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Global temperature change discrepancy 8000 year plateau
    #9530305 -



If you look at a graph like this and study climate change you'll notice a distinct difference between current conditions and previous. There always seems to be a sharp increase in temperatures flowed by a steep decline the reason for this is commonly accepted among the climate/geology science to be the result of runaway greenhouse effects mainly due to methane and carbon dioxide. However when we look at the last 10,000 years you'd find counter to the past events we've found a 8,000 year plateau of relative temperatures as seen in the flowing image.


Now I'm not vouching for the quality of these temperature maps (I simply Google imaged them) but I've noticed that this 8,000 year period is quite unique in comparison to past records and frankly I'm trying to figure out why this plateau has happened. I can't say that I remember reading or hearing a good reason why (though I may re-search a book that may have mentioned it and I may have forgotten it) and I've read/seen/heard a lot on the subject.

All other aspects aside I'm wondering why this unusual plateau has occurred.


--------------------
"Have you ever seen what happens when a grenade goes off in a school? Do you really know what you’re doing when you order shock and awe? Are you prepared to kneel beside a dying soldier and tell him why he went to Iraq, or why he went to any war?"
"The things that are done in the name of the shareholder are, to me, as terrifying as the things that are done—dare I say it—in the name of God. Montesquieu said, "There have never been so many civil wars as in the Kingdom of God." And I begin to feel that’s true. The shareholder is the excuse for everything."
- Author and former M6/M5 agent John le Carré on Democracy Now.
Conquer's Club

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9531019 -

Humans, getting agriculture started :wink:


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Once, men turned their thinking over to machines in the hope that this would set them free.
But that only permitted other men with machines to enslave them.

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Re: Global temperature change discrepancy 8000 year plateau [Re: trendal]
    #9531176 -

feels like a little ice age in my house

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Re: Global temperature change discrepancy 8000 year plateau [Re: trendal]
    #9531265 -

trendal said:
Humans, getting agriculture started :wink:


Then why did the temp go down later when there were more humans doing more agriculture?

It could just as easily have been humans were able to start agriculture since the temperature was warmer.

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9532498 -

ScavengerType said:




I don't even see a discrepancy.  I see several 8000 year plateaus on that graph.

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Re: Global temperature change discrepancy 8000 year plateau [Re: ChuangTzu]
    #9533173 -

yea but during the peek periods (the parts with the sharpest inclines) that are onset by the change in Milenchovitch cycles, it is always a sharp offset. I've highlighted the 4 points in that image here:


As is my understanding the previous one plateaus slightly in that it drops slowly due to a massive release of methane and CO2 that was banked in the previous cold era. However I was wondering why the plateau occurs at such a low peek, both in respect to how long the increase happens and the net increase in temperature, and also why the 8000 year plateau occurs at this point.

Actually I was looking at an old temp/gas map and I think I found the answer.

A drop in methane at around the time that this occurs is probibly why it occurs. However since methane emission from the soil usually increases as temperature increases I'm still left wondering why the sudden drop in CH4 occurs.

Edited by ScavengerType (01/02/09 07:36 PM)

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9548480 -

I'm not sure that it is unique. I think it is just expanded data, and this period of the last 10,000 years we have the most accurate climate data.

You should know that as the temperature increases the solubility of carbon dioxide is sea water decreases, which means that as temperatures rise, for whatever reason, massive amounts of carbon dioxide gas is released from the ocean.

If you look on a geological timescale since the Cambrian period the temperature of this planet has been pretty much independent of the CO2 levels in the atmosphere. The thing that affects temperatures more than anything is actually the arrangement of the continents, which controls ocean and air flows.

It couldn't have been agriculture that affected the climate during the Holocene period because agriculture was not the predominant way that prehistoric humans made their living. If that was the case then why did the temperatures dip around 3500 years ago, when agriculture was much more widespread?

I think that as things stand right now nothing is happening out of the ordinary on our planet, aside from having higher concentrations of CO2 than you would expect from the best guesses of scientists who study CO2 levels before 300 years ago. But of course if the temperature continues to climb at this rate there will be serious consequences.

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9548506 -

So I guess what I'm saying is... who knows? :shrug:

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9549484 -

Quote:
If you look on a geological timescale since the Cambrian period the temperature of this planet has been pretty much independent of the CO2 levels in the atmosphere. The thing that affects temperatures more than anything is actually the arrangement of the continents, which controls ocean and air flows.


