Putting Global Warming into Context: We are Ice Age Creatures Living on a Planet That Was Already Getting Warmer Before We Started Speeding Up the Process

18 July 2017

I think I've pretty well figured it out. Speaking in terms of the Phanerozoic Era and a bit longer (750 million years or so), our planet is usually more than 7° Celsius warmer than today. The earth has already warmed almost 3° C, half of it before the industrial revolution. 

We're still in an ice age now (the ice is just disappearing rapidly). The last ice age ended roughly 280 million years ago (they don't happen often). Humans have speeded up warming dramatically. The oceans are already up 300 feet from their ice age lows. They have 225 more feet to go. 

Humans and our evolutionary progenitors have existed only during the ice age of the past 6-8 million years. We can probably extend the current cool period by not putting carbon into the atmosphere (though possibly not indefinitely, and at some point, it may be too late --- possibly now). 

Climate is twice as variable when the planet is cooler (as it is now). When the planet is hot, it's basically hot everywhere, and probably too hot for human survival at the equator. The sun is gradually growing warmer. Thus the long-term trend over hundreds of millions of years is almost certainly going to be towards somewhat hotter temperatures. 

Modern humans have walked the earth for only 200,000 years, 2/3 of that time only in Africa. It is possible, perhaps probable, that without the recent ice age, we couldn't have come to exist. We were almost extinguished as a species only 70,000 years ago. Could it happen again? We should be alert to the possibility. 

Thinking over the next few centuries, I'm pretty sure we'll stop adding carbon to the atmosphere, and we'll probably start removing it. Fossil carbon is limited in supply, and we've already burned most of the easy-to-find fossil carbon. It would be better to use carbon to synthesize organic molecules. To our descendants, burning carbon for fuel will appear incomprehensible. Will the end of carbon burning stop global warming, at least for a while? Not in itself. However, I'm optimistic. I think the current (natural) warming trend can be reversed or slowed, though possibly only temporarily. 

It's conceivable, perhaps likely, that humans may eventually learn how to manage global mean temperature for the benefit of biological diversity. The best way to start will be by developing non-carbon forms of energy generation. While solar and wind and other sustainable methods will be helpful, fusion power will eventually transform the power grid. 

Though fusion power doesn't generate carbon as a waste product, it releases considerable levels of heat, and thus will still contribute to global warming. It will be better to get started on living without carbon sooner rather than later, but we will eventually need to learn how to manage all forms of human energy generation and to regulate global climate. 

If the ice age norm of the past 6 to 8 million years can be sustained, our planet will remain more diverse. It may be that we can achieve this as a long-term climate goal. Much more examination of that question will need to take place than has so far occurred. 

A positive and desirable multi-species outcome to the current problem of global warming is possible. We must remember that what we don't know is still markedly greater than what we do know. We have much to learn, and many important decisions to make. 
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WHAT WAS THE EARTH'S CLIMATE LIKE WHEN THE GLOBAL MEAN TEMPERATURE WAS LAST AT 22° CELSIUS?

15 July 2017

I've been doing a little bit of research, based on the observation that humans are ice age creatures, even though ice ages have made up only 5% or so of our current era (roughly the past half billion years or so). So today's topic is, "What was the earth like during the much warmer climatic periods during which humans and our precursors hadn't yet evolved?" An implication of this discussion is that, due to human-initiated massive carbon release, we might be headed back to such conditions sooner rather than later (that is, in a few hundred years, vs. several million years).

The underlying question we're asking is, "Did the earth have to cool before humans could emerge?" Our working hypothesis is that humans are specialists in handling ecological and climatic diversity, and that the "hot" earth that is more typical of the last several hundred million years lacked the diversity that may have been needed for humans and our precursors to evolve. It is notable that even our evolutionary forebears don't show up in the fossil record until the earth transitioned into its most recent ice age (we're technically still in it) about 6 million years ago. Homo Sapiens has about a 200,000 year history, and our genus (homo) has been around for only about 2-1/2 million years.

