Carbon Emissions Haven't Been This High Since Dinosaurs Went Extinct

Carbon Emissions Haven't Been This High Since Dinosaurs Went Extinct

Carbon hasn't entered our atmosphere this quickly in at least 66 million years -- since an asteroid slammed into our planet and wiped out the dinosaurs, or perhaps even earlier. Our addiction to fossil fuels has pushed the planet into a "no-analogue" state that's "likely to result in widespread future extinctions", an exceedingly humourless study published today in Nature Geoscience concludes. It's no secret that industrial society is racking up a serious carbon bill, nor that our CO2 emissions -- roughly 2000 billion tonnes since the start of the industrial revolution -- are warming and changing the planet. But to understand just how exceptional this moment in Earth's history is, we need to look at the geologic record.

That's what Richard Zeebe of the University of Hawaii at Manoa and his colleagues did, and what they found is truly terrifying. Modern carbon emissions outpace anything our planet has seen over the entire Cenozoic -- the period that began after the K-T extinction -- by at least a factor of ten.

For a long time, geologists have considered the Palaeocene -- Eocene Thermal Maximum (PETM) a close analogue to modern global warming. Fifty-six million years ago as the supercontinent Pangea was breaking apart, global temperatures rose at least 5C, possibly due to a massive release of methane from the seafloor. But the timescale of high carbon emissions during the PETM isn't well known: did all that methane gush skyward over the course of decades, or did it leak slowly for thousands of years? Answering that question can help us determine whether the PETM really was comparable to the present.

In their study, Zeebe and his colleagues re-evaluated the carbon-13 and oxygen-18 isotope records -- which track atmospheric carbon concentrations and global temperature, respectively -- from sediment cores collected on the New Jersey coast. They learned that carbon emissions and global warming occurred nearly simultaneously during the PETM, suggesting a slow release of greenhouse gases. (If billions of tonnes of methane had poured out of the ground in a sudden burst, Earth's climate would have taken some time to catch up.)

Using climate and carbon cycle models, the researchers calculated that somewhere between 2000 and 4500 billion tonnes of carbon were released over a period of at least 4000 years. The annual emissions rate was somewhere between 0.6 and 1.1 billion tonnes per year.

Today, humanity is offloading 10 billion tonnes of carbon into the atmosphere each year -- and that rate is still going up, despite our recent resolution to end fossil fuel consumption this century. We're emitting carbon way, way faster than the planet was during the PETM.

And if the most abrupt global warming episode of the Cenozoic doesn't measure up to the present?

Well, we have to look even deeper into the geologic past. At the K-T boundary 66 million years ago, a six-mile wide asteroid slammed into the planet with the force of a billion Hiroshima bombs, kicking off a period of intense volcanic activity that lasted approximately a half million years. It's possible that this dramatic chapter in Earth's history saw a comparable carbon release. But we can't be sure. "It's not well known if or how much carbon was released [at the K-T boundary]," Zeebe told Gizmodo in an email, adding that "geologic records are getting progressively worse for older events".

Still, it's unsettling to think that we can't find any comparison to the present since the dinosaurs kicked the bucket. The authors note that life during the PETM would have had some time to adapt to global climate change and ocean acidification, given the slow rise in atmospheric carbon concentrations. Life during the present? Maybe not so much.

"If anthropogenic emissions rates have no analogue in Earth's recent history, then unforeseeable future responses of the climate system are possible," the researchers write.

If I had to make a prediction? We're going the way of the dinosaurs.

Top: Sarychev eruption in 2009, as seen from the International Space Station. Image: NASA

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    Yes we're all going to die. Actually we're all going to die anyway even if we didn't pollute the world so badly. Dying is a part of life. And human kind will die off on earth eventually because the sun will destroy the earth in the end and I don't think we'll ever populate another planet so, let's just party and enjoy life right now. It would be nice if we didn't wreck the earth but since the rich greedy don't give a damn about the future, we're doomed. Short of killing off governments and beheading the rich and greedy, then there's bugger all we can do, so all this panic is doing nothing but make us anxious and that's no way to live. So, again, party and enjoy life because we're all going to die anyway. Cheers

    Which is sort of good as the CO2 level are far too low for 99% of plants

      Current levels are actually quite low on a geological scale, but the plants seemed to be coping just fine (when not being destroyed wholesale, as in the Amazon.)

      Unfortunately, when combined with "higher temperatures, increased precipitation or increased nitrogen deposits in the soil" (some of the anticipated side effects of climate change) the net effect on plant growth was found to be negative by a 2002 Stanford study.

