Global warming, climate change, all these things are just a dream come true for politicians. I deal with evidence and not with frightening computer models because the seeker after truth does not put his faith in any consensus. The road to the truth is long and hard, but this is the road we must follow. People who describe the unprecedented comfort and ease of modern life as a climate disaster, in my opinion have no idea what a real problem is.
Like Don Quixote suffering a coffee overdose, once again I mount my steed, take up my lance, and go tilting at windmills.
Hereโs a thought experiment. Consider the Earth with no atmosphere and with the same surface albedo of 12.5% that it has now. How warm would it be?
In this condition, because there is no atmosphere, there are no heat losses from the surface by sensible or latent heat. For the same reason, thereโs no reduction in incoming solar power as a result of reflection from clouds or solar radiation absorbed by the atmosphere. Solar radiation absorbed at the surface is radiated straight back to space. So, we can calculate the temperature directly from the absorbed radiation using the Stefan-Boltzmann equation. This equation relates watts per square meter of surface radiation to the corresponding temperature of the radiating surface. I used the S/B equation with the average emissivity of the Earth, which is ~ 0.98, to calculate the surface temperature. All values are in watts per square meter (abbreviated variously as W/m2 or W/m2).
Figure 1. Total surface radiation absorption, Earth with no atmosphere, with the same albedo as the current Earth. Total absorbed solar radiation is the incoming 340ย W/m2ย minus the 43 W/m2ย reflected solar radiation. Integer errors are due to rounding. All values are in watts per square meter (abbreviated as W/m2 or W/m2)
Minus two degrees C. What you might call totally chill. Just below freezing, in fact.
Now, over millions of years, letโs slowly add in an atmosphere and when it matches the modern atmosphere in all respects, let it percolate for another few million years.
After adding the atmosphere, there are lots of changes. Atmospheric absorption cuts down on the amount of solar radiation hitting the surface, which cools the surface. Of course, reduced surface radiation also reduces the amount reflected. However, this reduction in solar radiation at the surface is more than compensated for by the atmosphere adding in 340 W/m2 of downwelling longwave (thermal) radiation from the atmosphere to the surface (yellow arrow in Figure 2 below), which provides significant warming.
And back to the chill side, having an atmosphere allows for sensible and latent heat loss to the atmosphere, which cools the surface. In addition, with an atmosphere we get atmospheric absorption of sunlight, emergent phenomena like thunderstorms, and cloud radiative effects, all of which cool the surface.
Itโs a mixed atmospheric bag that ends up with about 20ยฐC less temperature change from the no-atmosphere to the with-atmosphere condition than youโd expect based on the large increase of ~ 212 W/m2 in absorbed radiation at the surface.
With that as prologue, hereโs the surface radiation absorption with our current atmosphere to the same scale as Figure 1.
Figure 2. Total surface radiation absorption, Earth with an atmosphere. This 510 W/m2ย is all the power absorbed by the surface. (Yeah, yeah, I know thereโs geothermal heat. Itโs on the order of tenths of one W/m2, so itโs always ignored for this level of analysis.) The yellow/black arrow is the downwelling longwave (thermal) radiation from the atmosphere to the surface.
OK. Some simple math.
The amount of radiation absorbed by the surface increased from 298 W/m2 with no atmosphere, to 510 W/m2 with an atmosphere, an increase of 212 W/m2.
Due to surface cooling from reduced solar hitting the surface as well as sensible and latent heat loss to the atmosphere, when the atmosphere was added, the temperature only went from -2ยฐC to 18ยฐC, an increase of 20ยฐC.
This means that for each additional W/m2 absorbed by the surface, including all possible influences and feedbacks from clouds, water vapor, sensible and latent heat loss, etc., in the long term the temperature increased by 20ยฐC / 212 W/m2 = 0.09ยฐC per W/m2
If we use the IPCC canonical value of 3.7 W/m2 per doubling of CO2, this would mean that the equilibrium climate sensitivity at the surface is 0.35ยฐC per doubling of CO2.
โBut waitโ, I hear you thinking. โClimate sensitivity is how much the temperature changes, not with downwelling longwave radiation at the surface, but how much temperature changes with the โgreenhouse effectโ radiation (GHE) from the atmosphere and the clouds, as measured at the top of the atmosphere (TOA)โ.
And youโd be right. Thatโs the definition.
However, we can allow for this by understanding the relationship of surface downwelling longwave and downwelling โgreenhouse radiationโ from the atmosphere and clouds.
When we look at the current global correlation between the poorly named atmospheric โgreenhouse radiationโ measured at the top of the atmosphere (TOA) and the surface downwelling longwave radiation, when the TOA-measured greenhouse radiation changes by 1 W/m2, due to internal feedbacks, the surface downwelling longwave radiation changes by 1.26 W/m2. Or vice versa. In either case, they move in synchrony.
Figure 3. Scatterplot, surface downwelling longwave radiation versus TOA-measured โgreenhouseโ radiation from the atmosphere and the clouds. At the monthly level, there is no temporal lag between the two. Current average GHE radiation is 158 W/m2.
Multiplying the surface sensitivity by 1.26 to convert to sensitivity to greenhouse gases increases the equilibrium climate sensitivity from the surface value of 0.35ยฐC per doubling of CO2 calculated above, to a final figure of 0.44ยฐC per CO2 doubling.
OK, thatโs one way to get there. Interestingly, for verification of the sensitivity estimate, we can calculate the equilibrium climate sensitivity in a totally different manner. Consider the same thought experiment as above.
With no atmosphere, the GHE radiation is zero W/m2. Currently, the GHE radiation is 158 W/m2. That gives us 20ยฐC / 158 W/m2 * 3.7 W/m2_per_CO2_doubling = 0.47ยฐC per CO2 doubling โฆ compared to the 0.44ยฐC from the previous calculation using a different method, thatโs excellent agreement. So to be conservative, let me call the warming on the order of half a degree C from a doubling of CO2.
This ~ half degree C of surface warming per doubling of CO2 represents a long-term equilibrium calculation, because it includes all known and unknown atmospheric factors and feedbacks involving water vapor, cloud radiative effects, latent and sensible heat losses, atmospheric absorption of solar radiation, all of that. The climate system during the Holocene is basically in a long-term (millennia) dynamic steady-state.
One advantage of using this method to calculate climate sensitivity is that the radiation numbers are large. As a result, small variations or uncertainties in them donโt change the answer much. For example, the current calculated ~ 2 W/m2 increase in โgreenhouse radiationโ since โpre-industrialโ times is not significant because it is only ~ 1% of the change in downwelling longwave radiation from the no-atmosphere to the with-atmosphere condition. Basically, the answer is the same whether itโs included or not.
And while my estimate of the equilibrium climate sensitivity of ~ half-degree per CO2 doubling is well below the three degrees per doubling that the IPCC uses as the sensitivity, itโs not outside historical estimates.
Figure 4. A large number of different estimates of the equilibrium climate sensitivity over the last half century, coded by color. Pale blue lines show the IPCC uncertainty values. My estimate of a half-degree per doubling is shown by the horizontal dotted black line.
Here are the authors, dates, and values of the best estimates shown in Figure 4 that are under 1 W/m2.
Author Year ECS Class 1 Specht et al. 2016 0.37 Theory & Reviews 2 Idso 1998 0.42 Theory & Reviews 3 Lindzen and Choi 2009 0.47 Observations 4 Harde 2017 0.65 Theory & Reviews 5 Lindzen and Choi 2011 0.72 Observations 6 Bates 2016 0.92 Observations
In closing, in my post โTesting A Constructal Climate Modelโ, I described how the Constructal model estimates a climate sensitivity of 1.1ยฐC per doubling of CO2. However, in that post I said:
Finally, this is a maximum sensitivity which does not include the various emergent thermoregulatory mechanisms that tend to oppose any heating or cooling. This means the actual sensitivity is lower than ~1.1ยฐC per 2xCO2.
This latest result, of ~ half a degree warming per doubling of CO2, which includes not only emergent phenomena but all atmosphere-related phenomena, is in line with that assessment.
In related news, providing this method holds up, this means
โAPOCALYPSE CANCELLED! SORRY, NO REFUNDS!โ
Itโs very unlikely that we will double the current CO2 level. Burning all total known reserves, not just the proven reserves, but all known reserves, will emit about 4,800 gigatonnes of CO2. This will raise the CO2 level in the atmosphere by ~ 280 ppmv. Thatโs far from doubling the current 420 ppmv atmospheric CO2 level.
This means that about a third of a degree of future warming lies in the ground in the form of fossil fuels.
Sadly, I fear the chance that this analysis will convince any true believers is small. Theyโre caught in the Upton Sinclair Trap. He famously said:
โIt is difficult to get a man to understand something, when his salary depends on his not understanding it.โ
It does seem recently, however, that more and more people are seeing through the climate grift. At least the US Government seems to be getting off the climate merry-go-round of endless failed predictions.
And to return to my analysis, what am I missing here? Where are my math mistakes or the holes in my logic? Why isnโt this a solid estimate of the equilibrium climate sensitivity, giving the same answer when calculated in two different ways?
Regards to all on a cloudy fall day,
w.
[UPDATE] In response to comments, a clarification.
A general comment for all, to clarify my position.
I do think that radiatively active gases affect the temperature. But I donโt think that small variations of a few watts per square meter in the resulting downwelling radiation change the temperature anywhere near as much as the conventional wisdom would have you alarmed to believe.
In addition to theoretical arguments and other evidence, my own climate model is able to do a very good job of emulating the real-world temperature using only albedo and the Ramanathan โgreenhouse factorโ, the percentage of upwelling surface radiation that is absorbed in the atmosphere.
Here is a more recent graphic from my ever-evolving Constructal climate model, showing how those two measurable environmental variables, albedo and greenhouse factor, are all you need to emulate the absolute temperature.
This also makes physical sense. Albedo controls how much energy is entering the system at any time. The greenhouse factor controls how much energy is leaving the system at any time. Any imbalance between those two will be reflected in a temperature change โฆ just not as much as folks think.
