Climate Denier Arguments #1: Correlation Between CO2 and Climate


This is the first of my series of short essays on common climate denier claims, so let’s get into it. A claim often given by climate skeptics is that Carbon Dioxide (CO2) has no correlation with Earth’s temperature; and therefore increases in Earth’s CO2 level that we’ve seen today are nothing to worry about. The graph often cited by these skeptics is shown below in Figure 1.

Figure 1.

This graph is from a seminar given by Christopher Monckton in 2006, who for those who don’t know is a leading climate skeptic blogger, and is based on the findings of Berner, who compiled a graph of CO2 levels, and Scotese, who compiled a graph of temperature. When put together, it does appear that there is no correlation between global temperatures and CO2 levels; however there is a reason for this. Scotese did not do research into the correlation of CO2 and temperature, but lucky for us, Berner has. So since climate skeptics enjoy using Berner’s research to “disprove” the fact that CO2 levels do impact the climate, let’s see what Berner himself has published about the topic. In February of 2001, Berner published a paper in the American Journal of science titled “A REVISED MODEL OF ATMOSPHERIC CO2 OVER PHANEROZOIC TIME” (1) in which he studied of effect of CO2 on average temperature, let’s see his conclusion:


Results for GEOCARB III, as presented in the present paper, are compared to those for GEOCARB II in figure 13. As one can see the modeling has retained its overall trend, and the GEOCARB II curve falls within the error margins for GEOCARB III, based on the sensitivity analysis of the present paper. This means that there appears to have been very high early Paleozoic levels of CO2, followed by a large drop during the Devonian, and a rise to moderately high values during the Mesozoic, followed by a Fig. 12. Effect of global degassing on RCO2 vs time for the Mesozoic-Cenozic. fG(t) 5 1 and fC(t) 5 1 means no change in degassing rate over time. 200 R.A. Berner and Z. Kothavala—GEOCARB III: gradual decline through both the later Mesozoic and Cenozoic. This type of modeling is incapable of delimiting shorter term CO2 fluctuations (Paleocene-Eocene boundary, late Ordovician glaciation) because of the nature of the input data which is added to the model as 10 my or longer averages. Thus, exact values of CO2, as shown by the standard curve, should not be taken literally and are always susceptible to modification. Nevertheless, the overall trend remains. This means that over the long term there is indeed a correlation between CO2 and paleotemperature, as manifested by the atmospheric greenhouse effect.

Now, how can the underlined conclusion be possible given that Figure 1. clearly shows no correlation between CO2 and temperature? Are climate scientists all in on some globalist conspiracy to set up a world government?  Well no, it can be explained using basic science. To explain this, I will use the analogy of a cabin with a heater. If you were living in a cabin somewhere off in the middle of the woods, you would most likely have a heater. In the winter, your heater would most likely be at full blast to keep the temperature in the cabin stable. However come summer, you turn the heater down to keep the temperature in your cabin a normal temperature. If you were to graph the average temperature of the cabin vs the output from your heater, you would see no correlation between the two because how could it be possible that your heater is low in the summer yet temperature remains constant or even goes above what it normally does? Anyone should be able to tell you the answer, it’s because the temperature of the cabin is not only dependent on output from the heater, it is dependent on both the heater’s output and the weather outside (cabin analogy courtesy of potholer54). This same logic can be used when trying to see Earth’s climate, because the climate is not only dependent on CO2 emissions, but rather both CO2 and the sun; and one can have more of an effect on temperature than the other depending on the rate at which they are being radiated. And when we put CO2 emissions and the sun into the same graph we see:

Figure 3. (2)

Just because the sun plays a very important role in regulating the Earth’s temperature, it doesn’t mean that CO2 cannot also play a role. Throughout the history of the Earth, sometimes the sun has driven climate, and sometimes greenhouse gases like CO2 has driven the climate. Today however, the evidence shows us that CO2 is being the main driver of the climate due to the fact that solar output has been decreasing, yet global temperatures continue to rise:

Figure 4. (7)

Further research into the correlation between CO2 levels and Carbon Dioxide has been done extensively and time and time again proves to be strong. Now why is this? Why is it that CO2 impacts the climate of the Earth? This is because, CO2 causes something known as the greenhouse effect, which is when energy arrives from the sun in the form of visible light and ultraviolet radiation. Then the Earth emits some of this energy as infrared radiation. Greenhouse gases in the atmosphere, such as CO2, capture some of this heat, then emit it in all directions, one of which is right back to the surface of the Earth (3). This problem only gets worse as we dive deeper into the chemistry behind this. Because CO2 warms the temperature of the Earth, this allows for more water vapor to evaporate into the air. Water vapor is also a greenhouse gas, which warms the temperature even more, which allows for more water vapor to be evaporated, and so on (4). This is called a positive feedback loop, or the “magic multiplier” that Stefan Molyneux doesn’t seem to understand; and it’s not the only one in climate science.  Another example of a positive feedback loop is when it comes to the arctic ice melting. Ice/Snow is the most reflective natural surface on Earth, which means it has the capability of reflecting sunlight back to space. As CO2 levels increase in the atmosphere and temperatures rise, this causes the Arctic sea ice to melt, as we’re seeing (5), which in turn exposes more sea water. Sea water, is one of the darkest natural surfaces on Earth and, as anyone who has ever worn a black shirt during summer, therefore absorbs light from the sun and further raises the temperature of the oceans, which melts more ice, which exposes more sea water, and so on (6). If this feedback loop is true, that means we should be seeing a rise in not only sea temperatures, but sea levels as well and:

Figure 5. (8)
SeaLevel (2).png
Figure 6. (9)

based on the data from these graphs, that is exactly what we are seeing. We are seeing a rise, not only in sea temperature, but a rise in sea level as well. And another fun, yet scary, fact about sea levels is the fact that not only are they being risen by melting Arctic ice, but basic chemistry tells us that an increase in greenhouse gases leads to thermal expansion (10) which means that the water molecules will expand, increasing their size, which increases sea levels even more. From all the evidence, we can see a clear link between CO2 levels, and average global temperature; and if all the evidence presented so far still doesn’t convince you, I’ll end with a quote from a paper by NASA physicist, Dr. Andrew A. Lacis [et al.] (11)

Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

This will conclude my first of a few essays I have started writing going over common climate denier arguments. If you feel I was unclear about something, want a source for something, or just have any questions in general, feel free to comment or DM me on Instagram. If you have recommendations for climate denier arguments you’d like me to address, please comment them or DM them to me.


  2. “CO2 as a primary driver of Phanerozoic climate”, D. Royer et al, GSA Today, March 2004
  10. “Thermal Expansion and Sea Level Rise”, Centers for Ocean Sciences Education Excellence
  11. “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature”, Andrew A. Lacis et al.



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