How do you figure? It seems to me that temperature is moving in line with CO2 and CH4 looking at the last graph I showed. If you take into account the role of the 115,000 year Milenchovitch cycles in forcing the temperature up and down and controlling the historical levels of those gasses.

I saw no obvious difference between temperatures and the arrangement of the continents and temperature. Could you explain what you mean by this?

It seems that Milankovitch cycles have a much more consistent effect on the earth's temperature.


--------------------
"Have you ever seen what happens when a grenade goes off in a school? Do you really know what you’re doing when you order shock and awe? Are you prepared to kneel beside a dying soldier and tell him why he went to Iraq, or why he went to any war?"
"The things that are done in the name of the shareholder are, to me, as terrifying as the things that are done—dare I say it—in the name of God. Montesquieu said, "There have never been so many civil wars as in the Kingdom of God." And I begin to feel that’s true. The shareholder is the excuse for everything."
- Author and former M6/M5 agent John le Carré on Democracy Now.
Conquer's Club

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9549491 -

The Cambrian is hundreds of millions of years ago.

During most of earth's history there was no ice at the poles. There have been I think 3 or 4 ice ages since the Cambrian, we are currently in an ice age right now.

Your graph only goes up to 1 million years ago.




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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9549529 -

Another thing... you realize that just prior to the industrial revolution CO2 levels were almost at their lowest concentration since the evolution of multicellular organisms?

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9550296 -

I don't know the source of that data, but it's often the case that there was nobody around with a thermometer on a particular year to run around the whole earth and measure temperature in 1000 different places to give an accurate global average.  Instead, temperature is inferred from stuff we can measure including some of the data in the graphs above.  Which means that if you calculate temperature from atmospheric methane concentration, you can't then use that data to show any link between methane concentration and temperature, since you assumed that link to generate the temperature data to begin with.

Of course, the more different types of measurements and the more of them you incorporate, the more accurate your estimate will likely be, but even 10 years ago, we had nowhere near the capacity to get an accurate global mean temperature as today.  100 years ago, our data was shit, and 200 it was practically non-existent.  If you try to extrapolate a million (or a hundred million) years into the past, you're not doing much better than pulling numbers out of your ass since relative shifts of a degree or so are significant and your error bars begin to become larger than the graph itself...  And then there is the issue of how you fit a curve.  If you expect a certain pattern and then fit that type of curve to the data, you might end up seeing patterns that didn't really exist--especially when the error is massive, you can really fit any curve to any data.  Anyway, the point I'm trying to make is that you may putting way too much significance in those charts.

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Re: Global temperature change discrepancy 8000 year plateau [Re: ChuangTzu]
    #9552453 -

Quote:
Anyway, the point I'm trying to make is that you may putting way too much significance in those charts.


Yea, I second that notion.

They dont even have error bars...  :rolleyes:  When I TA freshman physics I mark off for that shit.  :lol:

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Re: Global temperature change discrepancy 8000 year plateau [Re: ChuangTzu]
    #9554151 -

Of course the charts are going to be highly inaccurate, but they are much better than simply guessing without any supporting evidence.

We know for example that hematite alterations occur at a certain point in history from drilling into very deep rock formations. Since there is no hematite before  a certain point we can infer that there was not sufficient oxygen in our atmosphere to oxidize minerals before that point, which infers that photosynthesis was not widespread before that point.

I know that any measurement is basically meaningless without an associated error, but you can make certain distinctions that can be considered, I guess, very good assumptions. At one time scientists thought the sun was made of iron, that was a very good assumption as well, so we know that these things can be proved wrong over time.

However, I do think it is safe to say based on geological evidence from core samples, that the pre-industrial CO2 levels were just about the lowest they have ever been since multicellular life first evolved on this planet. I find it highly noteworthy that CO2 level began to rise at precisely the point in time in which they were pretty much the lowest they have ever been in the past half a billion years, based on the best guesses of scientists.

We can't really know exactly what the climate was like 150 million years ago. However things like ice ages leave evidence for geologists to find because glaciers cause very distict and recognizable erosion patterns and mineral formations. Again it is just a "best guess" but it is way better than simply picking a random date and asserting something about it.

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9554464 -

Quote:
However, I do think it is safe to say based on geological evidence from core samples, that the pre-industrial CO2 levels were just about the lowest they have ever been since multicellular life first evolved on this planet.


How do you figure this? I can't say I've ever heard a credible academic make this claim. In fact I haven't even heard a non- credible one claim it.


