A couple of excerpts:
As we have explained in 2006, Vostok ice core records show that the carbon dioxide concentration averaged over a few centuries has been correlated with temperature at least for half a million of years. However, we know for sure that the temperature was the cause and the CO2 concentration was its consequence, not the other way around. It follows that the greenhouse effect hasn't been important in the last half a million of years.
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However, the most popular - and the most straightforward - explanation of the direction of the causal relationship is the fact that in all cases, the CO2 concentration only changed its trend roughly 800 years after temperature had done the same thing. There have been many papers that showed this fact and incidentally, no one seems to disagree with it. For example, a recent paper by Lowell Stott et al. in Science (2007) showed that 19,000 ago, when the last ice age started to go away, CO2 lagged by about 1,000 years, too.
Every sane person knows that this detailed insight implies that the greenhouse effect couldn't have been among the most important effects. Not only the ice core data fails to provide us with evidence supporting the greenhouse theory of the climate; it provides us with strong evidence against it.
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8 comments:
The pertinent discussion today is that increasing CO2 causes increased temps on earth. Period. The CO2 molecule is unambiguously a greenhouse actor. Period.
It is expected in the past, since there are 5 primary gh gases and other factors such as sun activity that can also increase temps, that there will have been increasing earth temps that were caused by something other than a delta in CO2 concentrations. Likewise temps can be cooling even if CO2 is going up because there are CO2 independant variables (sun activity, volcanic eruptions) that counter CO2's effect.
In the past you can find periods of lags but the explanation is always fairly basic and centers around some of the other variables.
This constant, simplistic searching for time periods that seem to contradict CO2 correlation when it is an accepted fact that CO2 is a greenhouse gas is an example of vacuous logic. Its insulting....to some.
The pertinent discussion today is that increasing CO2 causes increased temps on earth. Period.
Actually, the pertinent discussion today is how much a given quantity of increased CO2 increases temperature on earth.
There is overwhelming historical evidence that CO2 is not a major driver of climate change on earth.
Period.
Anon,
What I find insulting is the fact that those that are proselytizing the "CO2 human caused global warming catastrophe" story won't debate the facts.
Will play in your sandbox as long as you engage the exact points and not avoid the obvious direction I or others are going in.
CO2 increases the atmospheres temp..we do agree on that but you want to talk degree...fine, thats important.
What are you saying is the differential relationship between T and c of CO2?
Also what do you say IS your expectation if you controlled the world (scary) for CO2 atmospheric c by 2100 and 2200 (its not increasing linearly as we all know)if we do what I assume you are proposing...eg no control of CO2 emissions?
FV
...you want to talk degree...fine, thats important.
I guess it's only important if you think that a slight warming is significantly different than a catastrophic vision involving mass extinction, maybe massive numbers of human refugees or deaths, etc etc. :^)
Regarding the CO2 sensitivity, to me it looks to be in the neighborhood of 1 degree from pre-industrialization until 2100. A lot of relevant information is here .
One excerpt:
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When you substitute the concentration of 560 ppm (parts per million), you obtain something like 1 Celsius degree increase relatively to the pre-industrial era. But even if you plug in the current concentration of 380 ppm, you obtain about 0.76 Celsius degrees of "global warming". Although we have only completed about 40% of the proverbial CO2 doubling, we have already achieved about 75% of the warming effect that is expected from such a doubling: the difference is a result of the exponentially suppressed influence of the growing carbon dioxide concentration.
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I would appreciate it if you would now answer this fair, yes-or-no question: Do you think that Al Gore has promulgated some seriously misleading information about climate change?
Come on Tom you can do better than that. Quite frankly your insulting the intelligence of climatologists to suppose that they might not have noticed this lag. It’s well known and completely accounted for in the climate models.
It’s well known and completely accounted for in the climate models.
Ok. Please explain why we consistently see temperature rise *first*, then see CO2 levels rise. Why do the CO2 levels rise, if it's not that "the ability of oceans to store gases decreases with increasing temperature and this effect is clearly much stronger than the greenhouse effect".
Also, how do you respond to these two paragraphs from Motl?
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For whatever reason, some people are not willing to accept this obvious conclusion. That's why they invent various bizarre verbal constructs to circumvent the otherwise inevitable conclusion. The whole "group" at RealClimate.ORG has agreed that there was a lag. But they say that in the first 800 years when the influence of temperature on CO2 is manifest, it was indeed temperature that drove the gases. But in the remaining 4200 years of the trend, it was surely the other way around: CO2 escalated the warming, they say.
Everyone who has basic understanding of feedback theory knows that what they talk about is a textbook example of a positive-feedback system, and if the climate were such a system, the mutually supportive interactions would lead to exponentially escalating temperatures in one of the possible directions. That's clearly not observed in the data and the positive-feedback hypothesis is thus falsified.
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“Please explain why we consistently see temperature rise *first*, then see CO2 levels rise. Why do the CO2 levels rise, if it's not that "the ability of oceans to store gases decreases with increasing temperature and this effect is clearly much stronger than the greenhouse effect".
The first part of your statement is correct. The second part debatable because it’s not so much which is stronger that matters, but the extent to which each is changing, how much this change affects temperature and length-of-time taken for these changes to occur.
In response to Motl’s comments: yes temperatures would spiral exponentially in one direction or the other if ocean carbon storage was the only feedback process and solar radiation remained constant. Firstly there are other feedback process, some negative (length of growing season etc) and solar input is not constant (Milankovitch cycles). The latter can change the direction of the spiral. I reiterate, these feedback processes are accounted for in the climate models:
From the Hadley Model webpage:
“The terrestrial carbon cycle is modelled within the land surface scheme of the AGCM, and the marine carbon cycle within the OGCM. The carbon cycle model is needed in order to capture several important climate feedbacks on carbon dioxide concentration, for instance fertilisation of plant growth by carbon dioxide and uptake or outgassing of carbon dioxide by the oceans”
Cheers
Ilya (also author of the above anonymous comment)
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