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Post by sentient on Nov 6, 2009 4:46:06 GMT
No worries mate
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Post by poitsplace on Nov 6, 2009 5:30:03 GMT
Heh, my point wasn't that the glacial/interglacial changes were initiated by water vapor and geography...its that the current layout of the continents leads to changes in the distribution of water and the forms that it takes...leading to times when feedback is so high that the intervening temperature ranges are highly unstable.
If the landmasses were broken up and spaced out a bit more and the arctic/antarctic were open oceans, the impact from the variations in orbit, wobble, etc would be less pronounced and the world would probably be a bit warmer. Obviously right now it tends toward being colder than usual and suffers from wild fluctuations in temperature.
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Post by donmartin on Nov 6, 2009 7:07:14 GMT
Sentient, I don't think I understand. If CO2 concentration maxima corresponds to the middle or end of a glaciation, how would it ameliorate the occurrence of glaciation, if by ameliorate you mean delay?
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Post by sentient on Nov 6, 2009 17:58:17 GMT
donmartin, you need to distinguish between Dansgaard-Oeschger oscillations, also referred to as stadial/interstadials and the ice age/interglacial cycles. Whereas they both have the same characteristic sawtooth shapes, the D-O/stadial/interstadial oscillations occur wholly within the much longer ice age/interglacial cycles.
At present D-O oscillations occur on the average timeframe of 1,500 years, whereas since the MPT the ice age/interglacial cycle has been on roughly the 100,000 year clock, meaning you can have quite a few D-O events within a full glacial cycle.
So, to answer your question, Sole et al found that maxima in atmospheric CO2 concentrations occurred during the middle part or the end of the cooling period of the B and C class 1,500 year D-O oscillations, NOT during the middle or end of a 100,000 year glacial cycle.
The implication is rather profound, particularly when one looks at the sheer speed with which interglacial conditions normally relax back to the glacial state, the current half-precessional age of the Holocene and CO2 concentrations. If 9 out of the last 13 D-O oscillations evinced a far more gradual decay back to glacial cold, and these were the 9 which correlated with CO2 maxima towards the middle or end of the cooling period (within the ~1,500 year cyclicity) (the other 4 A types not showing any correlation with CO2 and relaxed quickly back to glacial cold), then it could very well be that the ramp-up in CO2 concentrations that has accompanied the industrial age might be just what is needed to slow the onset of the next glacial state, or perhaps to "skip a precessional beat".
If it seems to work for the much shorter D-O oscillations, would it work for the interglacial to ice age transition? And in particular, since we are at an eccentricity minimum, just like during MIS-11, which appears to have skipped a precessional beat all on its own, increased anthropogenic emissions of CO2 might astonishingly be the very prescription we need to do it again. In other words, we may very well need as much CO2 as we can reasonably get into the atmosphere as an insurance policy against the imminent end of the Holocene which just happens to be due right about now.
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Post by spaceman on Nov 6, 2009 21:52:07 GMT
very good sentient...
so I have a question: The tilt of the earth right now orbits around the sun so that one pole is facing the sun then the other, producing a change in seasons. I saw a spinning top that orbited round , much like the earth does now, then it switched so that the top part was facing away as it orbited around. Does that happen in these cycles? I tried that with a soda cup, surprisingly it rotated better with one pole facing away all the time.
The sub spayed itself with peroxide before it dropped into the lake. First law of interplanetary travel: nooo contact. Since, I haven't seen or heard anymore about it. Same with LIGO
I got the connection with the red and the blue. The other... maybe I need an ark or a planet with an orbit that doesn't wobble or wiggle.