--------------------
"Have you ever seen what happens when a grenade goes off in a school? Do you really know what you’re doing when you order shock and awe? Are you prepared to kneel beside a dying soldier and tell him why he went to Iraq, or why he went to any war?"
"The things that are done in the name of the shareholder are, to me, as terrifying as the things that are done—dare I say it—in the name of God. Montesquieu said, "There have never been so many civil wars as in the Kingdom of God." And I begin to feel that’s true. The shareholder is the excuse for everything."
- Author and former M6/M5 agent John le Carré on Democracy Now.
Conquer's Club

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9554738 -

Really? I've heard this mentioned on Canadian public radio by climatologists many times.

Let me ask you this, what was the earth's atmosphere made up of at the very beginning? I mean shortly after the moon was formed.

Was it like it is today?

The first atmosphere we had was probably mostly hydrogen and helium gas. As the crust formed this transitioned to a mostly carbon dioxide and ammonia gas atmosphere. It was only after photosynthesis evolved that oxygen became a major component of the atmosphere. This also had the effect of reacting with ammonia gas to form nitrogen. Photosynthetic organisms (and any organism that uses carbonates to form a shell) are also responsible for sequestering carbon dioxide, gradually reducing the concentration over hundreds of millions of years.

There was a period of time just before the Cambrian explosion where they think CO2 levels were extremely low, lower than they were just before the industrial revolution. But otherwise, based on geological evidence which is not completely accurate and never can be, scientists who study this agree that CO2 levels were probably quite a lot higher than they are today, in general.

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9554891 -

yea in the Cambrian and pre-Cambrian. However you said that the pre-industrial average was almost the lowest point of atmospheric CO2 since life began. Perhaps by your graphs which are absurdly long term this is true but in the shorter term as in thousands of years instead of millions CO2 fluctuates wildly and has been considerably lower.


--------------------
"Have you ever seen what happens when a grenade goes off in a school? Do you really know what you’re doing when you order shock and awe? Are you prepared to kneel beside a dying soldier and tell him why he went to Iraq, or why he went to any war?"
"The things that are done in the name of the shareholder are, to me, as terrifying as the things that are done—dare I say it—in the name of God. Montesquieu said, "There have never been so many civil wars as in the Kingdom of God." And I begin to feel that’s true. The shareholder is the excuse for everything."
- Author and former M6/M5 agent John le Carré on Democracy Now.
Conquer's Club

Edited by ScavengerType (01/06/09 01:14 AM)

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Re: Global temperature change discrepancy 8000 year plateau [Re: ScavengerType]
    #9554979 -

Yeah, it varied about 100 ppm, between 180 and 280 ppm, right?

That is still the lowpoint when there is evidence that concentrations were in the thousands of ppm during the time of the dinosaurs.

And I never said it was the lowest since life began, I said the lowest since multicellular life evolved around the time of the Cambrian explosion.

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9555206 -

The scale of those maps makes them irrelevant to spotting short term trends. However I think you are right about the continents, I can see for instance that a large temperature increase happened at the time when the Atlantic gulf stream started up in ~300m. Presumably they are related. I don't see any relevance in this as to short term effects because continents move really slow and the geological record is much sketchier margin of error than the ice data.

The reason why ice data doesn't have margins of error is because there are none that we know of. There are many factors that could effect geological records of gas concentrations, but ice packs are pretty solid. Nothing touches them and they always collect snow. Nothing leaches particles out of them. They may not go very far back but they are reliable in their readings.


--------------------
"Have you ever seen what happens when a grenade goes off in a school? Do you really know what you’re doing when you order shock and awe? Are you prepared to kneel beside a dying soldier and tell him why he went to Iraq, or why he went to any war?"
"The things that are done in the name of the shareholder are, to me, as terrifying as the things that are done—dare I say it—in the name of God. Montesquieu said, "There have never been so many civil wars as in the Kingdom of God." And I begin to feel that’s true. The shareholder is the excuse for everything."
- Author and former M6/M5 agent John le Carré on Democracy Now.
Conquer's Club

Edited by ScavengerType (01/06/09 02:25 AM)

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Re: Global temperature change discrepancy 8000 year plateau [Re: lIllIIIllIlIIlIlIIllIllIIl]
    #9555224 -

adjust said:
Of course the charts are going to be highly inaccurate, but they are much better than simply guessing without any supporting evidence.



Without data source, curve fit parameters, and error bars, you can't even say that.

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