Geology and Paleoclimatology thread

[poitsplace]

Sept 20, 2009 18:28:35 GMT socold said:

I don't see what your point is. I said the ice albedo effect reduces with time but doesn't simply stop at the present day. Your picture and text backs that up.

Ok, for starters the antartic doesn't participate in the remaining albedo at anywhere close to even the wildest projected temperatures for doubling of CO2. In the unstable times between the glacial and interglacial periods the antarctic sea ice DID affect it. Also the remaining ice is in a colder part of the world and won't ever disappear entirely. While you MIGHT be tempted to say "but it's not in the sun" it's already out of the sun most of the time. It will still reform every winter and remain until at least some time in august, reforming again probably around october (assuming the wild projections that have never shown the slightest hint of coming true). The remainder is also in the extreme north...and the water reflects far more of the light. Add to this the fact that in the summer the albedo of the ice ALREADY falls due to water pools forming on the top.

There is very little ice albedo left to be affected...and there is no observational data supporting the silly notion that it will provide significant (we can't even seem to detect it) feedback even relative to the piddly amounts of ice that remain that remain.

Much of the land mass that wasn't covered in ice was instead covered in desert or tundra. Both of these types of terrain reflect significantly higher amounts of light than today's tree or grass covered landscapes. In the case of a desert, it reflects almost as much as ice. These deserts were much closer to the equator and therefore they would have also had a much more substantial impact on temperatures.

So where's the sensitivity/feedbacks? During the glacial periods we're talking about albedo changes totaling something OVER 10% of earth's entire energy budget (plus whatever the malankovich cycles did)...and not as some kind of pseudo-scientific "well if absorption goes up it won't emit the energy again" nonsense. That ice age difference was in light that was reflected straight out into space having never warmed anything.

[socold]

What about the substantial snow cover in the northern hemisphere in winter and spring and pushing back of the snowlines to earlier dates in a warming world?

Here's an example of a study attempting to attribute the necessary positive feedbacks required to explain past glacial maxima:
www.springerlink.com/content/gk06813540261861/

[Ratty]

Sept 20, 2009 23:25:40 GMT socold said:

What about the substantial snow cover in the northern hemisphere in winter and spring and pushing back of the snowlines to earlier dates in a warming world?

Here's an example of a study attempting to attribute the necessary positive feedbacks required to explain past glacial maxima:
www.springerlink.com/content/gk06813540261861/

From the abstract in Socold's link:
A series of experiments is performed using an atmosphere-mixed layer ocean model in which these changes in boundary conditions are incorporated either singly or in combination. The model used has been shown to produce a reasonably realistic simulation of the reduced temperature of the LGM (Manabe and Broccoli 1985b). By comparing the results from pairs of experiments, the effects of each of these environmental changes can be determined.

Anyone know how those experiments would have been conducted?

[icefisher]

Sept 20, 2009 23:25:40 GMT socold said:

What about the substantial snow cover in the northern hemisphere in winter and spring and pushing back of the snowlines to earlier dates in a warming world?

Here's an example of a study attempting to attribute the necessary positive feedbacks required to explain past glacial maxima:
www.springerlink.com/content/gk06813540261861/

IMO, you are flogging a dead horse. Climate sensitivity can vary. TOA forcings may have very low climate sensitivity while albedo changes may be high. Its would be all in where the watts are applied. . . .like in any circuit.

In fact if you look at clouds as an insulator the sensitivity factor could be orders of magnitude different.

[sentient]

Had a chance to go something fun this weekend and missed out on the fun here.

First, I should probably clear something up for Socold, and in one instance for certain, agree with a question he has asked.

What is patently clear is that we still are missing one of the crucial pieces of the puzzle, and that is just what causes abrupt climate changes. None of the forcings we have yet identified appear to be capable of the amazing speed and range of the changes very apparent in the proxy record. We are still missing something.