This excellent goodness of fit of the Constructal climate model is further evidence that the greenhouse factor, the percentage of upwelling radiation absorbed by radiatively active gases in the atmosphere, does in fact affect the surface temperature.
Regards to everyone,
w.
As Is My Habit: I ask that when you comment, you QUOTE THE EXACT WORDS you are discussing. This is essential to prevent misunderstandings.
In Episode #160 of The Climate Realism Show from The Heartland Institute, Anthony Watts, Linnea Lueken, H. Sterling Burnett, and Jim Lakely are joined by newly minted meteorologist Chris Martz, who has been driving alarmists crazy on social media for years.
We get so many great questions in each episode of The Climate Realism Show that we decided to dedicate a whole episode to answering them. Wellโall of it except our coverage of the Crazy Climate News of the Week, of course.
This week:
– UN Secretary-General Antรณnio Guterres is once again calling for censorship of climate realists
– Another massive ship has been set ablaze and set adrift by EVs
– Our atmosphere is getting โthirstierโ (and thatโs bad, of course)
And a Florida TV weatherman is lying about not being able to predict hurricanes because of federal budget cuts
In Episode #160 of The Climate Realism Show from The Heartland Institute, Anthony Watts, Linnea Lueken, H. Sterling Burnett, and Jim Lakely are joined by newly minted meteorologist Chris Martz, who has been driving alarmists crazy on social media for years.
Join us LIVE at 1 p.m. ET on Fridayโand since this is a special Q&A episode, get those questions ready!
Approximately 34 million years ago (mya), during the Early Oligocene Epoch, the Earth entered its current โicehouseโ climate mode, with ice sheets covering Antarctica. After warming up again towards the end of the Oligocene, Earthโs climate began a long cooling trend, punctuated by a brief warm period during the Late to Middle Miocene Epoch.
Approximately 34 million years ago (mya), during the Early Oligocene Epoch, the Earth entered its current โicehouseโ climate mode, with ice sheets covering Antarctica. After warming up again towards the end of the Oligocene, Earthโs climate began a long cooling trend, punctuated by a brief warm period during the Late to Middle Miocene Epoch.
Figure 1. Cenozoic Era climate reconstruction rom Zachos et al., 2001 (older is toward the bottom).
The Middle Miocene Climatic Optimum (MMCO) was an anomalous warm interval from ~17 to ~14 mya. The incorrect assumption that CO2 is the climate change โcontrol knobโ has led to many attempts to link the MMCO to the CO2 and other greenhouse gas emissions related to the Columbia River Basalt Group (CRBG) eruptions. The CBRG eruptions do appear to be coeval with the MMCOโฆ
Flood basalts, the largest volcanic events in Earth history, are thought to drive global environmental change because they can emit large volumes of CO2 and SO2 over short geologic time scales. Eruption of the Columbia River Basalt Group (CRBG) has been linked to elevated atmospheric CO2 and global warming during the mid-Miocene climate optimum (MMCO) ~16 million years (Ma) ago. However, a causative relationship between volcanism and warming remains speculative, as the timing and tempo of CRBG eruptions is not well known. We use U-Pb geochronology on zircon-bearing volcanic ash beds intercalated within the basalt stratigraphy to build a high-resolution CRBG eruption record. Our data set shows that more than 95% of the CRBG erupted between 16.7 and 15.9 Ma, twice as fast as previous estimates. By suggesting a recalibration of the geomagnetic polarity time scale, these data indicate that the onset of flood volcanism is nearly contemporaneous with that of the MMCO.Kashbohm & Schoene (2018)
These flood basalt eruptions certainly would have emitted a lot of CO2, other volcanic gasses and sulfate aerosols. However, the CO2ย outgassing was probably only a fraction of what would have been required to explain the MMCO.
Armstrong McKay et al., 2014 estimated that the main phase of the CRBG eruptions, along with โcryptic degassingโ of country rock, etc., emitted 4,090 to 5,670 billion tons of carbon over a 900,000 period. This only works out to 5-6 million tonnes of carbon per yearโฆ Thatโs an order of magnitude less than a rounding error. Our current 10 billion tonnes per year is only equivalent to 3% of the total annual sources in the Earthโs carbon budget. Self et al., 2005 found that CO2 emissions from flood basalt eruptions were insignificant relative to the mass of CO2 in the atmosphere and unlikely to have played a significant role in past episodes of โglobal warming.โ Although they did note that the sulfur gas emissions and sulfate aerosols may truly have been unprecedented. However, these would have had a cooling effect on the climate.
Furthermore, there is little evidence of significantly elevated atmospheric CO2 associated with the CRBG.
Figure 2. Miocene atmospheric CO2ย (older is toward the left).
Neither the MMCO nor the subsequent cooling, leading the growth of the East Antarctic Ice Sheet (EAIS), appear to be driven by changes in atmospheric CO2.
There is no evidence for either high pCO2 during the late early Miocene climatic optimum or a sharp pCO2 decrease associated with EAIS growth.Pagani et al., 1999
While the cause of the MMCO remains somewhat of a mystery (probably tectonically driven changes in oceanic circulation), the cause of the subsequent cooling (AKA Middle Miocene Climate Transition or MMCT) may have now been identified.
Our Solar System Crossed โRadcliffe Waveโ during Miocene Epoch, Astronomers Say
As our Solar System orbits the Milky Way, it encounters various environments, including dense regions of the interstellar medium. These encounters can expose parts of the Solar System to the interstellar medium, while also increasing the flow of interstellar dust into the Solar System and Earthโs atmosphere. The discovery of new Galactic structures, such as the 9,000-light-year-long Radcliffe wave, raises the question of whether the Sun has encountered any of them. According to new research, the Solar Systemโs trajectory intersected the Radcliffe wave in the Orion star-forming region between 15 and 12 million years ago (Miocene epoch). Notably, this period coincides with the Middle Miocene climate transition on Earth, providing an interdisciplinary link with paleoclimatology.
[โฆ]
The Radcliffe wave is a narrow sinusoidal gas structure, which comprises many known star-forming cloud complexes, such as CMa, Orion, Taurus, Perseus, Cepheus, North America Nebula, and Cygnus.
This gas structure, with an estimated mass of 3 million solar masses, appears to coherently oscillate like a traveling wave and it is thought to be part of the Milky Wayโs spiral structure.
โImagine it like a ship sailing through varying conditions at sea,โ said Dr. Efrem Maconi, a doctoral student at the University of Vienna.
โOur Sun encountered a region of higher gas density as it passed through the Radcliffe wave in the Orion constellation.โ
The paper, Maconi et al., 2025, was recently published in the open access journal Astronomy & Astrophysics. The authors were very careful to not draw sweeping conclusions, however the correlation between our solar systemโs Radcliffe Wave transit and the MMCT is very interesting.
Figure 3. Miocene climate reconstruction from Zachos et al., 2001 (older is toward the left).
Here are the Miocene temperature and CO2ย reconstructions plotted together:
Figure 4. Miocene temperatures and atmospheric CO2ย (older is toward the left).
The Radcliffe Wave transit certainly appears to be more likely to have influenced the MMCT than a decline in atmospheric CO2. The notion of celestial climate drivers is not new. The concept is similar to that proposed by Nir Shaviv and Jan Veizer in their 2003 GSA Today paper.
Atmospheric levels of CO2ย are commonly assumed to be the main driver of global climate. Independently, empirical evidence suggests that the galactic cosmic ray flux (CRF) is linked to climate variability. Both drivers are presently discussed in the context of daily to millennial variations. To the extent that they actually exist, they should also operate over geological time scales. Here we analyse the reconstructed low-latitude sea surface temperature over the Phanerozoic (past 545 Myr) and compare it with the variable CRF reaching the Earth and with the reconstructed partial pressure of atmospheric CO2ย (pCO2). We find that at least 66% of the variance in the reconstructed temperature trend can be attributed to CRF variations arising from solar system passages through the spiral arms of the galaxy, an observation that enables us to estimate the CRF/temperature relationship. Assuming that the entire residual variance in temperature is due solely to the CO2ย greenhouse effect, or that one of the reconstructed Phanerozoic pCO2ย trends is validated, we can place an upper limit to the long-term โequilibriumโ warming effect of CO2, one which is potentially lower than that based on general circulation models (GCMs).
After incorporating their โcelestial driverโ model, Shaviv & Veizer estimated that the maximum equilibrium climate sensitivity (ECS) was 1.9 ยบC per doubling of atmospheric CO2, with a most likely value of 0.5 ยบC per doubling. Unknown celestial climate drivers may be the reason that ECS estimates derived from paleoclimatology data are nearly twice that of those derived from contemporaneous instrumental data.
The Radcliffe Wave was only recently discovered (2019), even though it is relatively close (~400 light years) to the current position of our solar system. It was an โunknown unknownโ potential climate change driver before the publication of Maconi et al., 2025.
How many other โunknown unknownsโ are out there?
Armstrong McKay, David, Toby Tyrrell, Paul A. Wilson, & Gavin Foster. (2014). โEstimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-studyโ. Earth and Planetary Science Letters. 403. 254โ262. 10.1016/j.epsl.2014.06.040. Special thanks to David Armstrong McKay for kindly sending me a copy of his paper.
Kasbohm, Jennifer, and Blair Schoene. โRapid Eruption of the Columbia River Flood Basalt and Correlation with the Mid-Miocene Climate Optimum.โScience Advances, American Association for the Advancement of Science, 1 Sept. 2018, advances.sciencemag.org/content/4/9/eaat8223.
