I got raypierre’s book recently. For some reason there was one available from Germany. It’s a beautiful book of pure physics. Now about that primer at Physics Today. pdf available where? $23?
[Response: It's worth stating that the pricing model for Physics Today makes absolutely no sense whatsoever. PT gets delivered to everyone with an AGU membership ($20 a year), and so a charge of $23 for a single article is simply ridiculous. The marginal cost of allowing access to the article is close to zero and the actual income from these articles has to be trivial for the magazine as a whole. PT should either charge a trivially small amount per article or charge $20 and throw in a free subscription. I would encourage everyone to send an email protesting these ludicrously arbitrary charges. - gavin]
[Response: I also think the Physics Today pricing model is ridiculous. In fact, it's so locked-down that people can't even get articles through the University of Chicago Library without a one year delay. You have to use your personal subscription for that. However, so far as I know, I am free to distribute reprints myself. Note that the pdf linked in the post is an a open-access version available from my reprint site. --raypierre]
Comment by Pete Dunkelberg — 28 Jan 2011 @ 9:19 AM
2nd attempt; sorry if this double-posts.
Did you miss this week’s good news from Nature that Greenland glaciers appear to slow down in warmer temperatures:
Stephen, read that Nature article again and some of the linked papers. It’s saying not to expect the Greenland (continental) glaciers to rush to the sea in summertime in floods of water carrying chunks of solid ice.
Not that they’re melting less, but that they’re melting so fast the meltwater cuts right through them and flows away during the summer, as happens with mountain glaciers. The paper isn’t about total meltwater volume but about the annual cycle observed so far.
The sequence they describe as I read it would be something like this:
Spring comes. The solid ice melts at the top; meltwater moves down through cracks to the base, builds up, lifts the ice and lubricates the contact with the rock; the glacier advances.
Summer comes. Water melts ice out along the base and escapes downstream; the ice sinks back into firmer contact with the base rock as the lubricating water runs right through the glacier in the open channels.
Fall comes. Less meltwater flows; it’s colder; the outflow channels freeze up; water builds up under the glacier and it advances again.
Winter comes. The ice squeezes the channels shut and settles against the rock, closing the openings.
A real scientist can do much better. As I recall only a few years ago it was just speculation that glaciers developed meltwater passages all the way through them annually.
Stephen @ 2
“seemingly ruling out unexpected large additions to sea level rise from accelerated melting of greenland glacers”
That is not a correct statement to be making. This study basically addresses the Zwally effect which is based on the theory that enhanced basal lubrication from meltwater reaching the bed would speed up glaciers. The study only shows that eventually the drainage becomes effective and the glaciers slow down after the initial pulse. The zwally effect is not considered to be the primary cause of accelerated ice losses from either ice sheet.
The primary cause of accelerated flow and accelerated losses is glacier acceleration due to grounding line retreat, removal of fringe ice shelves and removal of sea ice. These features provide backpressure on the glacier and when removed glaciers accelerate. Please consider consulting some reference textbooks or websites
On Ray’s book – I dropped by my local Borders (the only place I go for paper books these days) and took a look at the “Science/Environment” section on the chance his book might have made its way there already. I was horrified! It was filled with “skeptic” books – yes it had 1 copy of “An Inconvenient Truth”, but there was a big display of “Cool It” from Lomborg, many copies of Roy Spencer’s books, Singer’s nutty “Unstoppable” book, etc. etc. I was not heartened to see Pielke’s “Climate Fix” also rather prominent. I didn’t look hard, but Al Gore and Donella Meadows seemed to be the only representatives of the truth about global warming, and their books were single entries spine-out, not front-facing piles like some of the others.
Who makes these book placement decisions? Is somebody paying for all this? Can they really be selling that many of the “skeptic” books?
