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Doodad at 06:44 AM on 23 June 2016Climate's changed before
If past global warmings have been caused mainly by CO2, and it has caused temperatures higher than the present, then how did temperatures come back down and even into an ice age later? There were no animals trying to reduce CO2 emissions back then? That means CO2 emission came back down for some natural caused reason. Does that mean CO2 would also come back down naturally after a period of time after the present warming?
Moderator Response:[PS] Please read the intermediate version of this article. Climate has changed before for many reasons but in these changes, GHGs operate as amplifiers. Over very long time periods earth has a crude "thermostat" in rock weathering (releasing Ca). See here in particular for details and also here and in referenced papers for more. Also, see Mathews and Weaver for how fast temperatures could change under zero emissions etc.
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amhartley at 06:31 AM on 23 June 2016A brief history of fossil-fuelled climate denial
John Cook, the claim that “People who fear the solutions to climate change, such as increased regulation of industry, are more likely to deny that there is a problem in the first place – what psychologists call “motivated disbelief” ” seems a little uncharitable, if not an invalid argument. Some, at least, of those people might actually sincerely disbelieve a climate change problem exists, leading them to assert that no ‘solutions to climate change’ are needed.
As much as I disagree with Karl Popper on some things, I applaud him for giving others the benefit of the doubt, & trying to strengthen their arguments (before tearing them down, when needed). Would it be possible to adjust the claim about “motivated disbelief” to follow Popper’s example to us all?
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Mike Hillis at 04:11 AM on 23 June 2016Venus doesn't have a runaway greenhouse effect
Glenn, this is slightly off-topic but when speaking of emission elevations and temperatures, and optical thickness, you must specify wavelength. On Earth, emission of 15 micron IR occurs at the top of the troposphere at cold temperatures, but 9, 10, or 11 micron IR for examples, are emitted to space from Earth's surface (if not blocked by cloud) at very warm temperatures.
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Glenn Tamblyn at 03:15 AM on 23 June 2016A brief history of fossil-fuelled climate denial
I agree with Tom. In terms of the history of the science, this question was not understood till the 50's and the piece was reporting the scientific view of the time.
However it is still an example of some PR from the petroleum industry. At that time perhaps not unreasonable, it is how an industry responds as the science develops that is the key issue. -
Tom Curtis at 03:02 AM on 23 June 2016A brief history of fossil-fuelled climate denial
rocketeer @1, in 1937 scientists did not know the rate at which CO2 dissolved into the ocean, and more importantly, how rapidly it mixed with the deep ocean. They did not know this until nuclear testing increased the production of C14, giving them a marker with which to trace this in the 1950s. Nor did they know the rate at which CO2 was released by volcanoes (which I believe was not estimated until the 1990s) and hence did not know the rate of natural weathering. Most importantly, they had no clear data showing an increase in the atmospheric CO2 levels (not obtained until Keeling set up the Mauna Loa observatory until the late 1950s). In short, until the late 1950s, they did not have evidence that refuted that hypothesis.
It follows that that is not an example of climate change denial, but only of a scientist being wrong in the absence of relevant data. Scientists do that all the time. It is what drives them to find the relevant data to test alternate theories. Of course, presented today when we do have all that data, or indeed, anytime after the mid 1960s, that theory is denial because it flies in the face of some conclusive evidence.
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BBHY at 02:53 AM on 23 June 2016A brief history of fossil-fuelled climate denial
Another factor is that climate denial has effectively been turned into a "shibboleth".
People like belonging to a group, whether religous, political, idiological, or otherwise, and for many people people the group the feel affinity for is conservatism. A shiboleth something that people use to identify themselves as part of a particular group, and climate denial has been turned (intentionally, IMHO) into a way for people to identify themselves as a member of the conservative group.
The big difficulty with this is that trying to argue with those folks by presenting evidence and facts about climate change simply reinforces to them that you are "not one of them", an outsider, and therefore possibly not to be trusted. Studies have shown this is often the case, presenting more evidence about climate change to people can actually make them even more certain that their original view is the valid one.
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Dcrickett at 01:18 AM on 23 June 2016A brief history of fossil-fuelled climate denial
A few weeks ago I finished reading "This Changes Everything" by Naomi Klein. I have not been able to fault the book on accuracy; I do wish it were to show less political bias (altho Ms Klein tried valiantly to minimize this). Nonetheless, the book did make me think. Particularly about how and why intelligent, rational, well-meaning folks don't "get it" on the need for massive and immediate action (the less immediate the action, the more massive it must be).
Political people tend to ignore the "hair-on-fire" urgency of climate action because (a) they can ignore it and get away with it; and (b) their action paradigm does not see the utter nonnegotiability of Nature. Negotiation and compromise are core to a proper political action paradigm, but are immiscible with the science paradigm.
Unfortunately, this has consequences every bit as bad as the misunderstanding spawned by denialism.
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rocketeer at 00:06 AM on 23 June 2016A brief history of fossil-fuelled climate denial
This is the earliest example of climate change denial I am aware of. i suppose at this early date it could qualify as genuine skepticism rather than denial, but it does come from the petroleum industry so... Also, the arguments may sound familiar as they are still in use 80 years later. Enjoy.
Science - Supplement July 30, 1937
THE CARBON DIOXIDE CONTENT
OF THE AIR
Even though man has released into the atmosphere
some 180,000,000,000 tons of carbon dioxide gas by the
burning of mined fuel during the last half century, the
plants of the world each year return this carbon dioxide
a thousand fold through their decay or combustion.
Dr. Robert E. Wilson, president of the Pan American
Petroleum and Transport Company, who reports this result
in Industrial and Engineering Chemistry, also notes
that the fears of those people who shudder at the
" greatly " increased carbon dioxide content of the air
which is produced by modern industrial activity, are unfounded.
If all the carbon dioxide dumped into the
atmosphere in the last 50 years had not been removed by
returning the elements involved to the earth in some form
or other, the carbon dioxide content of the atmosphere
would have increased only two-thousandths of one per
cent. in that time; from 0.03 to 0.032 per cent.The controlling factor which determines how much carbon
dioxide there is in the air is the water of the earth 's
oceans. Available data indicate there is some 30 to 40
times as much carbon dioxide dissolved in the ocean as is
present in the atmosphere. The average partial vapor
pressure of this carbon dioxide is probably largely what
determines the average carbon dioxide content of the air,
so that well over 90 per cent. of any excess carbon dioxide
introduced into the atmosphere eventually finds its way
into the ocean, leaving the composition of the former
virtually unaffected.