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Post by sentient on Nov 7, 2009 1:20:47 GMT
spaceman If I understand you correctly the difficulty you may be having is in understanding our orbital dynamics. Although I rarely recommend something from Wikipedia for obvious reasons, this is actually a fairly good discussion of the subject: en.wikipedia.org/wiki/Milankovitch_cycles
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Post by spaceman on Nov 7, 2009 20:49:56 GMT
sentient,
The info is good. I can see in my mind's eye the orbit moving closer and further away, along with the tilt change ,changing the dynamics of the amount of energy the earth receives. So let me see if I can rephrase it. Right now the earth is rotating on it's axis at 23.44 deg or so and orbiting in a nearly circular orbit around the sun. So the movement around the sun, if you put a pin thru the earth so that the point would be on a solid surface. Since I'm in the northern hemisphere it is easier for me to visualize. So the .. hum I don't have a term for it.. the seasons change back and forth because the top part of the pin looks toward the sun, then looks away (bottom part does the same). When, IF, this change occurs, the angle would stay the same 23 deg. but the top half, the northern hemisphere, in this case, would go into winter come around toward spring, then move back towards winter. The southern hemisphere would be in summer, move towards fall, then back to summer. Or it could be reversed. That's what I saw. I was wondering if that could happen to the earth's fixation with the sun. I mentioned the cup because if you stand it on edge and rotate it and move it around an imaginary sun, it rotates much better than moving it like the earth is now moving around the sun. Moving the cup like the earth now moves you have to slide it to keep it going. ( a glass will do as well)
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Post by sentient on Nov 8, 2009 1:03:54 GMT
Now, spaceman, all sorts of things can change here. The tilt on our axis can go to 24.5 degrees, about another degree over in tilt, or it can swing back to 21.1 degrees, essentially raising the arctic and subarctic circles closer to the poles. Another degree of tilt to 24.5 will push the arctic circle south a touch.
Since our orbit about the sun is as close to circular now as we are likely to ever be (eccentricity minimum), then the swings between summer and winter are more or less equal. But if we have winter at near aphelion or near perihelion, further or closer to the sun during one or the other, obviously, since we are closer to the sun, we receive slightly more energy. So the obliquity and eccentricity can vary the amount of radiation we receive, and where we receive it, by certain quantities depending upon where the different age cycles place us at any time in our orbital oscillations.
The combination of these cyclicities produces the orbital precessional index of about 23,000 years.
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Post by spaceman on Nov 9, 2009 1:16:13 GMT
I couldn't explain this very well to real live people either. And with props.. Could a situation where one day on Dec 21 or 22 and it's winter as it should be. The days start out getting longer as they should be until spring. Then instead of the days continuing to lenghten, they start to get shorter again until summer, then they start to get longer again till fall. In the northern hemishphere we would have 2 winters and 2 springs in the same year. The southern hemisphere there would be 2 summers and 2 falls.
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Post by donmartin on Nov 10, 2009 18:27:15 GMT
Does that mean that on the equator there would be 2 springs, 2 falls, 2 summers, and 2 winters?
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Post by itsthesunstupid on Nov 10, 2009 18:57:49 GMT
I couldn't explain this very well to real live people either. And with props.. Could a situation where one day on Dec 21 or 22 and it's winter as it should be. The days start out getting longer as they should be until spring. Then instead of the days continuing to lenghten, they start to get shorter again until summer, then they start to get longer again till fall. In the northern hemishphere we would have 2 winters and 2 springs in the same year. The southern hemisphere there would be 2 summers and 2 falls. Earth vertigo?
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Post by northsphinx on Nov 10, 2009 19:44:23 GMT
www.isogklima.nbi.ku.dk/nyhedsfolder/uk_with_dk_companion/20080622_ngrip/"The ice age ended in one year “We have analysed the transition from the last ice age to our current warm interglacial period and there is such an abrupt change in climate that it is as if someone just pushed a button”, explains Dorthe Dahl-Jensen, professor at the Center for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen. The new data from the ice cores show that the climate shifted from one year to the next. The ice’s annual layers have been analysed at very high resolution for a series of substances, each of which tells something about the climate in its own way. " CO2? I dont think so.
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Post by stevenotsteve on Nov 11, 2009 0:11:13 GMT
socold. When you really think about it, CO2 probably did essentially nothing and none of the precariously placed, high feedback conditions remain." This is really an example of the void between realists and skeptics concerning climate science.
There never were any precariously placed, high feedback conditions, they are just GIGO outputs from flawed models. 71% of the world is covered in water, 0.03% of the atmosphere is CO2. It does not take a rocket scientist to work out which one would have more effect on the climate.
