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Post by poitsplace on Nov 1, 2009 23:01:14 GMT
I was pondering the transition between glacial and interglacial periods and it suddenly occurred to me. Due to the conditions at the glacial maximum...many of the ice sheets that form are essentially sitting in what will be water once the meltwater pulse hits, melting the ice sheets that much faster which raises sea levels, which melts the ice sheets...etc. en.wikipedia.org/wiki/Last_Glacial_MaximumIn fact, the dryness of the glacial maximum actually causes MOST of the ice to be deposited in these low lying regions and the down-wind regions in eastern europe and asia turn into dusty deserts (dust does go up at the glacial maximum according to ice cores). By the time the Milankovich cycles swing around to warming mode we have a world of deserts and dirty, low-lying ice. Once the melt starts... The oceans expand, melting and carrying off a huge portion of the ice and replacing the dirty ice (still higher albedo than a desert) with oceans that absorb most of the light that hits them. The deeper oceans also bring vast amounts of heat from the equator to the arctic (since its no longer land locked) The deserts green (decreasing their albedo very quickly) Water vapor content in the atmosphere skyrockets...once again tying up as much as 30% of the earth's energy budget to be released at night. So let's see, probably a 10% change in albedo of the earth, massive ocean circulation changes, reconnection of the arctic ocean, water vapor moderating what would otherwise be huge swings in temperature. When you really think about it, CO2 probably did essentially nothing and none of the precariously placed, high feedback conditions remain. |
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Post by sigurdur on Nov 2, 2009 0:51:40 GMT
Outside of a slab, co2 is a minor minor player in any shift in climate.
1. The sun will cause a shift. I know there are opposite opinoins, but as a farmer, I have come to understand just what the sun does and doesn't do. Looking at long term yeild records, and this is actually quit interesting, they do flucuate with the sun's cycle. I found this to be very amazing in fact.
2. The hydrologic cycle. This baby is the grandfather of responses and what drives our climate in reaction to the sun.
Just my humble opinion.
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Post by boxman on Nov 2, 2009 1:06:29 GMT
Outside of a slab, co2 is a minor minor player in any shift in climate. 1. The sun will cause a shift. I know there are opposite opinoins, but as a farmer, I have come to understand just what the sun does and doesn't do. Looking at long term yeild records, and this is actually quit interesting, they do flucuate with the sun's cycle. I found this to be very amazing in fact. 2. The hydrologic cycle. This baby is the grandfather of responses and what drives our climate in reaction to the sun. Just my humble opinion. Sun is only a small part of what drives the climate. Milankoivich cycles are definitely the main driver when you look at longer timescales. Glacial and interglacial periods all matches up with the oribital changes and the axial tilt of earth. Sun does seem to be a driver in shorter timescales though. |
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Post by socold on Nov 2, 2009 17:03:29 GMT
"So let's see, probably a 10% change in albedo of the earth, massive ocean circulation changes, reconnection of the arctic ocean, water vapor moderating what would otherwise be huge swings in temperature. 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.
Models are too uncertain to make conclusions about what co2 can do, but vague whims can be used to form conclusions like "CO2 probably did essentially nothing"
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Post by icefisher on Nov 2, 2009 19:36:20 GMT
Models are too uncertain to make conclusions about what co2 can do, but vague whims can be used to form conclusions like "CO2 probably did essentially nothing" To build a model that is going to work you have to believe you understand natural variation. If you do not believe you understand natural variation, spending years on building a model is tantamount to spending years building a boat that you don't know will float. Thats why all models agree. . . .its like a Brazil nut convention, only Brazil nut nuts show up. |
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Post by stranger on Nov 2, 2009 20:26:29 GMT
Outside of deserts, the "ground level atmosphere" generally contains 15,000 to 40,000 water vapor molecules per million gross molecules. Along with 380 molecules of carbon dioxide. Which have the same "greenhouse gas potential" as another 55 or so H2O molecules.
It is always amusing to see people trying to make the 55 equivalent H2O molecules do more work than the 15,000 actual H2O molecules.
