You asked a very simple and very core question to global warming, related to the mechanism by which CO2 is a greenhouse gas. You asked if we are still arguing this mechanism.
The short, general answer is that there are denier responses (I use “denier” because many climate change opponents, while claiming this term derogatory, refuse to offer a descriptor they find more acceptable) to every global warming claim, and that denial now includes challenges to the fundamental science of greenhouse gases.
My opinion has always been that healthy and informed skepticism is an important part of any scientific debate. But I am convinced the current attacks on “settled science” are neither healthy nor informed.
Getting back to your specific question, the effect of atmospheric CO2 upon temperature is not the entire story in global warming, but according to climate change experts it is the key catalyst and most critical variable. The basic scientific research on CO2 as a greenhouse gas is more than a century old. The denier attacks upon this settled science are numerous. But I will concentrate on just one that is currently argued in this forum.
The argument acknowledges CO2 as a potential greenhouse gas, but claims that atmospheric CO2 concentrations have reached greenhouse saturation. Somehow concentrations are already high enough that all the earth’s emissions at the key CO2 wavelengths are completely absorbed, so that no additional absorption is possible. Therefore it doesn’t matter how much higher atmospheric CO2 concentrations rise.
This “denier” argument totally misinterprets greenhouse gas theory. It implicitly models the atmosphere as a single monolithic layer. Any CO2 photon absorption anywhere above the earth’s surface can only originate from the earth (and not from other CO2 molecules), and such absorptions are the entirety of CO2’s greenhouse interaction. The subsequent photon emission from that initial CO2 absorption apparently immediately exits the earth’s atmosphere, and has no further interactions with anything atmospheric.
The reality is that greenhouse gas theory does not allow the atmosphere to be modeled as a single, monolithic layer. It must be modeled as a series of adjacent layers, with layer thickness a function of absorption efficiency at a given wavelength. Photons emitted after an initial CO2 absorption can and will be absorbed by other CO2 molecules before finally leaving the earth’s atmosphere. The number of CO2 absorption-emission interactions can be calculated by knowing the average mean-free path between CO2 molecules. Mean-free-path is a function of atmospheric CO2 concentration. Higher atmospheric CO2 concentrations result in more atmospheric absorption-emission interactions. And since each absorption-emission interaction consumes a finite period of time, additional interactions slow the exit of the photons from the earth. This additional atmospheric dwell time ultimately results in a new (and higher) thermal gradient.
From a larger perspective, you severely underestimate the creativity of the so-called “expert” skeptics and deniers. The core arguments against climate change are simple: “If the theory doesn’t understand and explain everything completely, it must be totally wrong” and “Unless the models are already perfect, explaining and predicting not only the macro trends but also real time local variations, then the model must be trash”. For a denier, proving any element of global warming as not yet being perfect means the entire concept is wrong.
At least within the US, there is a denier rebuke for every scientific finding related to global warming. There is a denier champion offered as an expert to promote that rebuke. It doesn’t seem to matter whether the denier champion or the denier response has any scientific credibility. More important is that the denier response sounds, to non-scientific listeners, like it could be scientifically credible. There is a huge world of media and Internet cheerleaders, usually with a political agenda, ready to pronounce each global warming denial as truth to their listeners. The listeners believe spokespeople they trust, rather than actual experts. Based upon 2016 elections we now have a President and a Congress who publicly pronounce that the entirety of global warming is a hoax.
97% of climate scientists agree that humans are causing global warming. This is because there are many lines of evidence that humans are causing global warming, including:
Magma changes cause climate change. Beneath our feet lies liquid rock convecting up heat from the Earth’s core. The inner part of this core is as hot as the surface of the sun. The only thing protecting us from instant death is a relatively thin crust of cooled magma. It is sobering to realize that there is enough heat beneath our feet to vaporize all water and with it all life in our ecosystem many times over.
As Thermodynamics 101 tells us in laymen’s terms, you let the heat out. The earth has been cooling since it was created. Of course, originally it had no crust. As it cooled the crust formed and later our ecosystem became cool enough for water vapor in the atmosphere to condense and fall to the earth. As more time went on more water vapor was introduced into our ecosystem through volcanic eruptions and through time the water in our ecosystem shifted from the majority existing as vapor in our atmosphere to the majority existing in liquid form as surface water. Which now this surface water covers over two thirds of our planet and holds over 97% of the water in our ecosystem.
