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Author Topic: Has climate change affected Earth previously?  (Read 6792 times)

Offline thedoc

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Has climate change affected Earth previously?
« on: 14/10/2013 22:49:01 »
fifty-five million years ago, the planet suddenly warmed. But why? New evidence suggests a huge release of carbon dioxide...

Read the whole story on our website by clicking here

  
« Last Edit: 14/10/2013 22:49:01 by _system »


 

Offline CliffordK

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Re: Has climate change affected Earth previously?
« Reply #1 on: 14/10/2013 23:51:23 »
For a long time we've known a correlation between CO2 and glacial/interglacial periods.  However, the timing seems to indicate an increase of temperatures preceding the increase in CO2 levels, with the interpretation that the rising temperatures drive the CO2 out of the oceans.

Is there any reason to believe that 55 million years ago the CO2 increase would have preceded the temperature increase?
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #2 on: 16/10/2013 06:16:17 »
The inherent properties of water lead to a bounded chaotic oscillation of atmospheric temperature if driven by a constant solar input. If we start with a dry atmosphere over a wet planet, evaporation increases the greenhouse effect (since water is the major greenhouse gas), thus raising the air temperature, encouraging more evaporation, and increasing the capacity of the atmosphere to hold water.  This positive feedback produces a rapid rise in temperature up to the point that the planet is covered with cloud which cuts off the surface heating but also reduces radiative loss, so it slowly cools down again. Hence the sawtooth temperature/time profile we find in ice cores.

When the sun shines, plants grow and extract CO2 from the atmosphere. As the temperature rises, the population and activity of coldblooded animals  increases and they live by converting plant material back into CO2. The converse happens as the temperature falls. Hence the CO2 level follows the temperature graph.

All of these mechanisms can be observed in the laboratory and locally on a daily scale, and there's no reason to suspect that the laws of physics and biochemistry have changed over geological time. Water is the thermostat, CO2 is the thermometer.
 

Offline peppercorn

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Re: Has climate change affected Earth previously?
« Reply #3 on: 16/10/2013 12:59:18 »
As with many systems, proportional variation over a long enough time is not so much the problem.  The rate of change is.

Trees, plants and animals will play a dampening role on the changes but this can't happen instantaneously.  As a result we are entering a mass extinction period.

No one is in doubt that the planet will eventually settle towards a new equilibrium (obviously it's never completely fixed), but it's possible we may not be around to see it as a species.
« Last Edit: 16/10/2013 13:01:42 by peppercorn »
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #4 on: 16/10/2013 15:02:20 »

No one is in doubt that the planet will eventually settle towards a new equilibrium (obviously it's never completely fixed), but it's possible we may not be around to see it as a species.

Everyone is (or should be) in such doubt! The geological record shows that it has never been in equilibrium, and the laws of physics explain why it never can be.
 

Offline peppercorn

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Re: Has climate change affected Earth previously?
« Reply #5 on: 16/10/2013 22:39:55 »
The geological record shows that it has never been in equilibrium

Do note I said "settle towards a new equilibrium", meaning it won't actually reach one.
Humans have just introduced a large forcer (think spring/damper) on top of the other natural actors previously in play. We have done this by liberating the CO2 stored in ages past.
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #6 on: 16/10/2013 22:43:46 »
There's a significant difference between an asymptotic equilibrium and an inherently unstable and chaotic oscillator. CO2 is irrelevant.
 

Offline Ophiolite

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Re: Has climate change affected Earth previously?
« Reply #7 on: 17/10/2013 12:46:42 »
All of these mechanisms can be observed in the laboratory and locally on a daily scale, and there's no reason to suspect that the laws of physics and biochemistry have changed over geological time. Water is the thermostat, CO2 is the thermometer.
1. Do you accept that humans have released a significant volume of CO2 into the atmosphere?
2. If so, in what way do you think this is not independent of the CO2 present as a consequence of the processes you describe?
3. Do you deny the greenhouse effects of CO2?
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #8 on: 17/10/2013 18:07:30 »
The infrared absorption spectrum of carbon dioxide is negligible compared with that of water vapor, and the albedo of clouds is the principal determinant of heat input and output. Unfortunately all we know about these drivers of climate is that they are overwhelmingly large and very variable, as the IPCC admitted in its very first report.

Because CO2 concentration varies with temperature, it is easy to assume that it has a causative effect, so you can construct a model that somehow links the two parameters as cause and effect. Huge efforts have gone into this, because anthropogenic CO2 is in principle controllable and can be taxed, so it would be nice if the theory had some predictive value. Alas, the models have so far failed to predict what actually happened, because they are based on a false assumption. Correlation is not proof of causation, and no such model can explain the geological history of temperature fluctuation without invoking sudden, mysterious and spontaneous appearances of vast amounts of CO2 about every 500,000 years. Which would be fine, if a little puzzling,  if the geological record showed CO2 increasing before temperature. But alas, it's the other way around. Not by a lot, but in my book, if the light comes on even a nanosecond after I press the switch, the light isn't causing the switch to close.   

