid state PV devices are not normally considered the photosynthetic part of an ecosystem. They enjoy the name of "cells"; but unlike biological cells they don't reproduce themselves. But PV cells delegate their reproduction to specialized entities; cell factories, just like worker ants delegate their reproduction to specialized entities: queen ants. So, it is all part of a new ecosystem that is emerging; one which starts from the beginning as eusocial.

We know that complex systems become more complex the more energy flows through them. If the solid state ecosystem turns out to be more effective than the biological one, then the perspectives are mind boggling even if we limit our horizon to the surface of the Earth. Of course, it is hard for us to imagine the consequences of such a revolution (think of how difficult it would be for a protist of the Proterozoic age to imagine the advent of vertebrates). What we can see is that such a system is born connected at the planetary scale. The rapid development of the internet is giving us a taste of this new situation of extended interconnectedness. From our viewpoint of human beings, it is an unpleasant loss of privacy. On the other hand, ants in an anthill don't enjoy much privacy. It is, again, one of the characteristics of eusociality: you pay the advantages of efficiency with a loss of individuality. But we can hardly say more than that: if the new system is to be born, it will. What it will do, it is impossible to say, but it can - theoretically - expand to the whole solar system and survive for the whole remaining lifespan of the Sun, about 5 billion years - and even more.

In a way, it would be the ultimate triumph for human beings who would have engineered the birth of a new ecosystem encompassing the whole solar system and perhaps over the whole Galaxy. Would they still exist in this new ecosystem? If so, which role could they play? And, if not, will they be remembered with gratitude? (Note, however, that we don't feel particularly indebted to our one-celled ancestors).


5. Where are we going, anyway?

All civilizations of the past have declined and collapsed. But collapse is nothing more than rapid change and, as long as the sun shines, the ecosystem has at least a chance to move to higher levels of complexity. The future that we can dimly see today is rich in possibilities. Billions of years ago, Mars - and possibly also Venus - had a chance to develop an organic ecosphere. But in both cases the time available was too short and soon both planets left the habitable zone and were sterilized. The Earth has had a much longer time, billions of years more to develop the ecosystem we know today. But the Earth never stood still and it is not standing still: change is accelerating to speeds never seen before in history. We may go down to a sterile planet or move on to a new system of unbelievable complexity. It is the ultimate challenge for humankind; one that we cannot avoid to face.

Gaia: you ain't seen nothing yet

The magnificent lady
who gathers up the divine powers of heaven and earth
and rivals great An,
is mightiest among the great gods.
She makes their verdicts final

(from the electronic text corpus of Sumerian Literature)




A review of the book by Tim Lenton and Andrew Watson "Revolutions that made the earth" (Oxford 2011)

The authors of "Revolutions that made the earth" start from the very beginning with mentioning the name of Gaia for the subject of their book; the story of the Earth's ecosystem. Some people see Gaia as a living being, some as a benevolent goddess, some as a tangle of feedbacks, and others think she just doesn't exist. Yet, out there, there is a pattern, there is a logic. The ecosystem, (aka "Gaia") is there to do something - it is there to dissipate entropy at the fastest possible rate. And it (She) does it very creatively, by means of the endless variety of things and creatures we see around us. We are just starting to understand how exactly this gigantic system works and how it (She) has changed over  the eons. It is perhaps the most fascinating story ever told - and it is not yet concluded.

If you know something of this multi-billion year story, you can't but feel sorry for the poor clods who think that the whole issue of climate change reduces to such silly statements as "climate is always changing". The Earth's climate, indeed, has been always changing, but always for some reason. And it is changing now very fast for a reason we understand: the human caused emissions of greenhouse gases. It is a change occurring way too fast for the planetary mechanisms that normally stabilize climate to intervene. The results could be very bad for human beings but Gaia doesn't care for humans. She simply survives.   

Unfortunately, humans don't seem to understand the mess they have put themselves in with their carbon emissions. One reason is that the Gaian climate mechanisms are described in scientific papers hidden behind publishers' paywalls and written in obscure and forbidding language. For the non initiate, learning the history of Earth and of its climate from academic papers is not unlike deciphering the hymn of the earth goddess Inanna (an earlier name for Gaia) from Sumerian cuneiform tablets. But the scientific knowledge about Gaia is starting to trickle down from the rarefied world of academia to the real world of ordinary people and the book "Revolutions that made the earth" gives you at least a fighting chance to learn the basics of the subject.

"Revolutions" is written in plain English, not in cuneiform, and the authors made a remarkable effort to be clear and understandable by the layman. That doesn't mean it is an easy book and Lenton and Watson are alerting the reader that "The book covers terrain that ranges in difficulty from easy to strenuous." They are right: sometimes you have the feeling that deciphering cuneiform could be easier than deciphering some sections of this book. That's probably unavoidable: Gaia is a complex system, one of the most complex systems we know of. As for all things which are important and fascinating, learning about the ways of the Goddess requires (and deserves) time and attention.