Maconi, E., J. Alves, C. Swiggum, S. Ratzenbรถck, J. Groรschedl, P. Kรถhler, N. Miret-Roig, S. Meingast, R. Konietzka, C. Zucker, A. Goodman, M. Lombardi, G. Knorr, G. Lohmann, J. C. Forbes, A. Burkert and M. Opher. โThe Solar Systemโs passage through the Radcliffe wave during the middle Mioceneโ. A&A, 694 (2025) A167 DOI: https://doi.org/10.1051/0004-6361/202452061
Pagani, Mark, Michael Arthur & Katherine Freeman. (1999). โMiocene evolution of atmospheric carbon dioxideโ. Paleoceanography. 14. 273-292. 10.1029/1999PA900006.
Royer, D.L., et al. 2006. โTertiary Paleobotanical Atmospheric CO2 Reconstruction. IGBP PAGES/World Data Center for Paleoclimatologyโ Data Contribution Series # 2006-021. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
Self, Stephen & Thordarson, Thorvaldur & Widdowson, Mike. (2005). โGas Fluxes from Flood Basalt Eruptionsโ. Elements. 1. 10.2113/gselements.1.5.283.
Tripati, A.K., C.D. Roberts, and R.A. Eagle. 2009. โCoupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Yearsโ. Science, Vol. 326, pp. 1394 1397, 4 December 2009. DOI: 10.1126/science.1178296
Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, K. โTrends, rhythms, and aberrations in global climate 65 Ma to presentโ. Science 292, 686โ-693 (2001).
First, there was some question about what a radiometer would see if pointed down at the surface. Figure 1 is educational in several ways. It is from the SURFRAD site at Desert Rock, Nevada on June 22, 2024. The four curves correspond to total downward solar radiation, total upward solar radiation, Upward and downward directed LWIR.
First, there was some question about what a radiometer would see if pointed down at the surface. Figure 1 is educational in several ways. It is from the SURFRAD site at Desert Rock, Nevada on June 22, 2024. The four curves correspond to total downward solar radiation, total upward solar radiation, Upward and downward directed LWIR. I have also included the local wind speed and 10m temperature in the lower diagram.
Figure 1. A description of the siteโs 10m tower where many of these instruments are mounted, and a photo of the area, isย available here.
Sunrise is around 6am local time (1300UTC; Local PDT=UTC-7hr). Almost immediately after the sun peeks over the horizon the surface begins to warm and the pyrgeometer detects a rise in upward directed LWIR. Downward directed LWIR rises with about an hourโs delay from the heating of the surface but well before surface convection begins to heat the atmosphere which is quite apparent on the wind speed chart starting at around 10-11 am. The peak of upward directed LWIR occurs a half an hour or so past noon at a value of 658W/m2. With an assumed surface emissivity of 0.97 this suggests a surface temperature of 137F โ far above the peak temperature at 10m elevation of 100F which occurs late in the day. There is a super adiabatic layer of heated air near the surface. The situation is exactly as I described it, using two atmospheric soundings at Albuquerque, Nex Mexico from August 3, 1993 in this addendum. This also, perhaps, explains why GEOS Band 16 images taken around Winter Solstice sometimes show northern Chile to be 60oC.
Downward directed LWIR curve, the Greenhouse effect, begins its rise almost coincident with both the rise in upward directed LWIR and the rise in 10m temperature, but reaches its peak value well after the peak in upward LWIR but long before the peak in 10m temperature. The Greenhouse effect results from rising air temperature, but this, in turn, results both from bulk transport from the surface and from absorption and re-emission of LWIR from the surface. It is not exclusively a function of air temperature as was claimed.
That upward directed LWIR remains 80W/m2 above the greenhouse effect throughout the night demonstrates how it is that natives in elevated and dry places have traditionally made ice overnight even when temperatures remain far above freezing (20F above) [1] and something I observed while camping overnight at Joshua Tree Monument on March 6 of 1982.
Violations of the Second Law of Thermodynamics
An idea that arises, it seems, in every post about the Greenhouse effect, is that energy cannot flow from the cold atmosphere to the warmer ground without violating the Second Law of Thermodynamics. This argument will simply not go away.
Simply put, molecules and atoms do not have temperature โ they have energy. Temperature is assigned by the distribution of kinetic energy in an ensemble of molecules and atoms, as in the Boltzmann distribution, where temperature is the only assignable parameter. Individual atoms and molecules are not guided by a temperature gradient in any way, but what net heat transport they accomplish is statistically in the direction from hot to cold.
Tom Shula provided a darned good reference to Harde (2013) that statesโฆ
โโฆany back radiation from colder and higher atmospheric layers can be absorbed by the lower and warmer layers, and this back radiation can also be absorbed by a warmer surface of the earth without violating the 2nd law of thermodynamics.โ
I might mention that careless application of the Stefan-Boltzmann formula is almost guaranteed to end up with a violation of the Second Law.[2]
Is the radiation field isotropic?
There was some discussion about the radiation field being isotropic, in fact, about the necessity of it being so. The radiation field, meaning the distribution of emitted radiant energy in the atmosphere, cannot be isotropic when there are temperature gradients involved. At each point in space (we call this the field point) there is an emitted field originating at that point. This emitted field is isotropic.[3]
In addition there is also a contribution originating at other points in the domain of the problem and passing through the field point. This field component is not isotropic as it is reflective of whatever is emitted by all objects and material within view of the field point. The total field is a vector integration of the two. A truly isotropic total field could only occur inside a cavity at uniform temperature, which would be an instance of thermal equilibrium, of a true blackbody, and without net heat transfer in any direction. When heat is transported, the field doing so is not isotropic.
Collision rates being far greater than emission rates
There was a discussion about why the emitted power from a molecule like CO2 is so intense when collisions de-energize the CO2 15u line at a rate of โ29,000โ times the emission rate. The fact that this collision rate, which redistributes kinetic energy locally and continually, occurs with far greater speed than the emission or absorption rate is responsible for maintaining local thermodynamic equilibrium (LTE).[4] It allows us to use atmospheric temperature in conjunction with the Planck function to calculate emission. It is what connects radiation to local atmospheric temperature.
Radiation annihilated?
Someone made a claim to the effect that โโฆ The surface field is completely annihilated and converted into sensible heat. The thermal atmospheric field is produced exclusively by collisional excitation and exists throughout the atmosphere all the way down to the surfaceโฆ.โ
For this to be so, radiation leaving the surface would have to be completely absorbed and through collisions converted completely to kinetic energy. Moreover, once converted completely to kinetic energy, would collisions be effective or not at raising IR active gasses from their ground state to a higher energy state?
The present radiational cooling of Earth involves different transport behavior at different wavelengths. In places the atmosphere is quite transparent, and transport is ballistic, in other areas the emission is created locally through collisions. Just to drive this point a bit further, Figure 2 shows an LWIR spectrum measured from satellite over the polar ice cap from the publication by Harde (2013).
Figure 2. From Harde (2013).
Red arrows point to segments of the spectrum from within the atmospheric window where there is little IR active gas to absorb radiation. The spectrum nicely follows a blackbody spectrum (dashed curves) just below the 268K ice surface temperature. There is nothing nearer the satellite with this temperature than the ice cap itself. Meanwhile, blue arrows point to other portions of the spectrum which suggest much lower temperature. These occur over wavelengths where IR active water vapor and CO2 hide the surface from direct view and emit radiation from lower temperature higher in the polar atmosphere.
Even if Earthโs atmosphere were more opaque than it presently is (greater optical depth), radiation from the surface would still make its way skyward. Photons would โdiffuseโ through a very opaque atmosphere much like thermal conduction except with a โthermal conductivityโ proportional to temperature cubed (the Rosselund approximation).
References:
[1]-My handwritten notes from 45 years ago are not entirely clear, but the report of natives of Bengal making ice overnight is probably: S. Tamara, Monthly Weather Rev., 33; 55, 1905.
[2]-A good example is Q=ฯ(A1T14-A2T24), where sigma is the Stefan constant. Just using areas for different radiators can lead to a large cold radiator delivering heat to a small hot one. Generally I donโt make reference to my own work, but this link will bring up a lecture I produced as a guest for a nearby community college nearly a quarter century ago that shows how little a person can accomplish with only the Stefan-Boltzmann formula and what little else is needed to make it useful.
[3]-Any radiation can be considered scattered. A phase function describes how the scattering takes place. For example, the โscatteringโ phase function of isotropic radiation is 1.0, unlike the phase function of, say, Rayleigh scattering which is 0.5(1+cos2ฮ), where the scattering angle is measured from the line connecting the Sun and the scattering object or volume. It explains why the blue of the sky is not uniformly blue.
[4]-LTE is simply a state of being close enough to thermal equilibrium to make reasonable use of results from true thermal equilibrium.
It could be that all the extra carbon dioxide in the atmosphere โ the steady increase year on year, reported since 1958, despite all the airplanes grounded through covid it kept on increasing โ is a consequence of the oceans breathing out a bit more, and nothing to do with you and me.
It could be that all the extra carbon dioxide in the atmosphere โ the steady increase year on year, reported since 1958, despite all the airplanes grounded through covid it kept on increasing โ is a consequence of the oceans breathing out a bit more, and nothing to do with you and me.
The amount of carbon sequestered in the oceans was meant to increase with the apparently significant increase in atmospheric levels because of industrialisation, except that observations, actual measurements, suggest that there has been no long-term increase. The oceans might be breathing carbon dioxide in, and out, to their own rhythm that has nothing to do with you and me โ or all the windfarms.
It could be that mankind is irrelevant to the cycles of ocean warming, that dictates atmospheric levels of carbon dioxide.
The Earthโs oceans contain somewhere in the vicinity of 50 times more carbon than the atmosphere. The global carbon ocean reservoir is about 38,000 gigatons of carbon, while the atmosphere contains only 730 gigatons. In the atmosphere carbon is present as carbon dioxide, which is just 0.04% of the atmosphere by dry weight.
Carbon dioxide is a tiny fraction of the atmosphere, and there is constant exchange of carbon dioxide between the atmosphere and the ocean. This exchange has been described as inhale and exhale, since forever.