The combined result of all our mining and chemical
activity to date has made but an infinitesimal alteration
in the composition of the earth 's crust or sea water.
And this, despite the fact that in the past half century
some 50,000,000,000 tons of carbon have been obtained as
either coal, lignite, crude petroleum or natural gas -
John Hartz at 23:49 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
pjcarson2015 @20:
You assert:
6. Until AGW raised its head ca 1985, not much concern was raised about bleaching, and was reflected in when or if it was reported.
How do you know this to be true?
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Tom Curtis at 21:55 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
scaddenp @20:
"Was there a coral bleaching event in 1965? yes. Is it comparable to events today in severity and coverage?- you need the larger scale evidence. Valerie says no but you appear to not to like that statement, but project heaps from the other one. Drawing a long bow from one observation instead of decades of study is highly unconvincing to me."
As previously noted, Valerie Taylor only state the extent of her, and her husbands travels in 1965, not the extent of the bleaching. However, she does not state that the bleaching was limited. From the information she gives alone, it could have been one or two small patches of bleaching, or a bleaching event comparable to that in 1998 and 2016. Of course, we know on other grounds that the later is not the case. Further, she does not even state when the bleaching occurred, or its cause. The bleached areas they saw could have been remnants of a bleaching event in the previous two years. The bleaching could also have been caused by large inflows of fresh water (as happens on inshore reefs during floods). It may have even be a Crown of Thorns Starfish outbreak, whose initial impact of the reef is superficially similar.
Not only is her account vague, but it is also that of a non-expert. She is a very experienced diver, but so also is Ove Hoegh-Guldberg, who was collecting for an Oceanarium before he left high school, and has been diving for at least 39 years. What Ove Hoegh-Guldberg adds to that is a lifetime of intensive research which makes him an expert, something pjcarson would immediately acknowledg, if only Ove Hoegh-Guldberg agreed with him. Unfortunately he does not, so he has to talk up a non-expert who does not explicitly disagree rather than acknowledge genuine expertise.
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Tom Curtis at 21:24 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
scaddenp @20, I think you will find that Ove is Australian Research Concil Laureate Fellow, Professor Ove Hoegh-Guldberg. His also John Cook's boss, and author of a very relevant series of posts on SkS (Part 1, Part 2, Part 3). I am unsure on what basis PJ Carson claims to be on a first name basis with him (his only described interaction certainly does not cut it).
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scaddenp at 20:06 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
1/ it is your framing i am objecting to. Your inference doesnt go with the other quote does it? Tom here pointed out that you were inferring more from her statement than it allowed.
2/ I have no idea who Ove is apart from fact that he is professional scientist studying coral. Comments about him or his age sound like rhetori to me.
5/ Sorry, on one TV show you cannot show pictures that give any framework to how widespread an event is, nor its context in larger time frame.
Was there a coral bleaching event in 1965? yes. Is it comparable to events today in severity and coverage?- you need the larger scale evidence. Valerie says no but you appear to not to like that statement, but project heaps from the other one. Drawing a long bow from one observation instead of decades of study is highly unconvincing to me.
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Glenn Tamblyn at 19:58 PM on 22 June 2016Venus doesn't have a runaway greenhouse effect
Mike Hillis
Here is whats on that page.- Vertical air movements produce a relative temperature gradient in an optically thick atmosphere with locally adiabatic conditions.
- These movements move heat up and down to establish and maintain that gradient, even in the presence of heat additions into the atmosphere from incoming sunlight, internal heat emissions from the planet etc. at any altitude.
- Since emissions to space are dependent on optical thickness, emission to space will originate from that altitude where the atmosphere, of whatever planet, is transitioning to being optically thin.
- For reasons of radiative balance the temperature at that level will tend towards the emission temperature needed to maintain radiative balance.
- Vertical air movements will balance atmospheric temperatures around that balance level, producing the GH effect.
- This occurs on Venus, Earth, modestly on Mars, on Jupiter, Saturn, Uranus, Neptune, Titan as a starting list.
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Glenn Tamblyn at 19:36 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
pjcarson2015
If it is H2S from volcanoes, presumably you can point to evidence along the current pathways from them to the GBR where we can see elemental Sulphur deposited on the sea floor as a result of H2S reacting with dissolved Oxygen and precipitating out. Whereas in contrast, when major H2S events have occurred in the geological record they come about at times of depleted oxygen in the oceans and large scale anaerobic bacteria population explosions -
pjcarson2015 at 16:59 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
#17 scaddenp.
1. I quoted Valerie in #3. What have I misunderstood?
2. Ove was about 7 years old in 1965, and completed his PhD in 1982; how could he compare relative bleaching if he hadn’t seen past bleaching? (See 5 below).
3. Wasn’t Ove the one appearing on Sir David Attenborough’s program “Death of the Oceans” the effects of higher CO2 levels on pH by blowing his own breath (ca 5% CO2) into seawater? A tad unrealistic - deceptive even?
4. I actually had a “conversation” with Ove (after one of his radio presentation) via a Bulletin Board concerning reef problems – it was dial-up then! - about 20 years ago. I asked him if they tested for H2S. Nope. They’re unlikely to find something if they don’t test for it!
5. One person’s observations are on TV for all to see. I’ve seen it.
So, either Ove has seen it – proving Taylors’ vision exists/existed- or he hasn’t - and his statement is false.
You choose which.
6. Until AGW raised its head ca 1985, not much concern was raised about bleaching, and was reflected in when or if it was reported.
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scaddenp at 15:22 PM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
What is doubted, it not what Valerie said, but your understanding of what she observed. I havent found the data sources of her observations for evaluation but I did find this from Ove Hoegh-Guldberg in which her observations are put in context:
"Underwater film makers like Valerie Taylor (personal communication) who extensively filmed on the Great of Barrier Reef during the 1960s and 1970s never saw coral bleaching on the scale seen since 1979. "
Comparisons with times of past high temperature have to be considered against the rate of warming which is far faster then any previous occurance except maybe PETM when nearly lost corals altogether.
And frankly, I have far more faith in systematic surveys than in one persons observations.
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chriskoz at 13:55 PM on 22 June 20162016 SkS Weekly Digest #25
With 2016 being federal election year in both US (rather trivial entertainment) and AUS (serious head to head contention), election polls are on the menu. E.g. in AUS:
Federal election 2016: Polls point to rising support for climate change actionMost interesting fact is that climate mitigation action demand grew mostly among NLP (party denying AGW problem, similarly to GOP in US although not to a ridiculous extent) supporters. The AGW awareness in general electorate in OZ is now largest since 2006-2008, when Inconvenient Truth came out.
