From the European Association of Geochemistry, a claim that looks to be little more than paleo-dowsing. Though, ya gotta love the silly claim that Earth would have hit a runaway greenhouse effect like Venus, had it not been for some mountains forming, sucking up all the CO2. Plus we’ve seen the Earth hit 5000PPM CO2 in the past, and it didn’t turn into Venus. This (Figure 1) from this post at the Met Office.
Of course it all just more model output, there’s no real earth science going on -all guesswork, no actual measurements.
How Earth avoided global warming, last time around
Geochemists have calculated a huge rise in atmospheric CO2 was only avoided by the formation of a vast mountain range in the middle of the ancient supercontinent, Pangea. This work is being presented to the Goldschmidt geochemistry conference in Sacramento, California.
Around 300 million years ago, plate tectonics caused the continents to aggregate into a giant supercontinent, known as “Pangea”. The sheer size of the continent meant that much of the land surface was far from the sea, and so the continent became increasingly arid due to lack of humidity. This aridity meant that rock weathering was reduced; normally, a reduction in rock weathering means that CO2 levels rise, yet in spite of this CO2 levels – which had been falling prior to the mountain formation- continued to drop, eventually undergoing the most significant drop in atmospheric CO2 of the last 500 million years. This phenomenon has remained unexplained, until now.
Now a group of French scientists from the CNRS in Toulouse have produced a model which seems to explain this contradiction. The period coincides with the rise of a vast series of mountains in the interior of Pangea, the “Hercynian” mountains”. These mountains arose in a wide belt, running from what is now the Appalachians, through to Ireland, South-Western England, through Paris and the Alps into Germany, and on further East.
According to team leader, Dr Yves Godderis (CNRS, Toulouse, France):
“The formation of these mountains meant that the rock weathering, which was threatening to slow to a walk through much of the supercontinent, was able to continue. The steep slopes of these Hercynian mountains produced physical erosion. Occurring in a humid equatorial environment, this physical erosion promoted rock weathering and removing CO2 from the atmosphere”.
He continued, “We believe that it is this which led to the dramatic drop in atmospheric levels of CO2. We estimate that if it hadn’t been for the formation of the Hercynian mountains, the atmospheric CO2 levels would have reached around 25 times the pre-industrial level, meaning that CO2 levels would have reached around 7000 ppm (parts per million). Let me put that into a present-day context; the current atmospheric CO2 levels are around 400 ppm, so this means that we would have seen CO2 rise to a level around 17 times current levels. This would obviously have had severe effects on the environment of that time. But the formation of the mountains in fact contributed to the greatest fall in atmospheric CO2 in the last 500 million years”.
The team believes that even if the mountains had not formed and CO2 levels rose sharply, this would not have led to a runaway greenhouse effect as happened on Venus, because the increasing temperatures would have led to rocks being ultimately weathered, heat compensating for the scarcity of water. Rock weathering would have removed CO2 from the atmosphere, thus stopping the rising temperatures.
“So it would eventually have been self-correcting” said Dr Godderis, “but there’s no doubt that this would have stalled Earth’s temperature at a high level for a long, long time. The world would look very different today if these mountains had not developed when they did.
This is a new model which explains some of the events in the 80 million years following the start of the Carboniferous period, and of course the ideas need to be confirmed before we can be sure that the model is completely accurate. The take-home message is that the factors affecting atmospheric CO2 over geological periods of time are complex, and our understanding is still evolving”.
When the climate people start in on venus, that’s when I know they are totally out of their league. Most about venus has already been hit in this thread but I don’t think all that many folks really get the ramifications. Earth and Venus are about the same size and are rocky planets and they share the same corner of the solar system. That is the limit of their similarity. Outside of an unfortunate collision with a Mars sized object (another one – not the last one), Earth cannot become like venus. Venus has the atmospheric equivalent of roughly 92 Earth atmospheres, 90 of them pure co2 and the other two essentially nitrogen (like Earth’s minus the o2). In reality, the co2 is concentrated at the bottom, being much heavier than n2 and there being no significant rotational forces to help create weather or motion in the atmosphere. It is more like our water oceans than something like our atmosphere. The differences get far more substantial from there.
