Geological History Does not Support CO2's Importance

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


If you look back over the last 600 million years you see that there really is not much correlation between temperatures and CO2 levels. Clearly CO2 is not a climate driver.


While there are indeed poorly understood ancient climates and rather controversial climate changes in Earth's long geological history, there are no clear contradictions to greenhouse theory to be found. What we do have is an unfortunate lack of comprehensive and well resolved data. There is always the chance that new data will turn up shortcomings in the models and unforeseen new aspects to climate theory, and I guarantee you scientists in the field are working hard to uncover such things - every scientist relishes the thought of uncovering new data that overturns current understanding. But it does not make any sense at all to reject CO2 as a primary driver of climate change today because it looks, through the foggy glasses of time, like CO2 has not always completely controlled climate changes in the past.

The climate system is complicated, even the configuration of the continents has a big effect, so one can not expect complete correlation on all timescales between temperatures and any single factor, such as CO2 concentrations, throughout its long and varied history.

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.

"Geological History Does not Support CO2's Importance" was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.

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I'd go a step further; CO2 seems to be a lagging rather than leading indicator of climate change.

Here is the essential problem with our understanding of the historical record. Everyone is concentrating so hard on what makes the temperature go up that no one seems to care about what made it go back down again in every instance in the historical record. The most striking thing is that the temperature starts to decrease when CO2 levels are relatively high. If we use models that incorporate the mechanisms that lead to increased temperatures, but completely neglect the mechanisms that cause the temperature to go back down, it is no surprise that we tend to see a drastic spike in our predictions.

I don't know why anyone thinks temperature drops are being ignored. The mechanism is the same as that which drove the rise: changes in NH insolation due to orbital variations (Mil. cycles) caused growing ice sheets and growing arctic sea ice even as CO2 remained elevated. These ice/albedo changes caused further temerature drops which then caused CO2 levels to fall (cooler ocean waters absorb more CO2; spreading permafrost locks CO2 away from the ocean atmoshere carbon cycle). Falling CO2 levels add their effects and drive temperatures further down and this feedback continues until Milankovich cycles reverse it again.

In the drops as in the rises, orbital variations, albedo and GHG's all work together to move the temperature about 5oC globally.

Hope that clears this up.

Coby, the temperature has dropped over the past ten years, so why do we the general public continually get bombarded with scary stories by Gore and the IPCC that say the opposite? Are they ignoring temperature drops?


No, the temperature has not dropped, though we are in a short term lull, but the issue is the long term trend. Natural variability is very large compared to the .2oC/decade trend so we do not expect a steady, consistent rise. I know 7 is the most common rool of two six-sided dice, but I also know I might roll four or five times under 5 in a row. It does not change statistical reality.

If you think an isolated 10 year period is conclusive of climate change, where was your concern about "the last 10 years" in 1998?

I strongly recommend you read Tamino's post on this subject to get a basic understanding of trends and noisy data.

My first reply did not work so i will try again.


Thanks for the link and yes i did read it. But first what is the difference between no temp drop and a short term lull? Also what has the rolling of dice got to do with climate science?

In regards to Taminos post i am pretty sure my basic understanding of trends and noisy data was of a sufficient level to understand what he was saying but just in case i have few questions for you:

firstly if a ten year tend is too short (which i agree) why is a 23 year trend considered good enough (75-98)?

He condems his peers work and bemoans the fact that Statisticians should know better but then uses stats to debunk their work?

If the last ten years of (cooling/short term lull) is a product of noise, what noise produced/aided the 75-98 temp rise? Or is it only noise when the temp goes down?

To me the 75-98 temp rise had considerable noise and this is +PDO, multiple strong El Nino events and of course the Sun which was at its most active for the last 1000 years, maybe other factors aswell (C02?). Surely this noise contributed to the recent warming but is not mentioned why?

I like the way he even predicts the next phase of warming (after the short term lull is over of course) he predicts warming out to 2035 just by using stats, just think of all the money Gore can save when he sacks all those computer programmers that cant get the models to predict tomorrows weather.

