it seems we have been mislead on CO2's effect

lewis198

i was watching a documentary on global warming that showed that co2 does not cause global warming, but rather co2 levels lag behind temp by a few hundred years. they cited the actual cause of global warming as solar activity. they showed that throughout history, there have been periods when the earth was much hotter than it is now, the latest period occurring during the medieval ages. it seems the whole global warming movement was aimed at discouraging third world development, or is at least that was a by product of it.

Andre

Your thread spans two different items, climate-CO2 and climate politics. Which one would you like to explore further? Climate CO2 is fine here. I would suggest that climate politics should go to PW&A. It could even be considered to ponder about the reason for the psychological collective fascination for climate issues in social sciences.

Sticking to paleo climate science, yes if we plot the CO2 concentration against the oxygen isotope variation (considered a proxie for temperature) then that lag is definitely there:

http://gallery.myff.org/gallery/145232/EPICA2.GIF

These are the highest resolution records of the last glacial termination between 20,000 and 10,000 years ago showing that the isotopes (temperature?), blue arrows, rose first followed by CO2, red arrows, several 100s years later.

Data from these, Monnin et al 2004 for the CO2 and these, Stenni et al 2001 for the isotopes,

Gokul43201

The conclusion stated in the first clause (made by this "documentary") does not follow from the observation described in the second clause.

Yes: CO2 levels lag temperatures
No: This does not imply that CO2 does not cause warming

PS: Please state the name and other details of this documentary. Also, please keep the discussion here to the scientific content. Finally, do take a look at the forum rules, and try to avoid speculation.

Ivan Seeking

Have you seen the one that claims we are alien hybrids? There is another one about Mallet's time machine that is pretty interesting. Danged thing doesn't work, but he is sure that his theory is correct.

Anyway, since some people here don't like the IPCC, here is an excerpt from recent report issued by the APS.

See
http://www.physicsforums.com/showthread.php?t=245897

So take your choice: We have a conspiracy at the APS, the IPCC, and probably a dozen other major scientific institutions, or the documentary was nonsense.

lewis198

The plot showed by andre echoes much evidence pointing to the fact that there is no proof for a rise in temp caused by co2. Surely the speculation lies with the claim that it does.

Andre

The scientific method expects the use of observations, to formulate an hypothesis, which would lead to predictions. This thread seems to be about the accuracy of observations in the past, but actually the only thing that is revelant is, how accurate are past predictions? And how much more cooling how much longer is required to accept that....

LURCH

Interesting opsition. In terms of causality, how can an incrase in temperature be caused by an increase in CO2 levels that has yet to happen? Usually, cause precedes effect.

aaroman

About this they usually say that CO2 is amplifying warming. It's not the cause that starts it, it just amplifies it afterwards. That usually would imply an acceleration of warming. Was that observed?

Andre

Exactly!

and no, not observed. See the OP in this thread.

DEMcMillan

lewis198 has started an interesting dialogue about CO2 rise and warming. His entry was followed by caveats and questions and led to a discussion with citations about the APS and its position on the question. As I went from site to site I came to realize that Viscount Monckton’s invited opinion had a much larger effect than I previously recognized. The new APS position in favor of efficiency http://www.aps.org/energyefficiencyr...ergyreport.pdf is hopefully short of supporting a third Colorado River dam but it is a long way from the IPCC position. Like Andre, I believe that the main reason is the recent temperature decline that signals a modeling failure. Now we need to examine the models to see why they failed. I have cited the similarity of Venus’ and Earth’s carbon dioxide-mediated outgoing radiation reduction despite the striking difference in atmospheric carbon dioxide concentration (96.5% vs. 0.03%). http://www.physicsforums.com/showthr...=231437&page=2 Fraunhofer A line (759.37 nm) behavior also shows that infrared imbalance and atmospheric gas (Oxygen) concentration do not need to be associated. A 30% reduction or increase in atmospheric oxygen would change Earth’s incoming radiation balance by less than 1%. I will start a new thread in a few days to indicate that a well supported explanation of the greenhouse gas model failure can have important effects on physical thinking. In the meantime, those that worry that criticism and evidence are ineffective should be reassured by the actual events. The APS has changed its view.

