With the most classical of globalwarmist sleight-of-hand, a Nov 6 press release by NASA titled “A Tale of Planetary Woe” surreptitiously changed the focus of MAVEN, a whole new mission to Mars scheduled to reach the planet in 2014.
Look at the following words:
Why did Mars dry up and freeze over? […] One way or another, scientists believe, Mars must have lost its most precious asset: its thick atmosphere of carbon dioxide. CO2 in Mars’s atmosphere is a greenhouse gas, just as it is in our own atmosphere. A thick blanket of CO2 and other greenhouse gases would have provided the warmer temperatures and greater atmospheric pressure required to keep liquid water from freezing solid or boiling away.
My first reaction was a “Wow!” followed by “Finally a CO2 mission by NASA!” (yes, the greenhouse effect has so far been singularly of absolute disinterest for planetary scientists, for some reason).
Alas, the feeling didn’t survive a quick investigation about MAVEN…
For example, from the MAVEN Fact Sheet, “Science Objectives”:
Determine the role that loss of volatiles from the Mars atmosphere ot space has played through time, allowing us to understand the histories of Mars’ atmosphere and climate, liquid water, and planetary habitability
No mention of CO2 or of blankets. And no mention of them in the MAVEN mission page either:
Mars once had a denser atmosphere that supported the presence of liquid water on the surface. As part of a dramatic climate change, most of the Martian atmosphere was lost. MAVEN will make definitive scientific measurements of present-day atmospheric loss that will offer clues about the planet’s history.
The Principal Investigator for MAVEN is renowned Mars expert Dr Bruce M Jakosky of the University of Colorado (can be seen in a video at this page). I haven’t been able to find anything abour Dr Jakosky showing any specific interest in an ancient “thick atmosphere of carbon dioxide” with or without greenhouse warming characteristics.
Given also the amount of time needed to put together a space mission, and the various review stages any proposal has to go through, we can safely consider any newly-found CO2 focus for MAVEN as an artifact introduced by whomever decided the gist of the Nov 6 NASA press release.
And luckily so: there is very little we know about the Martian atmosphere, hence any undue assumption such as obsessing with CO2 as a greenhouse gas would risk making us miss out important observations.
Archive for the ‘Venus’ Category
“Let’s compute (in a simplified manner!) what would happen were Earth suddenly equipped with an atmosphere as massive as Venus’ (ie 90 times more than ours).
Given the similarities in mass and diameter of the two planets, we can assume this new atmosphere would behave similarly to Venus’, and in particular, purely adiabatically below 60km (instead of below 12km as at present).
For another simplification, let’s also imagine the new atmosphere to be just as our current one but without any water.
The lapse rate for dry Earth atmosphere is known and is 9.760 K/km.
How higher would the surface temperature be, with a dry atmosphere and a 60-km-thick troposphere?
9.760 * (60-12) = 468K higher than at present (288K)
The total for Earth is then 756K. Compare that to Venus’ surface temperature of 735K.
For an amazing coincidence, that’s 97% of the above, whilst the ratio of absorbed Solar radiation at Venus compared to Earth is… 96%.
Note how the increase in temperature doesn’t depend on any greenhouse gas.
And so do we really need to believe in greenhouse warming when mere mass can explain the observations?”
This is it, get ready, the leading line dealing with the paramount point: How do we know CO2 matters?—tell me if you’ve heard this before…—’Venus’.
Watch him set himself up for a ridiculous leap of logic:
“Though [Venus] shares several features in common with our planet, hence its sometimes being called Earth’s “sister planet,” it differs in one crucial aspect: the amount of CO2 in its atmosphere.”
Whoah. Differs in just the one aspect? One? Haul out the old world book encyclopedia and find out that Venus is also 40 million kilometers closer to the sun; it spins backwards; a day lasts longer than a year; it has an atmosphere 90 times denser than earth, and it’s hot enough to melt lead on the surface. All this, AND the clouds are made of sulphuric acid.
It’s one hell of a ’sister’ with acid rain at 475 degrees. (Don’t park the Ford there, it’ll be gone tomorrow. Part gas. Part liquid.)
Jacquot ‘reasons’ (I’m feeling generous) that because the atmosphere on Venus is almost totally CO2 and the planet is hot, therefore, CO2 made it that way. But correlation is not causation, and sadly for the him this reason disappears faster than the interplanetary Ford. Let’s pick just one difference. With an atmosphere 90 times denser than Earth, Venus is ‘like’ the earth in the same sense that Bruichladdich Whiskey is ‘like’ water. They’re both clear liquids, but one will sterilize your bench top.
If Earth were wearing a three blanket wrap, poor Venus lucked out with a 270 layer equivalent. No wonder it’s hot.
On Earth, to get the same atmospheric pressure as Venus you need to get down about a kilometer below sea-level, and I don’t mean a kilometer down a mine shaft, I mean almost a kilometer below sea-level, or under the weight of 900m of water—go sit in a deep sea trench. If you went down a mine shaft, to get true equivalent ‘air-pressure’ to Venus, you’d need to be about 50 kilometers underground, which is 40 kilometers deeper than anyone has ever dug. There is no place on Earth like Venus.
Thanks to the super thick atmosphere, Venus is bound to be hotter no matter what gas it has up there. Ninety times! If Earth were wearing a three blanket wrap, poor Venus lucked out with a 270 layer equivalent. No wonder it’s hot. If you want to explore some numbers try this.
The next time a warmist yells Venus. Just yell back Mars. Its’ atmosphere is 95% carbon dioxide and yet, oops – it’s not 400 degrees, instead, it’s minus 40. The warmists with half a brain might come back at you with the explanation that Mars’s atmosphere is thin, but that’s just fine. That IS the point really isn’t it? Mars is cold because it’s atmosphere is so thin, and for exactly the opposite reason, that’s why Venus is Hot.