Well, let's take as an example the late Cretaceous period, roughly 65 to 100 million years ago, and just preceding the extinction of the dinosaurs: In general, the climate of the Cretaceous Period was much warmer than at present, perhaps the warmest on a worldwide basis than at any other time during the past 542 million years (the Phanerozoic Eon). No ice existed at the poles. The oceans were stagnant and similar to hot springs in temperature. Dinosaurs migrated between the Warm/Hot Temperate and Cooler (extreme north and south) Temperate Zones as the seasons changed. High temperature conditions were almost constant until the end of the period. The warming may have been due to intense volcanic activity which produced large quantities of carbon dioxide.

Floral evidence suggests that tropical to subtropical conditions existed as far as 45° N, and temperate conditions extended to the poles.

Large magma deposits were sufficient to raise sea levels to extremely high elevations, creating vast, shallow seas across the continents. The Tethys Sea connecting the tropical oceans east to west also helped to warm the global climate. Warm-adapted plant fossils are known from localities as far north as Alaska and Greenland, while dinosaur fossils have been found within 15 degrees of the Cretaceous south pole.

An equable temperature gradient from the equator to the poles (one-half that of the present) meant much less climatic variability than today, and weaker global winds, which drive the ocean currents, resulted in less upwelling and more stagnant oceans than today. This is evidenced by widespread black shale deposition and frequent anoxic events. Sediment cores show that tropical sea surface temperatures may have briefly been as warm as 42° C (108° F), 17° C (31° F) warmer than at present, and that they averaged around 37° C (99° F). Meanwhile, deep ocean temperatures were as much as 15 to 20° C (27 to 36° F) warmer than today's.

As to geography, the continents had differentiated from Pangaea, but were bunched together more closely than today. A vast watery channel divided North America north to south, with only the Rocky Mountains above the sea in the west. Despite sea levels more than 200 feet higher than today, Antarctica and Australia were still one continent. India was an island located east of Madagascar. There was much more sea surface, and much less land surface.

So, there are two questions to wrap up: (1) Is there any particular reason that our human precursors waited until the climate described above had cooled by about 10° C before showing up? (2) Are humans and other species going to adapt well to a planet that is 7-8° C warmer than today?

The scientist I have so far identified who seems most interested in this question is Dr. Rick Potts at the Smithsonian Institution. The following is an abstract for one of his journal articles.

THE RICK POTTS HYPOTHESIS

Variability selection (abbreviated as VS) is a process considered to link adaptive change to large degrees of environment variability. Its application to hominid evolution is based, in part, on the pronounced rise in environmental remodeling that took place over the past several million years. The VS hypothesis differs from prior views of hominid evolution, which stress the consistent selective effects associated with specific habitats or directional trends (e.g., woodland, savanna expansion, cooling). According to the VS hypothesis, wide fluctuations over time created a growing disparity in adaptive conditions. Inconsistency in selection eventually caused habitat-specific adaptations to be replaced by structures and behaviors responsive to complex environmental change. Key hominid adaptations, in fact, emerged during times of heightened variability. Early bipedality, encephalized brains, and complex human sociality appear to signify a sequence of VS adaptations—i.e., a ratcheting up of versatility and responsiveness to novel environments experienced over the past 6 million years. The adaptive results of VS cannot be extrapolated from selection within a single environmental shift or relatively stable habitat. If some complex traits indeed require disparities in adaptive setting (and relative fitness) in order to evolve, the VS idea counters the prevailing view that adaptive change necessitates long-term, directional consistency in selection. © 1998 Wiley-Liss, Inc.
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HUMANS AS AN ICE AGE SPECIES II

15 July 2017

Scientists have recorded five significant ice ages throughout the Earth’s history: the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present). Approximately a dozen major glaciations have occurred over the past 1 million years, the largest of which peaked 650,000 years ago and lasted for 50,000 years. The most recent glaciation period, often known simply as the “Ice Age,” reached peak conditions some 18,000 years ago before giving way to the interglacial Holocene epoch 11,700 years ago.

That humans arose during an ice age may be due to chance, but over the last 750 million years, the chances of a species emerging in an ice age (global mean temperature ~12C) would have been roughly 5%, as the planet is hot (~22C) something like 80% of the time. (Mammals showed up 220m years ago in the late Triassic, one of many warm/hot periods.)

