SEPP: Greenhouse Continued
Greenhouse Continued: For the past several weeks TWTW has described work by W. A. van Wijngaarden and W. Happer (W & H), on the thermal radiation of the five most abundant greenhouse gases. The most abundant greenhouse gas, water vapor, and the second most abundant, carbon dioxide, are extremely saturated. This means it would take major increases in the concentrations of these gases in the atmosphere to have a significant impact on global temperatures. For carbon dioxide to have a significant impact on temperatures, it would require burning of more coal and oil than are known to exist. [There is enough CH4 in methane clathrates on the continental shelf to provide 3,000 years of all 2020 energy.]
A Professor Emeritus of Physics, Howard Hayden spent most of his research career studing accelerator-based atomic and molecular collisions and published his first paper on the subject in 1964. A director of SEPP, Hayden sent a working paper to TWTW titled “CO2 and Climate: A Tutorial.” Though his approach is somewhat different, Hayden’s paper reinforces the findings of W & H: adding CO2 to today’s atmosphere will not cause significant (or dangerous) warming.
Hayden requested W & H to calculate greenhouse effects of an atmosphere with 50 parts per million of volume (ppmv); 100 ppmv, 200 ppmv, 400 ppmv (approximately today’s atmosphere) and 800 ppmv. They responded promptly, and Hayden clearly illustrates the results.
In explaining the influence of CO2, by itself, on today’s world, Hayden eliminates many of the complications of climate such as changes in natural influences that give rise to periods of glaciation interrupted by brief warm periods, changing sun, changing clouds, changing ocean currents, air circulations, etc. He assumes for the sake of argument that we have solved the basic problems of fluid dynamics, which we have not.
He then goes to the problem physicists faced in the 1800s, why is the earth warmer than it should be? They concluded that something in the atmosphere caused it to warm by blocking some of the cooling. As stated in previous TWTWs, in 1859 Irish physicist John Tyndall began experiments describing the partial blocking of the globe’s cooling by what are called greenhouse gases [GHGs], the primary one being water vapor. They block the cooling effect of planets. As Hayden writes:
“Since the only way for the earth to shed heat that comes from the sun is through radiation—and it has to be infrared radiation (IR)—you need to find somebody with expertise in the interaction between IR and the molecules in the atmosphere.”
Hayden then asks and answers the basic question:
“Is CO2 a strong greenhouse gas? The answer: It depends.” [Boldface are italic in original.]
The answer depends on the concentration of CO2 in the atmosphere. As the concentration increases, the strength wanes. Somewhat like the acceleration of a car, without gears. Initially, it will accelerate quickly but as it reaches maximum speed, acceleration slows, no matter how hard the driver presses the gas petal to the floor. As the concentration of CO2 increases the influence of each molecule declines.
“The lesson here is that at low concentrations, CO2 is a very effective IR absorber, hence a very effective greenhouse gas. By this, we mean that if a bit more CO2 is added, the greenhouse effect increases substantially.
“At higher CO2 concentrations, adding more CO2 does little to increase the greenhouse effect, for the simple reason that most (not all) of the IR that CO2 can absorb is already absorbed.”
When CO2 ceases to be an effective IR absorber, the wavelengths are said to be saturated. Additional absorption requires absorption by other IR wavelengths, which are not absorbed as readily.
“In other words, at very low concentrations, CO2 is a strong GHG; at the present concentration, CO2 is a weak GHG. This information has been around since long before Al Gore’s An Inconvenient Truth, and long before the First Assessment Report FAR) of the Intergovernmental Panel on Climate Change.
“To modify a fashionable sentence: Wavelength Matters. Any ‘climate’ discussion that ignores the details of the spectrum ignores the relevant science.” [Boldface Italics in original.]
Hayden illustrates the calculations of the IR absorption properties with photos of razor cutouts of graphs based on W&H calculations. One image shows the IR emissions of the surface of the earth at a particular temperature if the atmosphere were transparent, no greenhouse gases, no clouds, and no fine particles (dust). A second image shows the part of the emissions that are blocked by the atmosphere (greenhouse gases). A third image shows the IR emissions to space that come from the surface and the atmosphere.
It is important to realize that a significant portion of the IR emissions from the globe to space do not come from the surface, but from greenhouse gases in the upper atmosphere. Numerous internal processes, such as evaporation (which cools the surface) and condensation (which transfers that heat to the atmosphere) are important to consider, but in the end, the only way the globe sheds heat to outer space is by infrared radiation.
