Study finds “mass biodiversity collapse” at 900 ppm, and possibly a “threshold response … to relatively minor increases in CO2 concentration and/or global temperature.”

In 2007, the IPCC warned that “as global average temperature increase exceeds about 3.5°C [relative to 1980 to 1999], model projections suggest significant extinctions (40-70% of species assessed) around the globe.”  On our current emissions path, we will warm far more than that this century, which suggests we risk the high end of species loss.

A new study in Science study (subs. req’d) confirms this risk.  It examines “the pace of diversity loss leading to the Triassic-Jurassic boundary (TJB).”  It finds “the sudden diversity drop coincided with a mere ~100 to ~350 ppmv rise in CO2 concentration,” and “CO2-induced global warming was likely an important contributory factor to plant species turnover at the TJB.”

The study notes “The abrupt plant diversity loss … is consistent with expected plant responses to a catastrophically rapid rather than gradual environmental change,” such as might be caused from a massive release of methane  Good thing homo “sapiens” sapiens isn’t doing anything that might bring about catastrophically rapid climate change, like say 5°C warming in one century or a massive release of methane (see NOAA stunner: “Methane levels rose in 2008 for the second consecutive year after a 10-year lull”).

Worse, the study concludes:

An alternative explanation for the abrupt diversity loss is that it represents a threshold response of LT vegetation to relatively minor increases in CO2 concentration and/or global temperature.

Again, we are quite literally playing with fire here, risking massive species loss this century if we don’t sharply reverse greenhouse gas emissions trends soon.

And, of course, “When CO2 levels in the atmosphere reach about 500 parts per million, you put calcification out of business in the oceans.” There aren’t many studies of what happens to the oceans as we get toward 800 to 1000 ppm, but it appears likely that much of the world’s oceans, especially in the southern hemisphere, become inhospitable to many forms of marine life. A 2005 Nature study concluded these “detrimental” conditions “could develop within decades, not centuries as suggested previously.”

A 2009 study in Nature Geoscience warned that global warming may create “dead zones” in the ocean that would be devoid of fish and seafood and endure for up to two millennia (see Ocean dead zones to expand, “remain for thousands of years”).

Let me end with a long excerpt from a article on the new Science study, “Extinction risk to plant biodiversity may occur at lower levels of atmospheric CO2 than previously considered,” for those without a subscription:

According to the findings published in the leading journal Science, the current estimated levels of atmospheric carbon dioxide which are thought to lead to sudden biodiversity loss may have to be revised downwards.

However, the scientists from University College Dublin, The Smithsonian Institute in Washington DC and Oxford University, have cautioned that their study findings may not have accounted for additional atmospheric gases such as sulphur dioxide which may have emerged from extensive volcanic emissions at the time to also play a role in driving the rise in the Earth’s temperature.

“Examining the 200 million year old fossil leaves from East Greenland, we discovered that the ancient biodiversity crash happened at atmospheric greenhouse gas levels of approximately 900 parts per million,” said Dr Jenny McElwain from the UCD School of Biology and Environmental Science at University College Dublin, Ireland, the lead researcher on the project.

“If we continue with the current intensive use of fossil fuel energy, some estimates calculate that carbon dioxide levels in the earth’s atmosphere will reach 900 parts per million by the year 2100. This is exactly the same levels at which our study identified the mass biodiversity collapse in ancient Greenland.” But according to Dr McElwain, this is a worst case scenario.

“Clearly, our study on ancient ecosystems shows that we must take heed of the early warning signs of deterioration within modern ecosystems, as we have seen from the past that very high levels of species extinctions — as high as 80% — can take place very suddenly although preceded by long intervals of ecological change,” she explains.

The time to act is now (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm “¦ the worst-case IPCC scenario trajectories (or even worse) are being realised” “” 1000 ppm).

20 Responses to Study finds “mass biodiversity collapse” at 900 ppm, and possibly a “threshold response … to relatively minor increases in CO2 concentration and/or global temperature.”

  1. Gail says:

    So, if “the sudden diversity drop … coincided with a mere ~100 to ~350 ppmv rise in CO2 concentration,”
    and pre-industrial level was 280, we’re now at 385, it shouldn’t be surprising to see a sudden diversity drop, now.

    [JR: Not quite what the study said, but it isn’t clear.]

