Posted on 06/01/2006 1:02:47 PM PDT by Ernest_at_the_Beach
A treasure trove of scientific data is revealing detailed information about conditions of subtropical warmth at the North Pole about 55 million years ago while also providing a window into the future, when greenhouse gases are expected to reach the same levels that caused Earth's ancient heat wave.
Researchers aboard a fleet of icebreakers collected samples by drilling into the floor of the Arctic Ocean during a 2004 expedition, and scientific findings will be published for the first time in several papers to appear Thursday (June 1) in Nature magazine.
"This project was a technological feat, and all of the findings in these papers are especially new and exciting given the fact that nobody's ever taken core samples like this before from the floor of the Arctic Ocean," said Matthew Huber, an assistant professor of earth and atmospheric sciences in Purdue University's College of Science. "As a climate modeler, gaining access to this data is a once-in-a-lifetime opportunity."
The expedition was part of an international research effort called the Integrated Ocean Drilling Program, which explores the Earth's history and structure as recorded in seafloor sediments and rocks.
Huber used new data from the research to compare against results from complex climate-model simulations he performed to study and predict the effects of greenhouse gases. He co-authored two research papers to appear in Nature detailing conditions in the Arctic Ocean 55 to 50 million years ago during a time of unprecedented global warmth.
The cylindrical core samples contained the remains of ancient plant and animal life, which yielded critical new information about the Arctic Ocean during that time. Researchers used a recently developed technique called TEX-86, which enables scientists to measure the temperatures that existed when ancient organisms lived by analyzing the composition of fatty substances called lipids in their cell membranes. Using this technique, the researchers found that sea surface temperatures at the North Pole had soared to 23 degrees Celsius, or around 73 degrees Fahrenheit, during the Paleocene-Eocene Thermal Maximum, or the PETM, about 55 million years ago. Today's mean annual temperature at the North Pole is around minus 20 degrees Celsius, Huber said.
Researchers also discovered the remains of tiny algae called dinoflagellates, belonging to the species Apectodinium, which previously had been restricted to warmer regions of the world.
"The presence of Apectodinium during the Paleocene-Eocene Thermal Maximum provides confirmation that subtropical conditions arrived in the Arctic during this time," Huber said.
Among the most important reported findings was the discovery that 5 million years later, around 50 million years ago, the Arctic Ocean was frequently covered with dense mats of a freshwater fern called Azolla, which flourishes in ponds, said Henk Brinkhuis, a marine palynologist and biogeologist from Utrecht University in the Netherlands and lead author on one of the Nature papers.
"Imagine that the Arctic Ocean was a giant lake, with this vegetation growing in it," Brinkhuis said. "What these findings say is that the Arctic Ocean must have been isolated, or nearly cut off, from the Atlantic Ocean by land masses that later shifted into the present continents. Today, if you hop in a boat and head north in the Atlantic Ocean, you could go all the way to the Arctic Ocean. But back then it was more isolated, which prevented salt water from ocean surface currents from reaching there."
The beginning of the Paleocene-Eocene Thermal Maximum was marked by a huge release of a greenhouse gas, possibly carbon dioxide or methane, into the atmosphere. Methane, frozen in solid "methane hydrate" deposits on the ocean floor, might have been disturbed by some geologic event, such as mudslides or an earthquake, causing the gas to bubble to the surface. The methane would have then broken down into carbon dioxide in the atmosphere.
The resulting greenhouse effect caused global temperatures to rise by an average of about 5 degrees Celsius.
"This provides a beautiful natural experiment for understanding global warming and environmental change and is probably the best historical analogy for today's release of greenhouse gases from human-related sources," said Appy Sluijs, a doctoral student at Utrecht University's Institute of Environmental Biology and lead author on the other Nature paper. "There is no clearer evidence for greenhouse-gas-induced global warming in the geologic record."
"We now have a pretty good correlation between records of past warmth and higher carbon dioxide concentrations," Huber said. "What it tells you is that it's not too difficult to push the climate system to a warm state. This event was a large release of a greenhouse gas. That's why it's a good analog for today's greenhouse-gas emissions, and it shows without a doubt that if you pump a bunch of greenhouse gas into the atmosphere, the planet warms.
"If you work out the numbers, it's almost identical to what we are expected to do over the next few hundred years."