The ocean takes up carbon dioxide through photosynthesis by phytoplankton, as well as by simple dissolution, that is carbon dioxide dissolves in water. Carbon dioxide reacts with seawater, creating carbonic acid (H2CO3). Carbonic acid releases hydrogen ions, which combine with carbonate in seawater to form bicarbonate (HCO3-).
The amount of carbon dioxide absorbed by the oceans varies with latitude. At high latitudes/towards the poles the ocean will absorb/store more carbon dioxide and more easily, because of the lower temperatures.
An overall increase in ocean temperatures, especially at the poles where they vary according to long cycles, could mean more exhaling relative to inhaling of carbon dioxide, over the year over the Earth. That is not what the dominant paradigm has theorised. But it is what the measurements show.
Ocean temperatures also vary seasonally. Concentrations of bicarbonate peak in surface seawaters in April at the latitude of Hawaii, which is also the time of year when atmospheric carbon dioxide is highest as measured at Mauna Loa. Atmospheric concentrations of carbon dioxide vary seasonally, as does the sea surface temperature, at the latitude of Hawaii, which is the main site for monitoring global change in atmospheric levels of carbon dioxide.
I will be discussing all of this with Sydney University Professor Ivan Kenney on 25th February, by Zoom. There will be just 100 places if you want to be a part of this discussion, so make sure you are registered for my Mail chimp specifically tick the box โNew Theory of Climateโ here: https://jennifermarohasy.com/subscribe/
This zoom is part 2 of a discussion I began with Bill Kininmonth last year, more information about that here,
Ivan Kennedy is an emeritus professor in the School of Life and Environmental Sciences at the University of Sydney. His 2023 research paper โ entitled โThe Seasonal Keeling Oscillation in Atmospheric pC02 is Caused by Variation in Seawater Surface Temperatureโ published in the journal Examines in Marine Biology and Oceanography โ will be distributed to those who register for the zoom a few days before the discussion.
Seasonal variability in atmospheric levels of carbon dioxide and long-term trends will be the focus of this discussion with Ivan planned for Tuesday 25thย February at noon Brisbane time (Australian Eastern Standard Time, AEST โ an hour later in Sydney because of daylight saving and the day before in Texas because of datelines etc.). ย The link will be in the Mailchimp, for those subscribed to โNew Theory of Climateโ, and I will send it out next Tuesday. ย That is the plan.
Last year William Happer spoke on Radiation Transfer in Clouds at the EIKE conference, and the video is above. For those preferring to read, below is a transcript from the closed captions along with some key exhibits. I left out the most technical section in the latter part of the presentation. Text in italics with my bolds.
William Happer: Radiation Transfer in Clouds
People have been looking at Clouds for a very long time in in a quantitative way.ย This is one of the first quantitative studies done about 1800. And this is John Leslie, a Scottish physicist who builtย this gadget.ย He called it an Aethrioscope, but basically it was designedย to figure out how effective the sky was in causing Frost.ย If you live in Scotland, you worry about Frost. So, it consisted of two glass bulbs with a very thin capillary attachment between them. And there was a little column of alcohol here.
The bulbs were full of air, and so if one bulb got a little bit warmer it would force the alcohol up through the capillary. If this one got colder it would suck the alcohol up. So he set this device out under the clear sky. And he described that the sensibility of the instrument is very striking. For the liquor incessantly falls and rises in the stem with every passing cloud. in fine weather the aethrioscope will seldom indicate a frigorific impression of less than 30 or more than 80 millesimal degrees. Heโs talking about how high this column of alcohol would go up and down if the sky became overclouded. it may be reduced to as low as 15 refers to how much the sky cools or even five degrees when the congregated vapours hover over the hilly tracks. We donโt speak English that way anymore but I I love it.
The point was that even in 1800 Leslie and his colleagues knew very well that clouds have an enormous effect on the cooling of the earth. And of course, anyone who has a garden knows that if you have a clear calm night, youโre likely to get Frost and lose your crops. So, this was a quantitative study of that.
Now itโs important to remember that if you go out todayย the atmosphere is full of two types of radiation.ย Thereโsย sunlight which you can seeย and then there is the thermal radiation thatโs generated by greenhouse gases, by clouds and by the surface of the Earth.ย You canโt see thermal radiation but you you can feel it if itโs intense enough by its warming effect. And theseย curves practically donโt overlapย so weโre really dealing with two completely different types of radiation.
Thereโsย sunlight which scatters very nicely and off of not only clouds but molecules;ย itโs the blue sky the Rayleigh scattering. Then thereโs the thermal radiation which actually doesnโt scatter at all on molecules soย greenhouse gases are very good at absorbing thermal radiation but they donโt scatter it.ย Butย clouds scatter thermal radiationย and plotted here is the probability that you will find Photon of sunlight between you know log of its wavelength and the log of in this interval of the wavelength scale.
Since Leslieโs day two types of instruments have been developed to do what he did more precisely. One of them is called aย pyranometerย and this is designed to measure sunlight coming down onto the Earth on a day like this. So you put this instrument out there and it wouldย read the flux of sunlight coming down.ย Itโs designed to see sunlight comingย in every directionย so it doesnโt matter which angle the sun is shining; itโs uh calibrated to see them all.
Let me show you a measurement by a pyranometer. This is a actually a curve from a sales brochure of a company that will sell you one of these devices. Itโs comparing two types of detectors and as you can see theyโre very good you can hardly tell the difference. The point is that if you look on a clear day with no clouds you see sunlight beginning to increase at dawn it peaks at noon and it goes down to zero and thereโs no sunlight at night. So half of the day over most of the Earth thereโs no sunlight in the in the atmosphere.
Hereโsย a day with clouds,ย itโs justย a few days laterย shown by days of the year going across. You can see every timeย a cloud goes by the intensity hitting the ground goes down. With a little clear sky, it goes up, then down up and so on. On average at this particular day, you getย a lot less sunlight than you did on the clear day.
But you knowย nature is surprising.ย Einsteinย had this wonderfulย quote: God is subtle but heโs not malicious.ย He meant that nature does all of sorts ofย things you donโt expect, and so let me show you what happens on aย partly cloudy day.ย Here so this is data takenย near Munich.ย The blue curve is the measurement and theย red curve is is the intensity on the ground if there were no clouds.ย This is a partly cloudy day and you can see there are briefย periods when the sunlight is much brighter on the detector on a cloudy day than it is on the clear day.ย And thatโs because coming through cloudsย you get focusing from the edges of the cloud pointing down toward your detector.ย That means somewhere else thereโs less radiation reaching the ground. But this is rather surprising to most people. I was very surprised to learn about it, but it just shows thatย the actual details of climate are a lot more subtle than you might think.#
We know that visible light only happens during the daytime and stops at night. Thereโs a second type of important radiation which is the thermal radiation which is measured by a similar device. You have a silicon window that passes infrared, which is below the band gap of silicon, so it passes through it as though transparent. Then thereโs some interference filters here to give you further discrimination against sunlight. So sunlight practically doesnโt go through this at all, so they call it solar solar blind since it doesnโt see the Sun.
But itย sees thermal radiation very clearlyย with a big difference between this device and the sunlight sensing device I showed you. Because actuallyย most of the time this is radiating up not down.ย Out in the open air this detector normally gets colder than the body of the instrument. And so, itโs carefullyย calibrated for you to compare the balance of down coming radiation with the upcoming radiation.ย Upcoming is normally greater than down coming.
Iโll show you someย measurements of the downwelling fluxย here; these are actually in Greenland in Thule and these are areย watts per square meterย on the vertical axis here. The first thing to notice is that theย radiation continues day and nightย you can you if you look at the output of the pyrgeometer you canโt tell whether itโs day or night because theย atmosphere is just as bright at night as it is during the day.ย However, theย big difference is clouds: on a cloudy day you get a lotย more downwelling radiation than you do on a clear day. Hereโs a a near a full day of clear weather thereโs another several days of clear weather. Then suddenly it gets cloudy.ย Radiation rises because the bottoms of the clouds are relatively warm at least compared to the clear sky.ย I think if you put the numbers In, this cloud bottom is aroundย 5ยฐ Centigrade so it was fairly low Cloud.ย it was summertime in Greenland and this compares to aboutย minus 5ยฐ for the clear sky.
So, thereโs a lot of data out there and there really isย downwelling radiationย there no no question about that you measure it routinely. And now you canย do the same thing looking down from satellites,ย so this is a picture that Iย downloadedย a few weeks ago to get ready for this talk from Princeton and it wasย from Princeton at 6 PM so it was already dark in Europe.ย So this is a picture of the Earth from a geosynchronousย satellite thatโs parked over Ecuador. You are looking down on the Western Hemisphere and this is aย filtered image of the Earth in Blue Light at 47 micrometers.ย So, itโs a nice blue color not so different from the sky and itโs dark where the sun has set. Thereโs still a fair amount of sunlight over the United States and the further west.
Here is exactly the same time and from the same satellite the infrared radiation coming up at 10.3 which is right in the middle of the infrared window where thereโs not much Greenhouse gas absorption; thereโs a little bit from water vapor but very little, trivial from CO2.
As you can see, you canโt tell which side is night and which side is day. So even though the sun has set over here it is still glowing nice and bright. Thereโs sort of a pesky difference here because what youโre looking at here is reflected sunlight over the intertropical Convergence Zone. There are lots of high clouds that have been pushed up by the convection in the tropics and uh so this means more visible light here. Youโre looking at emission of the cloud top so this is less thermal light so white here means less light, white there means more light so you have to calibrate your thinking. to
Butย the Striking thingย about all of this: if you can see the Earth is covered with clouds,ย you have to look hard to find a a clear spot of the earth. Roughly half of the earth maybe is clear at any given time butย most of its covered with clouds. So, if anything governs the climate it is clouds and and so thatโs one of the reasons, I admire so much the work that Svensmark and Nir Shaviv have done. Because theyโre focusing onย the most important mechanism of the earth: itโs not Greenhouse Gases, itโs Clouds. You can see that here.
