A Deadly Climb From Glaciation to Hothouse — Why the Permian-Triassic Extinction is Pertinent to Human Warming

In looking at the potential impacts of human caused climate change over the coming decades and centuries, scientists have often pointed toward more recent times such as the Eemian (the most recent warm interglacial in which global temperatures are similar to what they are now and where they are expected to be over the next 20 years), the Pliocene (2-3 million years ago and the most recent time in which CO2 levels were about equal to those of today), and the PETM (about 55 million years ago and the most recent period during which CO2 levels were above 600 ppm and in which there was very rapid warming, possibly due to methane hydrate release).

The PETM has been a period of very intense study for leading climatologists such as James Hansen who has warned of the potential for a mini-runaway warming event of this kind should humans continue along a business as usual path of fossil fuel burning through the 21rst Century. In particular interest in the PETM corollary scenario is both the amazing velocity of the initial human warming, with CO2 and greenhouse gas releases occurring at rates that are five (CO2) to 27 (methane) times faster than the PETM (Hat tip to Timothy Chase, Source: Skeptical Science). So rapid and powerful a rate of forcing puts at risk of greater release a number of very large global carbon deposits including the massive CO2 and carbon stocks stored in the world’s melting permafrost as well as the even larger stores of carbon locked in methane hydrates scattered across the world’s oceans. Hansen and other scientists have noted a potential for a 4-7 degree Celsius or greater warming by 2100 (at between 700 and 1000 ppm CO2) through a combination of human greenhouse gas emissions and Earth systems carbon emissions. Overall warming by 2300 from Earth Systems feedbacks, even if human emissions were to stop by 2100, is likely to be twice this level.

That such a massive warming would be catastrophic is a given. There is no evidence in the geological record for such a stunning pace of warming over so short a period. And the potential climate change impacts from such high levels of heating, alone, would be extraordinarily difficult for human civilizations and the innocent inhabitants of our living world to manage.

Late Permian Just Prior to De-glaciation

Late Permian Just Prior to De-glaciation at approx 260 million years ago.

(Image source: Ron Blakey, NAU Geology)

But this scientific scenario is based, in part, on knowledge gleaned by studying past geological periods such as the Eemian, Pliocene, and the PETM hyperthermal (other information is derived from the still-developing climate models of terrestrial, ocean, and Earth systems). And, in looking at each of these paleoclimate periods, we find that a single key factor is missing: they all occurred during periods in which Earth was either ice-free, or in which Earth was settling into its current period of glaciation. In the case of human-caused warming, the exact opposite process is ongoing. As during the great Permian Extinction event of around 250 million years ago, the Earth is rising out of a period of glaciation and into a potential human-caused hot-house.

No More Ice Ages and a Start Down the Path Toward De-glaciation

In the current period of human-caused warming we encounter the novel and relatively uncharted territory of an Earth System that is being forced to arise out of a 40 million year long period of glaciation. This period has been characterized, first, by the freezing of the vast land mass of Antarctica, then by the freezing of Greenland and, later, by long ice ages in which glaciers expanded from the poles to cover large areas of land and water. This latter ice age-interglacial period began about 800,000 years ago and has dominated until today.

Glaciation since PETM

(Image source: James Hansen)

With atmospheric CO2 levels now at 400 ppm and with humans continuing to emit high volumes of CO2 for at least the next two decades, we can officially declare the period of ice ages and interglacials at an end (or at least put on extended hold). For retaining even a very small portion of our current greenhouse gas emitting infrastructure or agriculture would be enough to stave off another ice age. Hansen notes:

Forces instigating ice ages, as we shall see, are so small and slow that a single chlorofluorocarbon factory would be more than sufficient to overcome any natural tendency toward an ice age. Ice sheets will not descend over North America and Europe as long as we are around to stop them.

Ice ages are now stopped in their tracks and current human levels of CO2 at 400 ppm are now sufficient to begin melting Greenland and West Antarctica. We can see this melt in yearly losses exceeding 500 gigatons of melt water and ice from Greenland and from Antarctic melt losses in the range of 300 gigatons per year or more. And with the increasing human heat forcing, these melt rates are on a very rapid incline. Greenland is showing a doubling in its melt rate every 5 years.