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denisaf at 11:24 AM on 22 June 2016Development banks threaten to unleash an infrastructure tsunami on the environment
This discussion focusses on the flow of money in providing infrastructure to provide society with services at ecological costs. However, it does not take into account the fact that the proposed infrastructure construction irreversibly uses up many forms of irreplaceable natural resources. It is an unsustainable process that is bound to decline in the near future. Money flow will become impotent as nature bats last!
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pjcarson2015 at 11:13 AM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
oderator’s response to KR.
“So we'd expect largescale coral bleaching in 2016 but not 1965. “
Just as I wrote and explained for 2016 in #9 point 3.
How do YOU explain the warm peaks in your presented graph?
Are you still not accepting pre 1965 bleaching? (It was observed in 1965, therefore it happened pre-1965 – which matches your graph’s temperature peak.)
Yet you do accept it in the 1920s!?
[BTW. The Taylors were among the first “environmental warriors”, fighting to protect sharks, etc and the GBR. Yet you doubt her observations!]
Moderator Response:[Rob P] - The March sea surface temperature (SST) anomaly on the GBR in 1965 was 0.61°C below the 1961-1990 mean, whereas the March 2016 SST anomaly was 1.33°C above the mean. March 1965 ranks as the 20th coolest year in the entire record. Coral would not have been bleaching in 1965 because SST's were too warm.
And the large year-to-year fluctuations in sea surface temperature on the GBR, despite a long-term warming trend, are largely due to ENSO. In the 2nd year of an El Nino event, anomalously warm surface water entrained in the surface circulation is transported to the Coral Sea via the South Equatorial Current - the westward flowing current which is the northern arm of the anti-clockwise rotating South Pacific subtropical gyre. The anomalous warmth raises the summertime SST above normal - which is why the peaks in the graph tend to occur in El Nino years.
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Tom Curtis at 08:01 AM on 22 June 2016Climate scientists have warned us of coral bleaching for years. It's here
It now turns out that pjcarson2015 @11 (third point) now wants us to believe that:
i) Undersea volcanoes change ocean chemistry in their region so little as to be undetectable except over the last ten odd years;
ii) But that they change the ocean chemistry so much thousands of miles downstream that they cause mass bleachings; and that
iii) Undersea volcanoes have been undetectable except in the last ten years;
iv) But that he has been able to establish a clear correlation between such eruptions and bleaching events going back over decades;
v) And the established connection between bleaching events and high SST going back over four five decades swhould be ignored based on his evidence, which by his own claim cannot cover more than a decade or so.
He also wants us to believe that mass coral mortalities have been detectable going back to the 1870s (see graph @5 reproduced below), and major Crown of Thorns Starfish (Acanthaster) outbreaks have been detectable since the 1900s, while mass coral bleachings cannot possibly have been detected prior to the 1960s. Indeed, given the rapid ramp up of mass coral bleachings in the 1980s, he really requires us to believe they were not significantly detectable until the 1980s, for if he does not he must accept that they have recently become more frequent with the rise in SST.
In my opinion, he has already qualified to dine at Milliways, and should give it a rest.
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william5331 at 07:01 AM on 22 June 2016New methods are improving ocean and climate measurements
That was a great article on how one goes about comparing older with newer technologies but at the end of the article, I was expecting a comment on what difference this correction in fall rate of the XBT has made in our understanding of how much the ocean has warmed since measurements began. Does it increase or decrease the actual amount of heat we think the ocean has stored.
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Mike Hillis at 23:07 PM on 21 June 2016Venus doesn't have a runaway greenhouse effect
@ 168 Glenn Tamblyn
So as long as there is anything that can generate reasonable vertical movements, in an optically thick, adiabatic situation, the Lapse Rate engine keeps running.
Thanks Glenn, looks like we're on the same page now.
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pjcarson2015 at 16:02 PM on 21 June 2016Climate scientists have warned us of coral bleaching for years. It's here
KR #12: Comprehensive numbers and trends for pre and post 1960s, please show them!
Do you also doubt Taylors' observations? Eyesight and film is better than model numbers.
Do you have ANY data to show that current changes are different? Absence of data arising because no-one was looking does not count.
#13: How does examining AIRborne CO2 give you evidence of UNDERsea volcanoes!! They don’t produce airborne CO2 – unless from shallow seeps, they are generally kms below surface and CO2 dissolves. I mentioned an example in #3 and #9, and the large storms on the eastern coast over the past weeks are further examples. (Large Mag around Vanuatu again.)
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KR at 12:41 PM on 21 June 2016Climate scientists have warned us of coral bleaching for years. It's here
Incidentally, although difficult to localize, undersea volcanoes are well accounted for in total volume, by examining airborne CO2 isotopic fractions. Your imagined volcanic influences simply don't exist, not in any proportion or time sequence that would support your arguments.
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KR at 12:28 PM on 21 June 2016Climate scientists have warned us of coral bleaching for years. It's here
pjcarson2015 - It's all about numbers and trends, and singleton videos are in effect only anecdotal evidence without the numbers. The comprehensive numbers and trends from both periods indicate that current changes are, indeed, unlike those of the 1960's.
Moderator Response:[Rob P] - Indeed. In March 2016, sea surface temperatures on the Great Barrier Reef were much warmer than March 1965. So we'd expect largescale coral bleaching in 2016, but not 1965.
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ghagilaris at 12:15 PM on 21 June 2016There is no consensus
A point about messaging to the public. In the "Consensus of Scientists" video, John Cook makes the well-reasoned point about relying on expertise. But I think the general public could reasonably still be confused by the fact that non-expert scientists aren't showing nearly as strong of a consensus based on the current surveys. Is this because the wrong question is being asked of them, at least in terms of the type of question that is relevant to the public? Should there be a different survey that asks whether they trust the findings of the climate scientists in regard to climate change? In other words, should the quesiton be posed so that non-experts are not being asked about their personal confidence based on their expertise but rather of their trust in the findings of climate scientists, who are the experts? If the question was posed in such a way, would it show a much broader support in the science community for the acceptance of climate change and the need to act? Would this clarify the messaging to the public by separating a scientist's personal expertise from their support for the relevant experts? I guess one could just point to all the scientific societies that give the same supporting message on climate change, but maybe that could still be miscontrued by the public as a "top-down" opinion being pushed by representatives rather than an accurate reflection of the opinions of individual scientists.