While the climate models had predicted that researchers would discover the Arctic Ocean's freshwater past, the models have consistently underestimated by at least 10 degrees how hot the Earth would have been during that time, Huber said.
The models fail to explain another puzzling fact. The temperature difference between the North Pole and the equator today is about 45 degrees C. But the difference appears to have been much smaller during the Paleocene-Eocene Thermal Maximum time frame. Otherwise, it would have been too hot for vegetation to survive in equatorial latitudes.
"We still haven't explained why the tropics stayed cool," Huber said. "Somehow, we have to explain how you can warm the poles up to 23 degrees Celsius without having the tropics rise to at least 50 degrees, which is 10 degrees too hot for plants to carry out photosynthesis."
He said the implications are troubling because current models may be providing optimistic predictions.
"Today's models underpredict how warm the poles were back then, which tells you something disturbing — that the models, if anything, aren't sensitive enough to greenhouse gases," Huber said. "At the same time, it is possible that other forces in addition to higher-than-normal greenhouse gas concentrations were involved, otherwise we can't explain how the tropics maintained livable conditions.
"People have conjectured that polar stratospheric clouds or hurricane-induced ocean heat transport might have played crucial roles in amplifying polar heating, but much work needs to be done to prove this. Mechanisms that feed back onto global warming are poorly understood and not well represented into our current generation of models. This should be of great concern and will continue to be debated and explored in future research.
"Even people who describe themselves as global warming skeptics can accept the fact that massive changes happened in the past because research shows that climate change is natural. But the real point is that not only is climate change natural, but it's also easy to set in motion. All it takes is an increase in the concentration of greenhouse gases."
Scientists may explore several issues in future work, including research aimed at explaining specifically why the temperatures were so high 55.5 million years ago.
"There is a fundamental discrepancy between what kind of climate we expect to result from high atmospheric greenhouse gas concentrations, and what kind of climate really prevailed during these ancient epochs," Sluijs said. "We, hence, need to improve our climate models. An important question is, what was seasonality like in the Arctic? Was there an as-large temperature difference between summer and winter as there is nowadays?"
Source: Purdue University
I've researched this; though the cause is not entirely clear (it did happen 55 million years or so ago), it appears to have been due to a tectonically-caused sea level drop. The temperature rise follows the increase in methane/CO2 in the atmosphere. I'd have to find the references again; I should be able to.
Think Occam's Razor in this case, however.
They just don't know yet. Clearly their models -- the ones you folks so dearly rely on, are not even close to accurate.
Good scientific reporting will highlight where the uncertainties in the science are. Unfortunately, this tends to downplay the certainties. There are some certainties in the case of the PETM; one is that atmospheric concentrations of greenhouse gases rose markedly; two is that a large global temperature increase followed; three is that there weren't any other operative factors to cause the increase. You won't find anything contrary to this 1-2-3 story.
"There is no clearer evidence for greenhouse-gas-induced global warming in the geologic record."
"Appears", as in that's their guess. The truth is there is no hard evidence to prove what caused it. Again, this is a guess.
Good scientific reporting will highlight where the uncertainties in the science are. Unfortunately, this tends to downplay the certainties.
Lovely. They clearly state that the models are wrong, and you blow past that.
The reality is that typical news reporters, like in this story here, downplay the *uncertainties* (the writer buried the fact that the models are wrong deep in the story near the end) and instead emphasize only what agrees with their story angle.
I can only say that this article is a litmus test for how I consider your analysis in the future. This article clearly states the models are wrong. If you can't admit as much, and don't take that into account when doing analysis, then I must use that info when considering your conclusions.
"There is no clearer evidence for greenhouse-gas-induced global warming in the geologic record."
Yes, sir -- you started out with that conclusion. You read that the models were wrong. Then you ended up with the same conclusion you started with.
I see a flaw in the methodology, I believe!
ever heard of the HAB theory?
it says that the poles get too heavy from ice and then because of the earths wobble in it's rotation, inertia causes the poles to goto the equator and two new poles are born every 5000 - 7500 years.
http://www.habtheory.com/1/hab1.php
That is pretty wild stuff!
"Appears", as in that's their guess. The truth is there is no hard evidence to prove what caused it. Again, this is a guess.