It's interesting to apply the supposed CO2 forcing function to the atmosphere of Mars, knowing he solar inoput and the concentration of CO2 in its almost water-free atmosphere. It turns out that Mars is a lot colder than predicted, so the forcing function must be wrong.
 

Offline peppercorn

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Re: Has climate change affected Earth previously?
« Reply #9 on: 17/10/2013 20:01:47 »
The timing seems to indicate an increase of temperatures preceding the increase in CO2 levels, with the interpretation that the rising temperatures drive the CO2 out of the oceans.
... if the geological record showed CO2 increasing before temperature. But alas, it's the other way around.

I seem to have overlooked the data showing that temperatures rose prior to any CO2 being released 55m years ago.
 

Offline CliffordK

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Re: Has climate change affected Earth previously?
« Reply #10 on: 18/10/2013 00:00:55 »
I seem to have overlooked the data showing that temperatures rose prior to any CO2 being released 55m years ago.
In the glacial records, the temperature rise tends to occur before the CO2 rise.  However, I'm not sure if they have the data in the clay records to make the same determination. 

That doesn't remove the possibility of a positive feedback in which a small temperature rise could be amplified by a CO2 rise, causing a further temperature increase and greater CO2 release.
 

Offline Ophiolite

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Re: Has climate change affected Earth previously?
« Reply #11 on: 18/10/2013 00:12:17 »
It's interesting to apply the supposed CO2 forcing function to the atmosphere of Mars, knowing he solar inoput and the concentration of CO2 in its almost water-free atmosphere. It turns out that Mars is a lot colder than predicted, so the forcing function must be wrong.
Please provide peer reviewed citations to substantiate this. It would also be nice, for background understanding of your position, if you would answer the first of my three questions.
 

Offline CliffordK

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Re: Has climate change affected Earth previously?
« Reply #12 on: 18/10/2013 00:26:18 »
As far as water vs CO2 vs Methane & etc.

Each compound has a slightly different IR absorption spectrum, and it may even vary with the physical state (solid, liquid, vapor). 

So, while water vapor does have a broad IR absorption spectrum, there are "windows" in the spectrum.


http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png


Much of the IR absorption by CO2 occurs in one of the "windows" of the water absorption spectrum, around 15 microns.  Apparently, while it looks rather saturated, the peaks do widen with increasing atmospheric CO2.  So, the low absorption window is closed further with greater CO2 concentration.

The methane peak at about 8 microns may have a greater masking by the water absorption spectrum.

Altitude may also be important.  CO2 is a heavy molecule, and may cause the IR to be absorbed at lower altitudes, and thus would be more likely to impact the surface temperatures.
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #13 on: 18/10/2013 01:03:24 »
I note that the y-axes of the component graphs are not scaled, and the range of upgoing transmission is 2:1. Since the CO2 concentration doesn't vary much, that must all be due to water.

And of course water doesn't only occur as vapor in the atmosphere - it's present as liquid, solid (in several forms, some with over 90% albedo) , and umpteen gaseous forms as transient polymers. Dominant, chaotic, and unmeasurable. So the IPCC ignores it.
« Last Edit: 18/10/2013 01:09:27 by alancalverd »
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #14 on: 18/10/2013 01:15:30 »

1. Do you accept that humans have released a significant volume of CO2 into the atmosphere?


Measurable, or at least calculable, yes. Significant? I think not. And I hope not! 10% of all anthropogenic CO2 comes from humans breathing, and another 25% from farm animals. If our emissions are significant and significantly damaging to the ecosystem, we must kill ourselves and stop eating meat. 

I don't have a "position", just a vague scientific instinct that causes should precede effects, and the knowledge that it's very easy to draw false inferences from apparent correlations.

Sadly, I can't make head or tail of your second question. Could you rephrase it a bit? 
« Last Edit: 18/10/2013 01:26:00 by alancalverd »
 

Offline CliffordK

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Re: Has climate change affected Earth previously?
« Reply #15 on: 18/10/2013 02:06:17 »
1. Do you accept that humans have released a significant volume of CO2 into the atmosphere?
Measurable, or at least calculable, yes. Significant? I think not. And I hope not! 10% of all anthropogenic CO2 comes from humans breathing, and another 25% from farm animals. If our emissions are significant and significantly damaging to the ecosystem, we must kill ourselves and stop eating meat. 
99.9% of the food we eat is from consuming plants that convert CO2 into hydrocarbons and carbohydrates. 