But if you let yourself to be taken in by the story that the authors of "Revolutions" are telling, well, you don't have to go into the most complicated details (say, the question of the mass independent fractionation of sulphur isotopes). And what a story they are telling! It spans four billion years and went through a series of dramatic events; "revolutions", as the authors correctly term them. They list a total of 8 such events, from the appearance of replicating molecules to the origin of symbolic languages, with humans. Gaia has been stepping up her metabolism toward a higher and higher efficient transduction of solar energy; every revolution has been, basically, a metabolic revolution. Lenton and Watson estimate (p.49) that the metabolic efficiency improvement has been at least of a factor one thousand from the first life forms on Earth to the present biosphere.

So, you ain't seen nothing yet as the planetary engine is revving up and may well go past redline. This is the point that Lenton and Watson are making: revolutions are not over. There is plenty of room for Gaia to grow since the whole biosphere, today, does not capture more than about 2% of the energy arriving from the sun. So, we may be ready for a new jump that could bring the complexity of the ecosystem to levels unthinkable up to now. What this new revolution could be, exactly, is difficult to say. Here, the chapter of  "Revolutions" describing the future of the ecosystem is - I must say - the least satisfactory of the book. It tries an impossible task: a few pages are just not enough to tackle such a gigantic issue. It is sure, anyway, that revolutions are never painless and it would be wrong to think that the new metabolic jump will save humankind from the self-inflicted disaster of global warming. It may save just a few of us, or perhaps none. Gaia doesn't care for humans, she simply survives. We will see what the future has in store for us. In the meantime, I am reading "Revolutions" a second time - as it deserves.












 

Gaia: the missing bride

Toby Tyrrel's book "On Gaia" is an interesting book in many respects, but it misses some fundamental features of the self-regulating planetary system that we call "Gaia". (image from Alternative Energy Action Now)

Imagine that a friend of yours invites you to his marriage. You go there and you see everything you expect to see: the church, the flowers, the priest, the groom, and so on. But, as the ceremony goes on, you notice that your friend has overlooked something important: the bride is missing.

With the book by Toby Tyrrel, "On Gaia", you get a similar impression. It is well done in many respects and plenty of details are at the right place: evolution, life, climate, and more. But, as you keep reading it, you notice that the author seems to have overlooked something important: Gaia herself is missing. 

It is said that marriages fail because of excessive expectations of spouses. The same problem seems to be plaguing more than one study on Gaia, including this one. Some people seem to expect really too much from the poor lady and then they end up concluding that she doesn't even exist - as Tyrrell does with this book. His conclusion is wholly negative: there is no such think as a stabilizing feedback system called Gaia and the fact that the Earth has maintained conditions favorable to life for some four billion years is due mainly to "hazard and happenstance" (p 206 of the book).

The problem of excessive expectations appeared early in the history of studies of the stability of the Earth's ecosystem. James Lovelock, the originator of the idea of Gaia (together with Lynn Margulis), proposed that Gaia could "optimize" the ecosystem for the benefit of life. That was too much. The Earth's ecosystem is a complex system of interacting biological and geophysical loops - some tend to stabilize the system, some to destabilize it. The final result is the typical one of all complex system: the tendency of the system to oppose perturbations. That's not the same as optimization - it is homeostasis; something that tends to maintain the system's parameters within certain limits - not necessarily the optimal ones but, at least, in a range that maintains the cycles going.

There are many examples of this behavior; for instance your body is a complex system and it does exactly that: it seeks homeostasis. If the temperature of your body becomes too high, your internal thermostat will bring it down by sweating. But you can't expect the thermostat to be perfect and all powerful: if you fall into a vat of boiling oil, sweating won't help you much. The same is true for Gaia, which is - mainly - a planetary thermostat that tends to keep the planetary temperature within the limits needed for liquid water (and hence life) to exist. You don't have to expect the thermostat to be perfect and all powerful and, indeed, the Earth's history has seen all sorts of catastrophes occurring; when the planet became very hot or very cold, nearly destroying all life on it. But the system has always recovered and has countered all sorts of perturbations. That includes the gradually increasing solar irradiation over the eons that should have had a deleterious effect on life on Earth, had it not been balanced by a decrease in the concentration of greenhouse gases in the atmosphere.

Curiously, however, Tyrrell just can't see the thermostat in action. One reason is that it is very difficult to understand the Earth's feedback system without taking into account geology and, here, the author clearly has troubles in integrating geology in the discussion. Geology, indeed, is the true "missing bride" of the book. Not that geological phenomena are not mentioned in Tyrrell's book, but often in a cursory and insufficient manner. For instance, there is no real discussion of the cycles of the Earth's ecosystem which involve continuous exchanges of matter from the surface to the mantle and back. These cycles renew the atmospheric composition and provide the chemical elements necessary for life. Without a hot core that provides energy for these exchanges, the Earth couldn't be a live planet - it would be dead like Mars.

