Posted on 10/27/2003 8:38:20 AM PST by cogitator
Evidence Of Global Warming In The Past Supports Greenhouse Theory
Scientists have filled in a key piece of the global climate picture for a period 55 million years ago that is considered one of the most abrupt and extreme episodes of global warming in Earth's history. The new results from an analysis of sediment cores from the ocean floor are consistent with theoretical predictions of how Earth's climate would respond to rising concentrations of greenhouse gases in the atmosphere.
The new study, led by James Zachos, professor of Earth sciences at the University of California, Santa Cruz, will be published online by Science Express on October 23, and will appear in a later print edition of Science magazine.
The researchers analyzed sediments deposited on the seafloor during a period known as the Paleocene-Eocene Thermal Maximum, when a massive release of heat-trapping greenhouse gases is thought to have triggered a runaway process of global warming. Climate theory predicts that the increase in greenhouse gases would have caused temperatures to rise all over the planet, with greater increases in sea surface temperatures at high latitudes than at low latitudes.
Zachos and a team of researchers at UCSC and several other institutions have now obtained the first reliable estimates of the change in tropical sea surface temperatures during this period. When combined with existing records of sea surface temperatures at high latitudes, the findings fit well with the predictions of computer simulations based on current climate theory.
The study provides important backing for the climate models that scientists are using to predict the effects of the current rise in atmospheric carbon dioxide due to industrial emissions, Zachos said.
"The predictions from the models seem to be consistent with the geologic record, so I'd say greenhouse climate theory is alive and well," he said. "People have raised questions about how accurate these models are in terms of handling heat transport in response to rising greenhouse gases, but this study indicates that the climate people have got it right or close to right."
The Paleocene-Eocene Thermal Maximum, starting about 55 million years ago and lasting about 150,000 years, is marked by dramatic changes in the fossil record of life in the ocean and on land. Average global temperatures increased by about 5 degrees Celsius (9 degrees Fahrenheit). The increase in sea surface temperatures at high latitudes was 8 to 10 degrees Celsius, and the new study shows a 4- to 5-degree Celsius increase in tropical sea surface temperatures.
"This event is the best example of greenhouse warming in the geologic record, and for the first time we have been able to document the climate response on a relatively broad planetary scale, from the tropics to polar latitudes," Zachos said.
The temperature estimates were derived from chemical analyses of the shells of microscopic plankton preserved in the seafloor sediments. The chemical composition of the plankton's calcite shells reflects the temperature of the water in which they were formed. A key measurement examined in this study was the ratio of magnesium to calcium, which increases exponentially with the temperature at which the shells formed.
"The ratio of magnesium to calcium in seawater is relatively constant over the timescale of this event, so the ratio in the shells is really only sensitive to one variable, the calcification temperature," Zachos said.
UCSC graduate students Michael Wara and Steven Bohaty performed most of the chemical analyses. The researchers analyzed sediment cores recovered from a site called Shatsky Rise in the tropical Pacific during an expedition of the ship JOIDES Resolution in 2001 (Leg 198 of the Ocean Drilling Program). The cores provided a complete sequence of deposits representing the boundary between the Paleocene and Eocene epochs.
"There aren't many places in the Pacific where you can recover sediments of this age in which the fossils are not so recrystallized that they've lost their original geochemical signatures," Zachos said.
ODP Leg 198 and a complementary drilling expedition in the Atlantic earlier this year (ODP Leg 208) were designed to test the leading explanation for the Paleocene-Eocene Thermal Maximum, which attributes it to a massive release of methane. Methane, a potent greenhouse gas, accumulates in frozen deposits known as clathrates found in the deep ocean near continental margins and also in the Arctic tundra. For reasons that remain unclear, the clathrates suddenly began to decompose, releasing an estimated 2,000 gigatons (2 trillion tons) of methane.
Once released, the methane would have reacted with dissolved oxygen in the ocean to produce carbon dioxide, another greenhouse gas. Large amounts of both carbon dioxide and methane would have entered the atmosphere, raising temperatures worldwide.
In addition to Zachos, Wara, and Bohaty, the coauthors on the Science paper are Margaret Delaney, professor of ocean sciences at UCSC, Maria Rose Petrizzo and Isabella Premoli-Silva of the University of Milan, Amanda Brill of the University of North Carolina, and Timothy Bralower of Pennsylvania State University. Bralower and Premoli-Silva were co-chief scientists on ODP Leg 198.
