Guest essay by Eric Worrall
Despite the unsettling title, the authors are not trying to say Earth will end up like Venus if we don’t mend our wicked ways. But the Forbes article and study models positing an early ocean covered Venus appear to make a lot of assumptions, with very little evidence to guide those assumptions.
Venus was once more Earth-like, but climate change made it uninhabitable
December 14, 2020 12.04am AEDT
Richard Ernst
Scientist-in-Residence, Earth Sciences, Carleton University (also a professor at Tomsk State University, Russia), Carleton UniversityWe can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of 450℃ (the temperature of an oven’s self-cleaning cycle) and an atmosphere dominated by carbon dioxide (96 per cent) with a density 90 times that of Earth’s.
Venus is a very strange place, totally uninhabitable, except perhaps in the clouds some 60 kilometres up where the recent discovery of phosphine may suggest floating microbial life. But the surface is totally inhospitable.
However, Venus once likely had an Earth-like climate. According to recent climate modelling, for much of its history Venus had surface temperatures similar to present day Earth. It likely also had oceans, rain, perhaps snow, maybe continents and plate tectonics, and even more speculatively, perhaps even surface life.
Less than one billion years ago, the climate dramatically changed due to a runaway greenhouse effect. It can be speculated that an intensive period of volcanism pumped enough carbon dioxide into the atmosphere to cause this great climate change event that evaporated the oceans and caused the end of the water cycle.
…
Read more: https://theconversation.com/venus-was-once-more-earth-like-but-climate-change-made-it-uninhabitable-150445
The abstract of the study;
Was Venus the first habitable world of our solar system?
M. J. Way, Anthony D. Del Genio, Nancy Y. Kiang, Linda E. Sohl, David H. Grinspoon, Igor Aleinov, Maxwell Kelley, Thomas Clune
Present‐day Venus is an inhospitable place with surface temperatures approaching 750 K and an atmosphere 90 times as thick as Earth’s. Billions of years ago the picture may have been very different. We have created a suite of 3‐D climate simulations using topographic data from the Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 Gya, present‐day Venus orbital parameters, an ocean volume consistent with current theory, and an atmospheric composition estimated for early Venus. Using these parameters we find that such a world could have had moderate temperatures if Venus had a prograde rotation period slower than ~16 Earth days, despite an incident solar flux 46–70% higher than Earth receives. At its current rotation period, Venus’s climate could have remained habitable until at least 0.715 Gya. These results demonstrate the role rotation and topography play in understanding the climatic history of Venus‐like exoplanets discovered in the present epoch.
Read more: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016GL069790
The assumptions behind this modelling exercise appear to be a significant stretch. For example;
Venus was resurfaced by volcanic activity hundreds of millions of years ago [e.g., McKinnon et al., 1997; Kreslavsky et al., 2015], so its topography before that time is unknown. As an estimate with some observational basis, we use modern topographic data from the Venus Magellan mission via the PDS (Planetary Data System) archive (http://pds‐geosciences.wustl.edu/mgn/mgn‐v‐rss‐5‐gravity‐l2‐v1/mg_5201) and fill the resurfaced lowlands with water.
Read more: Same link as above
The postulated periodic “resurfacing” Venus experiences is far more violent than any volcanic event ever known to have occurred on Earth. The basis of the resurfacing theory is the lack of impact craters on Venus. The estimated age of impact craters which have been observed suggests the entire surface of Venus was covered in lava or otherwise destroyed in a violent volcanic upheaval around 300 million years ago. It seems a big assumption that the previous surface topography of Venus was anything like the current topography.
What about initial atmospheric conditions? Here the models make another big assumption, that the initial atmospheric conditions of Venus resembled Earth.
