Extinction risk to plant biodiversity may occur at lower levels of atmospheric CO2 than previously considered

Jun 29, 2009

(PhysOrg.com) -- Scientists have traced a sudden collapse in plant biodiversity in ancient Greenland, some 200 million years ago, to a relatively small rise in atmospheric carbon dioxide which caused a rise in the Earth’s temperature.

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 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.

Using a new technique developed by Professor Peter Wagner at The Smithsonian Institute, the team of international scientists were able to detect very early signs at which plant diversity in ancient ecosystems were in a state of steady decline before they went extinct.

The new method reveals the early warning signs that an ecosystem is in trouble in terms of extinction risk. “The differences in species abundances for the first 20 meters of the cliffs from which the fossils were collected, are of the sort you expect given imperfect sampling of the same ecosystem,” said Professor Wagner. “But the final 10 meters show dramatic loses of diversity that far exceed what can be attributed to sampling error: the ecosystems were supporting fewer and fewer species.”

"Earth's deep time climate history reveals startling discoveries that shake the foundations of our knowledge and understanding of climate change in modern times," said H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which partially funded the research.

Provided by University College Dublin

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User comments : 13

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dan42day
2.3 / 5 (9) Jun 29, 2009
Whine, Whine, Whine. It's just as likely that global warming will cause an explosion of plant diversity as new niches open up after us humans have all killed ourselves out of guilt.
mikiwud
1.8 / 5 (10) Jun 30, 2009
Bullshit! They blame CO2 then give other possible reasons. If one species dies out to be replaced by another it's called EVOLUTION.
If things don't change they will stay just as they are!
There, I've made more sense than they have, can I have the money now, please?
Godfather
2.3 / 5 (6) Jun 30, 2009
Exactly, we are trying to keep things the same, because right now the planet is habitable for humans. We have a responsiblity toward the environment which supports us.

And there is scientific evidence that increased CO2 does not increase plant growth, quite the opposite. Increased CO2 would also increase temperatures, increase precipitation, and increase Nitrogen content in soil. These things put together have been shown to decrease plant growth.
Velanarris
2.5 / 5 (4) Jun 30, 2009
The die out 200 million years ago is very closely related to the eruption of the Siberian traps and a large scale block out of sunlight, not due to CO2.

This particular article is nonsense.
mdk
3.4 / 5 (5) Jun 30, 2009
Godfather, I'm curious. What evidence supports the claim that CO2 does not promote plant growth? Since it's a major component in plant development and many greenhouses use CO2 at many times the 'outside' level to stimulate growth. Increased nitrogen content is a good thing as well since it's a major component in fertilizers. The industrial age really began at the end of the Little Ice Age so it's odd that this period is chosen as somehow being optimal. People who were alive then would very likely question that idea.

Claiming you can learn anything meaningful about a link between CO2 and 200 million-year-old fossils is hard enough but the idea that CO2 at a mere 900 ppm harmed them is ludicrous. Crack open a botany text and see for yourself.
Choice
2.7 / 5 (3) Jul 02, 2009
You are all entitled to your opinions, but if you are wrong than how about if you pay for the consequences, ok? And how about if we start collecting now for that payout, just in case. If you are right then you can have your money back. Of course, by then there may be no money capable of compensating for the losses, but the point is still worth pursuing: if you want to subject someone else to a grave risk than you must participate in the insurance program. This is similar to mandatory driver's insurance. There has to be a larger liability than just being able to say 'Ooops, sorry, we underestimated the impact of rising CO2 levels.' That sounds like what Greenspan said about the financial meltdown, only this time there is no 'bail out' possible, unless you happen to be G-d.
Velanarris
3.3 / 5 (3) Jul 02, 2009
You are all entitled to your opinions, but if you are wrong than how about if you pay for the consequences, ok? And how about if we start collecting now for that payout, just in case. If you are right then you can have your money back. Of course, by then there may be no money capable of compensating for the losses, but the point is still worth pursuing: if you want to subject someone else to a grave risk than you must participate in the insurance program. This is similar to mandatory driver's insurance. There has to be a larger liability than just being able to say 'Ooops, sorry, we underestimated the impact of rising CO2 levels.' That sounds like what Greenspan said about the financial meltdown, only this time there is no 'bail out' possible, unless you happen to be G-d.