ROTFLMAO! You really fell for that one! That "concern" is all about making money on methane hydrate by subsidizing it with Kyoto price fixing, or do really think that Julie and Susan Packard are competent energy investors? Yup, just sprinkle a few grants into the academic maw and they'll get the old whispering campaign going. Maybe there's a reason Susan's husband is the chief scientist in charge of spending the $130 million they (along with Exxon/Mobil) sunk into a federally subsidized public private research partnership at Stanford on that very topic?
What might happen if they disturb more than they recover and that hydrate bubbles to the surface? After sinking in all that money will they just pack up and go home to save the environment? Will they be subject to ANY oversight or liability?
Not a chance! They're members in good standing of the NRDC, and put a few dollars into protection money with a fat donation to The Energy Foundation. That means they enjoy the exemption from ALL liability pursuant to Clinton EO 12986 which indemnified the IUCN from any environmental liability. Seeing as they don't know how to run Hewlett Packard, perhaps Susan and Julie had to find (fund) a safe way to stay in clover? There's nothing quite like enviroracketeering for a safe investment!
The hucksters, the scam artists, once again bullshi****g the ignorant the clueless.
Lots of heat (pun intended) but no light whatsoever!
First of all, let me be among the first to suggest that the world's total economic output for the next 600 years be used to solve the "problem".
It's for the children!
99.999% of people have no concept whatsoever of how far it is from the Sun to Pluto. None. Zero. Zilch.
I've always been of the opinion that one of the greatest aids to teaching science would be to build several "Solar Systems" across the United States (of necessity limited to wide open areas). Build them to scale, and start with the "Sun" being a meter in diameter. How far away would Pluto be? What size? Anyone?
That improves the fit they can imagine for just the below 1000 ppm part. However, it also means the largest variation they can expect from present levels, to have any effect, is on the order of on more factor of 2. And we can measure the wattage from modest CO2 concentration changes. It is on the order 1-2 watts per square meter, maybe 3 being extremely generous. And that just isn't enough to account for more than 0.5C warming.
In other words, they can imagine a narrower portion of the scale being the only part that matters. That improves correlation fit with long time data. But it also caps the size of the effect to be expected, overall, on physical grounds (not enough power to overcome re-radiated light at a higher temperature). Too low to account for the size changes they want it to.
It is also striking on your graph that the largest effects seem nearly periodic but with an enourmous period of 140 to 150 million years. Lasting for variable lengths of time, but only a short portion of the overall graph. Now, people may not realize it but when you start talking about numbers that large for the time, the solar system can no longer be considered as an isolated system.
The proper motions of stars in the immediate neighborhood goes as high as 140 km per second (e.g. Barnard's Star). A more typical value is 30-50 km per second. What that means is if you divide the "years" by 2,500 to 10,000 you get LY traveled. Within 10 LY there are only a small number of stars, and we can look and see that encounters are unlikely. (E.g. Bardnard's will get as close at 3.8 LY in another 10,000 years). Which means on a time scale as long as ordinary ice ages, 10,000 to 100,000 years, we can consider the solar system to be effectively an isolated system.
But increase the time to 140 to 150 million years, and the proper distance traveled by typical stars rises to something like 10,000 to 25,000 LY. There are "thick disk" stars that eccentrically go above the galactic plane and back below it again, for instance, with speeds of ~50 km per second in the middle part of their path, and maximum deviations from that plane of 3500 to 5000 LY. Even if you estimate mean speed in the "z" direction at half the 50 km per second figure, each such "thick disker" goes out and comes back past the plane with a period on the order 100 million years.
Other processes come into play on such time scales, too. Sirius A is estimated to be only 300-500 million years old. It's white dwarf companion was a giant star at some previous time on the same rough scale, since giants only last about a billion years from nuclear ignition to "still hot but no fusion fuel left" remnant.
To expect every cause of variation on hundred million year time scales to be internal to the earth's atmospheric system, or even to the earth-sun system, would be "astronomically naive". Some encounters might be ruled out by continued stability of planet orbits, and some effects would have characteristic time scales for which things in your data would probably be too long. But it is a leap to exclude it, once the years looked back gets above even 25 million. Stars are moving thousands of LY over those time scales.
I'd be much more likely to be convinced if the article had actual data in it, instead of conclusion claims.