Stuck in a pit of poor reason, Jacquot keeps digging:
“In fact, many of its unique characteristics can be attributed to the fact that its atmosphere has such a large mass of CO2—roughly 97 percent of it.”
This is just plain sloppy. Many of it’s attributes? So now Venus has some differences to earth, but instead of crippling his ‘evidence’ they’re somehow due to the CO2? Name one. (And then explain how any of this is connected to The Skeptics Handbook).
What’s really depressing though, is that Jacquot claims he got this from a professor. (Ouch-really? There’s a university that gives out professorships for people who make basic mistakes in reasoning?).
The problem with this kind of assertive ill-mannered non-reasoning is that casual lazy readers soak it up.. . it becomes the daily dog food of those who want their beliefs on Global Warming shored up.
Jeremy acknowledges a few differences in the sibling planets… but he says, “it does demonstrate that there is a link between higher CO2 and higher temperatures”. Yes indeedy. That’s a ‘link’ with analytical power like the link between GDP and Santa. (Look out: nations that Santa visits are wealthier than those he skips over. So, let’s do Christmas twice a year and improve national productivity? Heck-let’s do Christmas every day. You can use this kind of reasoning to justify anything you can think of. Want to connect dairy products to scientific paper production? Look at national rates of Diabetes type II. It does wonders for national peer-reviewed scientific output. Countries without insulin resistance hardly publish anything. I can see the campaign: “Butter for Botswana—improve scientific research.” )
Yes, Jeremy, the link between CO2 and temperature that has analytical power is well known. On Earth, higher temperatures raise CO2.
This is exactly the muddy, poor quality science communication and dismal reasoning that got us into trouble in the first place. Jacquot claims sceptics are ‘muddying the debate’, but he thinks it’s ok to brush dozens of variables under the carpet of one ‘not quite perfect’ argument to demonstrate a specious ‘link’? This is either inept or dishonest, or both.
“Feature: Does Venus really suffer from “runaway greenhouse effect”?
So often in enhanced greenhouse discussions we still hear how carbon dioxide emissions risk Earth suffering “runaway greenhouse” “just like Venus”. The question is, does Venus really suffer from extraordinary greenhouse effect?
In recent months we have been showing you calculations (and scripted calculators) for Earth’s expected temperature given solar output and our distance from the Sun. To compare Venus then, all we need is the planet’s atmospheric pressure/temperature profile and we see that at an altitude of about 50Km the “morning star” has an atmospheric pressure similar to Earth’s and a temperature of about 300 K (about 27 °C), slightly warmer than Earth’s 288 K (15 °C).
Aha! Some will say, that’s because Venus is closer to the Sun!
Well, yes and no. Let’s look at the calculation a little more closely.
Venus is closer to the Sun at 0.723332 AU (1 Astronomical Unit = Earth’s average distance from the Sun) which means a simple blackbody calculation (for that altitude) would be higher due to an insolation of ~2615 W/m2 compared with Earth’s 1367 W/m2 resolving to an equilibrium temperature of 328 K (55 °C). Taking into account the higher albedo of the bright little planet (about 75% compared with Earth’s ~30%) drops that to 232 K (-41 °C) and requires a feedback (greenhouse effect) of 65% to yield the observed ~300 K (27 °C). Of course, some or all of this albedo could come from below 50 Km, in which case our greenhouse feedback is anything from a little to a lot too high — we’ll just assume it’s sourced at or above 50 Km for the sake of these calculations.
Told you! Say the enhanced greenhouse fraternity, it’s hotter due to greenhouse.
Actually, we wouldn’t get just too excited about that. Venus has an atmosphere somewhat different from Earth’s with 96.5% CO2 (965,000 ppmv) rather than our 0.039% (385 ppmv). This suggests 2500 times the CO2 concentration delivers at most a trivial 1.6 times the greenhouse effect (Earth’s feedback from GHE is thought to be about 40% or about six-tenths that of Venus).
So why has Venus got a surface temperature of about 735 K? Pressure. Venus has a massively dense atmosphere and a surface pressure a little over 90 times that of Earth. Its listed adiabatic lapse rate, dry, is 10.468 K/Km, so 50 Km deeper into the atmosphere delivers an expected warming of 50 x 10.468 = ~525 K, meaning it is actually about 100 K cooler than expected at the surface. In fact Earth’s environmental lapse rate is about 6.5 K/Km rather than the listed dry rate of 9.76 too, so the probe-measured rate of ~8 K/Km for Venus down to 10 Km altitude makes more sense.
Because Earthlings are somewhat ethnocentric, let’s look at what would happen if we added 50 Km to Earth’s atmosphere:
50 x 6.5 = 325 + 288 = 613 K (340 °C). Always provided the lower environmental lapse rate held in a massively increased atmosphere that’s a little cooler than Venus but allowing for the difference in solar irradiation not by much. Of course, if the lapse rates of similarly massive atmospheres aligned then there’d be just the difference accounted for by solar proximity, meaning Venus is not experiencing any enhanced greenhouse effect from all that CO2 at all.
Where does that leave us? For one thing it means we are certain Earth is not like Venus and humans cannot make it so by tweaking trace atmospheric constituents. To make Earth another Venus we’d need to add another 90 atmospheres (all CO2) and get rid of all the water on the planet. Venus is not Earth’s “evil twin” and does not appear to be significantly warmed by enhanced greenhouse effect. In fact there’s the possibility (probability?) some or all of the morning star’s albedo is sourced below 50 Km, making its greenhouse effect even smaller than calculated above.”