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pjcarson2015 at 11:50 AM on 21 June 2016Climate scientists have warned us of coral bleaching for years. It's here
1. Rob P: Are you doubting Valerie’s honesty? (Be careful in a public forum.) Are you sure there’s no footage? There are probably some around still. I remember seeing bleaching on film from about that time – probably the Taylors’, perhaps Cousteau’s – but such events were then seen as another unexplained natural phenomenon about which people weren’t jumping up and down. (Note Tom Curtis re 1965.)
2. #10 Tom Curtis.
As I quoted in #3, “I’ve seen reefs in PNG that were as white as snow …”
indicates large scale – yet they recovered. Don’t be so selective in what you read.
If high CO2 and temperatures caused these in 1965 (or even back to the 1920s according to Rob P), then how did they recover in higher CO2 (and therefore higher temperatures according to AGW)? Why do reefs bleach sporadically then recover?
[“Sporadic” = occurring at irregular intervals or only in a few places.]
Underwater observations of any sort were scarce before Cousteau’s innovations in the 1940s. The Taylors were among the pioneers of underwater documentaries, starting ca 1965. One can’t see bleaching if one’s not there, but the Taylors certainly saw extensive bleaching before the 1980s.
3. Your statement “Undersea volcanic activity did not spike at that time, but sea temperatures did, and high sea temperatures are highly correlated with bleaching events.”
You’ve no idea if that’s correct. Undersea volcanic activity has simply not even been observed let alone recorded until the past 10 (or less?) years. Even Black Smokers were first observed in the mid 1970s. They were a surprise that helped substantiate Wegener’s theory.
4. Which high sea temperatures are you referring to, general or localised? It’s difficult to assign CO2 as the cause unless it’s general. The thermal stress graph in Rob P’s response to my #3 shows it is localised, albeit carried on ocean currents. Undersea volcanic activity produces toxins plus heat from magma, satisfying those criteria easily. Chapters 2 & 4 show it also matches the timing criteria.
Moderator Response:[Rob P] If you have links to Taylor's film footage of GBR coral bleaching in 1965 then please share. If no footage exists, and given the lack of scientific evidence, such claims can be summarily dismissed.
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william5331 at 06:31 AM on 21 June 20162016 SkS Weekly Digest #25
The solutions to the changing climate are pretty obvious. A bunch of reasonably bright year 12 students could set out a game plan that would pretty well cover what we need to do. The underlying critical probem that makes the whole thing like pushing the brown stuff up hill is the effect of money from vested interests on politicians. It's not so much that they have been bribed and therefore do the bidding of their bribers. It is that they know with certainty, if they don't do what they are told, they won't get the bribes next time. It is not only support for their next election campaign that motivates them, but a cushy job when they leave office - often as a lobyist, continuing to corrupt politics. It looks like we have just missed our last chance with Bernie. This was his core message. Get big money out of politics. It might just be too late. Have you noticed what has happened to Carbon dioxide readings over the last few months - especially April to April. 4.16ppm. I hope this is a laboratory error but not likely.
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Tom Curtis at 23:33 PM on 20 June 2016Climate scientists have warned us of coral bleaching for years. It's here
pjcarson2015 @9:
1)
"Aren’t Valerie Taylor’s observations large-scale? They were 50 years ago and bleaching was as extensive as today’s."
That is not what Valerie Taylor said. She said that "In 1965 we went from one end of the reef to the other, over six months, and we found bleaching then." The phrase "we went from one end of the reef to the other" refers to the extent of the travel. It does not indicate the extent of the bleaching, which from what Valerie Taylor said, may only have been at a few locations on the reef.
More importantly, the 1965 bleaching virtually escapes comment either in scientific publications, or on the web (not to mention from Valerie Taylor's films). While the 2016 event was comparable to that of 1998 and 2002, 1965 certainly was not.
2) In the 1998 and 2002 events, 50% of effected reefs were bleeched, and there was lasting damage to 5% of reefs. In other words, reefs can, but do not always recover from bleeching events, and the more intense the event the less likely is recovery.
3) First, bleaching events are not sporadic. They were virtually unheard of prior to the 1980s, when they became common. Undersea volcanic activity did not spike at that time, but sea temperatures did, and high sea temperatures are highly correlated with bleaching events.
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pjcarson2015 at 15:19 PM on 20 June 2016Climate scientists have warned us of coral bleaching for years. It's here
1. Rob P’s quote “We cannot yet be certain, but it is unlikely that mass coral bleaching has, until very recently, occurred for thousands of years.”
Aren’t Valerie Taylor’s observations large-scale? They were 50 years ago and bleaching was as extensive as today’s.
2. The corals also self-repaired later - despite CO2 levels being higher. If bleaching is caused by warming due to high CO2 levels, how is it that repair occurred at higher levels than the damage? In spite of this you conclude
“Of course this doesn't have to be, but humans, collectively, have shown no intention of curbing industrial carbon emissions and so the demise of coral reefs seems inevitable.
3. [You know where to find more on this topic.] As bleaching/repair occurs sporadically, one would suspect the cause to also be sporadic. Undersea volcanism fits the bill, both in location and in its irregularity, and it produces localised toxicity and heating; witness the Qld, etc floods in 2011 (when bleaching followed) and 2016 which match the preceding large Mag seismicity around Vanuatu. Expect more bleaching soon.
4. The Eemian was about 2C higher than now (Vostok data). As you note, such temperatures may well recur.
5. I’m still puzzled by the this article’s title when the Taylors - and you - note that bleaching has preceded the “warnings” by decades.
Moderator Response:[Rob P] - "Aren’t Valerie Taylor’s observations large-scale?"
And yet no film footage. Curious considering the amount of underwater filming that they have captured over the decades. -
Glenn Tamblyn at 14:47 PM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Michael Sweet
Two points. Your first one about heat transfer from cold to hot is referring to the 2nd Law of Thermodynamics. And this can be a bit confusing. Firstly, the 2nd Law refers to Net heat flow, based on all the energy flows between a hot and cold point. More importantly, the 2nd Law applies to a closed system. It does not apply to an open system. So if we think of the system and ask what the boundaries are, they need to preclude flows from outside the boundary. The atmosphere isn't that, there are flows from the surface, flows in from the Sun, flows out to deep space, and even miniscule flows in from other stars and deep space.