… Given the fact that Venus shows substantial N2 in its atmosphere today and has few modern day sources or sinks (unlike Earth), we assume that an ancient Venus could have had a ~1 bar N2 atmosphere (1012.6 mb) in its early history. A modern Earth amount of CO2 and CH4 is also included (400 ppm, 1 ppm), given otherwise poor constraints on these gas concentrations. …
Read more: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016GL069790
Don’t get me wrong, speculative modelling is obviously an interesting intellectual exercise, and might be useful to explore model boundaries or limits. But I think it would be a big leap to believe that models which struggle to explain the current climate of the Earth can tell us anything meaningful about events which occurred hundreds of millions of years ago on another planet.
Quote:
“”lack of impact craters on Venus.””
With an atmosphere as dense as Venus’, would *anything* falling even make it to the surface?
Quote:
“”an intensive period of volcanism pumped enough carbon dioxide””
Am I crazy, maybe, but doesn’t the CO2 coming from earth’s volcanoes originate from ancient and tectonically subducted limestone. As per what happens in a Lime (Cement) Kiln
Limestone created by ‘Life Processes” – does it come from *anywhere* else?
Quote:
“”resurfaced by volcanic activity hundreds of millions of years ago”
Considering that the tectonics and volcanoes are powered by heat from decaying radio-isotopes…
… that *they* were all created in one or more super-nova *at *least* 5 billion yrs ago
…AND that they all have ‘Half-Lives’
– what caused them to wait until a few hundred million years ago before bursting into life?
[Possibly a near miss from an errant planet-sized lump wandering the Galaxy?
Or the what-dya-call-them hi-way builders from Hitchhikers – MUCH more likely than the garbage we’re presented here]
I’d assert and have done, that volcanoes are Fountains of Ambrosia. For plants.
That the lack of tectonics on Mars explains its ‘Climate’ and that seemingly there *was* liquid water and life there – how could there not?
Also assert that the relentless expansion of deserts on Earth, accelerated by our farming, city-building and (de)forestry practices will turn Earth into another Mars
The radio isotypes that power ‘resurfacing’ are now all very old.
Modern volcanoes are few & far between *and* are feeble weak affairs compared to how they were and what created the blossoming of life.
Re the errant planet. Does that connect with the age of our oil/coal reserves, created by a massive greening of Earth circa 100mya- stuff grew so fast it couldn’t decompose fast enough and got buried?
Maybe there is a diamond in this mountain of rocks?
Otherwise *far* too many Weasel Words – can someone count them please?
It is currently raining in london england, A clear sign of climate change.. We don’t need venus or mars as a lesson in green houses gasses, everything is climate change, a sunny day, snow, birds singing, wind, no wind…
“The Venusian surface has been altered by objects from outside the planet as well as by forces from within. Impact craters dot the landscape, created by meteorites that passed through the atmosphere and struck the surface. Nearly all solid bodies in the solar system bear the scars of meteoritic impacts, with small craters typically being more common than large ones. This general tendency is encountered on Venus as well—craters a few hundred kilometres across are present but rare, while craters tens of kilometres in diameter and smaller are common. Venus has an interesting limitation, however, in that craters smaller than about 1.5–2 km (1–1.2 miles) in diameter are not found. Their absence is attributable to the planet’s dense atmosphere, which causes intense frictional heating and strong aerodynamic forces as meteorites plunge through it at high velocities. The larger meteorites reach the surface intact, but the smaller ones are slowed and fragmented in the atmosphere. In fact, craters several kilometres in size—i.e., near the minimum size observed—tend not to be circular. Instead they have complex shapes, often with several irregular pits rather than a single central depression, which suggests that the impacting body broke up into a number of fragments that struck the surface individually. Radar images also show diffuse dark and bright “smudges” that may be have resulted from the explosions of small meteorites above the surface.”
Encyclopedia Britannica
Wind speeds on the surface are only 10 km/h but very dense. The pressure is the same as under 900 m of water. Why the need for a resurfacing event and not just erosion?
And the air temp at the bottom of the grand canyon is a few degrees warmer. Boyles law. Compress gas and it warms.
The act of compressing a gas warms it. However gas at a constant pressure is neither warmed nor cooled by the pressure.
Think of it another way.
When you pump up a bicycles tire, the tire heats up. However once you stop pumping air, the tire quickly returns to the ambient temperature.
