Posted on 09/28/2007 5:31:36 AM PDT by Red Badger
Carbon dioxide did not cause the end of the last ice age, a new study in Science suggests, contrary to past inferences from ice core records.
“There has been this continual reference to the correspondence between CO2 and climate change as reflected in ice core records as justification for the role of CO2 in climate change,” said USC geologist Lowell Stott, lead author of the study, slated for advance online publication Sept. 27 in Science Express.
“You can no longer argue that CO2 alone caused the end of the ice ages.”
Deep-sea temperatures warmed about 1,300 years before the tropical surface ocean and well before the rise in atmospheric CO2, the study found. The finding suggests the rise in greenhouse gas was likely a result of warming and may have accelerated the meltdown – but was not its main cause.
The study does not question the fact that CO2 plays a key role in climate.
“I don’t want anyone to leave thinking that this is evidence that CO2 doesn’t affect climate,” Stott cautioned. “It does, but the important point is that CO2 is not the beginning and end of climate change.”
While an increase in atmospheric CO2 and the end of the ice ages occurred at roughly the same time, scientists have debated whether CO2 caused the warming or was released later by an already warming sea.
The best estimate from other studies of when CO2 began to rise is no earlier than 18,000 years ago. Yet this study shows that the deep sea, which reflects oceanic temperature trends, started warming about 19,000 years ago.
“What this means is that a lot of energy went into the ocean long before the rise in atmospheric CO2,” Stott said.
But where did this energy come from" Evidence pointed southward.
Water’s salinity and temperature are properties that can be used to trace its origin – and the warming deep water appeared to come from the Antarctic Ocean, the scientists wrote.
This water then was transported northward over 1,000 years via well-known deep-sea currents, a conclusion supported by carbon-dating evidence.
In addition, the researchers noted that deep-sea temperature increases coincided with the retreat of Antarctic sea ice, both occurring 19,000 years ago, before the northern hemisphere’s ice retreat began.
Finally, Stott and colleagues found a correlation between melting Antarctic sea ice and increased springtime solar radiation over Antarctica, suggesting this might be the energy source.
As the sun pumped in heat, the warming accelerated because of sea-ice albedo feedbacks, in which retreating ice exposes ocean water that reflects less light and absorbs more heat, much like a dark T-shirt on a hot day.
In addition, the authors’ model showed how changed ocean conditions may have been responsible for the release of CO2 from the ocean into the atmosphere, also accelerating the warming.
The link between the sun and ice age cycles is not new. The theory of Milankovitch cycles states that periodic changes in Earth’s orbit cause increased summertime sun radiation in the northern hemisphere, which controls ice size.
However, this study suggests that the pace-keeper of ice sheet growth and retreat lies in the southern hemisphere’s spring rather than the northern hemisphere’s summer.
The conclusions also underscore the importance of regional climate dynamics, Stott said. “Here is an example of how a regional climate response translated into a global climate change,” he explained.
Stott and colleagues arrived at their results by studying a unique sediment core from the western Pacific composed of fossilized surface-dwelling (planktonic) and bottom-dwelling (benthic) organisms.
These organisms – foraminifera – incorporate different isotopes of oxygen from ocean water into their calcite shells, depending on the temperature. By measuring the change in these isotopes in shells of different ages, it is possible to reconstruct how the deep and surface ocean temperatures changed through time.
If CO2 caused the warming, one would expect surface temperatures to increase before deep-sea temperatures, since the heat slowly would spread from top to bottom. Instead, carbon-dating showed that the water used by the bottom-dwelling organisms began warming about 1,300 years before the water used by surface-dwelling ones, suggesting that the warming spread bottom-up instead.
“The climate dynamic is much more complex than simply saying that CO2 rises and the temperature warms,” Stott said. The complexities “have to be understood in order to appreciate how the climate system has changed in the past and how it will change in the future.”
Ping!!!!
Someone left the freezer door open a crack.....