Obviously species have had successes against longer odds than that. However, my working hypothesis is that there is more ecological diversity during ice ages (though not snowball earth of 650m years ago). If the earth usually has palm trees and crocodiles in the arctic circle, then there would be a lot less maple, walnut and apple trees elsewhere. This is not to say that humans did not originate in the tropics, as it seems we did, and there is a lot about the transition from forest to savanna that I don't know much about. Also, the African drought-induced near-extinction was apparently overcome by moving to the seashore, which gets you into the aquatic ape and ecosystem boundary hypotheses.

Keep in mind that the planet was 2-3 C colder then than it is now, and a bit more than half the difference is pre-industrial (most sea level rise has been/will be preindustrial). I think it's clear on the 750m year chart that we have been in a warming phase since we became tool and technology users, at the very least. So global warming was already happening, though I think it's obvious that this is the first time in geological history that fossil carbon has been burned. Thus, this cycle can go (and obviously is going) faster and possibly higher than in the past. Other causes of climatic variation include fluctuations in solar intensity, atmospheric clarity and orbital variations (Milankovitch), but the big cycle seems to be carbon-driven, which in my view is the strongest single argument that humans putting carbon into the atmosphere is changing things (that is, accelerating an existing trend). In fact, it is bluntly an irrefutable argument if you study geological history.

One can also see that at least 8 degrees C of the big fluctuations happen very quickly (less than 1 million years) in geological terms. I honestly believe (1) that if we don't get smarter, we'll move from 15 to 22C in only a few hundred years (a new geological record), as that will put all the carbon there is into the atmosphere, but also (2) given a few hundred years, we will get much smarter and actually more or less totally eliminate carbon burning, or at least highly restrict it, and that much sooner than that, we'll have the technologies to capture carbon and take it back out of the atmosphere (no UN bureaucracy or carbon credit system needed, because we'll be rich enough that we can easily afford it).

Note that around 13-14C is where the bigger/faster moves usually happen anyway, as that is enough to get the positive feedbacks going with methane, forest fires, tectonic rebalancing, etc. That is, whatever the bureaucrats may think, we've been past the breakaway threshhold for some time already.

So let's just say that humans had tried to get their start at 22C, which would take you roughly to 35m years ago. There would have been no coral reefs, the entire equatorial region would have been uninhabitable (>120F), and there would have been only tropical and desert ecosystems. I'm pretty sure it would have been a less diverse world, which is not to say that tropical systems are not diverse.

It is probably also not accidental that we are post Cretaceous-Paleogene extinction creatures (66ma), as the meteor impact that extinguished 75% of earth's life forms occurred at the height of the last warm period, which also (perhaps meaningfully) marked the rise of mammals, though it was still very hot for another 40m+ years after the mass extinction (there is also a current mass extinction being driven by human modification of all planetary ecosystems). The meteor impact at 66ma doesn't even show up on the longterm climatic cycle chart, but it would have been very cold for a very short time, geologically.

Importantly, humans didn't show up, even our precursors (who emerged no more than 6m years ago), until temperatures dipped down to ice age levels. However, Haplorrhini (apes, monkeys, tarsiers) are a human precursor who showed up immediately post extinction event (63ma), so maybe that is also meaningful.

Finally, the real advances in human technology have occurred in only the last few thousand years, which has been a period of significant glacial retreat (warming with positive feedbacks engaged long before industry started). I have just refreshed myself on Lake Agassiz, which oversat Kenora, Ontario (where I live) as well as most of central Canada and the North Central US. Interestingly, the central North American glaciers melted for thousands of years without sea level rise, because the lake was held back by a glacial dam that first broke about 13,000 years ago, then reformed, and had its last break about 8000 years ago (both events raised sea levels several feet, and one or both may account for the multicultural flood narratives).

The rupturing of Lake Agassiz is linked to the rise of systematized agricultural in Europe which enabled the rise of cities, and that is also dependent on the Atlantic Meridional Overturning Circulation (AMOC), which sustains moderate European temperatures, but which has reduced 30% since 1957, associated with increased warming-induced freshwater flows into the Arctic Ocean, and thus with southward flows into the Atlantic (conversely, the Arctic Ocean is shrinking due to warm water penetration further north). On a positive note, when the AMOC reduces, we have fewer Atlantic hurricanes. On the downside, Europe would turn much colder very quickly if the circulation turns southwards (it currently forks, and half flows north around Europe, and half flows towards West Africa.