Yet even this, rapidly expanding, melt pace may seem slow if humans continue along their current path of greenhouse gas emissions growth. Last year, over 32 gigatons of CO2 were emitted into the atmosphere and the net human greenhouse gas emission was equivalent to more than 45 gigatons of CO2. At the current rate of emissions and emissions growth, we are now on track to hit between 500 and 600 parts per million of CO2 by the middle of this century. And this range of CO2 is enough or nearly enough to melt all the world’s ice, setting us on a path toward a place not seen in at least 40 million years. A path toward long-term temperatures in the range of 6 degrees Celsius hotter than the 1880s. If emissions continue until the end of this Century, the path is almost certainly toward that of a hyperthermal and one with unique consequences given the speed at which we approach it and the fact that we will send massive volumes of fresh meltwater into the oceans as we approach it.

The PETM and the Great Dying

And this is where we encounter a bit of a problem. Because the world is rapidly rising up out of a 40 million year long glacial period, it is bound to encounter changes not visible 40 million years ago as the Earth was steadily cooling down toward glaciation or even during the PETM as the Earth emerged from a lesser cool period and entered a hothouse state. In the case of the Permian and the current day, Instigating the loss of glaciers presents its own, rather unique, set of problems and difficulties.

In looking at the geological record, we find that the last major cold period with temperatures close to those of the recent ice ages (aside from a somewhat cool period during the late Jurassic and early Cretaceous) occurred during the late Carboniferous and the early to mid Permian period.

Past Hot and Cold Periods

Hot and cold periods during the last 500 million years (best proxy data used).

(Image source: Commons)

During the late Permian and early Triassic, however, very rapid and intense warming roughly equivalent to that of the Eocene of 55 million years ago occurred. Both events resulted in extinctions in the oceans and on land. Both events showed major temperature spikes toward the end that are theorized to be linked with large methane pulses and amplifying Earth Systems feedbacks. And both are typical to a mini runaway hyperthermal of the kind James Hansen warns is possible under a regime of human warming.

The primary differences between these two events is that, first, the Permian Triassic extinction event occurred after a long period of glaciation and, second, that the Permian extinction was the greatest mass extinction ever recorded in the geological past. What resulted killed off a devastating 96% of the species in the oceans and 80% of all species on land. It is for this reason that the Permian-Triassic boundary layer extinction is known as the great dying.

By contrast, the PETM resulted in a similar, but far less, extreme event. About 35-50% of the benthic forminifera of the deep ocean went extinct. Many other ocean species, especially those of the deep ocean, exhibited stress and losses. Life on land, especially among mammals, was pushed toward dwarfism to deal with the extreme high temperatures. But, overall, stresses to land and ocean animals was far, far less than that of the Permian extinction.

Putting a Lid on the Ocean — Glacial Melt’s Role in Enhancing Anoxia

At issue here is the likely anoxic ocean states resulting from major warming events. As the oceans are heated, they are able to hold less oxygen in solution. This steady depletion results in growing regions of anoxia and related algae blooms that can be very dangerous to marine and, in extreme cases, terrestrial organisms. Warmer, anoxic oceans are more likely to host blooms of deadly green and purple algae.

Troubling Green Algae Bloom North of Scandinavia.

Troubling Green Algae Bloom North of Scandinavia.

(Image source: NASA/Lance-Modis)

These primordial creatures once ruled the seas during the days of ancient Earth, before higher levels of oxygen were present. Now, a mixed, oxygen rich ocean keeps their development in check. But the warmer ocean during the time of the PETM is thought to have brought anoxic states back to the world’s deep oceans.

In short, ocean circulation is thought to have reversed. Heating at the tropics resulted in seas becoming saltier as waters there evaporated. These saltier waters grew dense and sank toward the ocean bottom drawing fresher, cooler water in from the poles. This type of ocean circulation is thought to have dominated for about 40,000 years during the PETM and contributed greatly to anoxic ocean states by concentrating warmer, anoxic water at the bottom of the world’s oceans.