Next, there are huge differences between the ocean and the atmosphere. Firstly, water is essentially imcompressible. So although pressure can increase hugely at depth very little actual compression occurs. So the density of parcels of water in the ocean doesn't vary by much; so much so that even changes in the salinity of sea water is a significant contributor to relativedensity change. And it is density differences that drives vertical convective movement.The atmosphere on the other hand has huge density changes with altitude, with pressure. As a consequence, vertical movement is much easier, and any tendency to stratification is easily disrupted. Also the impact of coriolis forces is more profound. Since air velocities are much higher than ocean current velocities, change in location happens much faster, both horizontally and vertically. So more Coriolis force generated turbulence and vorticity effects. Next with its much lower density air is more easily able to move vertically since it takes much less energy to move a parcel of air vertically than the same size parcel of water. Horizontal air movements can more easily trigger vertical air movements , not just horizontal movements that infill the volume previously occupied. So turbulence and mixing can happen more easily.
So vertical movement is much easier. In the case of bottom heating which is how most heat flows into the Earths atmosphere, convection due to heating is easy to understand. However, even with top heating, which is more like what happens on Venus, mixing can still generate vertical movement. And some of the light from the Sun does penetrate to reasonable depth in Venus, enough to create some bottom driven convection.Also, wind speeds on Venus are higher than on Earth, up to 700 km/hr in the mid levels. More speed, more turbulence.
So as long as there is anything that can generate reasonable vertical movements, in an optically thick, adiabatic situation, the Lapse Rate engine keeps running. -
Bob Loblaw at 11:28 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
One last comment for now. Mike Hillis has stated:
"Only the sun can change the total heat content of the atmosphere."
The is simply not true if you are talking direct heating, and you do not include oceans or land as part of the atmosphere. Most of the heating of the atmosphere comes from the surface, where most of the solar radiation is absorbed.
This post by Keven Trenberth provides details and graphics, such as this image:
The temperature structure of the stratosphere is driven by absorption of solar radiation (mainly UV), but the troposphere is dominated by energy gains from the surface in three forms:
- thermal energy gains from the surface
- latent heat contained in water vapour (changed from liquid to vapour at the surface - i.e. evaporation - and changed from vapour to liquid in the atmsphere - i.e., cloud formation).
- infrared radiation emitted from the surface and absorbed in the atmosphere.
You can argue that all that energy ultimately came from the sun, but it reaches the atmosphere indirectly. Ignoring that indirect path is not a particularly good idea, especially in a discussion of lapse rates, adiabatic processes, and the greenhouse effect.
Moderator Response:[RH] Resized image.
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Bob Loblaw at 11:15 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Since I've jumped in, I'll mention that wikipedia has an article on lapse rates.
There are three important lapse rates in earth meteorology:
- The dry adiabatic lapse rate applies when vertical movement of air occurs ("parcels") without any phase change of water (condensation, evapoartion, or sublimation). It is the direct result of the vertical pressure gradient.
- The wet adiabatic lapse rate is like the dry - but water is changing phase so energy is being released to thermal energy in proportion to the latent heat of vaporization (or sublimation). It is most commonly seen in rising air with condensation (cloud formation), and results in a much smaller decrease in temperature with increasing height. Just how much less depends on temperature, through the saturation humidity vs. temperature realtionship.
- The environmental lapse rate is simply the current observed relationship between temperature and height. There is a global average, but the local value varies widely depending on meteorological and climatological factors. It will only equal the dry or wet adiabatic lapse rates by pure conincidence. It is a blend of the adiabatic processes plus every other factor that affects vertical temperature and energy transfer.
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Bob Loblaw at 11:05 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Michael Sweet:
Read Glenn's following text, and then let me try to explain it:
Vertical movement of air downwards transfers heat, energy, downwards since the energy content of the moving parcel of air moves down with it. And a parcel of air moving upwards transfers heat, energy upwards.
Glenn's statement applies to instantaneous transfer, not time-averaged. Energy content is a property of mass. If you move that mass in any direction, the energy it contains is moved with it. Upward movement of air is always moving energy upward; downward movement of air is always moving energy downwards. The exact vertical thermal energy flux is (heat content)*(vertical velocity). It does not matter - instantaneously - how the temperature of that air relates to air above it, below it, or around it. The simple movement of air moves energy.
Averaged over time, net mass transfer is zero (otherwise you'd create a vaccuum somewhere and an excess of air somewhere else), but net energy transfer is not. Net energy transfer depends on whether the upward moving air is - on average - warmer or colder than downward moving air.
This principle is actually used to measure the rate of sensible heat (thermal energy) transfer in the atmosphere, using a method called eddy covariance. The exact same method can be used to measure water vapour flux or CO2 flux (or any other measurable property), by using the commbination of humidity or CO2 concentration and vertical velocity. Water vapour flux is often used to determine surface evaporation, and vertical CO2 flux tells you about surface respiration/phiotosynthesis rates.
Although you must use very-fast-response instruments, so you can catch every puff, the necessary instrumentation is available off-the-shelf.
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michael sweet at 09:27 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Glenn,
I do not understand how energy can be transferred from a colder upper layer in the atmosphere to a warmer lower atmosphere. It seems to me a contradiction of the second law of thermodynamics.
The ocean forms a thermocline where circulation is restricted because the energy enters primarily from the top. I htought that the energy to circulate the atmosphere (even on Venus) comes from the sunlight absorbed by the surface and then transferred upward.
I have never an taken atmospheric science class so it may be some basic understanding that I lack. Can you provide a link that explains better how the lapse rate is maintained? I read the Wikipedia lapse rate article but I only understood what the lapse rate is and not how it is maintained in the atmosphere. I did not find much helpful on Google, but I do not know what to look for.
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Tom Curtis at 09:15 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Mike Hillis @158:
"The big question not answered here is Jupiter. How can there be a greenhouse effect on Jupiter when its atmosphere is made of H2? Answer, there isn't."
Ignoring for a moment the high cloud in the Jupiter atmosphere (which also generates a greenhouse effect), Jupiter's atmosphere contains 3000 ppmv of methane, 260 ppmv of ammonia, 6 ppmv of ethane, and 4 ppmv of water, all of which are greenhouse gases. The later two may be ignored, but the 3000 ppmv of methane and 260 ppmv of ammonia mean Jupiter's atmosphere is optically thicker for infra red radiation than is the Earth's. Specifically, at 1 bar atmospheric pressure, the infrared optical depth of the Earth's atmosphere is 1.9, while on Jupiter it is 6.3 (τ0 on Table 1 here). That in turn means the effective altitude of radiation to space for Jupiter (ie, the altitude where the optical depth equals 1) is closer to the tropopause for Jupiter (optical depth = 0.064) than it is for Earth (optical depth = 0.050).