The very best proxy records we have regarding CO2 and its potential as a causative forcing are the Greenland ice cores. They extend into the Eemian and were the place where Dansgaard and Oeschger first identified the D-O events. As I mentioned in my long post earlier, not only do CO2 concentrations lag the abrupt warmings, only possibly coming into play during the last half of the cooling period (B and C classes), perhaps easing the transition to the cold state, which seems to happen anyway. The A classes are even more telling. If you look closely in some cases the concentrations decline right through an A class warming without a burp.

Many other meticulous studies show a lag for CH4 as well, with the carbon isotope signature suggestive of tropical responses to the warming, which happened BEFORE the methane appeared on the scene.

But Socold did ask what I think may be a very pertinent question, one difficult to answer from the proxy data to some degree. Could it have been the sun?

Many studies looking at isotopes of nitrogen and beryllium seem to suggest that this may indeed be the case, but these proxies alone contain too much natural noise as they are complexed with processes which degrade their signals such that we cannot say for certain if the sun changed very rapidly and was the cause.

Imprints of the 1500 year solar cycle can be seen in proxy data from right within the Holocene, the signal muted perhaps because we are already in the warm state, so not as much warming is possible.

We do not yet fully understand the complex workings of the sun, but the evidence suggests that when orbital dynamics are favorable for a shift from the cold to the warm state, the same signature as is found for the D-O events is the same for at least Terminations I and II.

What one is left to ponder is that something much stronger and much faster than any forcing we think we understand happens at these natural climate transitions. But when paired with favorable orbital dynamics, which themselves do not seem capable of performing these feats alone, this is sufficient to switch states from cold to warm, the orbital dynamics seeming to be strong enough to hold it for at least 10% of the time over the past million or so years.

Could it be the sun? Well, the sun never sits at the exact center of mass of the solar system, it too wanders about the center of mass on a regular cycle in pace with the orbital dynamics of the other large reservoir of mass in the solar system, the Jovian planets.

I have found a few studies which suggest that the effects of this on the plasma (a.k.a fluid) mass of the sun could, in some yet unidentified way, alter its circulation on this ~1500 year cycle, perhaps producing a strong, perhaps not so long lived, spike in solar irradiation. T he data I have found to date suggest this but are not of sufficient quality to confirm it. Perhaps yet.

One must keep many things in mind when attempting to unravel something as obviously complex as climate. Whereas we do not know that GHGs can produce a tipping point, we do know that it has never conclusively done so. One can find conjecture on both sides of this point, but as we all know, facts don't lie, just those that use them. If GHGs can cause a spike, how will we be able to tell it from a natural shift? This places us rather firmly in the arena of signal to noise.

And until someone can convince me, with solid data, that GHGs not only can do this, but have done it before (for certain), then being able to separate such a signal from the natural noise becomes the domain of the clever mathematician. Such a study I have not seen yet, but this would be met with healthy and mandatory skepticism commensurate with the knowledge that separating sub-noise signal from the noise itself failed to work in the recent financial mess, and was also achieved by remarkably similar mathematics.

Physicists are not the only ones hoping to expand the market for their services. At about the same time they expanded into the global warming market, they also expanded into the financial ones. Their application of chaos modeling did indeed have success we can accurately measure. Bailout anyone?

[poitsplace]

It annoys me that everyone keeps trying to pin it on essentially one cause. Its made worse by the fact that they're trying to pin it on something that obviously ISN'T the cause. Because of the wild fluctuations in the region between glacial and interglacial states I think it's pretty safe to assume that there are actually quite a few factors.

One of the great ironies in all this is that the current state of the "science" of climatology assumes absurdly high feedbacks and sensitivity when (in this state) feedbacks and sensitivity are low. Then they look at everything and say "that's not enough" and blame CO2...which is also quite clearly not enough (although CO2 can't really have pronounced affects in the climate's current mode)

The malankovich cycles set the stage for the ice ages. The tilt of the earth allows the sea ice (and glaciers) to expand greatly and then during the summer it's several degrees closer to the equator, increasing the effectiveness of the albedo affect relative to the northern hemisphere (which is where the greatest potential for ice sheets exists). In case nobody noticed here...the tilt of the axis causes ice albedo to b

With the expanded ice in place and ice albedo's feedback strengthened by the malankovich cycles, the natural climate swings would become quite a bit more potent. The climate continues various cycles driven by ocean and wind currents. The sun continues to cause minor fluctuations and eventually the currents go into cooling mode while the sun goes into hibernation and...then probably a volcano goes off or a desert spits out a huge cloud of dust.