Planetary albedo is totally coming from the upper layers of clouds which reflect the vast majority of light from the Sun, which would be almost double what the Earth receives per unit area. For a simplistic radiation balance calculation like Earth’s which suggests about 255k would be its averaged temperature with no atmosphere, Venus would be more like 180K because there is very little light from the Sun being absorbed. The photos taken by the landers (Soviet Veneera craft from the 1970s) show a dull dreary place that is rather reddish with the color analysis. The cameras were likely near IR sensitive as well as visible light so it’s possible some of the scenery was lit by the glow of the hot surface atmosphere rather than by the dim diffuse remnants of sunlight making its way to the surface.
Were Venus to not have this massive co2 ocean – whose mass is about 1/2 that of Earth’s water oceans, and if Venus’ sky did not have totally cloud cover, it would be a disastrous place as high noon there would last for weeks, allowing the temperatures to rise unbelievably and doubtlessly creating massive amounts of air turbulence as we would have a hot area and a cold area slowly moving around the planet.
This ocean of co2 does have a massive effect on temperatures because it drastically slows down radiation energy transfer – especially under high pressures. However, the upper cloud cover that reflects most of the Suns incoming energy will also be blocking most of the upwelling IR from the surface anyway and since there is essentially no weather in the troposphere, just uniform temperature, there is very little convection either. Much of this heat may be the original formation energy or possibly a slightly more recent collision (that might be the reason why the rotation was slowed to near zero).
Note that Venus has no significant magnetic field. Such fields are associated with the rotation of the planet and the fact that at least part of the core is liquid. Earth has both and a nice protective magnetic field. Mars has similar rotation to Earth but evidently no molten core so it has no field. It would seem that Venus has a molten core available – but no rotation of consequence – and hence no magnetic field. There is some variation in atmospheric concentrations that have been detected which suggests that Venus still has volcanic activity going on. The radar imaging of the surface shows substantial volcanic activities have occurred sometime.
To claim or think that Venus could have been just like Earth before a runaway greenhouse effect happened is just total BS. The simple fact that the rotational speed of the planet is extremely low guts any possibility of that being the case. The presence of 90 atmospheres of co2 brings up the question of whether the Earth might ever have had that much and then disposed of it via geological processes.
Curiously, whenever I bring up Earth’s magnetic field, it is asserted as the reason it has an atmosphere at all, the claim being made that without it, the solar wind would strip the Earth of its atmosphere. Yet Venus has been around as long as the Earth unless/until proven otherwise, has NO magnetic field, is exposed to both more intense solar wind and to more intense sunlight, and yet it has an atmosphere with 92 times the surface pressure. True, CO_2 is more massive than e.g. O2 or N2, but not that much more massive — one would expect for the factor of 2+ in insolation and solar wind to more than compensate given geological time.
This leaves me a bit dubious about the magnetic field being critically protective of atmosphere. I rather suspect that the thing that thinned out the Earth’s atmosphere was the hypothetical but evidence supported collision with the proto-moon Theia, which probably blew off most of the atmosphere of both planets. As for the oceans, I hold no opinion — maybe cometary bombardment, maybe oxidized outgassing of elementary hydrogen in the original mix. There’s plenty of water to be had around the solar system — no shortage of hydrogen, not much shortage of oxygen. That doesn’t mean the magnetic field isn’t important, only that maybe it isn’t as important as people like to assert without any real possibility of doing an experiment to see if they are right.
rgb
Dear alarmists, work a model for this:
We have definitive proof that Venus and Earth were both identical in their original makeup. Both had oceans, clean air and abundant life. Unfortunately Venus evolved a parasite race. This parasite ravaged their world with their SUVs, sucking all the CO2 from the ground and pumping it into the air. As their world began to die, they built ships to transport them to their close neighbor. Fortunately the parasite lost their technology shortly after coming to Earth about 1MYA, but unfortunately redeveloped it. In the 1MY since, all evidence of life on Venus has disappeared, along with their oceans and cities, since the surface temperatures are hot enough to melt rock.