And you know what no matter how hard i looked i did not find one shred of evidence that proves that any of this data manipulation via stats is caused by man made C02 funny about that. But then what do you expect when the grand poobar himself declared "the science is in" i am ready to make millions out of this.

I suggest you and your mate Tamino should travel through the NH on a meet and greet tour, you can tell the Germans who are experiencing the coldest winter in 100 years that what they are seeing is just noise, or England, or Holland or Spain or France i am sure your cheery disposition will be warmly welcomed (pun intended) and all this on top of top of last years bitterly cold winter

Or what about going to the USA and seeing first hand all that noise lying on the ground, in fact there is so much noise in the USA that in 2006/07 they had more noise than ever recorded and this year they have even more noise!!!!

You can even go to the north pole and find the north west passage that Gore claims to have seen (albeit on a computer screen)I am sure there is plenty of noise up there for you to look at.

I suggest you hurry up though as this short term lull now known as noise in AGW speak will be gone soon, or will it?


Craker14 - I've been here myself, you might be interested to read the absurd statement that Gavin Schmidt made on Real Climate that in fact makes your question harder to answer-…

So, in summary: things are very confusing and just noise when temps go down, but they are very clear and obviously only due to CO2 when they go up.

The answer I received revolved around one being a "trend" and one being noise. But I have asked at least 4 times on this site for a definition of what a "trend" is, and what the rules might be that I could apply to a temperature series to see if it is a trend or not. I haven't had an answer yet.

Crakar and paul: I highly recommend reading Tamino's post for some insight into how to tell the difference between a trend and noise in a data set like global temperature variation.

Very steep rises (like the 1988 - 1998 period) and temporary pauses (like 1998-2008) are not just expected, but inevitable.


You sent me the link on Jan 11, i am still waiting for you to explain the difference between no temp drop and a short term lull?

Is the theory something like this:

C02 goes up and temp goes up = AGW, when C02 goes up and when temps go down (or in a short term lull)= Climate change? or Its only weather?, noise? Hell idont know.

Here is my attempt at using stats and trends:

Using the magical 30 year figure, the Antarctic has cooled considerably and has increased in ice extent. The arctic is about the same temp (maybe slightly higher) and has about the same amount of ice.

Conclusion: Long term trends show no ill effects of AGW. Theres nothing to see here, please move along.

However Tamino has settled on a 23 year period of 75 to 98 to make his case so lets use these dates. Now we all know the 23 year period showed a warming of about 0.5C approx which has been widely claimed as the smoking gun if you like which proves the AGW theory.

However if we look at the 23 year period from 1985 to 2008 we find the warming of that period to be almost immeasurable. Therefore C02 goes up temperature remains the same. But....but....but.... Al Gore said.

You will notice i have completely ignored all the major climate drivers as per you mate Tamino and have manipulated the stats to suit my own argument, once again just like Tamino.

My point is stats are nice to look at but do they actually prove that man made C02 will/is causing planetary wide warming? No of course not.

This simple trick may work with the rebels without a cause tree huggers of the world but not with the majority of the worlds population.

I believe there are 4 problems with the AGW theory and therefore the IPCC.

Problem 1. Many years ago a small band of scientists started talking about the AGW theory unfortunately for them not one politician could be bothered listening. So they had to exaggerate their claims by touting Nostradamus like predictions of extinction Levelling Events.

Problem 2. This got some stupid politicians attention and once all the scary stories had been told the politicians were convinced. Of course they needed proof so a software programmer wrote a bunch of code to match the scary stories. Unfortunately the only way politicians know how to fix a problem is to apply a TAX.

Problem 3. This would mean a TAX applied to every man, woman and child on the face of the planet, a TAX that would condemn 3rd world countries to eternal poverty and simultaneously driving the economies of 2nd and 1st world countries into the dust. This got the attention of the general public and a massive propaganda campaign was launched retelling all the scary stories to convince the mob that it was their fault the planet is dying and guilt them into paying a TAX.