But a Joule is a Joule. You may herd a few into a confined space, resulting in local heating. That works quite well in the passenger cabin of my truck, especially in the summer. It works almost as well when the summertime humidity hits 100% plus! But you cannot make one Joule into ten, or a hundred, or a thousand.
Unless you have a measurable source of new energy, you must eventually have a zero sum result. When I open my truck door, the temperature inside and outside soon equalizes. When a waft of dry air floats in from the west, the area cools down. So yes, we have "weather." Which is constantly changing.
But we do not have "magic" capable of amplifying radiant energy without an outside source of power, whether you invoke the mythical hockey stick or not.
Stranger
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Post by socold on Nov 2, 2009 20:33:28 GMT
Models are too uncertain to make conclusions about what co2 can do, but vague whims can be used to form conclusions like "CO2 probably did essentially nothing" To build a model that is going to work you have to believe you understand natural variation. But to conclude "CO2 probably did essentially nothing" you don't need to understand natural variation? |
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Post by dontgetoutmuch on Nov 2, 2009 20:39:15 GMT
But to conclude "CO2 is a driver" you don't need to understand natural variation?
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Post by socold on Nov 2, 2009 20:39:17 GMT
Outside of deserts, the "ground level atmosphere" generally contains 15,000 to 40,000 water vapor molecules per million gross molecules. Along with 380 molecules of carbon dioxide. Which have the same "greenhouse gas potential" as another 55 or so H2O molecules. Where did you get the 55 figure from? |
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Post by poitsplace on Nov 2, 2009 23:44:56 GMT
This is really an example of the void between realists and skeptics concerning climate science. Models are too uncertain to make conclusions about what co2 can do, but vague whims can be used to form conclusions like "CO2 probably did essentially nothing" OK, CO2 is responsible for its share...hmmm, about 2.5 watts per meter for CO2 changes between glacial/interglacial...and then we've got about 34watts/meter for albedo changes due to changes from desert to forest/grassland, ice albedo and continental shelf to ocean. Let's see, that means CO2 is responsible for as much as 7% of the interglacial change. If that 7% change is out of a grand total of about 10C temperature variation globally...we're looking at it causing a whole .7C increase of the glacial/interglacial temperature change. Keep in mind of course that since temperature changes are what drives ice albedo, the desert albedo, ocean expansion AND CO2 that the ones with the greatest impact can be said to be the primary drivers...so with its 7% share CO2 is most certainly not the PRIMARY driver. ALSO, since the massive increases in water vapor (from glacial maximum to interglacial) cannibalize some of CO2's spectrum CO2 probably didn't even do that much. |
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Post by socold on Nov 3, 2009 0:30:05 GMT
This is really an example of the void between realists and skeptics concerning climate science. Models are too uncertain to make conclusions about what co2 can do, but vague whims can be used to form conclusions like "CO2 probably did essentially nothing" OK, CO2 is responsible for its share...hmmm, about 2.5 watts per meter for CO2 changes between glacial/interglacial...and then we've got about 34watts/meter for albedo changes due to changes from desert to forest/grassland, ice albedo and continental shelf to ocean. Let's see, that means CO2 is responsible for as much as 7% of the interglacial change. If that 7% change is out of a grand total of about 10C temperature variation globally...we're looking at it causing a whole .7C increase of the glacial/interglacial temperature change. Keep in mind of course that since temperature changes are what drives ice albedo, the desert albedo, ocean expansion AND CO2 that the ones with the greatest impact can be said to be the primary drivers...so with its 7% share CO2 is most certainly not the PRIMARY driver. ALSO, since the massive increases in water vapor (from glacial maximum to interglacial) cannibalize some of CO2's spectrum CO2 probably didn't even do that much. Where do you get 34wm-2 albedo change from? Your value seems to be very different from this one: books.google.co.uk/books?id=8-m8nXB8GB4C&lpg=RA1-PA452&pg=RA1-PA451#v=onepage&q=&f=false |
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Post by icefisher on Nov 3, 2009 1:03:13 GMT
To build a model that is going to work you have to believe you understand natural variation. But to conclude "CO2 probably did essentially nothing" you don't need to understand natural variation? Who concluded that? What one can conclude is that the IPCC grossly over exaggerated the effects of CO2. And one can relatively safely assume any increase in warmth is essentially nothing since I sure can't physically tell the difference. . . .and I still live in the same neighborhood today. Therefore, its essentially nothing from what has been actually observed if one cannot discern any difference. Obviously that doesn't mean its true, it just means that nobody has established any essential difference. |
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Post by sentient on Nov 5, 2009 2:48:29 GMT
I suspect it isn't just all water and geography. Four kilometers, give or take a few hundred meters, is about how thick continental ice tends to get. It might get thicker in special circumstances, but at Lake Vostok in Antarctica, which is in a natural bedrock basin and possibly contains the oldest freshwater on earth, the Vostok ice core project was actually restrained from penetrating below, if I remember correctly, about 3.8 kilometers or so in order to prevent possible contamination of this unique resource. I also remember recently seeing something about a remote operated submarine vehicle being used to explore Vostok recently. I think it was on Discovery or Science channels, or one of those ilk.