I think it's supposed to be combined with the phony illness/breast implant articles for the headline:
"Reduction In Massive Breast Implants Causes Global Warming" Since the elimination of silicon breast implants in 1992, scientific data now proves global warming is on the rise... Reasearchers at the Pamela Anderson Clinic for Inflated Frontals (PACIFic) have proven that...
Quote mining alert. You didn't even quote the whole sentence. "There aren't many places in the Pacific where you can recover sediments of this age in which the fossils are not so recrystallized that they've lost their original geochemical signatures," Zachos said. Your misquotation changes the meaning of the original.
A couple of observations on your graph. First, making out the best possible case for the warming crowd (not that I buy it, but it is the right way to investigate things to make the other guy's case as strong as possible), you might imagine no correlation for anything above 1000 ppm on the left scale of your graph, say because the atmosphere gets saturated at that point. I.e. the sky is "closed" from below in CO2 frequencies, and any additional amount is way off into diminishing returns.
That is the case long before you ever get to 1000 ppm, it is true for the current atmosphere (extinction of 15micron radiation occurs within the first 100ft of the atmosphere.
That is why radiative forcing from CO2 absorption wavelengths is proportional to the log of concentration rather than a linear function, and absorption at the CO2 spectrum under the Earth's blackbody curve, at a mere 300ppm, is saturated.
The HITRAN calculation for CO2 absorption for a doubling of CO2 concentration from current levels is instructive and indicative of the problem that the global warming crowd face.
In the presense of water vapor, the spectrum broadens substantially but absorption/emissivity remains proportionate to the log of concentration.
The reality is a doubling of atmospheric CO2 concentration over current levels, that the UN/IPCC "story line" pretends, even if were true, could not induce significant temperature change whatever its source.
Climate Catastrophe, A spectroscopic Artifact?
"It is hardly to be expected that for CO2 doubling an increment of IR absorption at the 15 µm edges by 0.17% can cause any significant global warming or even a climate catastrophe.
The radiative forcing for doubling can be calculated by using this figure. If we allocate an absorption of 32 W/m2 [14] over 180º steradiant to the total integral (area) of the n3 band as observed from satellite measurements (Hanel et al., 1971) and applied to a standard atmosphere, and take an increment of 0.17%, the absorption is 0.054 W/m2 - and not 4.3 W/m2.
This is roughly 80 times less than IPCC's radiative forcing.
If we allocate 7.2 degC as greenhouse effect for the present CO2 (as asserted by Kondratjew and Moskalenko in J.T. Houghton's book The Global Climate [14]), the doubling effect should be 0.17% which is 0.012 degC only. If we take 1/80 of the 1.2 degC that result from Stefan-Boltzmann's law with a radiative forcing of 4.3 W/m2, we get a similar value of 0.015 degC."
Ocean Burps and Climate Change
This provides the research background and data/evidence that there was a large methane release at this time, and also discusses why other possible causes of the observed effect (a major 12C/13C ratio shift) aren't as plausible as the methane hypothesis.
I found this Web page very interesting, informative and understandable: until I read the article that led off this thread, I'd never heard of the Paleocene-Eocene Thermal Maximum.
Note - nothing in this actual study is addressed to a particle of this. It is taken as established by previous studies.
"Its effect on the low-latitude surface ocean has remained unresolved due to the absence of reliable sea surface temperature (SST) records from the tropics."
Meaning, no reliable data. No data? No reliable data, anyway.
"Zachos et al. now present an SST reconstruction based on a sediment core from the tropical Pacific Ocean."
55 million years ago. India is an island, Australia is part of Antarctica, etc.
"After measuring both oxygen isotopes and Mg/Ca in the skeletons of long-dead surface-dwelling foraminifera, they produced a record of temperature and salinity and found that SSTs rose by approximately 5°C"
Science Express abstract rather than journalist spin.
The whole ocean, including deep ocean, supposedly got 5 C warmer. The cold surfaces in the upper lattitudes supposedly got more than proportionally warmer. For which the measurements are...
That the temperatures seen by these people in their cores matched the whole ocean numbers.
And the reason to believe the upper lattitude figure, twice as high, is? Not in this study.
Connection of any of the above to the cause of the past warming? Nothing in this study. To scale of effects traceable to greenhouse. Nothing in this study.
The great success of the climate models is supposed to be that they say "if'n it gets a whole lot warmer, that chilly icewater up 'round Greenland won't be so chilly. Meanwhile, warm tropical waters will be warm and tropical."
Therefore, anything a global warming modeler says about anything must be true. You heard it here.
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