April 24, 2024
Concern with Climate Change rests on the assumption that increased atmospheric CO2, presumably from human activity, will cause increased heat retention in the atmosphere, leading to potentially dangerous over-heating of the planet.
The principle is pretty stratightforwar
But atmospheric gases, including CO2, absorb and re-emit, in all directions, some amount of this energy, which would otherwise escape directly to space. Basically its like a faint secondary reflection, which transmits some amount of radiant energy back toward the surface, heating it by some amount. More CO2 means more energy captured and re-radiated by the atmosphere, meaning more heating of the surface and atmosphere, or so goes the thinking.
But the energies involved are fairly small. The IPCC estimates that increasing from 280-ish ppm of CO2 to 420-ish has added the equivalent of 2.5 Watts of radiant energy for every square meter of surface.
To put that in context, the clear-sky summer sun at noon delivers about 1400 Watts per square meter of radiant energy, while the whole-earth, 24/7 average is about 342 W m^2.
So if this figure is accurate, then the additional CO2 has increased the radiant energy reaching the surface, on average, by only about 0.7 percent. energetically speaking, that's the difference between having a chicken salad sandwich for lunch and having that same sandwich plus about a quarter of a potato chip.
OK, so maybe it's not really a problem right now. But if you add more CO2, this smallish value will become a much larger one, right?
Maybe, maybe not. Let's take a closer look.
The "absorption spectrum" of CO2, meaning the wavelengths it absorbs and re-emits, is pretty patchy. The gas absorbs very strongly in only one narrow band centered on about the 1500 nanometer wavelength, pretty close to the center of the OLR spectrum. Water vapor, which is very abundant throughout most of the lower atmosphere, also absorbs in this wavelength, though not as efficiently as CO2.
CO2 absorbs this wavelength so strongly that it is effectively blocked, even at very low concentrations.
This leads to sharply diminishing returns. At 50 ppm CO2 is capturing maybe 80 percent of the 1500 nm band, at 100 ppm a few percent more, at 200 ppm a couple percent more, and so on. By the time you get to 400 ppm, more than 90 percent of the OLR that can be captured, is. If you double it again to 800 ppm you capture just a couple percent more bit of the available energy. Full saturation, meaning essentially 100 percent capture, occurs around 4000 ppm.
This principle is central to the issue of climate change, because at this point CO2 has pretty much reached its limit as a driver of climate change. Any increase of CO2 in the atmosphere will add only a tiny bit of additional heat to the atmosphere.
This knowledge, widespread in the field of atmospheric science, has pretty much been unknown to the general public, and ignored by those pushing climate alarm for fun or profit, mostly profit. For good reason. Because a LOT of money is on the line, not to mention careers and reputations. And what would the media do to grab eyeballs if it lost one of its favorite Narratives?
Climate Change is now a multi- multi- billion dollar international business. Goldman-Freakin
But the walls are starting to crack. Here and there scientific publications that still have some integrity have published original research that verifies this principle, first established by Happer and Wiijngarden some years ago.
The debate among serious folks is over climate sensitivity. That means how do feedbacks work.
Everyone who knows anything knows carbon dioxide warming craps out at about 2* and that's that. BUT the argument is over what happens after that. The alarmists argue that this will trigger a positive feedback as more water evaporates, leading to more outgassing of co2, to more water vapor, etc. Eventually it leads to the permafrost melting and methane being released. Methane is a powerful greenhouse gas.
The only thing is there is no proof of that scenario. Water vapor also forms clouds which block sunlight. That is an example of a negative feedback.
Mars is so cold because it's air is thin. It's air is thin because of negative feedbacks which cool the planet whenever it warms and permafrost sublimates there. So if the Earth's atmosphere works at all like Mars then negative feedback loops will tamp down excessive warming.
The IPCC pick a very high sensitivity for the climate so that minor rises in carbon dioxide will trigger much larger positive feedbacks. But they have no real proof of that.
On the contrary every prediction they've made has failed, suggesting a much lower climate sensitivity.
Posted by: Timothy Birdnow at
12:03 PM
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