Now this is a single frequency let me show youย what happens if you look down from a satellite and do look at the Spectrum.ย This is the spectrum of light coming up over the Sahara Desert measured from a satellite. And so here isย the infrared window; thereโs the 10.3 micronsย I mentioned in the previous slide itโs itโs a clear region. So, radiation in this region can get up from the surface of the Sahara right up to outer space.
Notice that the units on these scales are very different; over the Sahara the top unit is 200, 150 over the Mediterranean and itโs only 60 over the South Pole. But at least the Mediterranean and the Sahara are roughly similar so the right side here these three curves on the right are observations from satellites and the three curves on the left are are calculations modeling that weโve done. The point here is that you can hardly tell the difference between a model calculation and observed radiation.
So, itโs reallyย straightforward to calculate radiation transfer.ย If someone quotes you a number in watts per square centimeter you should take it seriously; that probably a good number. If they tell you a temperature you donโt know what to make about it. Because thereโs aย big step between going from watts per square centimeter to a temperature change. All theย mischief in the whole climate business is going from watts per square centimeter to to Centigrade or Kelvin.
Now I will say just a few words aboutย clear skyย because that is the simplest. Then weโll get on to clouds, the topic of this talk. This is aย calculation with the same codesย that I showed you in the previous slide which as you saw work very well. Itโs worth spending a little time because this isย the famous Planck curve that was the birth of quantum mechanics.ย There is Max Planck who figured out what the formula for that curve is and why it is that way. This isย what the Earth would radiate at 15ยฐ Centigrade if there were no greenhouse gases.ย You would get this beautiful smooth curve the Planck curve. If you actually look at theย Earth from the satellites,ย you get aย raggedy jaggedy black curve. We like to call that the Schwarzchild curve becauseย Carl Schwarzchildย was the person whoย showed how to do that calculation.ย Tragically he died during World War I, a Big Big loss to science.
There are two colored curves that I want to draw your attention. Theย green curve is is what Earth would radiate to space if you took away all the CO2,ย so it only differs from the black curve you know in the CO2 band here this is theย bending band of CO2 which is the main greenhouse effect of CO2.ย Thereโs a little additional effect here which is the asymmetric stretch but it it doesnโt contribute very much. Then here is aย red curveย and thatโsย what happens if you double CO2.
So, notice the huge asymmetry.ย If taking all 400 parts per million of CO2ย away from the atmosphereย causes this enormous change 30 watts per square meter,ย the difference between this green 307 and and the black 277, thatโs 30 watts per square meter. Butย if you double CO2 you practically donโt make any change.ย This is the famous saturation of CO2. At the levels we have now doubling CO2,ย a 100% Increase of CO2 only changes the radiation to space by 3 watts per square meter.ย The difference between 274 for the red curve and 277 for the curve for today. Soย itโs a tiny amount: for 100% increase in CO2 a 1% decrease of radiation to space.
That allows you to estimate the feedback-free climate sensitivity in your head. Iโll talk you through the feedback-free climate free sensitivity. So doubling CO2 is a 1% decrease of radiation to space. If that happens then the Earth will start to warm up. But it will radiate as the fourth power of the temperature. So temperature starts to rise but if youโve got a fourth power, the temperature only has to rise by one-quarter of a percent absolute temperature. So a 1% forcing in watts per square centimeter is a one-quarter percent of temperature in Kelvin. Since the ambient Kelvin temperature is about 300 Kelvin (actually a little less) a quarter of that is 75 Kelvin. So the feedback free equilibrium climate sensitivity is less than 1 Degree. Itโs 0.75 Centigrade. Itโs a number you can do in your head.
So, when you hear about 3 centigrade instead of .75 C thatโs a factor of four, all of which is positive feedback.ย So how is there reallyย that much positive feedback?ย Because most feedback in nature are negative. The famousย Le Chatelier principleย which says that if you perturbย a system it reacts in a way to to dampen the perturbation does not increase it.ย There are a few positive feedback systems that weโre familiar with for example High explosives have positive feedback. So,ย if the earthโs climate were like other positive feedback systems, all of them are highly explosive,ย it would have exploded a long time ago.ย But the climate has never done that, so theย empirical observational evidence from geologyย is that the climate is like any other feedback system itโs probably negative Okay, so I leave that thought with you and and let me stress again:
This is clear skies no clouds; if you add clouds all this does is suppress the effects of changes of the greenhouse gas.
So now letโs talk about clouds and the theory of clouds, since weโve already seen clouds are very important. Here is the formidable equation of transfer which has been around since Schwarzchildโs day. So, some of the symbols here relate to the intensity, another represents scattering. If you have a thermal radiation on a greenhouse gas where it comes in and immediately is absorbed, thereโs no scattering at all. If you hit a cloud particle it will scatter this way or that way, or some maybe even backwards.
So, all of thatโsย described by this integralย so youโve gotย incoming light at One Direction, and youโve got outgoing light at a second Direction.ย And thenย at the same timeย youโve gotย thermal radiation,ย so theย warm particles of the cloud are are emitting radiationย creating photons which are coming out and and increasing the Earth glow and this is represented byย two parameters. Even a singleย cloud particle has an albedo, this is is theย fraction ofย radiationย that hits the cloudย that is scattered as opposed to absorbedย and being converted to heat. Itโs a very important parameterย for visible light and white clouds, typically 99% of the encounters are scattered.ย But for thermal radiation itโs much less.ย So, water scatters thermal radiation only half as efficiently as shorter wavelengths.
The big problem is that in spite of all theย billions of dollarsย that we haveย spent, theseย things which should be known and and would have been known if there hadnโt been this crazy fixation on carbon dioxideย and greenhouse gases. And so, weโve neglected working on these areas that are really important as opposed to the trivial effects of greenhouse gases.ย Attenuation in a cloud is both scattering and absorption. Of course, you have toย solve these equations for every different frequencyย of the light because especially for molecules, thereโs a strong frequency dependence.
In summary, let me show you thisย photoย which was taken by Harrison Schmitt who was a friend of mine on one of the first moonshots. It was taken in December and looking at this you can see that they were south of Madagascar when the photograph was taken. You can seeย it was Winterย because here theย Intertropical Convergence Zone is quite a bit south of the Equator; itโs moved Way South of India and Saudi Arabia. By good luck they had the sun behind them, so they had the whole earth Irradiated.
Thereโs a lot of information there and and again let me draw your attention to how much of the Earth is covered with clouds. So only very small parts of the Earth can actually be directly affected by greenhouse gases, of the order of half. The takeaway message is that clouds and water vapor are much more important than greenhouse gases for earthโs climate. The second point is the reason theyโre much more important: doubling CO2 as I indicated in the middle of the talk only causes a 1% difference of radiation to space. It is a very tiny effect because of saturation. You know people like to say thatโs not so, but you canโt really argue that one, even the IPCC gets the same numbers that we do.
And you also know that covering half of the sky with clouds will decrease solar heating by 50%. So for clouds itโs one to one, for greenhouse gases itโs a 100 to one. If you really want to affect the climate, you want to do something to the clouds. You will have a very hard time making any difference with Net Zero with CO2 if you are alarmed about the warmings that have happened.
So, one would hope that with all theย moneyย that weโveย spent trying to turn CO2 into a demonย thatย some good science has come out of it.ย From my point of view this is a small part of it, thisย scattering theoryย that I think will be here a long time after the craze over greenhouse gases has gone away. I hope there will be other things too. You can point to theย better instrumentationย that weโve got, satellite instrumentation as well as ground instrumentation. So thatโs been a good investment of money. Butย the money weโve spent on supercomputers and modeling has been completely wasted in my view.
โThe atmosphere is a heat engine/refrigerator, and it works like this. When the lapse rate is less than the DALR (about 9.8 K/km), when air is forced to rise by turbulence, it expands and cools adiabatically as pressure reduces. The cooling rate is basically the DALR. With this greater than the lapse rate, the air becomes cooler and denser than the neighboring air, and so work is done pushing it higher. That comes from the KE of the wind. Work is done to transfer โcoldโ upwards โ ie heat downwards, against the temperature gradient. It is a heat pumpโฆ.โ
In a recent guest blogger essay a side debate broke out between Nick Stokes and I over whether or not it is possible for thermal convection from a surface, such as Albuquerque on August 3, 1993, which was my boundary layer example, to reach high above, and produce substantive cooling of the surface.
The debate started thusly from Nick:
โThe atmosphere is a heat engine/refrigerator, and it works like this. When the lapse rate is less than the DALR (about 9.8 K/km), when air is forced to rise by turbulence, it expands and cools adiabatically as pressure reduces. The cooling rate is basically the DALR. With this greater than the lapse rate, the air becomes cooler and denser than the neighboring air, and so work is done pushing it higher. That comes from the KE of the wind. Work is done to transfer โcoldโ upwards โ ie heat downwards, against the temperature gradient. It is a heat pumpโฆ.โ
Continued thusly:
โIf the lapse rate is 7 K/km, and DALR is 10 K/km, then air that leaves the surface 3K warmer than surrounds [sic] will lose that excess at height 1000m. Then it works against gravity to go higher, so slows down.
If the lapse rate is 9 K/km, it can rise to 3 km. It can happen, but such thermals are not easy to find.โ
And ended here with my final reply:
โ I would agree with you if all there was was a parcel with a tiny bit of K.E. in an environment lapse rate of 7-10 C/km; but thatโs not all there is, and I am sayinโ no more until I have thought it all outโฆโ
Last night I went looking for data that I hoped to find which would make my point. I found it in several forms in several different places.
First, rather than reiterate all the examples I gave in the original essay, I will reference the paper by Renno and Williams from which the RPV data came, and point specifically to Section 6, the discussion, which is jam-packed with such, and which ends with thisโฆ[1]
โThe observation that the air participating in natural moist convection originates in the surface layer is not surprising. More than half of the solar radiation energy absorbed at the surface is transferred to the atmosphere as both sensible and latent. This energy is vertically transported by the convective motions, and then radiated to space.โ
I would only add that the same is true for dry convection as well.
