Empirical Evidence Shows Temperature Increases Before CO2 Increase

By Dr. Tim Ball – Re-Blogged From WUWT

The question is how does the Intergovernmental Panel on Climate Change (IPCC) determine that an increase in atmospheric CO2 causes an increase in global temperature? The answer is they assumed it was the case and confirmed it by increasing CO2 levels in their computer climate models and the temperature went up. Science must overlook the fact that they wrote the computer code that told the computer to increase temperature with a CO2 increase. Science must ask if that sequence is confirmed by empirical evidence? Some scientists did that and found the empirical evidence showed it was not true. Why isn’t this central to all debate about anthropogenic global warming?

The most important assumption behind the hypothesis that human activities are causing global warming is that an increase in global atmospheric CO2 will cause an increase in the average annual global temperature. The assumption became almost the total focus of the IPCC because of the definition of climate change given them by the United Nations Framework Convention on Climate Change (UNFCCC).

The definition predetermined the method and procedure of the IPCC, which in turn, eliminated a logical scientific approach to consider human impact on climate and climate change in the larger context of natural, that is without the human portion, climate, and climate change. The definition and the structure of the IPCC excluded the scientific method, which requires the hypothesis be disproved. Instead, everything was done to prove the hypothesis. The definition did not allow for consideration of a null hypothesis. The structure accepted the very limited, untested, conclusion of Working Group (WG) I as the basis for the research done by Working Groups II and III. This means WG II only considered the negative impact of warming. They did not consider the positive impact of warming, nor the possibility of global cooling. As a result, WG III only offered policies and remedial actions on the negative impact of global warming.

The definition given to the IPCC should have required them to examine the entire issue of climate and climate change. Then and only then, should they have considered the possible human-caused portion of climate change. Apparently, after the debacle of the 2001 Report in which a deliberate attempt was made to rewrite climate history, the IPCC acknowledged the problem of the definition by offering a better one. However, it only appeared as a footnote in the 2007 Summary for Policymakers (SPM), the simplified and exaggerated Report produced for the politicians. It said,

“Climate change in IPCC usage refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs from that in the United Nations Framework Convention on Climate Change, where climate change refers to a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods.”

The problem is this appeared in the SPM not in the WG I Report. It was impossible to apply it to “IPCC usage” in the 2007 WGI Report because that document is cumulative and built on the limited material of all previous Reports. To apply it in the 2007 Report required starting the entire process over. It appears it was presented to mislead the policymakers reading the SPM. It appears it was included so IPCC could point to it and say to those who questioned the limitations created by the original definition that their work was a result of consideration of, “natural variability or as a result of human activity.” It is, in effect, a most remarkable phenomenon, a retroactive deception.

As I recall, nobody at the time challenged the assumption that an increase in CO2 caused an increase in global temperature. Rather, the challenges focused on how the definition allowed the IPCC to downplay the much greater volume and importance of water vapor as a greenhouse gas. It allowed the IPCC to effectively overlook it because while humans produce water vapor, the amount is insignificant relative to the total atmospheric volume.

In 1999 the first significant long term Antarctic ice core record appeared. Earlier cores were in the record, but as I recall, the one by Petit, Raynaud, and Lorius were presented as the best representation of temperature, CO2, and deuterium over 420,000-year core drilled to 3623 meters. I recall Lorius warning people not to rush to judgment. One of his concerns was the size of the graph depicting such a long record. Lorius reconfirmed this position in a 2007 article.

“…our [East Antarctica, Dome C] ice core shows no indication that greenhouse gases have played a key role in such a coupling [with radiative forcing]”

In the original article, as Euan Mearns notes in his robust assessment, the authors believed that temperature increase preceded CO2 increase.