During the Permian, anoxic ocean states were thought to be far, far more intense. Paleontological research conducted by Peter Ward found a massive series of three extinction events ranging over the course of about 165,000 years in which death began at the bottom of the Permian ocean and climbed toward the atmosphere.

It is thought by some scientists that rapid warming during the Permian enhanced both glacial melt even as it amped up the hydrological cycle to increase fresh water runoff from the continental land mass. The result was a much greater freshening of the ocean surface. Enhanced evaporation at the equator is thought to have driven a similar ocean circulation to that of the PETM in which hotter, saltier water sank to the ocean bottom. Glacial melt, in this case, greatly enhanced an ocean circulation change that was already leading to anoxic ocean states. The result was that ocean layers became even more stratified and less mobile further amplifying anoxia. In the case of the Permian, ocean anoxia eventually enveloped a majority of the worlds oceans, permeating all the way to the surface and eventually invading the atmosphere.

The Emergence of the Canfield Ocean

A stratified, anoxic ocean developed which started increasing mortality among deep water life forms first. As anoxia rose through the deep and mid levels of the ocean, death advanced up the water column as green and purple algae found sunlit regions and proliferated, adding hydrogen sulfide gas as a killing mechanism to ocean acidification and low ocean oxygen levels. Eventually, the hydrogen sulfide reached the surface waters at which point it began bubbling into the atmosphere. The anoxic ocean had fully transitioned to a primordial Canfield Ocean.

Hydrogen sulfide gas is directly toxic to both plants and animals alike and this great out-gassing likely resulted in the massive loss of land species. Ironically, high temperatures (on the order of 9-12 degrees C hotter than now) enhance the lethality of hydrogen sulfide gas. When the gas reaches the stratosphere, it depletes the ozone layer, causing even greater harm to land species. Fossil remains show evidence of genetic damage indicative of a depleted ozone layer and related Canfield Ocean state.

Human Warming is Much, Much Faster

It took about 20,000 years for the Earth to warm 6 degrees Celsius during the PETM. During the Permian, the final extinction and related warming events lasted about 165,000 years. In the case of the PETM, it is thought that volcanism in India stoked global warming until a rapid methane release over a 20,000 year spike period occurred. During the Permian, volcanism is thought to have burned through coal patches over a large region of Siberia, possibly eventually setting off similar very large methane pulses to those suspected to have occurred during the PETM.

In both cases, temperatures rose to between 9 and 12 degrees Celsius hotter than today. But, in the case of human warming, we have the potential to warm the Earth by as much as 7 degrees Celsius by the end of this century and, possibly, to Permian/PETM levels over the next 300 years. Such a rapid pace of warming holds no corollary in either the Permian, the PETM or during any other major warming event visible in the geological record of Earth’s past. So while we may look to the Permian for potential enhanced ocean circulation and anoxia impacts due to glacial melt and increasingly intense ocean stratification, we have no rational means by which to determine how far behind increasing temperatures and glacial melt such events may arise. In the case of the Permian, it took about 165,000 years for a Canfield Ocean to arise. But anoxic ocean states emerged and intensified as warming ramped up. So it is likely that ocean anoxia and stratification will become an increasing problem as the Earth rapidly warms due to human forcing. We can also expect glacial melt to amplify the problems caused by anoxia by increasing stratification and by pushing warm, oxygen-poor waters toward the ocean bottom where they have little opportunity to recharge oxygen stores. Lastly, in the worst case, we can look for Canfield Oceans as a potential tail-end risk for human warming, especially if global temperatures approach 9 to 12 degrees Celsius above the 1880s average and if very large fresh water pulses from glaciers shut down and reverse current ocean circulation.