Iceland: “…. The release of meltwater from glacial lakes can take place as a result of two different conduit initiation mechanisms and the subsequent drainage from the lake occurs by two different modes. Drainage can begin at pressures lower than the ice overburden in conduits that expand slowly over days or weeks due to melting of the ice walls by frictional and sensible heat in the water. Alternatively, the lake level may rise until the glacier is lifted along the flowpath to make space for the water and water discharges rise linearly, peaking in a time interval of several hours to 1-2 days. In this case, discharge rises faster than can be accommodated by melting of the conduits….” http://hal.archives-ouvertes.fr/hal-00480676/
Hank, I think what Stephen is saying is nonlinear versus linear. If you can’t get large amounts of ice into the sea, does that support his statement that the possibility of nonlinear SLR is “ruled out?”
JCH, that’s not in the paper. The melt rate can continue to increase (more warm days, more meltwater into the ocean) without lifting the whole glacial mass and making it slide into the sea.
It’s the difference between disastrous and catastrophic. The trend is not expected to be linear, in any recent work I’ve seen.
FWIW, Pierrehumbert’s book “Principles of Planetary Science” is a great bargain by contemporary book price standards. Not only is it 600+ pp of gorgeous text, mathematics and graphics for only $80 plus shipping, but the Python code for all the exercises is provided online and much else is available online besides. The author includes informative commentary on the references. I was surprised by the brief introduction to Lebesgue integration. I am sure that many more surprises are included.
There does not seem to be any actual definition of “climate”. Wikipedia says that it is the statistics of measured attributes such as temperature, pressure, wind speed, rainfall, etc. Would it not be better to call it the “distribution” of measurable attributes, including the spatio-temporal variation in the distribution. The statistics based on the measures can fluctuate with no change in the underlying distribution, and the distribution can change before there are confirmed changes in the statistics. Just curious.
I am sure that no one here will regret buying the book.
Stephen gives half the story: “Greenland glaciers appear to slow down in warmer temperatures.”
The paper is about how, after warm weather first speeds up the glaciers, then if the meltwater opens big enough holes, those drain that lubricating layer off, and the ice slows down compared to its peak speed. They’re saying sometimes outburst floods won’t happen. But the evidence is they’re happening.
Hank, I perhaps misunderstand this. That would be nothing new, but water melting and flowing into the sea is linear melting and has been modeled by Vermeer and Rahmstorf and many others, and it arrives at a prediction of ~1 meter of SLR by 2100.
Modeling nonlinear melting requires understanding how large amounts of ice, exceeding the background, will find their way into the sea ahead of “schedule”, which is what Hansen expects will happen during this century: closer to 5 meters than to ~1 meter.
Your second link hints that their work can be a basis for that, which is exactly the sort of thing for which I have been looking.
Hm, that paper is being widely blogged. Pat Michaels at Cato claims ( http://www.cato-at-liberty.org/the-current-wisdom-3/ ) that paper proves sea levels won’t rise, because melting will stop when fossil fuels run out before the planet warms to equal 10,000 years ago.
I don’t see how. Make a hole under the ice one year, the ice flows down in to fill them during the winter, and then that melts out the next year; that’s a different kind of flow than horizontal. It happens in loose dirt too, look up “tunnel gully” — those might be an interestingly analogous process if drainage openings enlarge sufficiently for surfaces to collapse into them. I suppose someone’s watching for surface sag on the ice.
It’s a lively area. I’ll await comments from someone who actually does science, I’m read out on this for a while.
The Nature paper seems to be saying that the enhanced basal slipage due to meltwater is a selflimiting process. We could still get increased overal flow, if the area of the icesheet which suffers significant enough annual melting to supply water to the base increases. It also says nothing about the trajectory of surface albedo with time in the melt zones. How much dirt accumulates from year to year, versus how much is flushed down the moulins? I think this is a crucual question concerning a potential acceleration in the rate of melting.
Now that your book is available again, could you please use it to explain what is wrong the the chapter on the Venus Syndrome in James Hansen’s book ‘Storms of my Grandchildren’? His book is available at your library. You seem to think that based on first principles, a water vapor runaway can’t happen but I’d like to know if his specific argument is countered by what is in your text. Thanks.