In their seminal paper on the Vostok Ice Core, Petit et al (1999) [1] note that CO2 lags temperature during the onset of glaciations by several thousand years but offer no explanation. They also observe that CH4 and CO2 are not perfectly aligned with each other but offer no explanation. The significance of these observations are (sic) therefore ignored. At the onset of glaciations temperature drops to glacial values before CO2 begins to fall suggesting that CO2 has little influence on temperature modulation at these times.

The question is how did the interpretation become that, the Antarctic ice core record confirmed that a CO2 increase causes a temperature increase. It could be the nature of the graph as Lorius said.

Joanne Nova expressed that concern in her article, “The 800 year lag in CO2 after temperature – graphed.” when she wrote,

“It’s impossible to see a lag of centuries on a graph that covers half a million years so I have regraphed the data from the original sources…”

The Lorius warning didn’t prevent people automatically assuming it confirmed the CO2 preceding temperature increase relationship. However, Nova concluded after expanding and more closely examining the data that,

The bottom line is that rising temperatures cause carbon levels to rise. Carbon may still influence temperatures, but these ice cores are neutral on that. If both factors caused each other to rise significantly, positive feedback would become exponential. We’d see a runaway greenhouse effect. It hasn’t happened. Some other factor is more important than carbon dioxide, or carbon’s role is minor.

How about considering carbon dioxide’s role is non-existent? Fortunately, after the 1999 paper was released, a few people didn’t accept everything at face value and began to test the data. By 2003 Caillon et al., (including Jouzel) produced “Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination III.” Here the concern was more with the “gas age-ice age” difference. This speaks to the problem that it takes decades for the gas in the bubble to become enclosed or trapped. In a 2006 paper, the authors state,

Gas is trapped in polar ice at depths of ~50–120 m and is therefore significantly younger than the ice in which it is embedded. The age difference is not well constrained for slowly accumulating ice on the East Antarctic Plateau, introducing a significant uncertainty into chronologies of the oldest deep ice cores.

They add;

In the case of slowly accumulating East Antarctic ice cores, this difference is very large, up to 7 kyr during glacial periods, and the timing of climate changes recorded in the two phases will not be accurate unless the gas age–ice age difference can be well constrained.

To put the best spin on it, they conclude,

The uncertainty in the Vostok gas age–ice age difference is still ~1 kyr, complicating an accurate assessment of climate phasing between Greenland and East Antarctica during the last ice age.

This means the only thing we can conclude agrees with Nova that temperature increases before CO2. It is important to note that more precise correlation between temperature and CO2 is made difficult by the application of a 70-year smoothing average to the raw data. The impact of this smoothing on the elimination of data that would help resolve the relationship and lag time. It is seen in the 2000-year comparison of different measures of atmospheric CO2 (Figure 1).


Figure 1: The original caption provides source and explanation.

It is reasonable to say that virtually all potential diagnoses are eliminated by the removal of annual variation, but especially the sequence of events. Notice that the overall atmospheric average of CO2 is different, approximately 260 ppm to 300 ppm. This is a difference that the IPCC claim took us from about 50% CO2 control of global temperature in 1950 to 95% + today.

A really good indicator of the validity and threat to the IPCC dogma of this claim were the immediate attacks by proponents of the evidence and their conclusion. They knew it struck right at the heart of their claims, their most fundamental assumption. I will not mention any specific sites and give them more credit than they deserve, but a simple keynote search for CO2 lag will suffice. The fact they knew this and deliberately tried to downplay the evidence was seen in the deception Al Gore used in his propaganda movie, An Inconvenient Truth. It was an inconvenient truth that he could not allow a sharp-eyed audience to see, so he separated the graph of temperature and CO2 enough to make visual juxtaposition of the graphs difficult. He then masked it even more with the histrionics of riding up on a forklift to the exaggerated 20th century reading.