  2. Knoxville, TN says:

    I saw a summary of this paper a few days ago, and it seems that not being able to account for sulfur dioxide emissions leaves this study with a great big question mark hanging over it, given how SO2 contributes to acid rain. Was it the heat or the acid rain or both that caused the mass extinction event? We don’t yet know. This study leaves me concerned, but not in a panic (yet).

  3. Andy says:

    We’ll probably see this amount of species lost without global warming. The rate of loss is increasing exponentially at present and is being driven by habitat conversion/destruction and the artificial introduction of species from one continent to another (zebra mussels, dutch elm disease, etc.).

    Our children’s grandchildren will probably look back on these times as the lost garden of eden.

  4. pete best says:

    This is a no brainer but we have not managed 1C yet although i know the oceans are itching to give us another 0.6C on our already 0.6 to 0.8C making 1.4 to 1.6C in total. We all know that 2C is near and possibly already likely due to aerosoles and cooling agents locally masking global warming of GHGs to some degree but th entire 3 to 7C argument is abaout business as usual paths which include using all of the remaining fossil fools which is seemingly unlikely on economic grounds and the resonant scientific knowledge of AGW.

    It is just people trying to scare us all into acting that we are going through?

  5. GeneB_NoAGW says:

    This study obviously ignores the fact that CO2, in the past, as well as now, increases AFTER warming has already begun.

    Warming causes CO2 increase.

  6. paulm says:

    yes geneB we know that.

    CO2 also causes the temp to increase! So whats the point?

    The future is now…

    Droughts and floods threaten China’s economic growth, forecaster warns

    Cost of crop failure soars as weather disasters become more frequent and severe

    the annual Red Cross report said that a rise in weather-related disasters worldwide over the last decade – from around 200 a year in the 1990s to around 350 – was continuing. Its secretary general, Bekele Geleta, warned that extreme-weather events would become more frequent and more severe.

  7. GeneB_NoAGW says:

    paulm, what does this hae to do with Man and CO2?

    The Sun is causing Climate Change.

    And it will keep on changing — whatever stupid Climate Bill we pass.

  8. paulm says:

    Gene, yes we know the sun causes climate change.
    But so does CO2 generated by us.

    We are changing the climate making it warmer which is not so good for us.

    In any case the climate bill could have been cause the “Security Bill” or the “Energy Bill” as our dependency on oil needs to move on to a more workable setup.

  9. paulm says:

    Gene, we have to tackle the CO2 issue as well.

    This bill is only a start. The coal plants have to be phased out from spewing CO2 immediately if there is any reasonable chance of alleviating the catastrophe around the corner.

    ‘We need radical direct action now’

    Twenty-two defendants went on trial today charged with obstructing a freight train which was carrying coal to Drax power station. Martin Wainwright hears from environmental protesters outside Leeds crown court

  10. GeneB_NoAGW says:

    paulm, that’s where I think you’re wrong. We don’t have to tackle the CO2 issue. The fear mongering about CO2 has poisoned the minds of the public as well as the politicians. There is much evidence that CO2 is a very minor player in the Earth’s Climate — dwarfed by naturally occurring factors, such as the Sun, Ocean Current Oscillations, Volcanic activity (above ground and below the oceans).

    If anything, let’s keep studying all these factors. But let’s NOT destroy our economy on the very slight chance that a *slight* reduction in man’s CO2 contribution will cause even a dent in the Earth’s temperature.

  11. paulm says:


    There is a huge, overwhelming amount of evidence that human CO2 emissions plays the critical role in the Climate warming we are now seeing.

    Who wants to destroying the economy. That happened last year anyway. There is no reason not to resuscitate it in a sustaible mannar that tackles all the problems we now face.

    I am sure the studying of these factors will continue:) I don’t understand how it is you can’t accept that additional CO2 produced by man cannot affect the climate.

    Just because it is in relatively a small proportion does not rule out the fact that it may have a big impact on the system. Haven’t you heard of the butterfly effect?

    Consider this …

    The followers of the peace lobbies of the 1930s resembled the environmentalist movements now; their intentions were more than good but wholly inappropriate for the war that was about to start. It is time to wake up and realize that Gaia, the Earth system, is no cozy mother that nurtures humans and can be propitiated by gestures such as carbon trading or sustainable development.

  12. David B. Benson says:

    GeneB_NoAGW — I fear you have it all bass-ackwards.. For reliable information, read “The Discovery of Global Warming” by Spencer Weart:

  13. Jim Eager says:

    Gene, the conclusion that the lag in the ice core record proves that temperature does not respond to CO2 is nothing more than false logic.