That's finally the tipping point. Temperatures fall, ice sheets build, water vapor levels fall enough over europe/asia to form deserts...and the ice extends until SOMETHING stops it. Obviously this is a kind of a rough guestimation. Some things are more powerful than others and I'm not sure which those are. There's all sorts of odd interplay going on. The ice sheets start out in the north of europe/america and appaerently slowly migrate south...replaced by tundra and desert. I'm sure other oddball things happen as well.

Its a complex world and I'm not under any illusion that I understand a significant amount of it in a meaningful way. HOWEVER, I know that even during the warming period the climate didn't show half the warming rate necessary to get us over the next tipping point before we run out of fossil fuels...and at its extremely likely that the bulk (if not all) of the recent warm period warming was natural.

[socold]

Abrupt climate changes before the holocene are probably not forced but are triggered when forced gradual change reaching a certain point at which point something "happens". Eg in this case the hypothesis is a change in the rate of meltwater discharge from declining ice sheets causes a sudden change in ocean circulation that results in an abrupt cooling:

chriscolose.wordpress.com/2009/07/22/more-on-abrupt-climate-change/

As for the more gradual warming transition from glacial to interglacial, this is probably orbitally forced and amplified by feedbacks in the climate system (ice albedo, greenhouse gases, etc)

[stevenotsteve]

socold.
Eg in this case the hypothesis is a change in the rate of meltwater discharge from declining ice sheets causes a sudden change in ocean circulation that results in an abrupt cooling:

Mmm yes, saw the film 'The day after Tomorrow'.

Probably setting myself up for a fall here socold but can you give me a few examples of natural positive feedbacks that do not involve proxy data or models? I mean real life positive feedback that occurs on a regular basis here on planet earth and is not disputed. Apart of course from human failings.

[sentient]

Now if you guys really force me too, I will dig up the papers I have read within the past few months that more or less negate the meltwater thesis. The timings are not that coincident with the changes.

Can we test this? Child's play. Again, for the umpteenth time, we will look at the D-O events AND the major terminations which shift us into the interglacials.

You are at glacial conditions, perhaps 20C below global average temperatures of today in the Holocene. At the depth of a deep freeze, suddenly, in from a few years to perhaps a couple of decades, the global temperatures rise 1/3 to 1/2 of this difference. Obviously, this was a meltwater event trigger. And here is precisely why. Suddenly, without warning, at 20C below present, water inexplicably melts all on its own, on a 1,500 year cycle, causing massive meltwater pulses that warm the planet.

Now would you quit bogarting that joint? In a few puffs I can come to exactly that same conclusion. No problemo. Now what was this $hit called? Train wreck? This is some good $hit man!

Naw man, it was CO2! Oh yeah man, I can see it (exhale audibly). at the depth of the deep freeze, the massive increases in planetary life, only capable in your freezer, begins emitting lots of CO2! (inhale) Its beautiful man!

Once the THC levels in your bloodstream go down (no, not Thermohaline Circulation), you find out that the "A" D-O cycles happen independently of CO2. Blowhole in theory numero uno. "B" and "C" cycles DO happen in association with the temperature shifts, but at the latter half of the cooling cycle, NOT in concert with the abrupt temperature rises. And that is when you get it. Ice doesn't melt in your freezer just because it wants to, you have to unplug it and leave the door open. Blowhole in theory numero dos.

So this boils down to two of my favorite sayings: "I can explain it to you, but I can't understand it FOR you". And if that doesn't work, all I can tell you is that "Ignorance can be cured, but dumb? That's forever...."