Now, on the efficacy of CO2 as a climate trigger, there is some serious denial to be performed by known members here as regards the results of Sole, Turiel and Llebot writing in Physics Letters A (366 [2007] 184–189) which identified three classes of D-O oscillations in the GISP2 Greenland ice cores; A (brief), B (medium) and C (long), reflecting the speed at which the warming relaxes back to the cold glacial state:
“In this work ice-core CO2 time evolution in the period going from 20 to 60 kyr BP [15] has been qualitatively compared to our temperature cycles, according to the class they belong to. It can be observed in Fig. 6 that class A cycles are completely unrelated to changes in CO2 concentration. We have observed some correlation between B and C cycles and CO2 concentration, but of the opposite sign to the one expected: maxima in atmospheric CO2 concentration tend to correspond to the middle part or the end the cooling period. The role of CO2 in the oscillation phenomena seems to be more related to extend the duration of the cooling phase than to trigger warming. This could explain why cycles not coincident in time with maxima of CO2 (A cycles) rapidly decay back to the cold state. ”
The evidences discussed above could justify why A cycles
decay faster, but they do not explain the differences in decay
between B and C cycles, however, as CO2 maxima seem to
correlate equally well with both types of cycles. What could
explain such a difference is astronomical cycles [19], which are
known to affect to total budget of solar radiation received by
the Earth [14]. The relative abundance of class B (7 cycles) and
class C (2 cycles) suggest that the anomalously long cooling
phases for class B and class C cycles could be coupled with
an appropriate astronomical cycle. The existence of only two
C cycles separated away about 40,000 years suggest that C cycles
are coupled with the tilt cycle [24], while B cycles could
have an important coupling with the precession cycle (although
a periodic repetition of B cycles is less clear in the data). But
in no instance the warming phase seems to be perturbed by the
astronomical cycle.
....Nor CO2
concentration either the astronomical cycle change the way in
which the warming phase takes place. The coincidence in this
phase is strong among all the characterised cycles; also, we
have been able to recognise the presence of a similar warming
phase in the early stages of the transition from glacial to
interglacial age.
So it would seem, as is often reported in the literature, that we don't know yet what causes the brief but strong releases of energy that cause the warmings, we only know that CO2 was not the agent provocateur for the most recent 13 warmings prior to the Holocene. and those that have studied in depth the transitions in the Vostok, Dome Concordia and Law Dome cores know that CO2 did not play a role in any of the ice age/interglacial transitions dating at least back to near the Mid Pleistocene Transition.
Sole et al conclude:
"Some other sources of global variability, specially those ones hich could release sudden pulses of energy able to explain the steep warming phase in global oscillations, must be researched."
However, if you happen to be inclined towards geoengineering our way out of the next climate change, the work of Sole et al provides an intriguing possibility.