There, the perfect alarmist story. Now get busy modelling it so we can all know it’s true.
Thank You!
[my emphasis]
That’s what I was wondering—whether Earth and Venus started off with similar properties (thick, CO2+ atmospheres, maybe the result of heavy volcanism) and then diverged. Could it have been the putative collision with another body that created our Moon, which also tore off most of the atmosphere? If so, we’ve got that unknown planetoid to thank for our ‘Goldilocks’ planet. If the water on Earth came from outer space (comets), then it probably wouldn’t have survived the descent through a primordial Venus-like atmosphere.
Just speculation on my part. Is there evidence pro or con such a scenario? Links? I’d like to offer it vis-a-vis the apparent consensus (thanks, Carl Sagan) of “runaway global warming” on Venus.
/Mr Lynn
If you plotted a trend line of that CO2 graph above, you’ll see that it’s heading towards zero. Before it hits zero, plants and trees would start starving, I think the level is around 180 ppm
So in a sense, fossil fuels companies are replenishing plant and tree food back in the atmosphere and in the process, are prolonging life on Earth.
If there ever was a paper that demonstrated grant gravy train chasing, this one fits the description to a T. Ya know folks, when the cat is FINALLY let out of the bag and people all over the world wake up to the swindle, there will be hell to pay politically. And not even the innocent pigs at the trough will escape.
This business of Earth destroyed by runaway warming like Venus started with Hansen and his death trains. If we didn’t stop burning fossil fuels, he warned, this runaway warming would finish us up. The oceans would boil and the atmosphere would become like Venus, mostly hot carbon dioxide. Before he joined GISS he had been an astronomer on the Pioneer Venus project, even had an experiment going up there by spacecraft. But he abandoned that, quit NASA Pioneer project, and joined GISS. In three years he was boss. Combined with his sudden change of venue it looks to me like he was set up to change it into a global warming institution. You would think that someone who has been an astronomer on a Venus project would know something about Venusian geology but no luck – he was just ignorant. The difference between the Earth and Venus is that Venus has no plate tectonics. Radioactive heat from the interior of Earth is constantly vented by plate boundary volcanism. On Venus it just accumulates beneath the crust which eventually so weakens it that it breaks up into giant slabs that sink into the interior and a new crust is formed. From impact crater counts it has been estimated that the approximate time between such resurfacing events is from 300 to 600 million years. If Venus is the same age as Earth it has had time for perhaps as many as ten such makeovers by now. Its atmosphere is not formed by boiling oceans but a product of these giant eructations it periodically experiences.
L. E. Joiner says:
June 12, 2014 at 1:05 pm
The collision which formed the moon might have contributed to earth’s apparently unique form of plate tectonics. Venus was once highly volcanic, but now much less so. And we have the moon.
Earth’s atmosphere was at one time probably about as rich in CO2 as Mars’ or Venus’. It was however most likely never as dense as Venus’. The many differences between the two sister planets are so great that Hansen’s “Venus Express” is beyond laughable.
Please also bear in mind that the temperature of the Venusian atmosphere at the point where its pressure is around the same as at earth’s surface is also about equal. This despite the fact that it’s almost entirely composed of greenhouse gas & closer to the sun.
I’ve been maintaining a database of all CO2 estimates through time from all studies which make the data available and are not just cherrypicking one date or three dates but provide at least ten estimates over some period (there is a huge amount of cherrypicking in climate science and especially with respect to CO2 levels).
There are a few types which appear to be unreliable (producing unrealistically low estimates and unrealistically high ones that I have discarded).