      Fortunately global emissions seem to finally be heading towards a decline, but we'll still need to cope with what's already in the atmosphere. The biosphere has a limited capacity to absorb carbon, and most of what's in the atmosphere we basically dug up, so the trend downward will be pretty slow.

        this is false, most hothouses run at 1,200ppm of CO2. and the CSRIO has demonstrated the earth is greening fast thanks to this CO2 increase.Futhermore, for most plants, increase CO2 also increases heat resistance.

        The earth has never been as welcoming than when it was warm ( with plenty of CO2).Earth is currently too cold & too dry, we are fixing it.

          It's relatively cold and dry because we're in what would normally be an interglacial. As has been true for the entirety of human history (and most of our prehistory).

          High CO2 - in isolation - is good for plants. The long term effects of same are not particularly good for humans; and higher CO2 levels bring other changes.

          News flash: large, sudden changes (and a hundred years is an eyeblink on geological scales) are almost never good for the ecology. Plants that are evolved for one set of conditions abruptly find that those conditions have changed - and they die. Current plant stocks can demonstrably cope with current CO2 levels, but they may not be able to cope with the changes in temperature and rainfall that result. Higher CO2 is good for plants, all other things being equal - but all other things are NEVER equal.

            Don't put a global ice-age onto a pedestal. A global ice-age kills the majority of life on the planet. I don't know about yourself, but I would rather see our weird and wonderful species of plants an animals not go extinct.

              OK, let me spell this out for you.

              Rapid global change is, in the short term, bad for species diversity due to habitat destruction. (There's nothing inherently bad about the climate getting warmer. It's the pace at which it's happening which causes problems.)

              The plants and animals in an area, evolved for one set of climatic conditions, find that those conditions have changed, in a matter of decades rather than centuries or millennia, as usually happens. This is faster than the genetic mechanisms that drive evolution can cope, so species die out.

              The rate of species lost in recent times is unprecedented(*), and this is mostly due to habitat loss rather than explicit action by humans (although that's also happening.) Some of that habitat loss is also deliberate (such as the Amazon logging) but a fair bit of it is due to climate change, most notably the bleaching of coral reefs.

              (*) I say unprecedented, but of course it has happened before, most recently at the K-T boundary, which was thought to be due primarily to a combination of an asteroid impact and severe volcanic activity. The species loss was mostly due to rapid global cooling, AKA climate change (admittedly in the opposite direction to what's happening now.)

              The Earth has been through a cycle of repeated glaciations over the last few million years, and so all current extant species have successfully dealt with glaciation in the geologically recent past; in other words, they come from stock which survived a glaciation, not from stock which survived recent rapid global warming. What current species have evolved for is pretty much the opposite of the change that we're forcing on the planet.

              If the climate warms up by a relatively small amount (under five degrees, can't recall the exact number) portions of the earth near the equator will become effectively uninhabitable by human beings because they will occasionally experience periods when the combination of temperature and humidity will not be survivable by human beings. I would be very surprised if we're the only species so affected.

              A global ice age does not "kill the majority of life on the planet" unless you're talking about the sort of Snowball Earth scenarios which haven't happened for hundreds of millions of years. All the species that can't cope with an ice age are already gone, since we've had several recently.

                You really didn't have to write a wall of text. Especially when you make claims like and so all current extant species have successfully dealt with glaciation in the geologically recent past Yes and no. The last iceage destroyed all but a small percentage of species, the majority of which had come from already cold environments. Countless animals and plants went extinct. For example, Australian geographic have a write up of the immense ice age extinction event which wiped out a massive amount of diverse plant life in south east Australia (Victoria).

                So by your own logic rapid global warming is ok because the species of animals and plants that dominate our deserts will survive rapid warming and they are the only plants and animals that matter.

                Last edited 29/03/16 11:00 am

                  We've had several ice ages recently. The impact on the number of species hasn't been anywhere near what were seen at the K-T extinction, certainly not what happened with the Permian event. Unless you're talking about a Snowball Earth scenario, ice ages barely figure because ice moves very slowly and most animals and plants have a chance to move out of the way.

                  The Australian Geographic article you mention cites 69 known extinct species, with modelling showing the number is probably higher. We are currently losing considerably more than that per YEAR, between 0.1% and 0.01% of all extant species, or 200-2000 species per year. The late Holocene extinctions (aka Anthropocene extinctions) are thought to be due almost entirely to human activity (with a side order of climate change... climate change being bad.)