Pre-emptive policy is a relic of the cold war days, dusted off and exercised during the Iraq wars.

Do you want to look for weapons of mass climate change? I'd prefer to do the proper analysis before dooming millions to lives of poverty.

Americans are lucky, most of us won't hurt other than financially if there are missteps in the regulation of GHG's, however, not everyone on the planet lives in the food production heartland of the world.

Any regulation, regardless of the views of those involved, must be well thought out and performed appropriately so that both the environment and the health and well being of our fellow man can be maintained.
Quantum_Conundrum
2.1 / 5 (7) Jul 02, 2009
Godfather, I'm curious. What evidence supports the claim that CO2 does not promote plant growth? Since it's a major component in plant development and many greenhouses use CO2 at many times the 'outside' level to stimulate growth. Increased nitrogen content is a good thing as well since it's a major component in fertilizers. The industrial age really began at the end of the Little Ice Age so it's odd that this period is chosen as somehow being optimal. People who were alive then would very likely question that idea.



Claiming you can learn anything meaningful about a link between CO2 and 200 million-year-old fossils is hard enough but the idea that CO2 at a mere 900 ppm harmed them is ludicrous. Crack open a botany text and see for yourself.



Lol. Too true. I gave your response a 5.
Godfather
3 / 5 (2) Jul 03, 2009
There was a study done by Stanford, think it was called the Jasper global change project. The finding was that where nitrates and temperatures are increased, the introduction of high CO2 levels hindered plant growth.
mariob
2.3 / 5 (3) Jul 03, 2009

Lol. Too true. I gave your response a 5.


Translation: "I'm a moron too, high five!"
Godfather
3.7 / 5 (3) Jul 03, 2009
mdk - I only just realised what you said about 200 million year old fossils. Wow you are right, lets not look at those records buried in the rocks, thats just crazy talk!
mariob
2.3 / 5 (3) Jul 03, 2009

Godfather: Don't bother trying to defend yourself with "science" this place is a hang out for people with no real grasp of reality and have already decided what they want to believe. Its basically where like-minded dicks come to beat each other off and pretend their opinions actually matter to anyone other than themselves. You can find the same kind of folks talking about UFOs, crop circles, etc., all over the net. They bitch about how the 'main-stream' is always wrong and they are the ones who 'know the truth!'. Meanwhile, the real world ignores them and carries on with actually making a difference. Thank god they are they constrained to writing bullshit on little comment sections below the real articles, where nobody but their sad little followers come.



Imagine if these guys actually made a difference in the world?? We'd be fucked!!



Oh, sorry for interrupting guys, carry on as you were! Where were again...oh yeah "them scientists don't know shit, I knows stuff cos i got the internets! yuk yuk!"



I'm outta here!
dachpyarvile
1 / 5 (3) Jul 03, 2009
...

And there is scientific evidence that increased CO2 does not increase plant growth, quite the opposite. Increased CO2 would also increase temperatures, increase precipitation, and increase Nitrogen content in soil. These things put together have been shown to decrease plant growth.


Malarky! There have been several studies with CO2 and plants that have shown increases of plant mass and crop yield as high as ~39% by doubling CO2 levels of those at present.

Plants can continue to grow and photosynthesize in levels as high as 0.9% of the atmosphere before being unable to function properly. Today's levels are at between 0.03% and 0.04%.

By the way, plants grew to huge heights in prehistoric times due to higher levels of CO2! There was enough to go around, and then some, too! It was when the levels fell that plants began dying off.

Another thing that is of interest is that plants still carry the genes that allow them to process higher levels of CO2. In a couple studies I read these ancient genes switched on when levels of CO2 were increased.

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