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Post by sentient on Nov 11, 2009 4:15:58 GMT
This is why I am so astonished when I see long and intricate discussions here, and most everywhere else for that matter, on this trend or that, why this is so, why this isn't. It reminds me very poignantly of Crocodile Dundee's one-liner "It's like two fleas arguing over who owns the dog they are riding on". Even one of the shortest oceanic cycles we see, El Nino, takes far longer to evolve and has far less effect than the dramatic changes we see with astonishing clarity in the proxy records, including the recent proxy records. The change back to glacial conditions of the Younger Dryas occurred just a few thousand years before we graduated to the written word, just 8,000 years before the Iron Age kicked off.
Climate change happens in nature with astonishing swiftness. And with equally astonishing frequency. Often, we see intense arguments over 0.5C to 2C in a century and what belief structures accompany why. Such things barely qualify as noise in the paleoclimate record, it beggars the imagination to even suggest this is a signal that can even be measured against such noisy backdrops.
Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. For example, roughly half the north Atlantic warming since the last ice age was achieved in only a decade, and it was accompanied by significant climatic changes across most of the globe. Similar events, including local warmings as large as 16°C, occurred repeatedly during the slide into and climb out of the last ice age.
Large, abrupt climate changes have affected hemispheric to global regions repeatedly, as shown by numerous paleoclimate records (Broecker, 1995, 1997). Changes of up to 16°C and a factor of 2 in precipitation have occurred in some places in periods as short as decades to years (Alley and Clark, 1999; Lang et al., 1999).
states the National Research Council in 2002 (Abrupt Climate Change - Inevitable Surprises).
One does have to wonder about the state of of our ability to process data when those that question the efficacy of a predicted anthropogenic source of 1-2C are termed "deniers", when those that do the labeling do their darnedest to ignore the canvas upon which this will supposedly be painted.
But then again, socialist/democrats are now blue and republicans are red. And as widely accepted as this piece of pretzel logic is, getting lost in the climate change weeds makes perfect sense. The Theory of Inverse Reality instructed me to replace "nonsense" with "sense" in the previous sentence. If I hadn't told you this, how many would have guessed it without being told?
An enormous amount of research has been done which relates orbital variations to the larger changes, but by the same token, they just don't seem to provide the forcing that is necessary to switch our temperature state from glacial cold to interglacial warmth, and especially so over such incredibly short time intervals as have been found throughout the proxy records.
Assume, for a moment, that CO2 is the agent provocateur, and that the next climate change will be on us. If this is so, then we have a problem that is almost unimaginable in size. We must find and quench natural sources of CO2 that can erupt with such speed that they can turn the climate on and off like a light switch and go almost completely undetected in the paleoclimate record. Oh we see the grand swings of CO2 concentration, after the warming/cooling events, but this should be no concern to flexible intellects capable of successfully redefining Red and Blue states.
But something IS turning climate on and off like a light switch. And we just saw it switch off recently. Where, or more properly when, is Solar Cycle 24? Or, alternatively, what other source of sufficient energy and orbital dynamics, in or perhaps near the solar system, can switch our climate on and off like a light switch with such remarkable regularity and range of swings?
If it isn't the sun, and it isn't GHGs, then what could it possibly be? Intergalactic shipping tailwash?
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Post by poitsplace on Nov 11, 2009 10:04:07 GMT
socold. When you really think about it, CO2 probably did essentially nothing and none of the precariously placed, high feedback conditions remain." This is really an example of the void between realists and skeptics concerning climate science. There never were any precariously placed, high feedback conditions, they are just GIGO outputs from flawed models. 71% of the world is covered in water, 0.03% of the atmosphere is CO2. It does not take a rocket scientist to work out which one would have more effect on the climate. The precariously placed, high feedback conditions I referred to (and that Socold replied to) were those of the glacial maximum. During the glacial maximum a significant portion of the european ice sheet was sitting on the continental shelf and a huge desert stretched across asia. Just add warmth and *poof* the oceans surge, the ice sheet melts and the desert explodes first into a grassland, then a forest. Feedbacks NOW however...are ever-declining in the warming direction ...until some stupid high temperature we could never reach without having the feedbacks in the first place.
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