So here is ALL of the 2,700 reliable estimates of CO2 over the last 750 million years. There is no point putting them on separate lines. They are all estimates of CO2 that are from different time periods anyway so just put them all together. I can break this down into tighter time-periods if someone wants.
http://s12.postimg.org/kuw5mqdst/CO2_LAST_750_Mys.png
The sources for this chart are all the estimates (excluding a few unreliable methods) from Berner GeoCarb III, Pagani 2005, Antarctic Ice Core Composite, Pagani 1999, Royer 2006 Composites, Pearson 2000, IPCC AR4 2007 – Royer 2008 Composites, Pearson 2009, Tripati 2009, Bao 2008, Hoenisch 2009, Beerling Royer 2011, Bartoli 2011, Seki 2010, Mcanena 2013
[Thank you. Request you add this comment to the CO2 reference page comments section. .mod]
This time period is completely foreign to the pro-AGW scientists. They do not know this is what the CO2 data from the last 40 million years shows.
http://s10.postimg.org/5fz8g5a3d/CO2_Last_40_Mys.png
Bill Illis says:
June 12, 2014 at 7:05 pm
How many estimates do you have for the Pre-Cambrian? Just eyeballing your graph, it appears that the highest CO2 level for the time period you’ve graphed was during the most extreme glaciation, the Cryogenian (hence the name!) Snowball Earth episode of the Marinoan.
http://en.wikipedia.org/wiki/Marinoan_glaciation#Cryogenian_Snowball_Earth
Thanks!
Bill Illis says:
June 12, 2014 at 7:12 pm
And consider what coincides with the big drop down at the Eocene/Oligocene boundary?
1) Recurrence of the 150 million year cosmoclimatological icehouse phase, with
2) Land over the southern polar regions, with
3) Antarctica isolated from other continents by deep ocean currents.
Compared with these “forcings”, CO2 is not a pimple on a penguin’s cloaca.
tty says
The probes that have landed there have landed in calm conditions.
Two probes have landed on Venus, both Russian. The first crashed and was crushed by the atmospheric pressure. No further contact. The second lasted for enough time to transmit one grainy red picture of a barren rocky surface and was then crushed. Surface wind estimates from onboard telemetry was of high winds. the second lander lasted only a few minutes so surface data was scant but very high temperatures, high pressure and high winds.
A couple of posts above give the impression that Venus had a different history to Earth. It did not. It formed at about the same time, with similar conditions, magma ocean etc. but differed in one very different way. For some reason it gained no water. Water is the key to a stable climate, it provides a thermostat to excessive heating because of the narrow band of liquidity of water and latent heat removal from the surface on evapouration. This vapour rises, cools, forms cloud which increases albedo so reducing heat reaching the surface.
Both planets had a similar atmosphere, very high in CO2 but without water there was no mechanism for changing this gas to oxygen. Earth’s proto atmosphere must have been well over 50% CO2 because all the oxygen in the atmosphere is from photosynthesized CO2. Given our 22% O2 atmosphere plus all the CO2 sequestered as limestone, the most common sedimentary rock, plus the O2 lost to oxidation of soluble iron in the oceans some 2Ga years ago adds up to vast masses of CO2. There were times when O2 levels were much higher than today given the mega insect life flying about a few hundred million years ago.
Water is the key.
@johnmarshall . 3:42am … “For some reason it gained no water.”
There are some possible reasons why Venus lost its water, .. if it had any.
_(Extracts from: #comment-1660646 . June 12, 2014 at 4:59 am.)_
1.. Venus (like Mars) does not have a strong magnetic core. Therefore there aren’t any extensive magnetic fields to help protect the planet. Apparently, gases like hydrogen, helium, and oxygen ions, would have been swept away by the solar wind, leaving the higher-mass molecules like carbon dioxide. (“Venus as a more Earth-like planet”, _Nature_ 450, Nov. 2007.)
2.. Venus was left with a very dense atmosphere. It is more than 96% carbon dioxide. The atmosphere’s pressure at the surface is 92 times more than Earth’s pressure.
3.. Venus is considerably closer to the Sun, at about 0.72 of the distance from the Sun to the Earth.
4.. The equator rotates at 6.5 km/h or 4 mph. (The Earth’s is about 1,670 km/h or 1,040 mph). Therefore a Venus day is *very long! Venus takes 243 Earth days to rotate once.