In addition, a typical spring/summer fair weather day here as one that begins largely clear, by 10 am or so fair weather cumuli appear, these may grow to a steady state density covering a great deal of the sky by 4 pm some days. After midday the cumulus may attain vertical development but by 8 pm the cumuli become pancake shaped and may vanish completely.
I would also ask readers to examine the video in a comment by David Dibbell found here. What this fascinating Band 16 timelapse of the western hemisphere shows is, repeatedly one day after another is this. The hottest portion of the day (brightest yellow) begins in the east and propagates across Argentina/Chile, then Mexico and finally across the U.S. Southwest. In between, in what is the Amazon basin, and in time order with all the other activity in the video, is the flaring up of thunderstorms with tops near the tropopause. Action follows the Sun. Surface heating organizes it all.
Now, regarding the RPV gathered data at Albuquerque on August 3, 1993, the story is told in a couple of atmospheric soundings, which I fetched from the archive at University of Wyoming. A sounding made at 6am local time and a second one made at 6 pm local time are shown in Figure 2.
Figure 2. Soundings at 6 am and 6 pm. Albuquerque. August 3, 1993
Overnight, the ground surface and air with a kilometer of the surface cooled, became mechanically stable. At 6 am (Figure 2A) the potential temperature (theta) is lowest near the ground surface, but the Sun begins heating the surface to a superadiabatic layer. This is soon unstable and begins to convect โ at first in a shallow layer near the surface then step by step to increasingly higher levels. Radiation from the warming surface also contributes heat to this layer.
The atmosphere is not static. It is dynamic and it is bootstrapping its way into a deeper and deeper layer of instability. By 6 pm (Figure 2B) the entire atmosphere from ground to 4,200m (2,600 above surface) has uniform potential temperature and any parcel heated to as little as 1K higher theta will always be adequately buoyant to reach a high elevation. Recall that surface measurements at 1:00 pm showed a pool of superadiabatic air at the surface 6K or more warmer than rising parcels. Overnight something like Figure 2A re-establishes itself through radiation cooling, perhaps some subsidence and adiabatic warming, and contact with the ground surface.
MONEX
In the summer of 1979 a field experiment (MONEX) designed to study the South Asian monsoon had discovered this same scenario taking place in the atmosphere above the Empty Quarter of the Arabian peninsula.[2] Peter Webster devotes Chapter 12 in his textbook to desert climates and makes use of the MONEX results.[3]
Conclusion
Just to head-off one objection early, I admit that mesoscale conditions may contribute to lesser or more development of this boundary layer convection. I have, in fact, observed surface turbulence and even a hydraulic jump in the atmosphere downstream from wave clouds over the Front Range. But not in the warm season. Perhaps boundary layer convection draws occasionally on some pre-existing potential or kinetic energy. Yet, where did this potential energy or kinetic energy come from? My view is it is a fraction of remaining available work from heat transfer by many other, earlier regional weather events, some of which makes its way into the general circulation.
References:
1-Renno and Williams, Quasi-lagrangian measurements in convective boundary layer plumes and their implications for the calculation of CAPE, 1995, Mon. Weather Rev., September, 2733.
2-Eric A. Smith, 1986, The Structure of the Arabian Heat Low. Part II: Bulk Tropospheric Heat Budget and Implications, Mon. Weather Rev., v.114, p. 1084. Note: I canโt seem to find Part I of this publication, but Part II contains more than adequate data and commentary.
3-Peter Webster, Dynamics of the Tropical Atmosphere and Oceans, Wiley Blackwell, 2020.
Two simple models, heat engine and refrigerator, compliment one another. If, for example, one is interested in how heat transfer produces the observed weather, a heat engine is a good place to begin. If, on the other hand, oneโs focus is how the atmosphere works to produce a stable climate, free of CO2 terror, then perhaps the refrigerator makes a better starting place.
Weather is made possible because transfer of heat also makes available some amount of mechanical work. The view of the atmosphere being akin to a Carnot heat engine has a long history involving many famous names in atmospheric science โ Sverdrup, Brunt, Oort, and Lorenz. To say that the literature around this topic is vast is an understatement.
Related views, rarely mentioned, hold the atmosphereโs working to be a refrigerator or a thermostat or even air-conditioning. WUWT guest blogger, Willis Eschenbach, often makes reference to these ideas, as he did here recently and even more recently here. The Winter Gatekeeper hypothesis belongs here, too.
Two simple models, heat engine and refrigerator, compliment one another. If, for example, one is interested in how heat transfer produces the observed weather, a heat engine is a good place to begin. If, on the other hand, oneโs focus is how the atmosphere works to produce a stable climate, free of CO2 terror, then perhaps the refrigerator makes a better starting place.
Carry this idea further to realize that the atmosphere is less like a heat engine than it is like a self-acting refrigerator/dehumidifier. As Paulius and Held [1] conclude regarding dissipation of available work, in cases where convective heat transport is mostly due to the latent heat, โโฆconvection acts more as an atmospheric dehumidifier than as a heat engineโฆ.โ
Dehumidifying the air makes it more transparent to long wave radiation, some of which originates right at the surface. This acts to cool our Earth.
Observations about Heat Transport
It is common for people to think that heat is carried all the way from equator to poles. Yet, most refrigeration seems to me local, as Figure 1 shows. Averages of outgoing longwave radiation (OLR) exceeds or is a large fraction of average local solar irradiance. The only exception being in the polar night where there is no solar irradiance to be had. Once heat is in motion by multiple means (ocean currents, wind, radiation) it is difficult to identify where it originated. So, my view is that most outgoing radiation occurs near where heat was absorbed and is accomplished by the characteristics of the regional weather.
Figure 1. Zonal annual mean incoming SW solar radiation against outgoing longwave IR. Modified from [2] (CC BY 3.0 DEED)
Another idea, reinforced by the near-obsession with the infrared properties of CO2, is that radiation is the predominant vertical heat transport mechanism. Figure 2 comes from Figure 1ย in an WUWT essay from last December.ย The radiation transport is calculated using MODTRAN and the temperature/humidity structure of a mid-latitude summer atmosphere free of clouds. It illustrates clearly that vertical radiative transport calculated from the Schwarzchild transport equation using observed temperature profiles, is not adequate to explain vertical heat transport โ the reason being, as explained in the essay, is that a full transport equation must satisfy the First Law of Thermodynamics and account for all transport mechanisms. The red curve of Figure 2 shows that radiation in this case accounts for less than half of net heat transport from the surface, but grows to encompass all transport toward the tropopause. The blue curve shows heat transport contributed by advection, convection, and latent heat.[3]
Figure 2, mid-latitude summer profile of upward heat transport by radiation (red curve) and other mechanisms (blue curve).
When people propose a heat engine model of the atmosphere, they typically draw a comparison to a Carnot engine. This is limiting for several reasons. First. because the Carnot engine is an abstraction. It is a โblack-boxโ. It accepts heat energy input and delivers a fraction of this energy as mechanical work according to Carnotโs formula โ (1-Th/Tc). It is more efficient than any real machine but contains no details about its workings. Second, the Carnot cycle imagines heat being exchanged with reservoirs. Yet, reservoirs are difficult to find. On Earth there is only one real reservoir to speak of and that is radiation to free space which is not reversible. Just identifying someplace like the Earthโs surface, or anvil of a thunderstorm as a reservoir is not convincing.
Figure 3. Blue arrows indicate refrigeration. Red arrows denote a heat engine.
Finally, the atmosphere doesnโt work like a heat engine. Three panels in Figure 3 illustrate the issue. Panel A) in the figure shows a heat engine as people usually think of one. In addition to its usual components there is a control surface which defines the system versus its surroundings. This is true whether the engine produces work, or whether it consumes work like a refrigerator or heat pump. In its typical form, the work made available by the engine travels beyond the control surface. The first law of thermodynamics then is Qc = Qh โ W; and using the second law result that reversible heat exchange between two isentropes makes heat quantity proportional to absolute temperature of reservoirs produces the efficiency of the Carnot engine โ n = (1-Tc/Th); or the coefficient of performance of a Carnot refrigerator โ COP = Tc/(Th-Tc).
However, for the atmosphere as a whole and for most distinct weather events working within, the control volume encloses the work as in panel B). Now, there is no result as simple as the Carnot efficiency. The value of Qc depends on the final disposition of the work. Is the work dissipated to heat, or, is some destroyed in another way? Even if entirely dissipated to heat, does this add to Qc or could some be recycled back into more work?[4]
Panel C) shows an engine operating off flow work provided by some external source. Flow work includes mechanical energy. Ocean waves raised by wind provide an example. Perhaps the tornado, or forward flank downdraft of cooled air in a thunderstorm are examples too.
The concepts of heat engine and refrigerator shouldnโt be taken too literally. The atmosphere differs from a heat engine and greatly differs from a Carnot engine. A refrigerator consumes work to move heat against temperature. As a refrigerator the atmosphere moves heat from hot to cold which would occur on its own โ COP is nonsensical in this case.
Calculating heat transferred
Entropy, as Clausius originally envisioned it, is simply a state variable. A differential element of a path (Tds) equals the amount of heat absorbed or gained on a small section of a (T,s) path describing a process. A very general way of showing the relationship between heat and work in a weather feature, then, is to construct a diagram showing temperature and entropy (T,s) of the air passing through.
The prescription for building this diagram is as follows: First, draw a schematic diagram showing the essential elements of a particular atmospheric phenomenon; that is, a diagram showing all substantial modifications to the working fluid. Then, at the same time, build a thermodynamic state graph from the schematic. Imagine following a representative parcel of fluid (i.e. a kilogram of moist or dry air) as it passes through the diagram. Path sections with positive Tds denote absorption of heat; negative Tds denotes rejected heat. Net of the complete path is available work; or it would be if this were an engineered machine.