Imagine a spinning raw egg with the egg white exerting force against the shell. Imagine now that the direction of rotation of the egg yolk and white is slightly off from the direction of rotation of the shell. Such is the case with our Earth. We know this from the geomagnetic forces set up by this rotating magma. We also know that the direction of this rotation has been changing. We also know the amount of this change has been accelerating in the last few decades. The location of the magnetic north pole had been moving for the last few centuries at around 10 km/yr but since around 1990 has been skyrocketing and since 2000 has been averaging around 60 km/yr.
We also know this magma is now causing localized magnetic anomalies with the strength of our geomagnetic field decreasing at a rate 10 times the rate just a few decades ago.
We had been observing a geomagnetic decay rate of around 6% per century starting around 1860. Which in itself is huge considering we had seen nothing close to that the previous 2000 years. If we had, we could be today where Mars is now with essentially no magnetic field. We know Mars at some time in its past had a significant magnetic field along with water on its surface.
Now we know, thanks to the European Space Agency (ESA) satellite array SWARM which went active in 2014 that the rate of collapse of the Earth’s magnetic field has increased around 10 fold to around 5% per decade.
I’m sure there will be those who will try to monetize the collapse of Earth’s magnetic field. Has not EMF pollution from Man coincided with this collapse? Has not electromagnets interacting with Earth’s magnetic field since Tesla’s invention of the induction motor proliferated during the last century? Have not use of super strong electromagnets in healthcare and superconductors in particle accelerator colliders greatly increased? Has not EMF from cell phones use greatly increased in the last two decades around the globe? Aren’t there some cell phones that give off considerably less EMF? And did not a Russian military journal warn that the consequences of our HAARP’s interaction with Earth’s magnetic field could destabilize our Earth’s magnetic field and even cause it to possibly flip?
The irony in all of this is we could have electric car manufacturers having to buy EMF credits from conventional car manufacturers instead of being able to sell CO2 credits to them.
Now our decaying global magnetic field would expectedly warm our ecosystem in two ways. One, would be to increase the amount of charged particles which would reach our Earth from the solar wind. This consists of alpha particles, electrons, and protons which are said to have thermal energies from 1.5 to 10 keV. There is also speculation that our magnetic field also protects our atmosphere from being stripped away by the solar wind. Although another study shows that other planets without a magnetic field seem to be losing their atmosphere at around the same rate as our own with a magnetic field.
The other way our decaying magnetic field would expectedly warm our ecosystem would be the increase of global internal turmoil of electrically conductive magma which would have a net effect of increasing circulation of higher velocity and higher temperature magma closer to the crust. This would increase heat transfer preferentially where the crust is the thinnest under the oceans.
So what can we expect from an increase of geothermal heat reaching our ecosystem? The O2 and CO2 equilibrium balances between the waters on earth and the atmosphere will change. Both O2 and CO2 have less solubility in water as the temperature of water rises. Less O2 will be available in the oceans for both plants and animals as both need O2 availability to burn food for energy.
While it has been said that only 1% of the oxygen in our ecosphere is dissolved in surface waters, we are told 98% of the carbon dioxide resides there. And the deeper one goes, the more soluble CO2 becomes. And pressures can reach in the deepest parts of the ocean over 1000 atmospheres.
Which means more CO2 will escape out of sea water into the atmosphere as ocean currents bring warmer deep water into shallow waters. Which today this causes the water to appear to boil from the escaping CO2 in many equatorial waters.
We can do a material balance using documented changes of both CO2 and O2 in the atmosphere over 24 years. This could give us an idea of how much atmospheric CO2 has increased due to higher water temperatures vs. how much may be due to higher production of CO2 such as from burning hydrocarbons.
Natural gas which is mainly methane is burned as follows. CH4 + 2 O2 = CO2 + 2 H2O. One molecule of methane uses up two molecules of oxygen from the air. This is a two for one oxygen to hydrocarbon burned along with CO2 created molecular ratio. The average for all hydrocarbons currently burned including oil and coal is closer to 1.4.