The links above are for Geological Society of America sessions on the PETM. You will see that there are several suggested causes. Googling also found a paper discussing a change in the location of deepwater formation could have led to a bottom-water warming that could have destabilized the methane hydrates. One paper in the session looks at the possibility of a continental cause. One of the problems is that there is a lot of evidence; there isn't a conclusive interpretation of the evidence that puts one possible cause ahead of all the others.
Here's two more:
Uncorking the bottle: What triggered the Paleocene/Eocene thermal maximum methane release?
This interesting paper contains a critical statement:
"A widely accepted explanation for the CIE [carbon isotope excursion] is the sudden dissociation of 12C-enriched marine gas hydrates [6-8]. Such a major dissociation event would seem to require either a thermal [6] or mechanical [9] precursor. However, high-resolution oxygen and carbon isotope records have yet to demonstrate a significant warming immediately preceding the CIE (e.g. [10-12] despite recent assertions to the contrary [13] ; see below) and a geologic event of suficient magnitude to provide a plausible mechanical trigger has not been identified."
If you're curious about reference 13, it only says that a brief period of surface water warming may have triggered the release of methane hydrates which then caused the subsequent dramatic warming. Reference 13 does NOT say that the dramatic warming caused the release of the methane hydrates. In all "cause" scenarios, the trigger released the hydrates (or in the case of the comet hypothesis, the trigger the source of the carbon and the impact released more), and it was the massive amounts of greenhouse gases in the atmosphere that caused the dramatic warming.
Lovely. They clearly state that the models are wrong, and you blow past that.
"the models are wrong" is an inaccurate characterization of what the article actually talks about. The basics are indisputable; the models don't reproduce all of the various effects with acceptable accuracy. So they will work on better models so that they understand the effects of the dramatic warming better. There's a big difference between saying "the models are wrong" and "the models are inaccurate".
As an analogy, let's say someone is practicing archery. Their arrows are hitting the target, but they are only hitting the outer circle and are way off the bulls-eye. Your interpretation of the archer's effort would be that the archer's aim is wrong, because he's not hitting the bulls-eye. My interpretation would be that the archer's aim is correct, because he is hitting the target, and with repeated attempts incorporating slight adjustments, he will get closer to the bulls-eye. This is called "improving skill", and modelers talk about "improving the skill of the model" all the time. (Particularly for models that could be used to make predictions.)
This article clearly states the models are wrong. If you can't admit as much, and don't take that into account when doing analysis, then I must use that info when considering your conclusions.
I will also have to consider what I view as over-interpretation and exaggerated characterizations in our discussions. In essence you are trying for black/white, right/wrong, when the real picture is shades of gray and better/worse.
Finally, considering the quote: PETM research is hot now precisely because it is the natural analogue to the manmade situation occuring today. It would be a massive bombshell if someone showed that the dramatic temperature increase preceded the CIE.
There's sufficient resolution in the data to show that this is not what happened, and all of the researchers are working in the framework of trigger -- CIE -- major warming event. Feel free to try and prove me wrong on that point, but I've devoted enough time demonstrating it to you.
(More on the "Flipping Point" thread later today.)
The models fail to explain another puzzling fact. The temperature difference between the North Pole and the equator today is about 45 degrees C. But the difference appears to have been much smaller during the Paleocene-Eocene Thermal Maximum time frame. Otherwise, it would have been too hot for vegetation to survive in equatorial latitudes.
"We still haven't explained why the tropics stayed cool," Huber said. "Somehow, we have to explain how you can warm the poles up to 23 degrees Celsius without having the tropics rise to at least 50 degrees, which is 10 degrees too hot for plants to carry out photosynthesis."
The models consistently underestimate. The models fail to explain this. The models still haven't explained that.
My friend, I just don't see how you can skate past this and expect others not to be disturbed.
There's a big difference between saying "the models are wrong" and "the models are inaccurate".
And it depends on the meaning of "is", too. This is parsing words in the finest Clintonesque manner. The models do not give accurate answers. And they do not explain a lot of the evidence. Therefore, the models as they exist now, are wrong. Unreliable. Inaccurate.
One of the problems is that there is a lot of evidence; there isn't a conclusive interpretation of the evidence that puts one possible cause ahead of all the others.
As I said -- They Do Not Know.
Feel free to try and prove me wrong on that point, but I've devoted enough time demonstrating it to you.
You have not yet once even discussed the actual accuracy of the data. Not once.
So if you blow off this point, it will be a concession.
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