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Glenn Tamblyn at 08:33 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Mike
You might find this article interesting, discussing the structure of planetary atmospheres and the GH effect. Notice how Jupiter (and Saturn, Uranus & Neptune) all have lapse rates in their tropospheres.
Note also the discussion of likely gases in their atmospheres, including Ammonia and Hydrogen Sulphide, both GH gases.
And consider something else. A GH Effect doen't have to just depend on incoming sunlight. Any heat source that can add significant amounts of energy into an atmosphere which is optically thick in the infra-red and thus capable of being roughly adiabatic will produce a GH effect.
So in the case of the gas giants, they do have an internal GH effect because of clouds and GH gases, changing their inner tempeature due to the fact that they produce large amounts of heat internally. Whereas for the inner planets, internal heat is minimal but solar is significant - the heat source doesn't matter. So of all the planets, Mars has the least GH effect because:- Internal heat is insignificant
- Solar is relatively weak
- Its atmosphere isn't very optically thick
- Convection is weak.
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Glenn Tamblyn at 07:56 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Mike Hillis
"Put very simply, any vertical movement of air in any atmosphere either takes heat from a higher altitude or adds it to a lower one."This statement is untrue Mike. Vertical movement of air downwards transfers heat, energy, downwards since the energy content of the moving parcel of air moves down with it. And a parcel of air moving upwards transfers heat, energy upwards.
So any vertical movement does move heat, but not all in the same direction. So any net movement of heat depends on the difference between thee two flows. And if the net of the two flows is zero, there is no effective flow.What determines whether the net heat flow is up or down? Whether the vertical temperature profile matches the Lapse Rate. If the upper air is too warm, net flow of heat is downward, cooling the upper level and warming the lower. If the lower air is too warm it is a net upward heat flow, cooling the lower level and warming the upper level.
In near adiabatic conditions vertical air movement always generates a lapse rate.Think about the logic of your idea that movement in either direction produces downward heat flow. If that we true, then heat would just continually build up and up in the lower level. Without radiation to provide an alternative means of loosing heat, the lower level would become impossibly hot, not merely 500 C or so.
As to your digression to Jupiter, vertical movement again explains the profile. If the depths of Jupiters atmosphere are optically thick, or on the case of Jupiter there are large quantities of clouds, then the adiabatic condition is met and a Lapse Rate can be created. There is no disparity.
And with clouds present, Jupiter will have a greenhouse effect to some extent. On the graph you linked to, note the clouds of different materials in the lower atmosphere, all contributing to a GH effect. Note also that some of the clouds are water, so there will also be water as vapour present - more GH effect.
Additionally, with some nitrogen present, there may be some GH type absorption and emission produced. This is due to what is known as 'collisionally induced absorption'. Molecules that aren't normally absorbers of IR radiation such as Nitrogen (N2) and Hydrogen (H2) can become transient absorbers and emitters during the finite time when they are colliding. This needs high densities and or low temperatures to make this possible, maximising the number and duration of collisions. So collisions between Nitrogen molecules on Titan for example allow N2 to create a GH Effect. And it has been theorised that collisions between N2 and H2 in the early atmosphere of the Earth may have contributed to the GH Effect then. -
HK at 04:15 AM on 20 June 2016Venus doesn't have a runaway greenhouse effect
Mike Hillis @147:
"Yup. Only the sun can change the total heat content of the atmosphere."OK, let’s try to figure out the expected consequences of that:
As you know, Venus is closer to the sun than the Earth is (108.2 vs. 149.6 million km), but also has a much higher albedo (77% vs. 30.6% according to NASA’s fact sheet). When combining these two facts we find that each m2 of Venus (mostly its cloud tops) absorbs less than 2/3 as much solar energy as the Earth does.
So, if the total heat content in an atmosphere with a certain mass and composition is determined only by the amount of absorbed sunlight, we should expect the average temperature of Venus’ atmosphere as a whole – top to bottom – to be lower than the Earth’s, right?Well, I tried to calculate a "mass-weighted" average temperature for both atmospheres based on the temperature and pressure at different altitudes.
The result for Earth was -22oC and for Venus.....+354oC !Any adiabatic process can obviously be ruled out as an explanation for this, as the very cold but very thin upper layers of Venus’ atmosphere have way too little heat capacity to "compensate" for the heat in the much hotter and denser lower layers. Actually, when I in my calculation lowered the temperature to absolute zero above 30 km, it only reduced the average for the entire atmosphere to +309oC !
And again: The spectrum of outgoing IR measured by the Venera probe reveals very clearly that the high temperature isn’t caused by any kind of internal heat source, but the simple fact that almost all the heat from the surface and lower atmosphere is prevented from escaping directly to space.
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RedBaron at 02:57 AM on 20 June 2016Timeline: How BECCS became climate change’s ‘saviour’ technology
Sir Charles,
It is my understanding that the Models used in the above don't specifically represent any single technology of drawdown. As far as technologies not existing, with respect to agricultural technologies (carbon farming) they certainly unequivocally do exist, so your youtube vid is unequivocally wrong on this point. Not only do they exist, there are many different ways to do it. Most of them are well vetted and have been for 20, 30 even 50 years or more. They were developed to improve soil fertility, not climate mitigation, but ultimately both are the same thing. There is more carbon missing from our soils than extra in the atmosphere. So if technologies designed to improve soil health, commonly refered to as "organic", were applied to carbon farm, there are many sources of information in how to do it. Technology is not the problem. Changing the infrastructure that supports agriculture is the only obstical left IMHO.
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SirCharles at 22:53 PM on 19 June 2016Timeline: How BECCS became climate change’s ‘saviour’ technology
It's a shame that scientists include in their models technologies which don't exist yet.
=> Survivable IPCC projections are based on science fiction - the reality is much worse -
Glenn Tamblyn at 21:51 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
MA Rodger
The Ideal Gas Law doesn't describe a process. It is a state law, so it describes a fixed state. Other things need to be considered to determine how and why the state changes. But the Ideal Gas Law will then describe the new state after a change.
So better to say that nRT is a constant if mass doesn't change and internal energy doesn't change. T isn't a measure of the total internal energy of a collection of molecules. It is a measure of the translational kinetic energy of those molecules.They also have energy in rotational motion, internal vibrations, and potentially electron energy levels. Also variations in potential energy of the molecules as they move closer or farther apart. Gravity is one source of potential energy change as objects move apart or together. Electro-magnetic forcs produce similar. So too inter-molecular forces such as Van Der Waals forces. Then Quantum Mechanics also impacts this hugely, constraining possibilities.