                  Incidentally "currently extant species" includes those that are current and therefore, by definition, survived and therefore dealt with the glaciation successfully. There's no "yes and no" about it. I don't know how you extrapolated from 69 species extinct to "all but a small percentage." That's a pretty spectacular exaggeration.

                  I fail to recognise my logic in yours. Rapid warming and rapid cooling are both bad, in terms of causing species extinction. Desert species are probably in more danger, not less, because they are already surviving at the edge of the survivable envelope. The more rapid the change, the more likely that species will go extinct, because they do not get a chance to adapt or migrate. Slower change will still cause extinctions - just not as many.

                  I have yet to see you explain why rapid change is somehow a good thing for most species.

    Never underestimate the human race! Stuffing up everything since the dawn of time lol

    Personally i believe were past the point of no return to 'repair' what we have done and wont be able to make global progression without unity which in my opinion is impossible (human nature).

    Im just glad I wont be around to see it collapse but at the same time there is nothing I want more than to see the world evolve over time.

      Don't worry, you'll see an economic collapse long before you see en ecological one.

      It's a shame - this is the best humans have ever had things and we are prepared to drive it all off a cliff for a religious dream about an idyllic world that never existed. Misty eyed climate 'scientists' who wouldn't know Popper from Play-Doh© may not know about the carbon cycle, but plants certainly do.. the ecology of the world is moving toward a pleasant optimum and our response is to ignore all the positives and fear CO2.. madness

      "since the dawn of time?" We have only been on earth for a tiny tiny fraction of its existence.

    Seems like there is no backing off in the sky is falling propaganda. Fear being the motive for bringing in draconian laws and taxes to instigate their new world order agendas.... Dubious science and statistics always lead the way.
    We just have to think outside the box they put us in.

    Last edited 22/03/16 1:54 pm

      1. 2015, 2014 and 2013 were, respectively, the hottest, second hottest and fourth hottest years on record. The only year in the top 15 that was NOT in this millenium was 1998 (tied at #6).
      2. Texas is a pretty large state (268820 sq. mil) and NYC is a very densely populated city (26,403/sq mi). That said,population is expected to peak this century. Global population is still a problem, but it's not expected to remain that way.
      3. Reducing carbon emissions is not necessarily an economic loss. Once the infrastructure is there it only needs to be maintained, so you no longer require the enormous overheads of digging stuff out of the ground and moving it around. You also get cleaner air, reducing economic externalities. I recall a study a few years ago that showed Australia would be better off by 2020 if emissions were reduced.

      Now, if you want dubious statistics, look to the cherry picking by those still claiming that global climate change isn't happening.

      I for one would rather leave the world in at least somewhat decent shape if possible. Perhaps "we didn't start the fire" (to quote the song) but it would be nice if we could put it out.

      Now, the last sentence in the article is definitely hyperbole, and in any case the dinosaurs are alive and well; we just call them "birds" these days. Doesn't mean it's a problem we can safely ignore.

        "years on record." hmmm not thinking about that are you.... Humans have only existed for a tiny tiny fraction of the life of earth. Since then we have only been recording temperatures for tiny tiny fraction of our existence. That means, the lovely "stat" is a tiny tiny tiny tiny "trend". You simply cannot gain any meaningful insight without the right data over the right time.

          Well, it's over the last 108 years, although we have other records showing it's also very high on a time scale of the last millenium or so. We can look at records of plant growth, for example, to figure out past records with some (not 100%) accuracy.

          It's definitely been warmer than that in the past. Just not in this interglacial.

          The main point about the highest years all being recent, is that there is a certain amount of random variability in climate year-on-year, but the pace of recent changes is so high as to effectively eliminate that factor. The world is getting warmer very, very quickly.

          Assuming that we're aiming for a planet where humans and those species that are currently extant can survive, we really don't want to return to Mesozoic conditions in the space of a hundred years. That would be very, VERY bad for species diversity, because species would not have time to migrate into climatic zones with a survivable temperature range.

          Certainly not the plants, which are noted for not being terribly mobile.

    If you look at extinction from the aspect of lifes suffering , then maybe extinction is best anyway. I can sum up life as being the seeking of survival by destroying other life. I consider this in the context of the savage insect & other lesser animal worlds as well as the human world. When life is dead, it cannot suffer. Joy is temporary.

      Well you better either:
      A. Kill; or
      B. Be killed.

      or an hero.

    Nature has the answer... Plants grow more with more CO2.

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