Calculating S
Temperature is measured but entropy we must calculate. In my examples, I use this formula which captures most entropy changes except for entropy of mixing water vapor with dry air:
S = (Cd+Cw*r)Ln(T)-RLn(P)-r*L/273+S0 Eq. 1)
Where; Cd and Cw are heat capacities of dry air and water vapor, T is absolute temperature, P is total pressure, R is gas constant of dry air (0.287), r is mixing ratio (kg/kg), and L is latent heat of vaporization at (2495-2.5(273-T) kJ/kg).[5] S0 is a constant to set relative entropy to zero at a convenient place in T-S space.
An example: The Polar Low
The schematic diagram in Figure 2 is that of an Arctic Low. I modeled it on the description and measurements of one such storm that occurred in the Barents Sea plus a recent review article.[6] Figure 3 shows this working fluid path.
Figure 4. A cross-sectional model of a Polar Low. Air properties are provided at each of four points along the machine process path.
Start the analysis at point 1 in the figure. This is cold, dry polar air that has come off an ice sheet. Surface air temperature and dew point are -10C and -13C, respectively, which translates to a mixing ratio of 0.0006 kg/kg. This air now travels along the sea surface, probably below an inversion which aids in preventing dissipating the modifying air, picking up heat and moisture as it goes.
There is often a steep gradient of sea surface temperature in the Barents Sea at the ice edge. Some of the sea surface is as warm as 8C courtesy of the North Atlantic drift. By the time air reaches the center of the storm at point 2 it has been modified to be substantially warmer and more humid than when it left the ice edge โ about 12C warmer with a mixing ratio many times as great (0.0021). This is so modified that it is buoyant and can rise through the inversion (undoubtedly gone within the storm).
On our thermodynamic diagram (Figure 3), the path (1->2) shows this modification of polar air. Path (2->3) shows the rise of moist air within the storm. It is a dry adiabatic rise for around 1200 meters, then saturated pseudo adiabatic above. I have placed the storm top around 500mb where a sounding recorded an environmental temperature of -46C. The saturation pseudo adiabat is about 3C warmer (231K), but quite dry (a mixing ratio probably less than 0.0002).
Closing the cycle
Closing the cycle of working fluid in Figure 3 is needed for two reasons. First, we need a closed path on our T-S diagram in order to calculate heat transfer and net work. Second, an open diagram would suggest air accumulating in places. Closing the diagram allows one to imagine a steady-state global atmosphere.
Air ejected from the storm top at 3 cools through radiation to space for some unknown time to eventually descend to the ice sheet again. The higher air so lacks humidity that cooling to space likely continues during the descent of air to the surface and there is radiation cooling of the surface too. Some process, perhaps sublimation of ice, adds humidity. There are no adiabatic paths to be had. Maybe, temperature declines at a rate something like 1-1.5C per day. The details donโt matter. What is required to close the cycle is that air returns to the ice surface at conditions equal to how it began. Path 3->4, then path 4->1, accomplishes this.
Figure 5. Simple calculations of the Tds path integral. Path 3->1 is speculative, but closes the cycle; that is, takes the working fluid properties from point 3 back to 1.
Results
The path 1->3 is entirely positive entropy change and therefore heat added to our engine (22.3 kJ/kg); the 3->4->1 is entirely negative and therefore heat expelled (or rejected) from our engine (19.4 kJ/kg). The net, which is the enclosed area, amounts to 2.9 kJ/kg of work made available by the machine; or that is how a person would interpret the diagram if this were a heat engine like Figure 3A. More generally a person would like to know the disposition of the 2.9kJ/kg of available work. Nonetheless, even without knowing this, interesting observations are possible.
For example, in contrast to the tropical hurricane in which โ of heat input comes from latent heat; this arctic hurricane obtains only โ from latent heat. The balance is from sensible heat. This polar cyclone runs on warm water transported from lower latitude. If more warm water were transported, then these cyclones would be more frequent or persist longer. The total absorbed heat during the steady state of this storm can be twice the heat input to the Nordic Seas by the North Atlantic Drift.
The dissipation of work
When we say the word โengineโ what we usually mean is some contraption that produces external work. Yet, storm engines are different. They mainly serve to move heat. This one we have just analyzed takes 22.3 kJ of heat per kilogram of air flowing through it, and immediately rejects 19.4 kJ of it quickly to space. It uses the balance to run itself โ to run the weather. Now, as the work output is actually contained within the control volume of Figure 3B, what becomes of it?
The short answer is that it is dissipated. But to answer this question more completely, think about the evolution of any weather event.
It begins as a small disturbance with a much smaller cycle than Figure 5. If dissipation of work at this scale is less than available work, the excess work can increase the intensity and scale of the storm. This continues until dissipation equals available work. During this steady state of the storm, which the Arctic hurricane might run for 18 hours, dissipation equals available work. As the reservoir of energy becomes depleted late in the storm life, intensity and scale decline to match available work. All work is eventually dissipated.
Here is a short list of dissipation and irreversible processes.
Fluid friction all along the surface path raises waves and associated spray on the sea. Raising waves is easy to see as an irreversibility since wind raises waves, which are eventually dissipated, but waves cannot raise wind.
Mechanical work is dissipated through drag of precipitation which occurs even as updrafts are operating to maintain the storm.
Dissipation through turbulence in the updraft and in the outflow above the storm.
Mixing (entrainment).
Many moist processes, such as evaporation into unsaturated air, are irreversible.
Radiation heat transfer over a finite temperature difference.
What matters in the limit is that all of the heat input to the working fluid is rejected and that air is dehumidified. The most common winter condition over the central Arctic Ocean, occurring during some 13% of weather conditions, Nygรฅrd, et al, refer to as circulation type 10.[7] It consists of the strongest and most persistent high pressures, a water content that is low, with subsidence and warming of the air, while surface radiation cools the air from below. It is coincidental with high latent and sensible heat transfer from the North Atlantic drift. Perhaps Figure 5 explains this condition.
Another example: Boundary Layer in Fair Weather
Figure 6. The outlines of an invisible column of rising air capped by a small cumulus cloud.
Renno and Williams [8] made measurements in dry-air convection over open ground near Albuquerque in 1993. They employed a remotely piloted vehicle (RPV) to stay within rising air parcels to make measurements. Rising parcels maintained a potential temperature 1C higher than descending parcels. The data were noisy because of both a tendency of the RPV to drift outside a parcel and noisiness of the instrumentation. Near the ground surface readings became increasingly variable, but there was a distinct group of measurements with a temperature about 6C above that of a rising parcel. This presumably was a superadiabatic layer at the ground surface.
Air parcels rose and fell 3.4m/s and 1.7m/s respectively, suggesting through mass conservation a 2:1 ratio of updraft to subsidence area. Mixing ratio of the updraft near ground was 0.0095 and declined to 0.009 at 800m altitude perhaps from entrainment. The downdraft approached the surface with a mixing ratio of 0.0091, although there is substantial variation in this data. Pressure is probably 835mb at ground surface (1600m).
There is simply not enough information about the atmosphere above flight level of the RPV to figure the relationship between rising and falling parcels. However, the point of this essay is that the heat absorbed at high temperature is equal to that rejected by the sum total of all operations of the refrigerator/dehumidifier. We focus, then, on heat absorbed.
Figure 7 shows (1->2) that absorbed heat is 3.4 kJ/kg. Without being able to close the diagram the net available work is unknown but probably very small because of small temperature differences. Even if only 1%, though, it amounts to 34J/kg which is sufficient to generate buoyancy and account for kinetic energy of 7.5 J/kg.
Figure 7.ย T-s diagram of mixing air in a descending parcel with air in the superadiabatic layer near the ground surface.
By mixing 17% of air in the superadiabatic layer with 83% of air in a descending parcel, we conserve mass, enthalpy and moisture to end up with air exactly like that at point 3. The rate of heat absorbed far exceeds what is required to remove solar insolation from the surface in this instance. The entity that is not conserved in this mixing is entropy. It increases because of this mixing. I figure this value as 1.5 J/KgK, which sounds small, but when multiplied by a dead-state temperature (around 300K) becomes 0.45 Kj of lost potential work. What this means is that one-half kilojoule of additional work would have been available for more vigorous convection if the mixing of air had been done in a reversible manner. The 1.5 J/kgK of increased entropy has to be exported to space eventually.
Climate change
Nowadays, the twenty-four thousand dollar question is: โHow does this relate to climate change?โ I will offer two views from the literature.
On the one hand Renno and Ingersoll formulated a model of fraction of Earth surface covered by convection cells.[9] They conclude that a climate warming will increase the intensity of updrafts, but areal coverage decreases, meaning the region of slowly descending dry air then increases. I havenโt analyzed how convincing this argument is, but it certainly sounds like the negative feedback of the adaptive iris.[10]
On the other hand, F. LaLiberte, et al, built an ambitious T-S diagram for the general circulation and concluded that the intensity of the hydrological cycle in warmer climates might limit the heat engineโs ability to generate work.[11] My reading of their supplementary materials showed meticulous completeness and attention to details. Nevertheless one cannot escape these observations: 1) the baseline and future forecast depends on a climate model (CESM) using RCP4.5, 2) the effect itself is small, amounting to 1% of available work per century in the presence of larger interannual noise, and perhaps most significantly 3) the baseline comparison between the climate model and MERRA reanalysis showed discrepancies attributed to parameterization of atmospheric convection.[12] They refer to this as the water in the gas problem. However, latent heat of water is so large that Rankine cycle plants show better efficiency with some water in their gas (i.e. outlet steam quality of 92%), and the weather canโt possibly run in any other way.
Conclusion
The atmosphere is less a heat engine than a collection of many self-running refrigerators/dehumidifiers operating in different ways to carry heat largely from surface to tropopause locally and the balance from equator to poles. An important, but perhaps underappreciated, effect of dehumidification is to make the atmosphere broadly more amenable to cooling by LWIR.