So Specific Heat Capacity, measured at constant Pressure, or constant Volume, is essentially posing/answering the question 'how much added energy manifests as increases in molecular translational kinetic energy - temperature - as opposed to increases in other modes of energy storage."
Read this article at Wiki, looking at Degrees of Freedom etc.So what is the basis for your statement that includes Cp/Cv. "As a result an adiabatic process changing p and V does involve a change in temperature."?
How are you determining that the total change in all internal energy forms - translational, rotational, vibrational, electron energy level, etc. - will result in a matching changes in only the translational component of energy - temperature.
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Mike Hillis at 21:37 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
Put very simply, any vertical movement of air in any atmosphere either takes heat from a higher altitude or adds it to a lower one. Is there vertical movement in an atmosphere? Of course. Must work be done to move the air up or down? Oh course, but that doesn't matter. All that matters is there is vertical movement. The fact that there is vertical movement proves that heat is being pumped downward. Even brownian motion does it.
The big question not answered here is Jupiter. How can there be a greenhouse effect on Jupiter when its atmosphere is made of H2? Answer, there isn't. The same thing happens on Jupiter as happens on Venus.
Venus' atmosphere is 93 bars. If you descend into Jupiter's atmosphere to a level where the density is 93 bars, the temperature is around 450 K according to
On that diagram, keep in mind there are 100,000 Pa to a bar so 93 bar is 9,300,000 Pa
Moderator Response:[RH] Shortened link that was breaking page format.
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MA Rodger at 20:38 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
Glenn Tamblyn @153,
The gas equasion pV=nRT when stated as pV=constant does not define an adiabatic process. Ignoring any gravitational field, the equation is pVγ=constant where γ=Cp/Cv which for air =7/5. The reason for this is because the specific heat capacity at constant pressure (Cp) is not equal to the specific heat capacity at constant volume (Cv). As a result an adiabatic process changing p and V does involve a change in temperature.
Mind, I don't believe this is, as Mike Hillis @146 asserts, something a high school chemistry teacher would be immediately familiar with. And it is certainly far less worthy of criticism than the assertion Mike Hillis continues with @146:-
"pV = nRT says if you increase PV, the T goes up even though you have not added heat. The work done to change the parcel's elevation and raise or lower the PV is uneven solar heating of the atmosphere."
Firstly, pV=nRT says nothing about added heat or not adding heat. Secondly, applying work to a parcel of air says there is added heat, so such a process cannot be adiabatic. (While the potential energy change could be construed conceptually as outside the boundary of the system under consideration, raising or lowering p or V cannot.)
What is so odd about the position presented by Mike Hillis is that he is proposing what he describes as a Katabatic process which is a phenomenon born of the convection process and cooling at altitude. Yet Mike Hillis uses it to explain warming at altitude, the exact opposite to the convection process. Even the mash-up account he appears to be basing his nonsense on (Nikolov and Zeller's 2011 conference poster linked @122 above) and which overplays its use of the convection process still uses it in its usual direction. So I struggle to see where Mike Hillis is coming from.
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pjcarson2015 at 18:03 PM on 19 June 2016Climate scientists have warned us of coral bleaching for years. It's here
To Rob P.
Thank you.
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RedBaron at 17:39 PM on 19 June 2016Timeline: How BECCS became climate change’s ‘saviour’ technology
Trevor,
Based on what? If I understand it correctly Kevin Anderson based his rebuttal mostly on using BECCS as a replacement for energy. Clearly not up to the task. Nor as I pointed out above, can true BECCS that is sequestering CO2 into geological formations work. But the quantity of carbon that can be sequestered by current agricultural soils is more than adequate in scale simply by changing the agricultural production models. All you need is roughly 8Gt CO2e/ha/yr +/- to offset all AGW emissions worldwide. That's trivially easy from a technical POV. Getting the world to change agriculture and do what we know how to do a bit harder. So waste materials could be converted to biochar, but it wouldn't even come close to our energy needs. However, changing the production models can actually increase total food for humans on the same acreage. So that is no limitation.
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Reason_4 at 17:31 PM on 19 June 2016Timeline: How BECCS became climate change’s ‘saviour’ technology
Strikes me that while these high tech solutions are worth pursuing, the lowest, easiest, cheapest is being overlooked.
In my experiments making biochar the easiest and best bang for buck is the pit method that anyone, anywhere can do with the highest tech required being a shovel and some means of putting out the fire - water if you have lots of it or some old roofing iron to smother the flames.
https://www.youtube.com/watch?v=I1jAo7qd_Q8
A 3rd world farmer could easily do this on site (no transport emissions) by coppicing fast growing (hopefully nitrogen fixing) trees - and either sell the biochar or enrich his/her own soil.
Millions doing small things, year in year out could have an ongoing significant impact
Great school project too.
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Glenn Tamblyn at 16:44 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
So to a basic point, and the link you gave to the hockeyschtick site is an example of this.
There are a number of climate denier sites that make this sort of argument, with dubious thermodynamics, that the existence of the Lapse Rate in some way invalidates the Greenhouse Effect. The 'Venus isn't hot because of the GH Effect, it is hot because of the Lapse Rate' type arguments. What they all uniformly don't get is something simple.
The Lapse Rate is a part of the Greenhouse Effect!
There are 3 processes that work together to create the GH Effect.1. Radiative Balance. The Earth has to radiate enough energy to space to balance the energy arriving from the Sun. If it doesn't radiate enough, heat builds up and everything fries, radiate too much and everything freezes. So 'the Earth' needs to be warm enough to generate the right amount of radiation to space. Too little and it warms until its right. Too much and it cools until it is right. Radiative Balance is always adjusting the temperature of 'the Earth' to keep it where it needs to be to match the flows.
Notice I have said 'the Earth'. Because actually it isn't the Earth, it is that part of the Earth where the radiation to space originates from. Radiation doesn't originate from 1000 meters down in the ocean for example. So Radiation originates from 'somewhere'. And Radiative Balance acts to manage the temperature of the 'somewhere'. Balance defines what that emission temperature is, but not where it comes from.
2. The presence or absence of GH gases in the atmosphere determines what altitude radiation to space originates from. More GH gases means it originates from hgher in the atmosphere. And if there were no GH gases present, then it would originate from the surface. GH Gases determine where the emission temperature is set by Radiative Balance.