[hunter]

Sept 22, 2009 19:15:39 GMT socold said:

Abrupt climate changes before the holocene are probably not forced but are triggered when forced gradual change reaching a certain point at which point something "happens". Eg in this case the hypothesis is a change in the rate of meltwater discharge from declining ice sheets causes a sudden change in ocean circulation that results in an abrupt cooling:

chriscolose.wordpress.com/2009/07/22/more-on-abrupt-climate-change/

As for the more gradual warming transition from glacial to interglacial, this is probably orbitally forced and amplified by feedbacks in the climate system (ice albedo, greenhouse gases, etc)

socold,
'Not forced but triggered'?
You can clarify that, I hope?
Yet in those much more dramatic changes, the climate never ran away, tipped over, etc.

[stevenotsteve]

Probably setting myself up for a fall here socold but can you give me a few examples of natural positive feedback's that do not involve proxy data or models? I mean real life positive feedback that occurs on a regular basis here on planet earth and is not disputed. Apart of course from human failings.

Mmm what, no comment?

Just the models then.

Ok. not true then socold and I guess you agree by your lack of denial that positive feedback's are really just AGW BS.

[nautonnier]

Sept 22, 2009 1:36:05 GMT sentient said:

<<<SNIP>>>

Could it be the sun? Well, the sun never sits at the exact center of mass of the solar system, it too wanders about the center of mass on a regular cycle in pace with the orbital dynamics of the other large reservoir of mass in the solar system, the Jovian planets.

I have found a few studies which suggest that the effects of this on the plasma (a.k.a fluid) mass of the sun could, in some yet unidentified way, alter its circulation on this ~1500 year cycle, perhaps producing a strong, perhaps not so long lived, spike in solar irradiation. T he data I have found to date suggest this but are not of sufficient quality to confirm it. Perhaps yet.
<<<<SNIP>>>

You should look at papers from Rhodes Fairbridge and others who hypothesized that the epitrochoid orbital motion of the Sun around the Solar System barycenter led to effects on the angular momentum and differential rotation of the layers of the sun causing the cycles in climate. The barycenter moves as the position of the major planets particularly Jupiter and Saturn orbit but is also affected by the orbits of the nearer smaller planets.


This was discussed at heated length on the 'old board' here and despite a research paper from NASA showing that the sun's activity did appear to statistically link to the orbits of the major planets, the critics called the hypotheses 'no better than astrology'.

See

Rhodes Fairbridge paper

www.griffith.edu.au/conference/ics2007/pdf/ICS176.pdf

and

Can origin of the 2400-year cycle of solar activity be caused
by solar inertial motion? - I. Charva tova

www.ann-geophys.net/18/399/2000/angeo-18-399-2000.pdf

[sentient]

Here is a paper describing the 1500 year solar cycle during the Holocene. The lead author is Gerard Bond, the noted discoverer of the "Bond Cycle" (bundled D-O events during which the coldest see the release of armadas of icebergs in the North Atlantic):

www.seas.harvard.edu/climate/pdf/bond_2001.pdf

Here we have a landmark paper by another legend in the paleoclimate field Eduardo Bard with co-author Martin Frank:

www.seas.harvard.edu/climate/pdf/bond_2001.pd

Now the above paper has a few detractors championing the NAO.

And another for the Younger Dryas:

cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf

And here is a nice one on the Holocene climate variability:

www.geo.uni-bremen.de/geomod/staff/mschulz/reprint/Sarnthein_etal_Boreas03.pdf

And another by Singer and Avery from their book:

ff.org/centers/csspp/library/co2weekly/20051103/20051103_26.pdf

Its getting alte and I have a long rest of the week, so signing off. Others might try various search strings on google.scholar.com using combinations of 1500 year, solar cycle etc.

[michaelb]

Not sure if this is the right section to place this link but thought it very interesting It comes up with an answer to the question over who—or what—caused an increase in CO2 emissions thousands of years ago . I recently read that humans caused the rapid increase which I thought a bit over the top but now Swiss scientists have an answer.

www.swissinfo.ch/eng/front/Man_not_to_blame_for_early_carbon_emissions.html?siteSect=105&sid=11260665&cKey=1253778369000&ty=st

[sentient]

Enjoy:

www.clim-past-discuss.net/volumes_and_issues.html