Tuesday, April 16, 2013

Another link between CO2 and mass extinctions of species

By Andrew Glikson, Australian National University
Andrew Glikson, earth and
paleo-climate scientist at
Australian National University

It’s long been known that massive increases in emission of CO2 from volcanoes, associated with the opening of the Atlantic Ocean in the end-Triassic Period, set off a shift in state of the climate which caused global mass extinction of species, eliminating about 34% of genera. The extinction created ecological niches which allowed the rise of dinosaurs during the Triassic, about 250-200 million years ago.

New research released in Science Express has refined the dating of this wave of volcanism. It shows marine and land species disappear from the fossil record within 20,000 to 30,000 years from the time evidence for the eruption of large magma flows appears, approximately 201 million years ago. These volcanic eruptions increased atmospheric CO2 and increased ocean acidity.

Mass extinctions caused by rapidly escalating levels of CO2 have occurred before. Global warming image from www.shutterstock.com
Mass extinctions due to rapidly escalating levels of CO2 are recorded since as long as 580 million years ago. As our anthropogenic global emissions of CO2 are rising, at a rate for which no precedence is known from the geological record with the exception of asteroid impacts, another wave of extinctions is unfolding.

Mass extinctions of species in the history of Earth include:
  • the ~580 million years-old (Ma) Acraman impact (South Australia) and Acrytarch (ancient palynomorphs) extinction and radiation 
  • Late Devonian (~374 Ma) volcanism, peak global temperatures and mass extinctions 
  • the end-Devonian impact cluster associated with mass extinction, which among others destroyed the Kimberley Fitzroy reefs (~360 Ma) 
  • the upper Permian (~267 Ma) extinction associated with a warming trend
  • the Permian-Triassic boundary volcanic and asteroid impact events (~ 251 Ma) and peak warming 
  • the End-Triassic (201 Ma) opening of the Atlantic Ocean, and massive volcanism 
  • an End-Jurassic (~145 Ma) impact cluster and opening of the Indian Ocean 
  • the Cretaceous-Tertiary boundary (K-T) (~65 Ma) impact cluster, Deccan volcanic activity and mass extinction 
  • the pre-Eocene-Oligocene boundary (~34 Ma) impact cluster and a cooling trend, followed by opening of the Drake Passage between Antarctica and South America, formation of the Antarctic ice sheet and minor extinction at ~34 Ma. 

Throughout the Phanerozoic (from 542 million years ago), major mass extinctions of species closely coincided with abrupt rises of atmospheric carbon dioxide and ocean acidity. These increases took place at rates to which many species could not adapt. These events – triggered by asteroid impacts, massive volcanic activity, eruption of methane, ocean anoxia and extreme rates of glaciation (see Figures 1 and 2) – have direct implications for the effects of the current rise of CO2.

Figure 1 – Trends in atmospheric CO2 and related glacial and interglacial periods since the Cambrian (542 million years ago), showing peaks in CO2 levels (green diamonds) associated with asteroid impacts and/or massive volcanism. CO2 data from Royer 2004 and 2006.
Figure 2 – Relations between CO2 rise rates and mean global temperature rise rates during warming periods, including the Paleocene-Eocene Thermal Maximum, early Oligocene, mid-Miocene, late Pliocene, Eemian (glacial termination), Dansgaard-Oeschger cycles, Medieval Warming Period, 1750-2012 and 1975-2012 periods.

In February 2013, CO2 levels had risen to near 396.80ppm at Mauna Loa Atmospheric Observatory, compared to 393.54ppm in February 2012. This rise – 3.26ppm per year – is at the highest rate yet recorded. Further measurements show CO2 is at near 400ppm of the atmosphere over the Arctic. At this rate the upper stability threshold of the Antarctic ice sheet, defined at about 500–600ppm CO2 would be reached later this century (although hysteresis of the ice sheets may slow down melting).