Links:

Climate Model Links Past Extinction to Higher Global Temperatures

Changes in Permian Ocean Circulation, Anoxia in the Permian Ocean, and Changes in the Permian Carbon Cycle

Rapid and Synchronous Collapse of Marine Ecosystems During Permian Biotic Crisis

Carbon Isotope Anomaly in Conjunction with Biotic Crisis

Biogeochemical evidence for euxinic oceans and ecological disturbance presaging the end-Permian mass extinction event

Storms of My Grandchildren

Under a Green Sky

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35 Comments

  1. Interesting. If hyperthermal events initiate biological extinctions that progress up the water column, closely monitoring the deep oceans should be a high priority. Yet, these regions remain poorly understood and are difficult to study. We better figure it out.

    The Phanerozoic Climate Change graph is fascinating. It shows an expected temperature dip precisely at the Chicxulub impact 65 million years ago, and the intense hyperthermal following the Siberian Traps event 250 million years ago. I’m curious about the larger spike about 30 million years earlier at approximately 280 mya. Is there any information on that?

    Reply
    • That’s a good question. To my knowledge, no. But some researchers, including Ward, have shown the Permian to be made up of not one, but three, separate mass extinctions over a 165,000 year timeframe. Some research has indicated an asteroid or comet impact, but this is not confirmed. If a comet impact occurred, however, we would have seen surface creatures dying off at greater rates than those in the deep ocean. What we see is the opposite.

      This is still cutting edge research and the Permian is still a bit of an enigma. However, there’s enough evidence to support an anoxic/Canfield ocean state to report on it. My opinion, and I have to qualify that this is only an opinion, is that the anoxic ocean evidence is very compelling.

      I’ll see what I can dig up RE the temperature fall.

      Reply
      • I did a little research, but didn’t find anything conclusive. Apparently, there was an extinction event at about 305 mya called the Carboniferous Rainforest Collapse. This occurred at the midpoint of a glacial episode extending from the mid-Carboniferous to the mid-Permian. The cause of that extinction is unknown.

        Temperatures during the Permian appear to have fluctuated wildly. The temperature spike I referred to earlier (at 280 mya) looks like it happened some 30 million years before the “great dying” hyperthermal. Any possible connection between the two would suggest a truly major planetary event since the time interval is so large.

  2. Reblogged this on Climate Force.

    Reply
  3. “Forces instigating ice ages, as we shall see, are so small and slow that a single chlorofluorocarbon factory would be more than sufficient to overcome any natural tendency toward an ice age. Ice sheets will not descend over North America and Europe as long as we are around to stop them.”

    This underlines the image we call “Earth Rise” and our exceptional situation which brought about us, we going to lose now what appears to be the foundation – the ability to prosper.

    Reply
    • I think Hansen’s solutions of using economic incentive (tax and transfer) to rapidly move away from carbon-based technology is well worth a shot. But anyone not realizing that the Earth, that water through stone, is the source of all wealth and opportunity for prosperity is as foolish as foolish can be. She is our greatest treasure. Our life. Our reason for being. And the only living rock that we know of in what seems to be a mostly sterile universe.

      All I have to say is we had better get this right.

      Reply
  4. And we already set in stone considerable SLR – because of the slow climate inertia.

    Each degree of global warming might ultimately raise global sea levels by more than 2 meters http://www.pik-potsdam.de/news/press-releases/jedes-grad-erderwaermung-koennte-den-meeresspiegel-auf-lange-sicht-um-mehr-als-2-meter-erhoehen

    Reply
    • If 2-3 degrees is enough to melt Greenland and West Antarctica long term, as the Pliocene would seem to indicate, then the report is very, very conservative. Those two hold 75 feet worth of SLR.

      If the report is for that level of SLR by the end of this century, then it’s probably a bit on the fast side. But who knows given the abnormally fast pace of warming.

      Reply
  5. Another uncertainty…

    Long-term warming equivalent to 10°C per century could be sufficient to trigger compost-bomb instability in drying organic soils.