One recent event portrays both the persistence of the CO2 model and the vulnerability that it can generate. James Hansen, head of NASA-GISS http://www.independent.co.uk/environ...ow-918057.html http://www.greenpeace.org/usa/press-...les-direct-act justified an attack on a coal power station in a British court as an environmental support action, swaying the jury to judge the defendants not guilty. Objection to this action generated a call for his firing http://wattsupwiththat.wordpress.com...es-hansen-now/ He usually charges the Administration with such efforts. How much money changed hands here?

enders

I believe the documentary is called "The Great Global Warming Swindle". It features several scientists from the IPCC and more that believe man-caused global warming is not true.

CO2 IS a greenhouse gas. That is, it reduces the amount of light (energy) that can leave the Earth's atmosphere, thereby increasing the temperature at which the Earth could achieve thermal equilibrium with its surroundings. However, the Earth's surroundings are constantly changing. The effect of CO2 on the Earth's temperature is insignificant compared to the effect that the variation in solar irradiation has. As lewis 198 mentioned, the CO2 levels increase AFTER the temperature increases. This is due to the large amount of CO2 dissolved in the worlds oceans. As the Earth's temperature increases (as a result of increased solar irradiation), the oceans slowly warm up and release CO2. The fluctuations in CO2 levels as a result of this far outweighs the affect humans have had. The warming period we have recently experienced can be explained by solar cycles. We have recently experienced some of the coldest temperatures in years and are now entering a short cooling stage.

I will continue this later..

Andre

Make that infra red radiation, not light.

Things are a bit different thatn that, considering that the variation in solar energy output is rather low and diminishes even more when the fourth root is drawn from it, according to the Stefan Bolzman law. What really makes a big difference is Earth Albedo, changing reflectivity mainly due to variation in cloud cover.

So it seems. indeed the CO2 increased after the isotope thermometer increased. The odd thing though is that the bulk of the CO2 in the oceans are stored in the deep where the temperature ranges between 0 and 2 degrees Celcius all the time, regardless if it is in the Arctic ocean or around the equator, only the upper 6-800 meters are warmer. So when atmospheric tempeature changes not a lot of the ocean is affected, hence variation in the CO2 storage capacity of the ocean may be sufficient to explain the variation in atmospheric CO2 during the "ice age" to "interglacial" transitions.

Can it? But how? Things are still unclear,

enders

If you truly knew that I was incorrect on this matter you would not need to use these tactics to make me appear stupid. I am not an expert on the matter, however I am able to respond to your statements:
Light does leave the earth, otherwise how would we be able to see it from space? I am speaking of reflection and emittance. You are probably correct that most emittance is infra red, which IS light though we cannot see it.

Firstly, irradiation is incoming light. Secondly, for emittance it is a power of 4, not a root (so a change in earth temperature by a couple degrees will have a fairly large effect on emittance).

If we speak of the heat transfer between the earth and space, the change in the earths energy (incl. atmosphere) = heat in - heat out. Heat in is light entering the atmosphere and heat out is light leaving the atmosphere. Light coming into the atmosphere can either be absorbed by the atmosphere or reach the surface of the earth (or as you mention, reflected by clouds). Upon reaching the surface of the earth, it is either absorbed or reflected. Light that is reflected by the earth surface and that which is emitted by the earth surface is then either absorbed by the atmosphere or passes into space (or reflected by clouds). My statement: was simply stating that while CO2 increases the amount of solar energy absorbed by the atmosphere, the effect is insignificant compared to how much the variation of light entering the atmosphere affects the earth temperature. I'm sure, as you state, cloud cover does have some effect since from memory (correct me if wrong): there is much more water vapour in the atmosphere than CO2, and it has more global warming effect.