Our global carbon reserves – including coal, oil, oil shale, tar sands, gas and coal-seam gas – contain considerably more than 10,000 billion tonnes of carbon (see Figure 5). This amount of carbon, if released into the atmosphere, is capable of raising atmospheric CO2 levels to higher than 1000ppm. Such a rise in atmospheric radiative forcing will be similar to that of the Paleocene-Eocene boundary thermal maximum (PETM), which happened about 55 million years-ago (see Figures 1, 2 and 4). But the rate of rise surpasses those of this thermal maximum by about ten times.
Figure 3 – Plot of percent mass extinction of genera versus peak atmospheric CO2 levels at several stages of Earth history.
Figure 4 – The Paleocene-Eocene Thermal Maximum (PETM) represented by sediments in the Southern Ocean, central Pacific and South Atlantic oceans. The data indicate a) deposition of an organic matter-rich layer consequent on extinction of marine organisms; b) lowering of ╬┤18O values representing an increase in temperature and c) a sharp decline in carbonate contents of sediments representing a decrease in pH and increase in acidity (Zachos et al 2008) 

The Paleocene-Eocene boundary thermal maximum event about 55 million years ago saw the release of approximately 2000 to 3000 billion tons of carbon to the atmosphere in the form of methane (CH4). It led to the extinction of about 35-50% of benthic foraminifera (see Figure 3 and 4), representing a major decline in the state of the marine ecosystem. The temperature rise and ocean acidity during this event are shown in Figures 4 and 6.

Based on the amount of carbon already emitted and which could continue to be released to the atmosphere (see Figure 5), current climate trends could be tracking toward conditions like those of the Paleocene-Eocene event. Many species may be unable to adapt to the extreme rate of current rise in greenhouse gases and temperatures. The rapid opening of the Arctic Sea ice, melting of Greenland and west Antarctic ice sheets, and rising spate of floods, heat waves, fires and other extreme weather events may signify a shift in state of the climate, crossing tipping points.
Figure 5 – CO2 emissions from fossil fuels (2.12 GtC ~ 1 ppm CO2). Estimated reserves and potentially recoverable resources.By analogy to medical science analysing blood count as diagnosis for cancer, climate science uses the greenhouse gas levels of the atmosphere, pH levels of the ocean, variations in solar insolation, aerosol concentrations, clouding states at different levels of the atmosphere, state of the continental ice sheets and sea ice, position of high pressure ridges and climate zones and many other parameters to determine trends in the climate. The results of these tests, conducted by thousands of peer-reviewed scientists world-wide, have to date been ignored, at the greatest peril to humanity and nature.

Continuing emissions contravene international laws regarding crimes against humanity and related International and Australian covenants. In the absence of an effective global mitigation effort, governments world-wide are now presiding over the demise of future generations and of nature, tracking toward one of the greatest mass extinction events nature has seen. It is time we learned from the history of planet Earth.

Figure 6: The Paleocene-Eocene boundary thermal maximum. http://www.uta.edu/faculty/awinguth/petm_research/petm_home.html

This article was earlier published at The Conversation (on March 22, 2013).

3 comments:

  1. What's happening with Earth is big and likely, given the resistance to change pesky man seems given to by evolution now with money ideas fix essentially to our make up of the way we think.
    Judging from looking at graph of past extinction events positions on % genera extinction v Carbon Dioxide maxima in atmosphere at the time in parts per million and where we are today both in rate of increase and in actual terms -and the volumes of sequestered carbon available and starting to show tentative signs of self release beginning; Judging from that and knowing how to pull out of a dive in a hang glider once a spiral dive is initiated, albeit with enough altitude and knowledge not to pull the wings off or to hit ground either due to panic or simply not enough knowledge about stopping high speed stall or prep in glider design to give washout design consideration. -I'd say we are too close to zero.
    Too close to ground to pull out and recover- certainly to have glider recover and fly again too.. But there are things we can do. -We can see too it our thoughts turn to our children and life. Because life is essential for hope.
    And who knows if it reduces fear then some thing like ripping through tree tops or emergency chute. If I'd had rocket deploy in right direction.. But maybe not. But it would be fun to try.. -Sorry about the mental meander from science.. But not too much.. Because what I'm saying is that by not freezing with fear and trying to think of others and how to turn the situation we can perhaps avert the worst of extinctions here on Earth and this in my opinion would be appreciated..
    The chances mankind can continue are low in the long run because we are particularly vulnerable to war among each other as food gets scarce and because oxygen levels will likely drop below what large creatures with high temperature of body need. Along with transpiration consideration to cool. An other things not too pleasant..
    But we can set in motion changes which could stop total extinction of genera from happening if we act fast and with logical intent.. Earth evolves.
    We can too and if our consideration is justice and children then by taking action together in peace and bringing industry to bear under no uncertain terms about how money is truly best used, then who knows, maybe as a by product is an invention of a way to avoid destruction of Earth.
    And maybe civilization can evolve so mankind lives and could become a better specie all round.