For the Earth that is around 5 km up and the temperature is around -18 C. For Venus that is over 50 km up and -80 - -90 C. And if the amount of GH gases is changed, then the altitude changes. So if we added enough GH gases to raise the average emission altitude for the Earth from 5 km to 6 km, then the 6km level would then be driven to an average of -18 C by Radiative Balance.3. Then the presence of the Lapse Rate pump re-balances the vertical temperature profile around the temperature at the average emission level. Because importantly, the Lapse Rate defines relative temperatures vs altitude, not absolute temperatures. It is Radiative Balance that sets that and the GH gases determine where. The Lapse Rate then drives the average temperature of the rest of the atmosphere column to fall into line with that.
So in my example, if GH gases increased the emissions altitude by 1 km, then that level would warm to an average of -18 C, and the Lapse Rate pump would then drive matching temperature changes through the rest of the air column. Including the surface. If the actual value of the Lapse Rate remained constant* (at -6.5 C/km), then adding enough GH gases to raise the emission altitude by 1 km would result in all parts of the air column warming by 6.5 C right up to the limits where the Lapse Rate pump works.So the surface gets warmed because the upper atmosphere has to warm and atmospheric mixing propagates that up and down.
The Lapse Rate doesn't disprove the GH Effect. It is a part of it.
Sites like hockeyschtick, with their dodgy understanding, don't get this and end up spreading mis-information.
* Actually the Lapse Rate will change. In a warmer would there will be more evaporation and condensation. So the contribution from evaporation and condensation in determining the actual value of the Lapse Rate will be more important and the Lapse Rate will fall a little. This is called the Lapse Rate Feedback, it is a negative feedback, and offsets a little of the warming from more GH gases. -
Glenn Tamblyn at 16:12 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
Next Mike, your comment to me and this comment &147.
"Yup. Only the sun can change the total heat content of the atmosphere.".
Of course thats true, but it isn't what we are discussing, or the point of my previous comment. We are discussing what can change the heat content of individual parcels of air, not the entire atmosphere. It isn't what changes the total heat content of the atmoisphere thar is at issue, it is the heat content at a smaller scale.
And at that scale there are processes that can change heat content of air parcels, I have described them in my previous comments.
There is a vertical movement of energy whan air rises and falls. Because the energy in an air parcel gets carried with it. So rising air carries haet to a higher altitude. Descending air carries heat to a lower altitude. Then pressure equalisation brings about a redistribution of that heat between the vertically moving air parcel and its surrpindings. And as a concequence, a vertical temperature distribution is created. This article about the Lapse Rate is worth reading. That is what it is all about.
So there is an engine that transports heat up and down until an equilibrium is established where the atmosphere has a vertical temperature profile based on the Lapse Rate for that planet and atmosphere. And if the atmosphere weren't in equalibrium, with one layer too warm or cold compared to other layers, this active pumping engine works to re-establish the profile.
So in the case of Venus, with most incoming solar energy being absorbed in the upper atmosphere, atmospheric mixing generates a substantial vertical temperature difference. And in the case of the Earth, where more incoming solar energy is absorbed at the surface, the same mixing generates a vertical difference as well.
Importantly, this only works when there is enough vertical movement and when the process is adiabatic. On Earth, this applies in the Troposphere but as we get up to the Stratosphere, these conditions breakdown. As the air thins, convection driving vertical movment drops right off, and as the atmosphere thins, radiation to space becomes a powerful factor, so things are no longer adiabatic. With substantial radiation loss to space, this trumps the weak Lapse Rate driver of circulation. So the temperature profile of the Troposphere is dominated by the Lapse Rate, but the temperature profile of the Stratosphere is dominated by radiative effects.
So in summary. You are right about there being a strong vertical heat pumping system but you are incorrect about the mechanism that drives it. Importantly, this mechanism is a heat distribution system. It is always working to balance amounts of energy at different altitudes to maintain a vertical temperature profile. So if energy is being added to the system at different altitudes from the Sun or tiny amounts from geotherml heat (or on Earth human energy usage) and at the same time being lost to space at other altitudes as infrared radiation, the Lapse Rate pump is continually moving this incoming heat around, trying to establish the temperature profile. And the net effect, after lots of moving around, is that the incoming energy is transported to the location that it needs to be at to get out to space. But the temperature profile of the entire optically thick, convective region of the atmosphere will be maintained by the pump, not just some parts of it.
So for Venus, where absorption and emission of radiation both largely happen at higher altitude, none the less the Lapse Rate pump will still ensure that lower levels in the atmosphere are hot enough to maintain the temperature profile. -
Glenn Tamblyn at 15:40 PM on 19 June 2016Venus doesn't have a runaway greenhouse effect
Mike
Lets consider a piston and cylinder with some air inside it. The air and the piston/cylinder are at a constant temperature.
Now I push the piston in, reducing the volume to half. If I do it quickly enough so there is no time for heat transfer between the air and the cylinder/piston then the process is essentially adiabatic.
So what should happen. No heat transfer, no mass transfer, so nRT is constant. So V is halved and P is doubled, and T doen't change surely.
But that isn't what happens. The work needed to compress the piston has to be added in. So the total internal energy of the air increases, T increases so nRT goes up. V is halved, and P increases by more than double! And we now notice that T has increased.
This often confuses people. They see the temperature increase and assume that the act of being more compressed is why T is higher.
It isn't.
T goes up because energy has been added due to the work needed to compress the piston.
There is a reverse case. If we allow the volume to double, P would be cut in half. Now if this expansion had to do work, then internal energy would be expended to do it, P would drop by more than half, and temperature would fall.
However, it is possible to contrive a situation where we can achieve this volume increase essentially without any work being done.
The setup looks like this.
A chamber is divided in two by a sliding door. On one side there is air at pressure P and temperature T. On the other side there is a vacuum. Everything is in thermal equilibrium, air and chambers.Then we very rapidly slide the door away and allow the air to expand into the other chamber. No work needed to be done on the air to allow it to expand.
What happens?
Volume doubles, n is unchanged, P is cut in half, and T remains unchanged!
This is called Joule Expansion and was first demonstrated by James Prescott Joule in 1845 although others had known about it before hand.
There is actually a cooling of the gas that occurs but this is due to a secondary process, not related to the simple picture of PV = nRT we are discussing here. This secondary process is discussed at the end of the Joule Expansion article and also a related one on the Joule-Thompson Effect which is essentially about throttling processes.
Again the cooling seen in a real gas due to the JT Effect isn't intuitive so people can be misled and think that the act of being less compressed is the cause of the cooling. It isn't.
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