Yes, most CO2 is deep in the oceans and it takes a LONG time to warm these depths and release CO2 (~600 year delay). As you said, only the 6-800 meters varies significantly and this is where CO2 is presently coming from. Note that large warming periods in the past have seen CO2 levels a lot higher than today (~10 times?) because these have had the time to release CO2 from deep in the ocean. We have just been through a short warming stage and CO2 levels have increased, we are now entering a short cooling stage and CO2 levels will decrease. Again I am referring to solar cycles, to which you said: As I said earlier, I am not an expert on this matter but the sun experiences a 22 or 11 year cycle during which the amount of light it emits significantly varies. There are also other cosmic effects which are still being studied.

I would like to conclude by saying: the amount of CO2 in the atmosphere remains to be directly related to the ocean temperature (whether we talk of the great depths or 6-800m). Evidence shows that CO2 levels in the past have been significantly higher than they are today. A CO2 global warming analogy: a CO2 increase is similar to putting on a shirt when you are outside; yes it will make you slightly warmer, but how warm you are really depends on your surroundings.

Andre

I'm sorry if my reply gave you the impression that I was trying to do that. By no means I did not intend that. It's just to caution that the discussion is not symmetric. Just remember, for Jack in the street, if one preaches global warming one is a hero, if one challenges it, one is a greedy crook. Hence discussing climate matters is just as risky as walking on eggs on thin ice. The tiniest mistake can be fatal.

Back to the subject, we are dealing now with two areas, CO2 and the ocean and the effect of CO2 in the atmosphere. Rather than getting entangled in micro discussions I'd like to recommend this this thread addressing the atmospheric CO2 more accurately. I intend to give an overview about that later.

Remains the CO2 interaction between the atmosphere and ocean on Ice age time scales. We discussed the lagging of CO2 on the ice core isotope thermometer. Indeed this is generally explained with the variation of CO2 storage capacity of the oceans with temperature changes. We need to be very careful there, with interpretations especially when comparing multiple proxies and records, and when the result is contradiction. And that happens a lot.

We can only conclude from that, that some interpretations must be wrong, especially about temperatures. Sea surface temperatures as derived hypothetically from ion ratios in foraminifera, or lipids (tex86) are generally not at all in line with the paleo isotope thermometer of the ice cores. Yet the oceanic isotopes are. This should mean utmost caution about what the isotopes seem to tell us. Meanwhile, these isotopes show us a strong but still unexplained 100,000 years (100 Ky) cycle, nicely matching the lagging CO2 signal. But it's not a Milankovitch cycle. One can easily see the problems of the Milankovitch explanation of the ice ages in that graph, for instance, where we see the biggest isotope spike together with the weakest variation in the solar insolation, around 400ka ago.

We also know from many different studies about isotope mixing that the oceans behaved weird especially during the glacial transition. Nowadays we know that when the oceans produce El Nino's and La Nina currents that the weather is affected on a large scale. Therefore it seems safe to say that whoever can explain the 100ka oscillation in the oceans and the ice cores also holds the key to explaining climate changes. That's what I meant to say about we don't know nothing yet. It's the oceans but how and why?

Does this help?

mheslep

Andre - From exactly what material are the oceanic isotopes drawn? Ocean floor core? Organic or non-organic material? You seem to be drawing a distinction between ocean surface organic material and 'oceanic isotopes', or do I misread you?

Andre

The oceanic isotope signal basically comes from calcite shells of "benthic foraminifera", in deep sea sediment cores.

This compilation of 57 different cores is thought to represent the global ice mass in the last 5.3 million years, hence an indirect paleothermometer. The idea is that the water cycle favors light isotopes for evaporation. When the global ice mass accumulates more light isotopes leave the oceans to get locked in the ice sheets, hence the remaining oxygen isotopes in the water get enriched with heavier isotopes (dD, d18O). This is thought to be reflected in the isotopes of the foraminifera shells.

It can be seen here that there is a very high correlation between ice sheets and this benthic stack in the last half million years. But there is also some fishy in there.

mheslep

Thanks