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  2. I don't think we are tracking toward another Paleocene-Eocene event but rather something on order of stronger that of Cambrian. The PETM flux at approx 35 to 36 million years ago was a settling of the planet into the high rate of ocean overturn an influence of southern continent ice mass 25 million cubic kilometer influence and presence of bottom water formation and decent. Which is now disrupted. We need to think big about what's happening and get in front of the situation because there is little time. -Specifically the krill cultivation idea to sink carbon to the deep needs to get going if it is to be able to be tried at all. There are serious indications ocean current flow is faltering..
    The Arctic needs serious shielding in specific ways the likes of which have no equal to human evolutionary potential.. The guys walking the beaches on way to Australia from Africa would have agreed -there are monsters out there in the outback that are not known and the place we are going is not known nor is where we originated but we have ideas.. The idea we know it all must en.

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    1. I always enjoy reading your astute perspective Mr. Lanan. The greatest hurdle scientists face is not the imminent crisis of global climate change but, rather, their lack of humility and ability to work or think outside of the parameters that they have been given. There are a myriad of variables, from seemingly disparate elements, that need to be examined as a whole for a clearer picture to be drawn of Earth's future.

      The fact that scientists are "shocked" by the latest developments in the Arctic is a clear indication of their closed-loop system, with extremely narrow parameters, in desperate need of the incorporation new information.
      Each day as I read more and more information about the dire situation in the Arctic I feel a sense of incredulity that, even with advanced technology and instrumentation, scientists could not predict this event? We can send probes to Mars but we cannot detect a future cataclysm on our own planet? I find this so difficult to understand....unless it is an intentional obfuscation by scientific or political institutions.
      I grew up in the 60's and 70's and was an avid weather watcher and carried this forward into my adulthood. What I find so bizarre is that forecasters were able to predict weather patterns with a high degree of accuracy compared to their modern day counterparts. Astounding! Our science and technologies have advanced but not our accuracy in prediction? Weather forecasters can no longer predict the weather hourly much less on a weekly basis.

      In 1992, when I returned to my home state for a visit, I noticed a perceptible change in the weather patterns. Intense humidity and heat were now a prominent feature of Tennessee summers...something I was not accustomed to while growing up there. So much has changed since then that I am truly astounded by the lack of information and obvious silence of meteorological scientists. Two years ago, while visiting my sister in Tennessee, I experienced a searing, smothering heat that left me completely drained and seeking shade...it was 97 degrees and only 10 am. With heat indices it reached a melting 117 degrees that day and remained into the 100's for the rest of that week. Grass died. Trees died. People died. Plants struggled for life and yet not a word on mainstream news outlets.
      Where are the meteorologists? Climatologists? Anyone? These temperatures are not normal nor are they life sustaining. Where are the scientists shouting at the top of their lungs in warning the population? Why are they being ambiguous in their tone?
      I try to provide the information that I read here but most people are completely oblivious to what is going on globally with the climate....this astounds me. Most people tell me that they do not "believe" that we are experiencing global warming while others say that it is nothing more than a scam to extort money from the public. Others are overwhelmed by the lack of forewarning....or, I should say, "official" forewarning.

      I feel like I live in a mad, mad world filled to the brim with sociopaths and sycophants. Everyone parasitically feeding off of the other while the planet burns to the ground.

      When you speak, Mr. Lanan,I can almost hear an echo in cyberspace....no one but I and a few others are listening it appears and for that I am made ashamed of my fellow travelers.




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