References:
1- Olivier Pauluis and Isaac M. Held, Entropy Budget of an Atmosphere in RadiativeโConvective Equilibrium. Part I: Maximum Work and Frictional Dissipation, Journal of the Atmospheric Sciences,Volume 59: Issue 2, Jan 2002, Page(s): 125โ139
2-Salzmann, Marc. (2017). The polar amplification asymmetry: role of Antarctic surface height. Earth System Dynamics. 8. 323-336. 10.5194/esd-8-323-2017.
3- An occasional visitor to WUWT, pdquondam, in his essay โHBC_model.pdfโ caused me to think of this graph.
4-Hewitt, McKenzie, and Weiss, 1975 Dissipative heating in convective flows, J. Fluid Mech., v. 68, part 4, 721-738.
5-There are other minor terms omitted involved in mixing water vapor with dry air. In addition, the process must have reached steady state and there isnโt strict conservation of mass in the cycle because of condensed water or snow carried in the air flow.
6-See for example: Rasmussen, E, 1985, A case study of a polar low development over the Barents Sea, Tellus, 37A, 407-418, Or Emanuel, K, and Rotunno, R, 1989, Polar Lows as Arctic Hurricanes, Tellus, 41A, 1-17, and Marta Moreno-Ibanez, Rene Laprise, and Philippe Gachon, Recent advances in polar low research: current knowledge, challenges and future perspectives, Tellus A: 2021, 73, 1890412, https://doi.org/10.1080/16000870.2021.1890412
7- Tiina Nygรฅrd, Michael Tjernstrรถm and Tuomas Naakka, Winter thermodynamic vertical structure in the Arctic atmosphere linked to large-scale circulation, Weather Clim. Dynam., 2, 1263โ1282, 2021
8-Renno and Williams Quasi-lagrangian measurements in convective boundary layer plumes and their implications for the calculation of CAPE, 1995, Mon. Weather Rev., September, 2733.
9-Nilton Renno, Andrew Ingersoll, Natural convection as a heat engine:a theory for CAPE,
J atmos sci, v 53, n.4, 572
10-Lindzen, Chou, and Hou, Does the Earth Have an Adaptive Iris? Bulletin of the American Meteorological Society, vol 82, no. 3, March 2001.
11-Constrained work output of the moist atmospheric heat engine in a warming climate
F. LaLiberte , et al, SCIENCE, 30 Jan 2015, Vol 347, Issue 6221, pp. 540-543
DOI: 10.1126/science.125710
12-Parameterization of processes that should be based on physics is the Achilles heel of modeling; creating energy ex nihilo, destroying entropy in the universe, or masking forbidden features โ all bad. See, for example, Jay D. Schieber and Markus Hutter, Multiscale modeling, beyond equilibrium, Physics Today, March 2020, p.36.
Venus is the least understood of the terrestrial planets. Despite broad similarities to the Earth in mass and size, Venus has no evidence of plate tectonics recorded on its young surface, and Venusโs atmosphere is strikingly different. Numerical experiments of long-term planetary evolution have sought to understand Venusโs thermalโtectonic history with indeterminate results.ย
Every once in awhile I read a news release and do a facepalm. I note that โsimulationsโ are not โevidenceโ and chaos (and uncertainty) works backward in time too. โ Anthony
From EurekAlert โ Venus had Earth-like plate tectonics billions of years ago, study suggests
Simulations produced by a Brown-led research team offer evidence that Venus once had plate tectonics โ a finding that opens the door for the possibility of early life on the planet and insights into its history.
PROVIDENCE, R.I. [Brown University] โ Venus, a scorching wasteland of a planet according to scientists, may have once had tectonic plate movements similar to those believed to have occurred on early Earth, a new study found. The finding sets up tantalizing scenarios regarding the possibility of early life on Venus, its evolutionary past and the history of the solar system.
Writing in Nature Astronomy, a team of scientists led by Brown University researchers describes using atmospheric data from Venus and computer modeling to show that the composition of the planetโs current atmosphere and surface pressure would only have been possible as a result of an early form of plate tectonics, a process critical to life that involves multiple continental plates pushing, pulling and sliding beneath one another.
On Earth, this process intensified over billions of years, forming new continents and mountains, and leading to chemical reactions that stabilized the planetโs surface temperature, resulting in an environment more conducive to the development of life.
Venus, on the other hand, Earthโs nearest neighbor and sister planet, went in the opposite direction and today has surface temperatures hot enough to melt lead. One explanation is that the planet has always been thought to have whatโs known as a โstagnant lid,โ meaning its surface has only a single plate with minimal amounts of give, movement and gasses being released into the atmosphere.
The new paper posits that this wasnโt always the case. To account for the abundance of nitrogen and carbon dioxide present in Venusโ atmosphere, the researchers conclude that Venus must have had plate tectonics sometime after the planet formed, about 4.5 billion to 3.5 billion years ago. The paper suggests that this early tectonic movement, like on Earth, would have been limited in terms of the number of plates moving and in how much they shifted. It also would have been happening on Earth and Venus simultaneously.
โOne of the big picture takeaways is that we very likely had two planets at the same time in the same solar system operating in a plate tectonic regime โ the same mode of tectonics that allowed for the life that we see on Earth today,โ said Matt Weller, the studyโs lead author who completed the work while he was a postdoctoral researcher at Brown and is now at the Lunar and Planetary Institute in Houston.
This bolsters the possibility of microbial life on ancient Venus and shows that at one point the two planets โ which are in the same solar neighborhood, are about the same size, and have the same mass, density and volume โ were more alike than previously thought before diverging.
The work also highlights the possibility that plate tectonics on planets might just come down to timing โ and therefore, so may life itself.
โWeโve so far thought about tectonic state in terms of a binary: itโs either true or itโs false, and itโs either true or false for the duration of the planet,โ said study co-author Alexander Evans, an assistant professor of Earth, environmental and planetary sciences at Brown. โThis shows that planets may transition in and out of different tectonic states and that this may actually be fairly common. Earth may be the outlier. This also means we might have planets that transition in and out of habitability rather than just being continuously habitable.โ
That concept will be important to consider as scientists look to understand nearby moons โ like Jupiterโs Europa, which has shown proof of having Earth-like plate tectonics โ and distant exoplanets, according to the paper.
The researchers initially started the work as a way to show that the atmospheres of far-off exoplanets can be powerful markers of their early histories, before deciding to investigate that point closer to home.
They used current data on Venusโ atmosphere as the endpoint for their models and started by assuming Venus has had a stagnant lid through its entire existence. Quickly, they were able to see that simulations recreating the planetโs current atmosphere didnโt match up with where the planet is now in terms of the amount nitrogen and carbon dioxide present in the current atmosphere and its resulting surface pressure.
The researchers then simulated what would have had to happen on the planet to get to where it is today. They eventually matched the numbers almost exactly when they accounted for limited tectonic movement early in Venusโ history followed by the stagnant lid model that exists today.
Overall, the team believes the work serves as a proof of concept regarding atmospheres and their ability to provide insights into the past.
โWeโre still in this paradigm where we use the surfaces of planets to understand their history,โ Evans said. โWe really show for the first time that the atmosphere may actually be the best way to understand some of the very ancient history of planets that is often not preserved on the surface.โ
Upcoming NASA DAVINCI missions, which will measure gasses in the Venusian atmosphere, may help solidify the studyโs findings. In the meantime, the researchers plan to delve deep into a key question the paper raises: What happened to plate tectonics on Venus? The theory in the paper suggests that the planet ultimately became too hot and its atmosphere too thick, drying up the necessary ingredients for tectonic movement.
โVenus basically ran out of juice to some extent, and that put the brakes on the process,โ said Daniel Ibarra, a professor in Brownโs Department of Earth, Environmental and Planetary Sciences and co-author on the paper.
The researchers say the details of how this happened may hold important implications for Earth.
โThatโs going to be the next critical step in understanding Venus, its evolution and ultimately the fate of the Earth,โ Weller said. โWhat conditions will force us to move in a Venus-like trajectory, and what conditions could allow the Earth to remain habitable?โ
The study also included Alexandria Johnson from Purdue University. It was supported by NASAโs Solar System Workings program.
For decades rock weathering has been thought to be a net sink in carbon budget models. New research finds rock emissions are a large net source of CO2 to the atmosphere.
A few years ago Buesseler et al., 2020 discovered that all of the climate modelersโ previous estimates of global ocean carbon uptake are substantially wrong because they were measuring from the fixed โcanonical fixed 150-m depth.โ The alleged new-and-improved way to assess carbon uptake is from much shallower depths: the euphotic zone (Ez). This is the section of the upper ocean layer that sunlight is able to penetrate, and it can โvary from less than 20 m to almost 200 mโ in depth.
When the variable Ez depth is used to estimate carbon absorption versus export, the absorption estimate changes by more than a factor of 2, from 2.8 petagrams of carbon (PgC) per year to 5.7.
Now, new research reverses the decades-long assumption that rocks exposed to the air absorb CO2 from the atmosphere. Instead, weather-exposed rocks โact as a large CO2 source,โ as they release โas much carbon dioxide as the worldโs volcanoes.โ Rock weathering as a net source of CO2 is thus โnot captured in climate models.โ
About 5 years ago it was discovered that modeled estimates of CO2 emissions from volcanoes are 10 times smaller than actual measurements indicate (Illyinskaya et al., 2018).
Another 2018 study (Gray et al., with a Physics Today press release) estimated the carbon uptake for the Southern Ocean. But instead of using the traditional ship-based measurement, the authors utilized biochemical floats. The results upended decades of modeling.
Instead of absorbing close to 1 petagram of carbon (PgC) per year, the Southern Ocean is barely even a carbon sink at all โ just 0.08 PgC of yearly absorption (with a ~14 times larger uncertainty range, ยฑ0.55 PgC/year). Large regions of the Southern Ocean near Antarctica are now considered a net source of CO2 to the atmosphere.
In other words, when estimates are float-based rather than ship-based, one estimate can be more than 10 times different than another.
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