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.


  1. You would think a scientist would know better.

    Climate myths: They predicted global cooling in the 1970s

    " A survey of the scientific literature has found that between 1965 and 1979, 44 scientific papers predicted warming, 20 were neutral and just 7 predicted cooling. So while predictions of cooling got more media attention, the majority of scientists were predicting warming even then."

    1. Moresoma, I didn't say that I agreed with those who criticize climate science in terms of "those silly scientists who thought we were going into a new ice age." I thought the irony was clear!

      On the other hand, counting the number of refereed papers is just one of the metrics you can use to evaluate the views of the time. The idea that we were going toward a new ice age was alive and well in the 1970s in popular science and in science fiction. John Michael Greer examined it in a post (which, unfortunately, I can't locate right now) where he noted how common it was. And I can cite from memory two science fiction stories from the 1960s that elaborated on the concept, one by Poul Anderson, the other by Arthur Clarke. In short, it was part of the memesphere of the time

    2. Anyway, I modified my sentence a little, to make it cleared. You know, I don't want to risk the destiny of Richelieu's enemies ("give me six lines written by a honest man and I'll find in it the way to put him to death")

    3. BTW, thanks for your comment. I think that now my post is better!

    4. John Michael Greer did not examine anything. He used to be a climate denier & was just repeating the 'back in the 1970's' BS because it's part of denier dogma. I've lived my entire life in N America & remember the 1970's quite well & I'm telling you that global cooling was not popular - Starwars, pop-rocks, Disco & pet rocks were popular, meaning almost every child & adult in the US & Canada knew what they were. A few sensationalized articles about a topic most were not even aware of does not qualify as popular and nor does 7 scientific papers on the topic.

      I just gave you a link to a paper that truly "examined" the matter. Why are you telling me what a guy who thinks & dresses up as a wizard & only recently gave up his climate denial thinks when I just handed you a study/the real numbers?

      As for the Wizard Greer, 5 minutes after he gave up his climate denial, which I will prove shortly, he's strutting around on his blog & others & in interviews acting like an expert on climate who knew it all along. Greer often talks history & how much of it ends up in the 'memory hole' which is exactly where Greer threw his denier past or rather tried to.

      The denier tactic here is to try & make you believe scientists were confused back then & are confused now & they throw in a sprinkle of other faulty logic - Argumentum ad populum, to go with their other faulty logic & lies.

      Below is a quote from Greer in denial mode, from Albert Bates blog.

      "Even John Michael Greer trudged out his tired old line about “don’t you remember 30 years ago when everyone was saying we would get another ice age — maybe fast? Show of hands? See! Climate science has no credibility.” Mark Cochrane, Senior Scientist at the Geospacial Sciences Center, thankfully addressed this in his later talk by noting the difference between science-fiction writers and actual climate scientists"

      "remember 30 years ago when everyone was saying" 'Everyone' goes with 'always' & 'never' in the denier, and bad arguments, playbook.

      I used to read Greer even when he was a denier, but like far too many Americans he tribed up & in Greer's case he went for team 'Right' & when I stopped he was making some comments that were sounding like the far right. Grees not the only one. There are a number of other American bloggers who've tribed up, both left & right & I simply have had to stop reading them because I'm not interested in radical American politics, while they have become obsessed with it. IMO this radicalization puts the US close to the cliff's edge.

    5. Why do you get so angry? The idea of a new ice age existed in the 1970s. Greer has his quirks, but as an analyst he is superb and he correctly noted that. And I was around, too, at that time: of course it wasn't mentioned in rock concerts but in popular science and sci-fi, yes. I remember that very well.

      There is nothing wrong with that: at that time, the data were not yet sufficient to rule out a new ice age. Then things changed. So it goes.

    6. Some more notes on this point -- this is not to be polemical, just to note how science is a social construct and that things do change as society evolves and new ideas appear. (I think I'll write a post on this subject)

      So, I have in my hands "The Global 2000 report to the President" published in 1980. It is an interesting document, because their investigation was mainly based they used a "consensus" method by polling various experts. There is a whole chapter dedicated to climate (chapter 4) where they interviewed 28 experts. The result was that the highest probability was that temperatures shouldn't have significantly changed (maybe increased of 0.1 C) by the year 2000 from what they had been in 1975. In the real world, themperatures increased of about 0.4 degrees.

      So, you see, science is not written in stone and scientists are human beings. It doesn't mean that climate science is bad science. It is the opposite. Climate science has shown a certain capability to correct itself. Not all fields of science have it.

    7. Ugo, entirely agree with you on Greer. Anger doesn't help the debate, and as nobody has a monopoly on the truth its beneficial to hear all opinions so that we can judge. For the record I find Greer the most astute commenter on the US political landscape, and not so accurate elsewhere. Always stimulating and entertaining. That is also the reason why I read your blog.

  2. Very useful science blog. Many viewpoints often induce further thinking and investigations. I enjoyed reading your work.And I am improved by it. Thanks.

  3. Ugo, the IPCC report shows up today. And Xkcd had a graph for it.