    First generation climate–carbon cycle models suggest that climate change will suppress carbon accumulation in soils, and could even lead to a net loss of global soil carbon over the next century. These model results are qualitatively consistent with soil carbon projections published by Jenkinson almost two decades ago. More recently there has been a suggestion that the release of heat associated with soil decomposition, which is neglected in the vast majority of large-scale models, may be critically important under certain circumstances. Models with and without the extra self-heating from microbial respiration have been shown to yield significantly different results.

    The present paper presents a mathematical analysis of a tipping point or runaway feedback that can arise when the heat from microbial respiration is generated more rapidly than it can escape from the soil to the atmosphere. This ‘compost-bomb instability’ is most likely to occur in drying organic soils with high porosity covered by an insulating lichen or moss layer. However, the instability is also found to be strongly dependent on the rate of global warming. This paper derives the conditions required to trigger the compost-bomb instability, and discusses the relevance of these to the concept of dangerous rates of climate change. On the basis of simple numerical experiments, rates of long-term warming equivalent to 10°C per century could be sufficient to trigger compost-bomb instability in drying organic soils. http://climatestate.com/2013/06/18/soil-carbon-and-climate-change-from-the-jenkinson-effect-to-the-compost-bomb-instability/

    Reply
  6. Japan Breaks National Heat Record. Chinese Heat Wave Continues

    How many have died as a result of the Chinese heat wave?

    On Sunday, August 11th, the temperature peaked at 42.7°C (108.9°F) at Shengxian, its hottest temperature measured so far during the heat wave. At Hangzhou the temperature reached 41.1°C (106.0°F) on August 11th and 40.3°C (104.5°F) on August 12th marking the 12th day since July 24th that the city surpassed or tied its previous all-time record high of 40.3° set on August 1, 2003.

    Eastern China, where about 30% of the population of the country and 5% of the global population reside (approximately 400 million people) has undergone a heat wave unprecedented in its history. No one really knows how many have died as a result of the heat wave (Chinese news sources claim ‘about two dozen’), but statistically it is almost certain that many thousands must have perished as the result of the heat over the past month.

    http://www.wunderground.com/blog/weatherhistorian/comment.html?entrynum=185#commenttop

    Reply
  7. It looks to me like glaciation ended some 20 million years before the PT extinction event, during a hot spell. Where does the meltwater come from, or am I mssing something?

    Reply
    • The ice sheets waned in the mid to late Permian in conjunction with increasing ocean anoxia. After the ice sheets were gone, fresh water is hypothesized to have come from increased rainfall events over continents due to an amping up of the hydrological cycle.

      Reply
  8. martin stock

     /  August 13, 2013

    I am not a climate scientist. I do find the clarity of articulation presented in this blog to exceed what I have been able to find anywhere else. That none of this seems to ever make it to the mainstream – regardless of who we can ‘thank’ for that, whether it be our short attention span, our aversion to intelligent and informed debate or the various funding initiatives operated by carbon based industries – is to me one of the greatest crimes of any age.
    We are addicted to cheap and fast, which is never going to result in good long term. Now we face a situation that requires that we operate fast, and given our reluctance to pay taxes – we will likely look for the cheapest ‘silver bullet’ we can find.
    I lived for a time in South India where 40 Celsius in Summer is not uncommon – (in their winter with temperatures at 25 Celsius the general population buys sweaters and wears touques) and people die from the heat even though they are greatly heat adapted already…
    What I understand from this blog is that we were basically out of time thirty, forty or more years ago when the population was very much smaller and our carbon footprint far less. The acceleration I have seen in my lifetime frightens me – while I frequently encounter many who seem to want it to be warmer, lacking understanding that the extremities of the weather are only intensifying. But as it does grow worse I fear we will fall into that awful human behaviour of finger pointing, scapegoating and in the process further waste time while moving into global behaviours that will be defacto war on every scale.
    Whether we believe that there are too many of us – since we seem to have exceeded planetary carrying capacity – or not, the consequence of our normative behaviours will, as Lovelock posited, drive us toward extinction over the coming centuries.
    I know there are those who constantly suggest that our ingenuity will find us a technological solution – but that is to blindly advocate for more of what brought us to our current pass, our love of toys and our arrogant attitude that proclaims that we know better than and can improve on natural cycles, processes and their balances.
    Meanwhile there are cyclones in the arctic, wildfires over the Tundra and heat domes the size of nations.
    Thank you for your efforts to make this more readily available.