Though not as precise as the actual calculations, Hayden’s images clearly show the changes in IR absorption properties of CO2 as concentrations of CO2 change. The pattern of the atmospheric CO2 absorption of infrared radiation does not change significantly, but the range of frequencies (width) expands slowly. This illustrates the logarithmic relations between CO2 and temperature increases. From calculations by W & H, Hayden develops a graph on IR Blocking by CO2. This
graph shows the logarithmic relationship between Infrared radiation Blocked in watts per meter squared (W/m2) and Atmospheric CO2 Concentration (ppmv). Several important items stand out:
First, the IR blockage by 50 ppmv—only one-eighth of the present CO2 concentration—is about 75% of the present amount of blockage by CO2, just as we noted above. Second, the present IR blockage is about 30 W/m2, a mere 20% of the total (150 W/m2), in agreement with the 20% figure given by Siegel  [Referenced in the paper but not here]. Third, the increase in blocking between 400 ppmv and its double at 800 ppmv is around 3 W/m2, in approximate agreement with that (3.7 W/m2) used by the IPCC as far back as its Third Assessment Report in 2001, and 3.5 W/m2 as used in present models. There is nothing controversial here.
In the consequences section, Hayden discusses the extent of agreement between what he writes and what the UN Intergovernmental Panel on Climate Change (IPCC) has reported. Hayden goes on to write:
But failing to consider the spectrum leads to erroneous conclusions. Similarly, failing to distinguish between the surface of the earth and the earth as a whole is a failure to understand what happens.
To understand the physics, let us repeat that at equilibrium, the solar radiation absorbed by the earth will be exactly matched by the radiation emitted by the earth as a whole, namely 244 W/m2. An increase in CO2 concentration will necessarily decrease the amount of IR emitted in the CO2 band, and will heat the surface somewhat. The warmed surface will radiate more IR at all wavelengths, allowing more IR to escape at other (non-CO2) wavelengths. In other words, all other things remaining the same, the earth will still radiate 244 W/m2 averaged over the entire globe out to space. In still other words, the effective blackbody temperature of the earth [including the atmosphere] does not change…” [Boldface Italics in original.]
TWTW will continue with Hayden’s paper next week, to include comments. The paper reinforces the research showing the relationship between CO2 and temperatures are logarithmic. Adding CO2 to the current atmosphere will cause little warming, and carbon dioxide capture and sequestering is an exercise of little value.
See www.energyadvocate.com “The CO2-Climate Relationship: A Tutorial” and links under Challenging the Orthodoxy.
Functional Obsolescence: After reviewing the papers by W & H and Hayden, TWTW searched for recent research by NASA on the role of CO2 on temperatures. The links went to the 2010 paper by Gavin Schmidt, now head of NASA-GISS (Goddard Institute of Space Studies) titled “Taking the Measure of the Greenhouse Effect.” It gives a graph of the outgoing spectral radiance as measured at the top of Earth’s atmosphere compared to Blackbody emission (no greenhouse gases). It is similar to the one used by W & H and by Hayden.
The write up states:
“We find that water vapor is the dominant substance — responsible for about 50% of the absorption, with clouds responsible for about 25% — and CO2 responsible for 20% of the effect. The remainder is made up with the other minor greenhouse gases, ozone and methane for instance, and a small amount from particles in the air (dust and other ‘aerosols’).”
Then comes Schmidt’s kicker:
“Given that CO2 has such a major role in the natural greenhouse effect, it makes intuitive sense that changes in its concentration because of human activities might significantly enhance the greenhouse effect. However, calculating the impact of a change in CO2 is very different from calculating the current role with respect to water vapor and clouds. This is because both of these other substances depend on temperatures and atmospheric circulation in ways that CO2 does not. For instance, as temperature rises, the maximum sustainable water vapor concentration increases by about 7% per degree Celsius. Clouds too depend on temperature, pressure, convection and water vapor amounts. So, a change in CO2 that affects the greenhouse effect will also change the water vapor and the clouds. Thus, the total greenhouse effect after a change in CO2 needs to account for the consequent changes in the other components as well. If, for instance, CO2 concentrations are doubled, then the absorption would increase by 4 W/m2, but once the water vapor and clouds react, the absorption increases by almost 20 W/m2 — demonstrating that (in the GISS climate model, at least) the ‘feedbacks’ are amplifying the effects of the initial radiative forcing from CO2 alone. Past climate data suggests that this is what happens in the real world as well. [Boldface added.]
As Hayden shows, the effect of adding some CO2 to the atmosphere becomes smaller and smaller as the concentration increases. How can it be that adding some CO2 to the atmosphere suddenly become bigger and bigger? Moreover, the climate effect of adding CO2 is nothing more and nothing less than increasing the surface temperature somewhat. Any increase in temperature from any cause whatsoever, should, by Schmidt’s reasoning, be amplified by the same factor of five. In other words, any temperature perturbation should bootstrap itself into searing heat.
It is very clear that modelers fail at modeling clouds which are assumed to be a positive greenhouse effect (adding to warming) by NASA-GISS. Apparently, NASA-GISS is unaware that over the past 40 years, great strides have been made in measuring the greenhouse effect and temperature trends in the atmosphere, largely by satellites. What may have been intuitive sense years ago, may be obsolete today. See links under Defending the Orthodoxy.
This article appeared on the SEPP website at http://www.sepp.org/the-week-that-was.cfm]]>