Does CO2 really drive global warming?


Chemical Innovation – May 2001

Interesting article that discusses if it is chemically and physically possible for carbon dioxide to be the catalyst for climate change. This article by a professor at Ohio State University, puts a very convincing argument out that it is not possible to come to this logical conclusion based on the molecular behavior of water (H2O) and carbon dioxide (CO2).

Rather than the rising levels of carbon dioxide driving up the temperature, the logical conclusion is that it is the rising temperature that is driving up the CO2 level. Of course, this raises a raft of questions, but they are all answerable. What is particularly critical is distinguishing between the observed phenomenon, or the “what”, from the governing mechanism, or the “why”. Confusion between these two would appear to be the source of much of the noise in the global warming debate.

The postulated driver, or mechanism, developed some 30 years ago to account for the “million-year” temperature oscillations, is best known as the “Arctic Ocean” model (2). According to this model, the temperature variations are driven by an oscillating ice cap in the northern polar regions.

So the model we now have is that if the Arctic Ocean is frozen over, as is the case today, the existing ice cap is not being replenished and must shrink, as it is doing today. As it does so, the Earth can absorb more of the Sun’s radiation and therefore will heat up—global warming—as it is doing today, so long as the Arctic Ocean is closed. When it is warm enough for the ocean to open, which oceanographic (and media) reports say is evidently happening right now, then the ice cap can begin to re-form.

What we have here is a sufficient mechanistic explanation for the dominant temperature fluctuations and, particularly, for the current global warming rise—without the need for CO2 as a driver.

This now starts to address the necessity or “only-if” elements of the problem. The question focuses on whether CO2 in the atmosphere can be a dominant, or “only-if” radiative-balance gas, and the answer to that is rather clearly “no”.

…the major absorbing gas in the atmosphere is water, not CO2, and although CO2 is the only other significant atmospheric absorbing gas, it is still only a minor contributor because of its relatively low concentration. The radiative absorption “cross sections” for water and CO2 are so similar that their relative influence depends primarily on their relative concentrations. Indeed, although water actually absorbs more strongly, for many engineering calculations the concentrations of the two gases are added, and the mixture is treated as a single gas.

Compared with CO2, this puts water, on average, at 25–30 times the (molar) concentration of the CO2 but it can range from a 1:1 ratio to >100:1.

This overall position can be summarized by saying that water accounts, on average, for >95% of the radiative absorption. And, because of the variation in the absorption due to water variation, anything future increases in CO2 might do, water will already have done.

So what we have on the best current evidence is that:

  • global temperatures are currently rising;
  • the rise is part of a nearly million-year oscillation with the current rise beginning some 25,000 years ago;
  • the “trip” or bifurcation behavior at the temperature extremes is attributable to the “opening” and “closing” of the Arctic Ocean;
  • there is no need to invoke CO2 as the source of the current temperature rise;
  • the dominant source and sink for CO2 are the oceans, accounting for about two-thirds of the exchange, with vegetation as the major secondary source and sink;
  • if CO2 were the temperature–oscillation source, no mechanism—other than the separately driven temperature (which would then be a circular argument)—has been proposed to account independently for the CO2 rise and fall over a 400,000-year period;
  • the CO2 contribution to the atmosphere from combustion is within the statistical noise of the major sea and vegetation exchanges, so a priori, it cannot be expected to be statistically significant;
  • water—as a gas, not a condensate or cloud—is the major radiative absorbing–emitting gas (averaging 95%) in the atmosphere, and not CO2;
  • determination of the radiation absorption coefficients identifies water as the primary absorber in the 5.6–7.6-µm water band in the 60–80% RH range; and
  • the absorption coefficients for the CO2 bands at a concentration of 400 ppm are 1 to 2 orders of magnitude too small to be significant even if the CO2 concentrations were doubled.

The outcome is that the conclusions of advocates of the CO2-driver theory are evidently back to front: It’s the temperature that is driving the CO2. If there are flaws in these propositions, I’m listening; but if there are objections, let’s have them with the numbers.

As always, the above is only part of the entire article. Please click through to read the entire article.

Technorati Tags: ,

Tags: , , , , , , , , ,

2 thoughts on “Does CO2 really drive global warming?”

  1. Bernice Otis says:

    From the beginning of time, the world has been changing. Scientists have long studied the cooling and heating patterns that the earth. Whether you’re for or against global warming, the facts cannot be denied that yes, the earth warms, and it just so happens we have been going through a steady warming period. However, what goes up should come down, and the earth will go through a cooling period as nicely. The trends have shown us this, and numerous say that we have already entered the cooling period. Thoughts?

Comments are closed.