Junk science redefined.
Chuckle. But Earth was once just like Venus,
Ancient Earth had a thick, toxic atmosphere like Venus — until it cooled off and became liveable (msn.com)
It’s not their distances from the Sun but their rotation rates which explain the different fates of twin planets Venus and Earth.
While Venus gets twice as much radiation at the top of its atmosphere, its surface recieves only 20% as much sunlight (direct and indirect) as our wonderful world.
modelling…
and a deja vu of Holdrens bullsh*t theory on venus
sigh
everyday another thing that makes you shake your head and laugh.
I am sure it has nothing to do with it’s proximity to the sun. scheesh.
Venus, we are told, has an atmosphere that is almost pure carbon dioxide and an extremely high surface temperature, 750 K, and this is allegedly due to the radiative greenhouse effect, RGHE. But the only apparent defense is, “Well, WHAT else could it BE?!” (besides/also molten core volcanism)
Well, what follows is the else it could be: (Q = U * A * ΔT) aka a contiguous participating media.
Venus is 70% of the Earth’s distance to the sun, its average solar constant/irradiance is about twice as intense as that of earth, 2,602 W/m^2 as opposed to 1,361 W/m^2.
But the albedo of Venus is 0.77 compared to 0.31 for the Earth – or – Venus 601.5 W/m^2 net ASR (absorbed solar radiation) compared to Earth 943.9 W/m^2 net ASR.
The Venusian atmosphere is 250 km thick as opposed to Earth’s at 100 km. Picture how hot you would get stacking 1.5 more blankets on your bed. RGHE’s got jack to do with it, it’s all Q = U * A * ΔT.
The thermal conductivity of carbon dioxide is about half that of air, 0.0146 W/m-K as opposed to 0.0240 W/m-K so it takes twice the ΔT/m to move the same kJ from surface to ToA.
Put the higher irradiance & albedo (lower Q = lower ΔT), thickness (greater thickness increases ΔT) and conductivity (lower conductivity raises ΔT) all together: 601.5/943.9 * 250/100 * 0.0240/0.0146 = 2.61.
So, Q = U * A * ΔT suggests that the Venusian ΔT would be 2.61 times greater than that of Earth. If the surface of the Earth is 15C/288K and ToA is effectively 0K then Earth ΔT = 288K. Venus ΔT would be 2.61 * 288 K = 748.8 K surface temperature.
All explained, no need for any S-B BB LWIR RGHE hocus pocus.
Simplest explanation for the observation.
(NASA planetary data sheet, engr tool box, first principles & math)
Seems to me that this ‘study’ was designed to provide the answers the authors were looking for. Is there any evidence that Venus ever had as much surface water as earth at any time in it’s history? If it’s atmosphere was ‘earth-like’ wouldn’t it’s proximity to solar radiation and slow rotational speed have made it unlikely that the planet cold retain surface water of any amount? Is there any evidence that Venus’ rotational speed was ever ‘earth-like’? I think the mars sized object collision with a young earth (which created the Moon) had something to do with earth’s rotational speed?
We’ve had satellites that can map the surface of Venus using radar. To date no evidence of ancient surface water has been found.
“It likely also had oceans, rain, perhaps snow, maybe continents and plate tectonics, and even more speculatively, perhaps even surface life. ”
Without a magnetosphere?
But at least they openly admit it is all speculative with the possibility of life “even more speculative”.
Fight Climate Fear. Warmer is Better.
Those silly Venusians. See what happens when you don’t pay a carbon tax? 😉
Study: “Earth was once more Venus-like, but climate change made it inhabitable”
In science it is often a useful exercise to turn a statement around and see if it still makes sense. The object of this exercise is to test your assumptions. If I take a telescope and look through it the wrong way what happens? I discover that I have also made a microscope.
Richard Feynman’s superb statement that we discover the laws of science by guessing carries a deeper truth, namely that we also make observations by guessing. Our guesses are comparators of what we are seeing. The first description of a biological cell when made through a microscope used the concept of a monk’s cell; this familiar name of an enclosed space was used by the observer to describe the objects being seen. Had the analogy of a bubble come to his mind we may just as easily be talking knowledgeably about the biology of bubbles.