All this came into question after 1998, rarely because people were examining what the few scraps of empirical evidence, but mostly because of what Huxley called the great tragedy of science; a beautiful hypothesis destroyed by an ugly fact. Up to that point in the modern record, the levels of atmospheric CO2 appeared to align with the rising temperature. Almost everybody overlooked the inconvenience that from 1940 to 1980 when the human production of CO2 increased the most, global temperatures went down. After 1998 the global temperatures stopped increasing while CO2 levels continued to increase in contradiction to their hypothesis. The excuses began quickly. It was a brief pause; it was an aberration; it was not a trend because it needed to last for an extended period to be significant. Santer said at least 17 years was required. Informatively, his fellow AGW proponents couldn’t wait as they faced the PR nightmare that the public began to notice the discrepancies between what they were saying and what was happening. Cartoons appeared.





The reaction was not to re-examine the science but to change the name of the hypothesis from global warming to climate change. A few noticed, but basically it took AGW proponents off the hook of explaining empirical evidence in the context of the theory. What appeared to allow them to point to any change as evidence of AGW became a trap. Now, every single change or piece of evidence had to fit the broader climate change hypothesis. As we know, many remained focussed on the original hypothesis because, although they changed the name they did not change the hypothesis.

The disconnect after 1998 between atmospheric CO2 levels and global temperatures continued and was called either the “pause” or the hiatus. The 17 years came and went, and cartoons again showed a wider audience were aware.


A growing amount of empirical evidence indicates the AGW hypothesis assumption that a CO2 increase causes a temperature increase is wrong, but it continues its sway even among many so-called skeptics. A few, like Anthony Watts, occasionally ask the question. Under the headline, “Claim: CO2 effects felt on decadal time scales, rather than centuries” he writes,

“But, why if that is true, why are we in a pause, when there’s been an increase in CO2 the last decade and no correlation with temperature?”

In the study he is reviewing, the lead author provides one explanation.

“Amazingly, despite many decades of climate science, there has never been a study focused on how long it takes to feel the warming from a particular emission of carbon dioxide, taking carbon-climate uncertainties into consideration.”

A year later in 2015, the abstract for an article in Environmental Research Letters says,

In a recent letter, Ricke and Caldeira (2014 Environ. Res. Lett. 9 124002) estimated that the timing between an emission and the maximum temperature response is a decade on average. In their analysis, they took into account uncertainties about the carbon cycle, the rate of ocean heat uptake and the climate sensitivity but did not consider one important uncertainty: the size of the emission. Using simulations with an Earth System Model we show that the time lag between a carbon dioxide (CO2) emission pulse and the maximum warming increases for larger pulses. Our results suggest that as CO2 accumulates in the atmosphere, the full warming effect of an emission may not be felt for several decades, if not centuries.

Apparently, in case anyone interpreted this to say there is no need to act now or even precipitously, the authors add,

Most of the warming, however, will emerge relatively quickly, implying that CO2 emission cuts will not only benefit subsequent generations but also the generation implementing those cuts.

In a “plain language” summary by Nic Lewis on Judith Curry’s website of a paper released by a group from the UK Met Office under lead author Andrews we learn,

The simulations show that the models’ effective climate sensitivity is substantially lower when driven by an observationally-based estimate of the evolution of SST and sea-ice over the historical period than when responding to long-term CO2 forcing. This finding underlies the authors’ conclusion that climate sensitivity estimates based on observed historical warming are too low.

The fact that this is presented as “plain language” explains why so many don’t understand what is going on and why the deception that AGW is proven and occurring continues. As the first comment on the Lewis piece says,

I’m sorry but I need a “plain English” translation of the “plain language” summary.

Climate sensitivity is the effect on global temperature of a change in forcing, in this case, the forcing is an increase in CO2. You can read the IPCC definition here. This accepts the assumption that a CO2 increase causes a temperature increase. The Andrews et al., although done using a model, shows that when the authors used empirical data the CO2 increase was “substantially lower.” Don’t forget, this is for just two variables, sea-ice and Sea Surface Temperatures (SST). Is it possible that with many more empirical values the climate sensitivity would go to zero? That is the empirical evidence based on studies and decrease in sensitivity over the last few years (Figure2).