[ Billions of years ago there may have been liquid water at the surface, which would have evaporated into the atmosphere. (“Searching for Evidence of Past Oceans on Venus”. Bulletin of the American Astronomical Society 39: 540, Oct. 2007.) ]
“L. E. Joiner says:
June 12, 2014 at 1:05 pm
cba says:
June 12, 2014 at 11:39 am
. . . To claim or think that Venus could have been just like Earth before a runaway greenhouse effect happened is just total BS. The simple fact that the rotational speed of the planet is extremely low guts any possibility of that being the case. The presence of 90 atmospheres of co2 brings up the question of whether the Earth might ever have had that much and then disposed of it via geological processes.
[my emphasis]
That’s what I was wondering—whether Earth and Venus started off with similar properties (thick, CO2+ atmospheres, maybe the result of heavy volcanism) and then diverged. Could it have been the putative collision with another body that created our Moon, which also tore off most of the atmosphere? If so, we’ve got that unknown planetoid to thank for our ‘Goldilocks’ planet. If the water on Earth came from outer space (comets), then it probably wouldn’t have survived the descent through a primordial Venus-like atmosphere.
Just speculation on my part. Is there evidence pro or con such a scenario? Links? I’d like to offer it vis-a-vis the apparent consensus (thanks, Carl Sagan) of “runaway global warming” on Venus.
/Mr Lynn
”
General theories of the solar system formation indicate it was rather stratified by distance from the Sun at formation, then all the anomalies not explained (like Venus essentially not rotating and in retrograde) get explained by catastrophes. It would seem that both Venus and Earth had major catastrophes early on and Mars which is much smaller managed to get a big gash in it. Mercury again is way too small for an atmosphere. These are our four terrestrial planet examples we have to work with. Mercury too had a minor major catastrophe – an impact affecting the far side of the planet and creating weird terrain.
The generally accepted Moon formation theory was an object around the size of Mars struck the young Earth. Material was blown off that formed the Moon and apparently the object was absorbed. The absence of rotation of Venus can be explained by an impact as well. Note there is still a solar system problem of what happened to all that angular momentum that should be present from the formation.
Neither Venus nor Mars has any significant magnetic field and Mars has only a tiny fraction of Earth’s atmosphere, almost all co2. Absence of magnetic field and small size might explain the loss of a serious atmosphere and there is evidence to suggest liquid water existed in substantial amounts at one time. Water from comet impacts makes sense as it would seem water needed to come from further out.
Earth’s current atmosphere is evidently its second one. Oxygen was freed up early on by biological activity. It is known there is a great deal of co2 present in rocks where it was captured via geological processes. I don’t recall seeing any theories or numbers suggesting that Earth had as much co2 as Venus has now though. Considering Mars also has a substantially co2 content in its atmosphere that is left, would suggest that since the Earth apparently formed between Venus and Mars, then it should have also mostly had co2 making up the initial atmosphere. Also, when we see volcanic eruptions, those two have lots of co2 coming back out from being trapped long ago. However, considering Venus has about the equivalent of two Earth atmospheres of nitrogen, it would seem that Venus may have had twice the total atmosphere of early Earth. It does not seem realistic that Earth which is further out than Venus and contains a substantial magnetic field would have lost atmosphere much faster than Venus.
That said, our two possibilities that come to mind are that Earth lost a substantial amount of atmosphere in collisions such as that which evidently formed the Moon or that it formed with perhaps half the atmosphere that Venus formed with or wound up with after a possible collision that stopped its rotation. I haven’t seen any numbers as to just how much co2 is actually trapped in rock by geological processes but it could be fairly substantial, very possibly a few atmospheres worth. Why Venus didn’t have the same thing happen might be related to too much atmosphere or no rotation. Also, Venus rotational axis is essentially perpendicular to the orbital plane – which suggests that it didn’t have a catastrophic collision.
With Jupiter (and the rest) along with Mars and Earth running interference, Venus should have had far fewer impacts from comets so much less water would have arrived. It would have become steam on the way down and there is evidence that despite its global ocean of co2, Venus does have impact craters as well as tremendous volcanic activity (at some point in time).
Your hypothesis is about as good as any other based on what is presently known (at least from what I can recall at the moment).