Thus you end up with a cycle in which the CO2 is absorbed by plants, eaten, released, and reabsorbed by plants.

And the same goes for cows (except for perhaps some extra cow methane).

The main concern with anthropogenic CO2 is from fossil fuels, I.E.  Carbon that has been sequestered deep under the earth for millions of years, and we're happily releasing back into the atmosphere.

There are, of course, also fossil fuels being used in food production and transport, as well as using fossil fuels to reduce nitrogen for the formation of nitrogen fertilizer.

If we don't change something, eventually we'll reach atmospheric conditions similar to before the dinosaurs roamed the Earth. 

The big question is whether the changes will be acceptable.
« Last Edit: 18/10/2013 02:14:45 by CliffordK »
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #16 on: 18/10/2013 08:10:51 »

99.9% of the food we eat is from consuming plants that convert CO2 into hydrocarbons and carbohydrates. 

Thus you end up with a cycle in which the CO2 is absorbed by plants, eaten, released, and reabsorbed by plants.


But the dynamic equilibrium, i.e. the concentration of CO2 in the atmosphere at any time,  obviously depends on the mass ratio of animals to plants. Simple fact is that the over 30% of the CO2 we return to the atmosphere every day is from the exhalations of animals that wouldn't exist if we didn't.

Don't blame cows alone for methane. It's a product of human sewage systems too - and a very useful one!
 

Offline peppercorn

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Re: Has climate change affected Earth previously?
« Reply #17 on: 18/10/2013 11:58:38 »
I seem to have overlooked the data showing that temperatures rose prior to any CO2 being released 55m years ago.
In the glacial records, the temperature rise tends to occur before the CO2 rise.  However, I'm not sure if they have the data in the clay records to make the same determination. 

That doesn't remove the possibility of a positive feedback in which a small temperature rise could be amplified by a CO2 rise, causing a further temperature increase and greater CO2 release.

In an effort to return to the original topic...
The glacial record that you speak of, is that one derived from cores taken near the poles?

If that's the case then it would seem to follow that an initial forcer - perhaps ghg release in more temperate zones (continent-wide forest fires, etc) - would, as you imply, create a thermal runaway situation which led to ice melts giving up their stores of CO2.
.... This may be our future too, I imagine!
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #18 on: 18/10/2013 12:47:58 »
If that were the case, there would surely be less CO2 in the "warmer" ice?

Unlike water, CO2 has no inherent positive feedback as its "solubility" in air is not temperature-dependent.
« Last Edit: 18/10/2013 12:50:18 by alancalverd »
 

Offline Steve Wickson

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Re: Has climate change affected Earth previously?
« Reply #19 on: 28/10/2013 00:29:33 »
I would bet the PETM (55 million years ago) had something to do with a nearby supernova or something astronomical. Notice how quickly the temperature returned to previous levels after the spike. Saw a talk by an IPCC scientist and even he admitted that the CO2 data didn't work very well for the PETM (Palaeocene-Eocene Thermal Maximum).
 

Offline ViolaSheen

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Re: Has climate change affected Earth previously?
« Reply #20 on: 13/11/2013 06:59:30 »
I would say that climate change has definitely affected earth. A lot of typhoons and hurricanes that we are experiencing these days are due to low pressure and warmer water. Global warming is the cause of most of these natural disaster. To learn more about climatic changes go to newbielink:http://www.researchomatic.com/essay/nature/ [nonactive] . You will see how little changes in the atmosphere can have ahuge impact on its inhabitatnts!
 

Offline alancalverd

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Re: Has climate change affected Earth previously?
« Reply #21 on: 13/11/2013 12:38:41 »
Not that Wikipedia is particularly trustworthy, but I see no reason for it to lie:   

Quote
The most active Western Pacific typhoon season was in 1964,[citation needed] when 39 storms of tropical storm strength formed. The least activity seen in the northwest Pacific ocean was during the 2010 Pacific typhoon season, when only 14 tropical storms and seven typhoons formed.

As with most climate change scare stories, the facts do not support the hypothesis.
 

Offline Bass

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Re: Has climate change affected Earth previously?
« Reply #22 on: 14/11/2013 01:45:03 »
...A lot of typhoons and hurricanes that we are experiencing these days are due to low pressure and warmer water. Global warming is the cause of most of these natural disaster.
I would hazard to guess that all typhoons and hurricanes are due to low pressure and warm water, both now and in the past.  Global warming is not the cause of these natural disasters.
 

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Re: Has climate change affected Earth previously?
« Reply #22 on: 14/11/2013 01:45:03 »

 

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