We live today in Marine Isotope Stage 1 (MIS-1), otherwise known as the Holocene, which is also the 6th interglacial dating back to the Mid Pleistocene Transition (MPT) when we switched from the 41kyr ice age/interglacial couple periodicity (which matches the obliquity in our orbit) to the 100kyr one (which matches the eccentricity in our orbit) we have been in since the MPT. Five of those 6 interglacials have each lasted about one half of a precessional cycle. The precessional cycle ranges from 19kyr to 23kyr, and we are at the 23kyr point today, making 1/2 11,500 years, the present age of the Holocene. If we are still on the 100kyr/half precessional cycle beat clock, then this interglacial is just about kaput. But what about that 6th cycle, the one that wasn't on the half precessional clock?
That would be MIS-11, about 400kyrs ago. or 4 eccentricity cycles back. That interglacial lasted about 30kyrs, or 1.5 precessional beats. Many MIS-11 workers have suggested it "skipped" a precessional beat. No one knows precisely why this happened, however GHGs have of course been cited as a possible explanation.
As it turns out, during both MIS-1 and MIS-11 we just happen to be at an eccentricity minimum, when our orbit about the sun approaches its most circular path. Eccentricity minima and maxima occur every fourth cycle offset by half a 4th cycle, or 200kyrs. So, in 200kyrs we will be at another maxima, another 200kyrs beyond that (400kyrs from now), we will be at another minima, and so on.
Interestingly, the 4th cycle maxima correlate rather well with hominid evolution:
“An examination of the fossil record indicates that the key junctures in hominin evolution reported nowadays at 2.6, 1.8 and 1 Ma coincide with 400 kyr eccentricity maxima, which suggests that periods with enhanced speciation and extinction events coincided with periods of maximum climate variability on high moisture levels.”
state Trauth, et al (2009) in Quaternary Science Reviews. As it turns out, periods of wet maximum climate variability (in modern lingo, global warming/global cooling correctly re-branded as climate change), cook-up the larger braincases. We went from 500-550cc braincases 2.8 mya to the average of about 2,500cc today in the most rapid encephalization of any mammal in the fossil record.
The last maxima, since we are at a minima now, occurred during MIS-7, you got it, about 200kyrs ago. Homo sapiens appears in the fossil record at that time and coexisted with H. neanderthalensis for about 30kyrs before they got rubbed out. Hmmmmm.
But I digress. If we take a stroll between this interglacial, and the last one back, the Eemian or MIS-5e, we find there were 24 Dansgaard- Oeschger oscillations, also known as interstadials. These occurred within the Wisconsin ice age. D-O events average about 1,500 years long (range is 1,000-4,000 years) and have the same characteristic sawtooth shape that the major ice age/interglacial transitions do, a rapid global warming, taking from just a few years to mere decades, and averaging 8-10C rise, before relaxing back to the glacial state. The normal difference between the glacial and interglacial states is about 20C so D-O events can shoot us from 1/3 to 1/2 of the difference between earth's cold and warm states in astonishingly little time.
To prepare you for the obvious conclusion, just think Red and Blue states. Anyone here old enough to remember the color once reserved for socialists/communists? We do get it wrong sometimes and it goes unnoticed sometimes for quite some time.
I am not going to give you the obvious answer, but I am going to set the multivariate processing stage for you. If you are a multivariate processor (MVP) you probably have already made the leap.
If MIS-11, at the last eccentricity minimum 400kyrs ago, skipped a precessional beat, and prolonged the slide into the Illinoian ice age, and if CO2 ameliorates just such a slide back to the glacial state, what do you suppose we could possibly do to geoengineer our way out of the imminent end of the Holocene interglacial?
And the answer is just as simple as the recognition of the true difference between Red and Blue states.
Maybe, just maybe, we got it backwards AGAIN?
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Post by sigurdur on Nov 5, 2009 3:54:56 GMT
Excellent Stranger.
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Post by sigurdur on Nov 5, 2009 3:55:40 GMT
Sorry......Sentient. Daughter walked in and I had a brain fart again. |
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