This slice of the climate dynamic is actually rather simple. The temperature warms and then - roughly 800 years later - the CO2 rises.
Bush's Fault!!!!!!!!!!!!!!
““I don’t want anyone to leave thinking that this is evidence that CO2 doesn’t affect climate,” Stott cautioned. “It does, but the important point is that CO2 is not the beginning and end of climate change.””
This isn’t anything particularly revolutionary - other particulates like methane, Milankovitch cycles and continental plate movement have all played roles in ice age models.
Unlike other conservatives here, I do believe that man-made carbon output is accelerating climate change. An increased greenhouse effect and a change in the Gulf Stream could very well bring an early-onset ice age. Of course, I’m open to all interpretations and scientific criticism. That’s the way science works. I just hate it when people dismiss man’s effect on climate with prima facia B.S..
Man, and his penchant for changing things in his local environment, does have some effect on overall climate. Witness the Three Gorges Dam project in China, an environmental disaster bomb just waiting to go off. But the global effects on long range climate changes that produce great ice sheets and alternatively great warm spells is yet to be determined, in that, man has never had the amount of population that exists now, nor the advanced technology that he possesses now. IOW, we’ve never done it before, so it remains to be seen whether we are, or even can effect the global climate machine. It may just prove out to be that it is way beyond anything that we could actually pull off if we were of a mind to..................
Gee, that pic of the Sun big enough for ya?
Big Al.
This timing has been called into question by recently published research.
New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr. (PDF)
The initial assertion that increased CO2 heats the earth through increasing the greenhouse effect seems logical. But so does saying that a bug splat on the windshield will decrease your mileage on a particular trip. Logical, but there are hundreds of variables. What if the bug splat cuts visibility and you reduce speed by 5mph?
If historical CO2 levels are the result of previous warming and not the cause, which the function of the carbon cycle and research suggests. Then the man-made CO2 input cannot be equated to a rise in temperature in a linear fashion.
Indeed, although increasing the greenhouse would appear to increase temperature, not even that is proven. Increased precipitation and cloud reflectivity might indeed cancel it out.
It would all make for a very interesting read on a Sunday afternoon, if one side of the discussion weren't attempting to ruin my standard of living to further their unproven cause.
Which begs the question--where did the ENERGY come from?? There are only two sources of energy available---radioactive decay from isotopes (which, since they are a constantly decreasing fraction of the earth's mass, cannot contribute), and the sun. We already have evidence to account for changes in the photonic contribution of solar output to the prehistoric geological record (various isotopes from the solar wind)--so exactly how is this extra energy "coupled" into the earth from the sun???
My own thought is that there is an electromagnetic effect related the the sun's magnetic field. In current time, we have measurements showing that the sun's magnetic field has DOUBLED in historic time. How does that doubling effect the earth?? We KNOW from the laws of physics that ANY conductor moving in a magnetic field generates an electric current flow. The earth has LOTS of conductive systems (magma, the oceans--to pick what are probably the two largest), so there MUST be increased ohmic heating happening. How big is it?? Could THAT be the "missing link" in understanding what drives ice ages??
Lots of questions, but, thus far, I've been able to find ZERO answers. As far as I've been able to find out, this question has never been raised in the context of "global warming" so-called "science".
More directly, I go with undersea volcanism. They still really don’t know the seafloor, not much data on energy leaking out of the mantle.
Smoke doesn’t cause fire.
Your link relates to a surface-based study of the Antarctic and was published 6 months ago; now we need a study to incorporate both sets of data; a process like this can go on as long as the funding lasts.
And no solution comes forth, just the same old “Turn out the lights...”
Thank you for that paper. Still raising the bar I see :0)
It looks like the authors have found a probable miscalibration in gas chronology techniques, using a known Be10 peak and a better-than-previously characterised CH4 peak.
One of the probable results is that the Temperature-then-CO2 lag isn’t 800+- 600 yrs, but something smaller. So the Vostok lines should get closer together.
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