As a caveat in doing this material balance there are assumptions that have to be made as to other parameters remaining static over time. For example the oxygen content of the air over 24 years is measured as the ratio to N2. The decrease in O2 to N2 ratio is taken as being 100% due to O2 being taken out of the ecosystem while N2 percentage remains constant. Technically, taking O2 out of the atmosphere without replacing it molecule for molecule with something else such as CO2 means the atmosphere shrinks and the N2 percentage by difference increases. Also, we know higher ocean temperatures mean N2 dissolved in the ocean water will be released to the air. Another is the conversion of CO2 to biomass releasing O2 has remained constant. Although it has been reported that the levels of phytoplankton creating biomass has decreased.
With all this in mind, using observations from the Mauna Loa, Hawaii from 1991 to 2015 without going into how representative it is, we can do a material balances.
We can come up with an O2 mol% decrease in air extrapolated per 100 years of 0.15 mol%. Likewise the CO2 increase in air extrapolated per 100 years would be 0.02 mol%. Taking the O2 decrease and converting it to equivalent CO2 using 1.4 molecules O2 per molecule of CO2 works out to 0.11 mol% CO2 increase per 100 years. As only 2% at equilibrium at constant temperature of this 0.11 mol% CO2 will stay in the air with 98% of the CO2 contained in the water, that leaves 0.0022 mol% CO2 increase due to atmospheric O2 decrease of the total 0.02 mol% increase per 100 years. This works out to around 11% that we can attribute to possible hydrocarbon burning and 89% that we can attribute to magma changes.
CO2 mol% equiv increase per 100 yrs from O2 @ 1.4 mol/mol
This ignores the argument by some that as long as the water sinks are not saturated, which they say they aren’t, all the increased generated CO2 is naturally stored in the water sinks. Which means shifting atmospheric CO2 concentrations merely reflect shifting CO2 equilibrium based ONLY on the water sink temperature changing. So this would mean in the last 24 years we have seen this water sink temperature to rise as confirmed and reflected 100% by the increasing atmospheric CO2 concentration.
I haven’t brought up whether this increased CO2 in the atmosphere has a net heating or cooling effect on the climate when coupled with the sun shining through the atmosphere. If it is a net heating effect then this will cause the surface water anyway to get warmer which will cause it to release more CO2 which will heat more surface water which will cause more CO2 to be released, etc. etc. Which sounds to me if true, something in process control we call an unstable positive feedback loop or possibly a self-integrating process. This question though is way too politically charged for me to take a stand one way or another. I will point to a fellow Chemical Engineer, Dr. Pierre Latour, who has taken a stand and written about four scientific ways atmospheric CO2 cools earth’s climate. Maybe he’s right.
But regardless, we are talking about the CO2 concentration increasing its percentage by 0.02% in the air when extrapolating over 100 years. Over the same time we are talking about the O2 concentration deceasing in by 0.15% or 7 ½ times as much. But this gets blown away in terms of the magnitude of chaotic changes in magma flow which has caused the Earth’s magnetic field to decrease 6% in the previous 100 some years and which is now falling off the cliff at nearly 10 times that at 5% per decade. However, there are many magma deniers out there.
Hi, Robert Redelmeier. You are right, there is a lot of noise in the surface temperature record. However, even if there was no surface temperature evidence of global warming, we would still know that global warming is occurring. There are many lines of evidence that show the globe is warming, including species are migrating poleward and to higher elevations (link.springer.com/article/10.1007/s10530-015-1025-x)sea ice has decreased (nsidc.org/arcticseaicenews/ and www.nasa.gov/content/goddard/nasa-study-shows-global-sea-ice-diminishing-despite-antarctic-gains)ice sheets have decreased (nsidc.org/cryosphere/sotc/ice_sheets.html)sea levels have risen (www.ipcc.ch/pdf/assessmentreport/ar5/wg1/WG1AR5_Chapter13_FINAL.pdf)spring comes earlier (nca2014.globalchange.gov/report/our-changing-climate/frost-free-season#intro-section-2)glaciers have retreated (wgms.ch/downloads/WGMS_GGCB_01.pdf)-Kirsten
I was interested in seeing the information on the layers of the atmosphere. I had tried to find information like this on my own but didn't see much. Thanks for the link.