The problem appears in particular for the main mechanism of the Earth's thermostat: silicate weathering. It is part of the planet-wide carbon cycle, a chemical reaction that removes carbon dioxide from the atmosphere. Its rate depends on temperature, so it has temperature regulating capabilities. (see this post of mine for an introduction and ref. (1) for an in-depth discussion). Tyrrell mentions silicate weathering for the first time only at page 141, quickly arriving to the conclusion that it is only a negative factor for life because of its cooling effect (2)). You need to arrive almost to the end of the main text (p. 191-192) to find a brief discussion of whether silicate weathering can be part of a temperature stabilizing mechanism. Here, too, Tyrrell's conclusion is negative, apparently on no other basis than generic skepticism.

Now, of course one may disagree on all current scientific interpretations, but considering that silicate weathering is a core element of the whole thermostat question, it would surely deserve more discussion before arriving to dismiss Gaia as non existent. This is not the only problem related to geology in the book. Other factors, for instance the effect of the sun's increasing luminosity, are missing or barely mentioned. So, it is really disappointing that the book misses so badly its avowed target - Gaia - especially considering that there are several sections of it that are well done and worth reading, such as the discussion about the temperature effects on biological productivity.

In the end, I think that there is a basic problem in Tyrrell's approach. In the "Conclusions" section, he states that accepting or rejecting the Gaia hypothesis has a strong effect on "how we decide to manage the Earth System" and that "Gaia, by the very nature of the hypothesis, inculcates a predisposition to suspect natural feedbacks to be stabilizing." In other words, Tyrrell emphasizes that Gaia could generate a dangerous feeling of complacency on people and hamper their efforts of fighting climate change.

I beg to differ on this point. Not that I don't share Tyrrell's worries about global warming but in my personal experience the concept of Gaia as a stabilizing factor on climate is alien to the mind of typical science deniers. Rather, most of them seem to use the exactly opposite meme: "climate has always been changing," normally without showing the slightest interest in what exactly causes climate to change - they just don't care. Of course, the internet is so wide that you can find just about anything in it and, as proof of his position, Tyrrell cites a specific site that goes under the name of "The Resilient Earth". However, apart for the title that indeed reminds the concept of Gaia, the contents of the site seem to be the usual mishmash of denialist memes: from "no warming during the past 15 years" to "Al Gore is fat". The general opinion that can be read in deniers' sites about Gaia is that the concept is not just ridiculous but, rather, living proof that climate change is not science but a religion - intended as a derogatory term. (see the figure below as an example of Gaia-bashing. From thepeoplescube.com)

So, I think the least thing we should be worried about is that the concept of Gaia could engender a dangerous "lasseiz faire" attitude. On the contrary, understanding the factors that determine the Earth's temperature can only generate a healthy dose of respect for the delicate balance that has kept climate stable during the past ten thousand years or so. Homeostasis is no guarantee of absolute stability; that holds for an entire planet, just as it does for bicycles (and the latter is something that everyone understands).

In the end, Gaia is not a Goddess, (and surely not a benevolent one). She is not all powerful, she has no ability of optimizing the Earth's environment for life, and she is no guarantee whatsoever that we can keep behaving as planetary hooligans without suffering the consequences of our actions. Gaia is a huge and complex system; a gigantic tangle of geological and biological feedbacks. We are just starting to understand how this system generates its overall tendency to homeostasis and how it has evolved over the billion years of its existence (3). It will continue to evolve until, hundreds of millions of years from now, it will "die" when the Sun becomes too hot for the homeostatic mechanisms to continue operating. In the meantime, we have to keep living on this planet (if we can). Gaia may not be the perfect bride; but we can't keep behaving as if she didn't exist. 



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1. For a review of the climate effects of silicate weathering, see Lee R. Kump, Susan L. Brantley, and Michael A. Arthur, Chemical Weathering, Atmospheric CO2, and Climate Annual Review of Earth and Planetary Sciences Vol. 28: 611-667 (Volume publication date May 2000) DOI: 10.1146/annurev.earth.28.1.611

2. This point illustrates the problems that this book has with geology. At page 142, Tyrrel attributes one of the "big five" mass extinctions, the Late Devonian one, to excessive cooling caused by silicate weathering. But he doesn't say anything about the generally held opinion that mass extinctions appear to be caused by excessive warming (including the Devonian one). See, eg. David L. Kidder, Thomas R. Worsley "Phanerozoic Large Igneous Provinces (LIPs), HEATT (Haline Euxinic Acidic Thermal Transgression) episodes, and mass extinctions"  Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 295, Issues 1-2, 1 September 2010, Pages 162-191

3. For a thorough description of the feedbacks cycles of the Earth's system, you'll do well in reading the book by Tim Lenton and Andrew Watson "Revolutions that Made the Earth". Beware: it is not an easy book to read, but it is surely worth the effort.


About Gaia, see also these posts by yours truly, Ugo Bardi,  

"The Great Chemical Reaction: life and death of Gaia"
"Man Vs. Gaia"
"The Next ten billion years"