As to unanswered questions, human have obviously benefited by the plummeting of global temperatures to their lowest historic levels perhaps 6-8 million years ago, but we have also capitalized on the bounceback to warmer temperatures, which coincides with hominid evolution over the last 2-1/2 million years. In brief, it appears that humans thrive when ecosystems are multiple and diverse, and my best guess is that the Quaternary Ice Age created the exact types of increasing diversity on which emerging humans eventually capitalized.

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IS THERE A REASON WHY HUMAN EVOLUTION OCCURRED DURING A RARE GLOBAL ICE AGE?

13 July 2017

I have become intrigued with the fact that modern humans emerged roughly 2.5 million years ago, at the absolute temperature bottom of one of the earth's relatively rare cold climatic periods (making up only 5% of the last 3/4 billion years or so). That is, we are unarguably ice-age creatures. I've found a couple of new charts that illustrate the link between human emergence and cold climate. Interestingly, a Google search on the subject doesn't really turn up anything beyond this.

If you look at the link between human evolution and climate, you get articles explaining how climatic variability may have prompted aspects of human evolution --- tool-making, language, an enlarged brain case, etc., but we're talking in these cases about variabilities in maybe a degree or two of global mean temperature, which is small stuff if you look at the longer-term climatic record of our planet, where there is evidence of 12-25° Celsius variation in global mean temperature (today's mean temperature is in the 14-15° C range --- still near its 12° C low of 2-5 million years ago.

I also tried a search about humans as ice-age creatures, and literally all that comes up are endless articles about how hungry humans caused the extinction of the large ice-age mammals.

An examination of global mean temperatures over the past 700 million years makes clear that only about 35 million of those years were typified by today's still very low global mean temperature in the range of 12-15° C (recently warming dramatically, as everyone knows).

Note that the earth's mean temperature is much more often in the 22° C range --- with 450-500 million of the past 700 million years at or near that level. Strikingly, the transitions occur rapidly in geological time, with upward or downward spikes of maybe 8° C occurring in the space of roughly a million years (maybe less?). Positive feedback loops --- as we are seeing today --- very likely account for those geologically rapid transitions.

Keep in mind that our planet started out as a very hot fireball 4.5 billion years ago. Elevated levels of greenhouse gases kept the earth quite warm until oxygen-based life forms evolved. In turn, emerging photosynthetic life forms cooled the planet until the equatorial climate was similar to Antarctica today. When earth was a Precambrian snowball about 650 million years ago (visible on the above chart), there were no life forms to absorb atmospheric carbon, and it gradually reaccumulated, warming the planet again. It's probably the release of stored carbon in permafrost and seabeds that drives the return to 22° Celsius. Add to that today that humans are burning long-buried fossil carbon. No wonder the earth is currently warming so rapidly! 

In summary, my search for WHY humans seem to be ice age creatures has not really turned up anything at all yet. I'm not sure why the topic is not being actively discussed. One thing we do know is that humans thrive at ecosystem boundaries, so my current working hypothesis is that we also do well at climatic boundaries --- that is, trending from warm to cold and (possibly) back again. Local and regional temperature variation, which is more notable at cyclical lows than highs, would thus create the kind of ecological variation on which humans and early humans have thrived for 2-1/2 million years! 

How will humans fare when, in less than another millions years --- and possibly in only a few centuries, the planet goes back to its 22° C climatic norm (or possibly higher)? The process is gradual in individual human years, but currently extremely rapid in geological and generational terms. Our children's children will certainly be living with the ever more dramatic consequences of the current human-induced "carbon era."

As an optimist, I believe we can resolve most or all of the problems associated with a rapid return to a much hotter planet. However, we'll have to be considerably more focused than at present to accomplish the necessary ameliorations and accommodations.

Based on my reading to date, we'll do best to hold back the natural and at some point inevitable return to much warmer global mean temperatures. This will enable us to save the coral reefs as well as many other species, to preserve maximum species diversity, to keep our coastal and tropical cities where they are, and to contain northward-migrating tropical and temperate region diseases. To accomplish this, we will require fusion as well as solar power, and we'll have to put robots to work to aid us in maintaining and repairing the environments and systems we have damaged. 

This article provides the best summary of earth's long-term climatic variation that I have found: click here.
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