    Reply
    • I don’t think it’s technology that was the problem, but the technological manifestation of exploitative systems. Switching technology to more sustainable systems greatly reduces the degree of harm and should be pursued as rapidly as possible. Some have argued that albedo management will also be necessary. But, in my view, the absolute worst thing we could do now is give up and cede to a defacto business as usual mindset.

      Reply
    • DaveW

       /  August 14, 2013

      ” Switching technology to more sustainable systems greatly reduces the degree of harm and should be pursued as rapidly as possible.” …

      Unfortunately, to a major degree, technology itself is the problem – or more precisely, using our technology to live an excessively high-energy lifestyle. The “renewable energy” technologies are not magical – we need to radically change our mind-set / lifestyles.

      Have a look at this article – The Fantasy of Energy Unicorns Rescuing Industrial Civilization – and the links in it. Some sober truths about “Switching technology to more sustainable systems…” !

      Reply
      • I find these reports to be radically too pessimistic. I think there is a practical middle ground between what I view as a modern incarnation of Ludditism expressed in the above and the mystification of technology as a magical fix. We have practical systems that are useful, helpful, and better alternatives than the fossil fuels that are causing so much damage, so we should use them. This is not magic, it’s common sense. As for the failed reasoning that only fossil fuel energy counts… don’t even start with that nonsense. I will not tolerate it here.

        As for changing economies and lifestyles to transition away from consumerism and systems that demand endless growth, I couldn’t support it more. But even such a transition will require an energy base. You completely jettison the energy base, and you wreck civilization. You wreck civilization and the result is a dark ages like none seen before. So I see renewables as a necessary feed in and support to a sustainable transition, not a magical unicorn. And I see this thinking that no energy technology is good or needed as a direct threat to an immense human life support system.

        So you should understand that I view such an ideology, based on a short-sited Ludditism, as anathema.

        In the parlance of old economic supply/demand thinking — change the supply to renewables and reduce the demand by increasing efficiency and forging systems that are more resilient to periods of low/slow/no growth.

    • No. To my knowledge, the Strangelove Ocean is an ocean that is killed when the carbon cycle is shut down by a large impact event such as that which took out the dinosaurs 65 MYA. In the Strangelove Ocean, surface creatures die first while those in the depths tend to survive. In the Canfield Ocean, death starts out near the bottom levels and then proceeds upward toward the surface.

      Reply
      • Thanks,

      • Could you maybe link to some sort of reference or book title?

      • http://geology.about.com/od/extinction/a/strangelove.htm

        In particular:

        “He was struck by the geochemical evidence from 65 million years ago, around the time of the great impact that killed the dinosaurs—apparently, every living thing in the ocean’s surface waters had died at the same time. After that, the sea was largely a sterile waste for thousands of years. ”

        Large impact ejects massive materials into the stratosphere blocking out sunlight and shutting down carbon cycle, killing off ocean surface = Strangelove.

        Stratified Oceans cause anoxia beginning at the ocean bottom and the proceeding through layers toward the surface = Stratified to Canfield.

        Two different mechanisms and processes.

        Think of Strangelove oceans as ‘nuclear winter’ type oceans.

  9. Because of your interest in the Permian and Triassic, you may find interesting a series of articles that discuss the possible large impact that development of the ability to digest cellulose by roaches and prototermites may have had on Permian ecology, climate, glaciers, and on the Triassic coal hiatus, Triassic 12% oxygen, and climate shown in http://www.angelfire.com/nc/isoptera/roach.html . The following end Permian extinctions are discussed in http://www.angelfire.com/nc/isoptera/permian.html If you see any errors in them or possible additions, please let me know.
    Sincerely, Charles Weber

    Reply
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