    What the lag proves is that an increase in CO2 does not precede and initiate the warming that ends a glaciation, but then that is already a well known and widely accepted fact, something that global warming/climate change deniers are apparently not aware of.

    What the *magnitude* of the warming in the ice core proves is that it was far greater than changes in insolation alone could produce. Even when amplified by changes in albedo as the ice melts there would not be nearly enough warming to end a glacial stade.

    Only by also adding amplification from rising atmospheric CO2, methane and water vapour would the change in insolation produce the observed 5-6C warming.

    In other words, what the lag in the ice core proves is that temperature *does* in fact respond to CO2.

    Your assertion that the current warming preceded the observed rise in CO2 is just plain silly.

    And no, its not the sun that is causing current climate change, no matter how many times you write that it is. You can look it up if you like.

    Nor are volcanoes, above ground or below the oceans, which on average emit less than 1% as much CO2 as burning fossil fuels do each year, and not nearly enough actual heat to warm . You can look that up, too, if you like.

    Go ahead, surprise us.

  14. Aaron says:

    I hate to do it but Gene, please point to some credible peer reviewed literature to support your findings. I’d love to read it first of all and secondly, I haven’t been able to find it myself. The so called fear mongering is based upon sound science, which is more than I can say for the opposing view point.

    Joe RE: “There aren’t many studies of what happens to the oceans as we get toward 800 to 1000 ppm.”

    There’s actually quite a bit of work done at extremely low pH levels on invertebrates. Equating to CO2 concentrations sometimes close to 2000ppm. This theme section in Marine Ecology Progress Series at the end of last year is a pretty good synopsis of the different fields of research under ocean acidification

  15. Chris Winter says:

    GeneB_NoAGW wrote: “If anything, let’s keep studying all these factors. But let’s NOT destroy our economy on the very slight chance that a *slight* reduction in man’s CO2 contribution will cause even a dent in the Earth’s temperature.”

    We will keep studying all these factors. But I have to wonder, if studies are so important to you, why you are unaware of studies of the sun’s output over the past 30 years — studies which show it declining slightly during that period.

    Meanwhile, over that time, temperature kept trending upwards and CO2 concentrations kept increasing. Studies documenting CO2 as the likely cause of the warming would now fill a library. But some people are somehow still able to believe all that work is “flawed” or “meaningless” and call for more studies before any action is taken.

    History tells us that’s the classic way the powers that be block needed action they don’t happen to favor.

  16. Agnotology: Culturally constructed ignorance, purposefully created by special interest groups working hard to create confusion and suppress the truth.

  17. Wonhyo says:

    As time passes, I notice there are more and more studies confirming the dire consequences of not taking dramatic action now to reduce human GHG emissions. This is what causes my ambivalence toward compromise climate bills and CFL light bulbs. I see many people promoting the use of CFL light bulbs, but they’re driving SUVs, not carpooling, not taking public transportation, buying a huge home, etc. We tend to take comfort in miniscule actions like CFL lights so that we can avoid the more difficult sacrifices that must be made. In this sense, CFL lights actually hurt our cause. We would be far better off if we DIDN’T upgrade to CFL lights, but instead, carpooled, drove fewer miles, and used public transportation more. So, I wonder about the climate bill. If this compromise climate bill passes, are we ready to campaign to strengthen it? Or are we going to breathe a sigh of relief and start borrowing against future carbon credits in a state of self-satisfaction?

  18. Gail says:

    So much for the “plant food” theory. Messing with atmospheric concentrations has to affect plants for the simple reason they are suited to our past atmosphere.

  19. Peer reviewed literature: How about the MIT “Wavelength Tables”? This is an encyclopedia-length series of books. We have been testing the optical properties of substances since the 19th Century. We know very well that O2 and N2 are transparent to infra-red but CO2 is opaque to infra-red. We have known this since the 19th Century. Doubters: Get your own degree in Physics and get yourself a spectrometer. The experiment is not difficult. It could be taught, or at least demonstrated, in high school. We can test precisely what any concentration of CO2 will do optically.
    A practical example: the planet Venus: CO2 is denser by half than water at the surface of Venus, and the rocks glow a dull red. Lead is a liquid there. The climate of Venus is what happens when the CO2 gets really dense. There is no life on Venus.

  20. You forgot to mention that Homo Sapiens would be among the 80% to go extinct.