So, what do we know about Venus and what can we deduce from our knowledge?
From astronomy we know that:
1. Venus is closer to the Sun than the Earth.
2. Venus is about the same size and mass as the Earth.
3. Venus has no moon.
4. Venus is a bright planet.
5. From observations of the transit of Venus Mikhail Lomonosov discovered that the planet has an atmosphere.
6. From radar studies we know that Venus has a retrograde rotation.
From direct exploration using planetary probes we know that:
7. Venus has a thick atmosphere of carbon dioxide gas and it has a searing surface temperature.
8. Venus has a young aged surface with few impact craters.
9. Venus has a surface topography with two highland areas Ishtar Terra and Aphrodite Terra indicative of long-term crustal formation processes.
I will start with the interesting fact that Venus has a significant quantity of Nitrogen gas in its atmosphere (3.5% by volume) and with a surface pressure of 92 bars, this means that by Dalton’s law of partial pressures the planet has an atmospheric component of 3.22 bars of nitrogen gas. By comparison the earth has a partial surface pressure of 0.79 bars of nitrogen and so Venus has 4 times as much nitrogen by mass in its atmosphere as the earth does. This is important for a number of reasons.
First this suggests that Venus has always had a significant atmospheric pressure on its surface from its time of formation. Certainly, there would have been sufficient pressure for liquid water to exist even under the reduced insolation of the early faint Sun. This is because of its closer proximity to the Sun the planet Venus would be in the reduced radius “Goldilocks zone” at its time of planetary formation.
But where does the nitrogen gas for the supposed thick atmosphere of early Venus come from?
I believe that the suggestion by Ian Miller in his 2001 paper “Early Martian Atmosphere and Biogenesis” has application here. Metal nitrides formed in the high temperatures of the early solar system nebula provide a valid mechanism to allow nitrogen to be accumulated in solid mineral form during the accretion of the planet Venus.
So, if we have on the surface of the early Venus a nitrogen atmosphere with liquid surface water, why is Venus now a carbon dioxide world?
If we assume that the standard processes of vulcanism on a terrestrial planet such as Venus produce a continual outgassing of carbon dioxide gas into the atmosphere, and that the early ocean of Venus was acidic (all that volcanic sulphur) and further that the ocean was warm, then the only place for the carbon dioxide to accumulate would be in the atmosphere.
So, as time moved on and the Sun became brighter, if it had a low albedo earth-like, water vapour dominated atmosphere then Venus would become hotter. Eventually the increasing solar irradiance from the developing Sun would trigger planetary surface water boiling and the oceans of Venus would evaporate into space.
I discussed the timing of this idea for the transformation of Venus in section 4.4 of our paper <a href=”https://www.researchgate.net/publication/340886704_Inverse_Climate_Modelling_Study_of_the_Planet_Venus”>Inverse Climate Modelling Study of the Planet Venus
</a>
Ho hum, I see there are new rules for posting links here.
Inverse Climate Modelling Study of the Planet Venus
You forgot to mention that the Solar Irradiance on Venus is almost exactly twice that of Earth.
We get 1300 W/m^2. Venus gets 2600 W/m^2.
“You forgot to mention that the Solar Irradiance on Venus is almost exactly twice that of Earth”
That is one of those “Yes, but” issues. I said Venus is closer to the Sun so the irradiance must be higher and that is why I said ancient Venus was inside the Goldilocks zone of a weaker early Sun.
But, the albedo of the modern sulphuric acid clouded Venus (0.77) is much higher than the water dominated albedo of the Earth (0.306)
Earth captures 1361*(1-0.306) = 944 W/m^2
Venus captures 2601*(1-0.77) = 598.3 W/m^2
So Earth is clearly going to be warmer than Venus (Yeah right, … it’s complicated).