A note to some of the other posters here. It is likely that Earth and Venus formed rather similarly. However, it is very likely that water was not part of either early planets but rather that it arrived later in comet bombardments and with Venus closer in, Earth, Mars, Jupiter, etc were getting more hits so there were less comets available to impact Venus. Note too that in the last 20 yrs, there have been two observed major impacts on the surface of Jupiter and at least one was a full bore comet chock full of h2o.
milodonharlani says:
June 12, 2014 at 7:16 pm
—————————-
CO2 at 570 Mya 3,277ppm; 635 Mya 12,000 ppm; 750 Mya 4,500 ppm
Last two are from the last Snowball Earth episodes and many times smaller than what would have been required to lift the Earth out of these ice ages. So it wasn’t CO2 that ended the Snowballs.
Magnetic reversal leading to O2 depletion as explanation for some mass extinction events:
http://blogs.discovermagazine.com/d-brief/2014/06/10/earths-magnetic-flips-may-triggered-mass-extinctions/#.U5szDEAXJLr
Alan McIntire says: June 12, 2014 at 5:07 am
…With NO greenhouse gases, temperatures would ultimately stabilize at a constant temperature all the way up.
No, it’s the total energy that evens out all the way up. With gravity included, what the higher molecules gain in potential energy, they give up in temperature.
Alan McIntire says:
“With NO greenhouse gases, temperatures would ultimately stabilize at a constant temperature all the way up.”
No they wouldn’t. This is a popular myth, probably due to the climate scientists’ obsession with radiative transfer and general ignorance of basic physics. Heat would still be transferred by conduction between ground and the atmosphere, and differences in ground temperatures would inevitably result in convection (at the dry adiabatic lapse rate). The convection would be weaker and shallower than in an atmosphere with GHG’s, but the atmosphere would never become isothermal (unless the planet was irradiated equally from all directions and had a completely homogenous surface).
The whole argument is theoretical in any case. It being extremely unlikely that there is a planet anywhere without GHG’s in the astmosphere.
tty.
the most powerful heat loss process in any atmosphere is convection. radiation is a very poor third. To convect there only need be a temperature difference from the surface. GHG’s make no difference to convection only to conduction/radiation. There can never be an isothermal atmospheric profile because gravity will still do work on it which heats it up. It also contributes to lapse rate.
tty
Jupiter has an atmosphere of Hydrogen and Helium. Neither are GHG’s but Jupiter radiates more heat than the Earth, in excess of 300W/m2, because the atmosphere heats itself by adiabatic compression.
I don’t buy it. First of all, why O_2? N_2 is lighter and more easily stripped. Second when they say oxygen dropped by 9%, I assume they mean 9% relative, not absolute, as it is unlikely the earth could have recovered from a drop of 9% absolute. 9% relative is less than 2% absolute, varying from 20% of the atmosphere to 18% of the atmosphere. This wouldn’t kill a flea. Available oxygen varies by more than that when you walk up a not-particularly-tall mountain. Third, there is no particularly good reason to think that pole reversal is the cause of the O_2 depletion. A far simpler explanation, and one with direct evidentiary support, is that the roughly 1% to 2% CO_2 concentration in the atmosphere ate 1% to 2% of the O_2 (note that it is carbon plus O_2!). It wasn’t “stripped” by solar wind, it was bound up in carbon dioxide, and in spite of this the Earth was in an icehouse phase, not a greenhouse phase. Note the following combined graph:
http://www.phy.duke.edu/~rgb/combined.png
The CO_2 data is consistent with large meta-analyses of multiple proxies for CO_2 from at least four or five major independent studies, and is probably correct. Observe that if this data is correct, then the “9% relative depletion” is almost perfectly explained by CO_2, which was around 2% at the time. Note also that (again) “icehouse earth” phases with 2% CO_2 are virtually impossible to explain within the confines of the existing models. Not one of them allows for a persistent glacial era with this level of CO_2, and yet the Earth’s historical record, in geological time, is rife with glacial epochs occurring with high CO_2. Not “high” like 400 ppm, but “high” like 4000 ppm, 2000 ppm, and the like.
rgb