Figure 2

The issue of CO2 climate sensitivity is central to the entire history of scientific examination. Academics, including those in the natural sciences, love to use argumentum ad verecundiam (appeal to authority) to bolster their studies. Proponents of the AGW hypothesis cite the work of Svante Arrhenius as their basis. Unfortunately, and especially nowadays in this age of the Internet and access to billions of pieces of evidence, it is hard to cherry-pick, or take information out of context. Again, Watts and others were in the forefront of this healthier and more rigorous research. His 2009 article identifies many of the difficulties with relying on Arrhenius.

A similar analysis was undertaken by The Friends of Science when they translated from the German a more obscure 1906 Arrhenius work. They wrote,

Much discussion took place over the following years between colleagues, with one of the main points being the similar effect of water vapour in the atmosphere which was part of the total figure. Some rejected any effect of CO2 at all. There was no effective way to determine this split precisely, but in 1906 Arrhenius amended his view of how increased carbon dioxide would affect climate.

The issue of Arrhenius mistaking a water vapor effect for a CO2 effect is not new. What is new is that the growing level of empirical evidence that the climate sensitivity of CO2 is zero is being ignored. Therefore, my view aligns with some of his colleagues who, “rejected any effect of CO2 at all.”

I am not saying there is no greenhouse effect. I am saying that the empirical evidence shows that an increase in CO2 does not cause an increase in temperature. Further, it appears that the entire greenhouse effect is reasonably explained by water vapor. Besides variation in water vapor is just one variable in a complex array of variables that cause climate change, which can cause global warming or global cooling.

As an exclamation mark I conclude,


2 thoughts on “Empirical Evidence Shows Temperature Increases Before CO2 Increase

  1. This discussion never quite reaches the point. The point is that CHANGES in CO2 matter very little in warming or cooling the planet. 500 million years of data show this clearly. CO2 is NOT a control knob. The Sun warms the planet, tectonics move the continents around, raising and lowering the atmosphere, and orbital perturbations cause slight variations in climate, resulting in glacials and interglacials. The orbital changes in heating are more than 50 times larger than the largest proposed ADDITIONAL CO2 greenhouse heating. The climate effect of CHANGES in CO2 is a very secondary effect. Most of the CO2 greenhouse occurs with the first 100 ppm of CO2, because the greenhouse increases as the logarithm. Arrhenius got that right in 1896!
    Why, then, do climate models predict a climate disaster? Actually, they do not.
    The modelers KNOW that CO2 from combustion cannot continue much longer since fossil fuels are finite; even the most generous estimate by the USGS has fossil fuels peaking within 2 decades. The IPCC actually agrees with this in its 2017 report, and confidently predicts the peak of CO2 production about 2050. This means the least or worst RCPs will never achieve their awful predicted outcome. The models will have vindicated themselves and have saved the world as a corollary. Sure…
    In fact, my four year old grandson can make the correct prediction with a pencil and a straightedge.


    • Yes, you certainly are right that CO2 is NOT the control knob for temperature. Tim Ball writes regularly at WUWT and agrees with you. He’s limited this discussion just to the idea that CO2 can’t be the control knob because it goes up (on various timescales) after temps change. (Cause doesn’t follow effect.

      On the amount of fossil fuels still in the ground, I disagree with you. Yes, they’re finite3, but 2 decades is wrong. Most likely, that figure was used because of the resource already discovered is around that much. Of course, as profit making businesses, it doesn’t make sense for them to look for additional resources until they’re needed. I expect that in 10 years, or 20 years, or 50 years that their discovered resources of petroleum & natural gas still will be around 20 years worth. Coal right now is supposed to be a couple of centuries worth.

      But, they still will not affect the global temperature because the burning process used is changing. A company called NET Power has put a 50 MW gas fired power plant into service/testing which produces zero CO2, and the process can be extended into oil and coal.


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