Problem 4. Unfortunately for the IPCC NOT ONE thats right NOT ONE of their scary stories have come true, the theory has been patched up so many times to cover all the holes that it is almost unrecognisable here is an example:

AGW cause GW but when things cool AGW causes GC but what happens when its 11 years long Its only weather, or manipulated stats or noise etc. Prediction after prediction has blown up in their faces like a bad trick cigar. The lying, the data manipulation the scaremongering can only last so long. The IPCC now looks like a punch drunk fighter staggering around the ring trying to hang on until the world stops cooling, in fact its trainer (Gore) should have thrown in the towel years ago.

This lack of ability to make accurate predictions has not been lost on the general public so much so that the IPCC is becoming a laughing stock.

The IPCC will soon be limited to running from 1 primary school to the other scaring the shit out of little children as no one else is listening. The reputation of the scientific community as a whole has been destroyed by these fools so much so i doubt it will ever fully recover.

The IPCC would have more luck door knocking with a bible in their hand as at least with religion there is some semblence of truth to debate with.

Time to throw in the towel Mr Gore.

Alright, I'll give this a shot using the dice metaphor playing with three six sided dice. The minimum roll is 3, and the maximum is 18, while the average is 10.5. This will represent what the average temperature is for that year.

So, weather versus climate, how many rolls of the dice are required to get a reasonable average? Why would I want to get a reasonable average?

Well, let's say we want to know if the person secretly rolling the dice is putting a modifier on the result by adding +1 to all the rolls. Obviously we could look for a 19 to come up because of the nature of the analogy, but let's say the die roller is crafty and turns the 19 into an 18.

So, how many rolls to make a firm statement about what the modifier is if there is one?

10-7-7-8-12 = 44 / 5 avg 8.8 ... is that enough?

7-10-11-8-14 + 44 = 94 / 10 avg 9.4 ... is that enough?

9-16-6-6-7 + 94 - 138 / 15 avg 9.2

All the rolls in this example were with a -1 modifier, so an average of 9.5 would be the expected average. If I had stretched it out to 30 sets the average likely would have become more solid around 9.5

As you can see, looking at any small trend in that data set is pointless for figuring out what the secret modifier is.

Now suppose for every data set of five rolls, I roll a six-sided die and on a 1 I lower the modifier one, and on a 6 I raise it one. Then we continue the data for a few dozen more sets of five, think you could make useful averages to guess when the modifier changes?

That's basically the issue here. The analogy can't be taken too far, but it should illustrate how a single roll or small group of rolls is pointless for determining the secret modifier on the roll.

Pointing out a specific weather event as evidence is like calling the die roller on cheating just because two threes came up back to back.

By Valor Phoenix (not verified) on 09 Feb 2009 #permalink


Lets talk about CO2 in history. I still point out that the high resolution record from ice cores over the past ~480,000 years shows that a climate driver causes warming and 600-2500 years later CO2 start rising. We know that CO2 is not that important a driver because the temperature peaks prior to the CO2 peak. If CO2 was that strong a driver, then temperature would not peak until CO2 did. Since it does not we know that the historical record shows that CO2 has a minor impact, if any, at best.

Yeah, coming in late but #12: your concerns were already answered by the OP in #4 etc. You and others keep pounding but statistical variability is not a hard science, there is no exact place where to draw the line. But just *look at* the graphs (now up again two years later) and you can *see* the upward trend line meddled with noise. And here's the kicker: if we had only the data or only the theory, it would be more doubtful. But when both agree, even if neither perfectly worked out: then saying there's very likely a real effect is the most reasonable conclusion. A a likely, mostly bad outcome is a serious risk worth doing something about.

Neil the only kicker i see is the one i get in the balls (TAX/ETS), how about i dont get kicked at all and you get kicked twice?

"You sent me the link on Jan 11, i am still waiting for you to explain the difference between no temp drop and a short term lull?"

There isn't one, cracker-ass.

Now please explain what either of them have to do with a temperature trend.

Ryan W:

CO2 seems to be a lagging rather than leading indicator of climate change

until around 200 years ago. I wonder what happened then? Gee, that's a tough one.

By Chris O'Neill (not verified) on 11 Jan 2012 #permalink