Carbon Dioxide Higher Today Than Last 2.1 Million Years ScienceDaily (June 21, 2009) â Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the earth's cycles of cooling and warming. The study, in the June 19 issue of the journal Science, is the latest to rule out a drop in CO2 as the cause for earth's ice ages growing longer and more intense some 850,000 years ago. But it also confirms many researchers' suspicion that higher carbon dioxide levels coincided with warmer intervals during the study period. The authors show that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change. In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years. The planet has undergone cyclic ice ages for millions of years, but about 850,000 years ago, the cycles of ice grew longer and more intenseâa shift that some scientists have attributed to falling CO2 levels. But the study found that CO2 was flat during this transition and unlikely to have triggered the change. "Previous studies indicated that CO2 did not change much over the past 20 million years, but the resolution wasn't high enough to be definitive," said Hönisch. "This study tells us that CO2 was not the main trigger, though our data continues to suggest that greenhouse gases and global climate are intimately linked." The timing of the ice ages is believed to be controlled mainly by the earth's orbit and tilt, which determines how much sunlight falls on each hemisphere. Two million years ago, the earth underwent an ice age every 41,000 years. But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million yearsâa change too great to be explained by orbital variation alone. A global drawdown in CO2 is just one theory proposed for the transition. A second theory suggests that advancing glaciers in North America stripped away soil in Canada, causing thicker, longer lasting ice to build up on the remaining bedrock. A third theory challenges how the cycles are counted, and questions whether a transition happened at all. The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research. "We know from looking at much older climate records that large and rapid increase in CO2 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic," he said. "We're heading in that direction now." The idea to approximate past carbon dioxide levels using boron, an element released by erupting volcanoes and used in household soap, was pioneered over the last decade by the paper's coauthor Gary Hemming, a researcher at Lamont-Doherty and Queens College. The study's other authors are Jerry McManus, also at Lamont; David Archer at the University of Chicago; and Mark Siddall, at the University of Bristol, UK.
Sudden Collapse In Ancient Biodiversity: Was Global Warming The Culprit? ScienceDaily (June 19, 2009) â Scientists have unearthed striking evidence for a sudden ancient collapse in plant biodiversity. A trove of 200 million-year-old fossil leaves collected in East Greenland tells the story, carrying its message across time to us today. The researchers were surprised to find that a likely candidate responsible for the loss of plant life was a small rise in the greenhouse gas carbon dioxide, which caused Earth's temperature to rise. Global warming has long been considered as the culprit for extinctions--the surprise is that much less carbon dioxide gas in the atmosphere may be needed to drive an ecosystem beyond its tipping point than previously thought. "Earth's deep time climate history reveals startling discoveries that shake the foundations of our knowledge and understanding of climate change in modern times," says H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which partially funded the research. Jennifer McElwain of University College Dublin, the paper's lead author, cautions that sulfur dioxide from extensive volcanic emissions may also have played a role in driving the plant extinctions. "We have no current way of detecting changes in sulfur dioxide in the past, so it's difficult to evaluate whether sulfur dioxide, in addition to a rise in carbon dioxide, influenced this pattern of extinction," says McElwain. The time interval under study, at the boundary of the Triassic and Jurassic periods, has long been known for its plant and animal extinctions. Until this research, the pace of the extinctions was thought to have been gradual, taking place over millions of years. It has been notoriously difficult to tease out details about the pace of extinction using fossils, scientists say, because fossils can provide only snap-shots or glimpses of organisms that once lived. Using a technique developed by scientist Peter Wagner of the Smithsonian Institution National Museum of Natural History in Washington, D.C., the researchers were able to detect, for the first time, very early signs that these ancient ecosystems were already deteriorating--before plants started going extinct. The method reveals 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 [in East Greenland] from which the fossils were collected," says Wagner, "are of the sort you expect. "But the final 10 meters show dramatic loses of diversity that far exceed what we can attribute to sampling error: the ecosystems were supporting fewer and fewer species." By the year 2100, it's expected that the level of carbon dioxide in the modern atmosphere may reach as high as two and a half times today's level. "This is of course a 'worst case scenario,'" says McElwain. "But it's at exactly this level [900 parts per million] at which we detected the ancient biodiversity crash. "We must take heed of the early warning signs of deterioration in modern ecosystems. We've learned from the past that high levels of species extinctions--as high as 80 percent--can occur very suddenly, but they are preceded by long interval of ecological change." The majority of modern ecosystems have not yet reached their tipping point in response to climate change, the scientists say, but many have already entered a period of prolonged ecological change. "The early warning signs of deterioration are blindingly obvious," says McElwain. "The biggest threats to maintaining current levels of biodiversity are land use change such as deforestation. "But even relatively small changes in carbon dioxide and global temperature can have unexpectedly severe consequences for the health of ecosystems." The paper was co-authored by McElwain, Wagner and Stephen Hesselbo of the University of Oxford in the U.K.
Very compelling argument, this paper. 2.1 million is a large enough time frame to deal with in geo terms. Thanks for gettin me up to speed TZ. Bigdave, appreciate the civilized debate. Will definitely look more closely at this now.
The last paper did define what I would consider a change in trend. Now, the question is, the earth would be a super tanker, rather than a speed boat. Unwinding our CO2 position will be onerous to say the least. Can man reverse the trend b4 a breach?
Nice try. Like I said, there is not one study that proves the rise in temps is due to a rise in C02. If there were, we wouldn't be having this discussion, would we? The best that can be said is, there is a strong correlation. That's it. That does not prove causation. Why do you think you hear terms like "concensus" when talking about GW? Because there is no PROOF. If there was PROOF, you should as hell wouldn't be hearing that word.....concensus. Does this sound like proof? But it also confirms many researchers' suspicion that higher carbon dioxide levels coincided with warmer intervals during the study period.
The point that the Global Warming skeptics don't seem to get is that reducing CO2 emissions is not a good idea, it's a really really great idea, no matter whether they're responsible for GW or even if GW is actually occurring. It's a good idea for reasons that have nothing to do with the effect of CO2 on the environment. People who argue that it isn't necessary to reduce worldwide CO2 emissions (which means moving away from hydrocarbons as a fuel source. Get it?) are people who have spent their entire lives within a few hundred miles of their birthplace. Their birthplace in a modern industrialized nation, usually the U.S. Not sayin' you're one of them, necessarily. Just sayin'.
I don't necessarily disagree with that view.....we should minimize our impact on the environment. Let me ask you this. If we are really serious about reducing C02, then shouldn't that be done with a global scope of the problem? Why should we in the US spend billions (maybe trillions) squeezing that last 5%-10% of efficiency out of our power plants when we have developing countries spewing out 10's and 100's of times the amount of C02? The fact that one country gets a pass while others have to share a bigger cost gives the lie to what the real motivation is, imo.
co2 lags temperature ... that has been proven everyone should live long and happy lives also ... saying it and taxing the economy into oblivion won't make it happen the left is irrationtal ... that has also been proven
We have already discussed this and it went right over their heads. I am not quite sure at what point CO2 became considered harmful pollution. The trees certainly seem to love it.