I must admit I should have read your post more carefully. (But I don’t buy the albedo argument. Albedo effect doesn’t happen at top of atmosphere)
“Albedo effect doesn’t happen at top of atmosphere”
It absolutely and emphatically does happen at the top of the Venusian atmosphere, that is where the reflective clouds are!. That is also why Venus is the brightest planet we see from the Earth.
The sunlight here on Earth does not get dimmer on a cloudy day?
Where does the reflected (and therefore not absorbed) light go to?
”… more Earth-like …” ?
The Earth is more Heaven-like than Hell
“It can be speculated that an intensive period of volcanism pumped enough carbon dioxide into the atmosphere to cause this great climate change event that evaporated the oceans and caused the end of the water cycle.”
t can also be speculated that the authors are using the WAG method.. Wild A** Guess,
The authors haven’t yet claimed that this is earth’s future unless we change our wicked ways. But give them a while and they will make that claim.
There is little or no water vapor in the Venus atmosphere, so where did that ocean go? The clouds are sulfuric acid aerosol created from sulfur dioxide and water that is measured in ppm.
“Venus was once more Earth-like, but climate change made it uninhabitable”
So, someone either thinks that Venus WAS habitable, or they are too ignorant to understand their own heading, or they are intentionally trying to exaggerate (lie) and mislead.
The heading is a lie … the only to reason to continue with the article is to find more lies.
All previous models found that Venus never cooled down enough for oceans to form.
Please explain why all previous models were wrong and yours is correct.
First they need to prove *any* of the models are capable of being correct. Doesn’t matter what the models say when you have no reason to believe the models are accurately modeling what they claim to be modeling.
Likely, Venus initially had comparable amounts of H2O, N2, and CO2 as does Earth.
But Venus lacks a magnetic field. Earth’s magnetic field protects its upper atmosphere from charged solar particles and disassociation of the H2O molecule. Atmospheric water on Venus, not so protected, slowly disassociated, and the H2 formed, having a greater molecular velocity than the Venusian escape velocity, was gradually lost over time. Evidence that such mass fractionation occurred is observed today in the much greater D/H isotopic ratio of hydrogen on Venus.
On Earth, atmospheric water vapor produces most of the greenhouse warming effect, sometimes estimated at some 30 degree-C. Loss of Earth’s atmospheric water vapor (assuming all other parameters constant, including cloud albedo) would cause Earth to cool. Presumably, loss of water vapor from Venus also had a cooling effect.
Venus’ inventory of CO2 is concentrated in its atmosphere, in large part because its high surface temperature disassociates the common condensed species, carbonate. On Earth, much of the near-surface carbon exists in carbonate. The massive atmospheric CO2 contributes to Venus’ elevated temperature, and this effect greatly outweighs greenhouse cooling from loss of water vapor.
<I>According to recent climate modelling, </I>
No need to read past that sentence because you know anything that follows is pure speculation based on no real data.
Mars has an atmosphere comprised of 95% CO2, but temperatures range from -150°C to 20°C.
Surely if CO2 was the temperature control knob it to would have the same surface temperature as Venus.
The atmosphere of Mars is very thin so 95% of squat is still squat. The two are not comparable.
Fight Climate Fear. Warmer is Better.
They may not be trying to SAY it, but with the headline (which is all that most read) they’re certainly trying to frighten people into believing it.
“we assume”
That pretty much wraps up their entire story.
“…an interesting intellectual exercise…”, also known as “mental masturbation”. Sorry to offend, but there’s no other way to adequately describe this work of fiction pretending to be science.
Another point – claiming that the lack of surface features at the bottom of such a heavy atmosphere must mean volcanic action resurfaces the planet regularly is just complete ignorance. One big likelihood is that no meteorites (etc) can get through the atmosphere in order to impact the surface.
A final question – how do the “know” that Venus changed 1 billion years ago? What evidence do they have that it was ever any different than today?
To fit their narrative, the GIGO modelers assume that the reworking of Venus’ surface occurred in a short period about a billion years ago. The evidence suggests however that resurfacing is a continuous process, the Venusian equivalent of tectonics.