[Response: I haven't gotten around to reading that section of Jim's book, but I have seen him present what appears to be similar claims at AGU. The answer to your question is: Yes, the fundamental physics which I go over in Chapter 4, as part of the discussion of the runaway greenhouse, absolutely rules out a water vapor runaway greenhouse on Earth, until the Solar luminosity increases sufficiently, which won't happen for a half billion to billion years. When you bring clouds into the picture (which I don't do in any detail in the runaway discussion in the book, because it's completely unresolved) it is harder to make absolute statements from any simple physical arguments, but clouds would have to do something so extreme that if the Earth were really subject to a cloud-induced runaway it is likely it would have happened during one of the high CO2 episodes sometime in the past. Basically, for clouds to induce a runaway you need near 100% cover of low albedo (large particle) clouds with high water content at very high altitudes. --raypierre]
Ray P, thanks for making that PDF available. I concur with you & Gavin: paywalling material like this is ridiculous and it leaves interested people little option but to hassle authors for PDFs in order to keep up with their reading – few individuals like myself can afford to pay for several dozen papers a year in these austere times!
[Response: Properly calibrating the solar irradiance measurements is important for getting better constraints on the variations in solar over the satellite era, but the actual mean value (or in this case the mean over the last three minima) doesn't actually matter that much for climate modelling. The impact of their suggested change is equivalent to rebalancing the energy balance at the top-of-the-atmosphere by a little less than a 1 W/m2 in climate model control runs. But this is such a small change that the climate sensitivity or climatology is not going to be noticeably affected. (Note that all climate models are tuned for radiation balance in their control set-up and small imbalances occur all the time as a function of changes in resolution, physics or parameterisations. This is a very different issue to how the models react to a transient change in TSI.) - gavin]
[Response: No. It does slightly narrow the uncertainty on the albedo (i.e the SW component) at the top of the atmosphere, but the errors there are too large for them to be a useful constraint on the real net radiative balance. - gavin]
Thanks for the pdf to the PT article (as a new member of the AGU I thought I would have access to it for free).
[Response: In fact you should. All members of AGU get Physics Today,
so far as I know. You just need to enter your data on the PT web page to get an account that gives you
electronic access. --raypierre]
Are there any plans to bring out The Warming Papers in an e-reader format (e.g Kindle?).
[Response: It would be nice; probably wouldn't be any cheaper than the paperback version, since the cost was mainly due to copyright fees the publisher had to pay. I could see it on an iPad, but the large format pages probably would be hard to read on a Kindle, unless they have a new large-format version out. --raypierre]
Comment by Daniel J. Andrews — 29 Jan 2011 @ 12:13 PM
Nice piece in C&E News, Gavin (http://pubs.acs.org/cen/books/89/8903books.html). And it’s good to see some “D” bombs being dropped in such a staid publication. It’s especially nice to see C&E News take it out from behind the paywall and make it available to the general public. Good and gutsy move on the part of the C&E News folks.
1) Rudy Baum, Ed-in-Chief of C&EN is a savvy guy regarding this topic.
2) Good review, but I offer a minor suggestion.
I increasingly believe that it is worth distinguishing between pseudoscience and anti-science, because the former is often chaotic and even outright silly, whereas anti-science is often quite serious and lumping it with the former can trivialize it. Of course, in a short review, there may be insufficient space.
“Anti-science especially seeks to bypass science with regard to public policy, using many tactics created for the tobacco wars, and employed widely since then against other areas of science.”
When ideas are repeatedly examined, often explicitly refuted, but originators persist in the face of a strong
imbalance of evidence, at some point it becomes pseudoscience, an attempt to convince scientists to adopt ideas for which the balance of evidence is strongly adverse. In some fields, its primary use is sales.”
Agnotology was coined by Stanford‘s Robert N. Proctor [PRO2008] to describe the deliberate production
of ignorance and doubt. When applied to scientific topics, it might be called anti-science, employed
especially when research results threaten strong economic or ideological interests. It is rarely intended to convince field professionals, but to confuse the public and especially decision-makers in government and business.”
P.8 has a chart. I’d claim that typical pseudoscience starts with some idea desired to be accepted by science, whereas anti-science doesn’t care about the specific ideas as much as obscuring science.
very slightly off topic sort of….
I thought it would be a good thing to list all of the internet articles based on denial and put into a archive for future review of false information and misinformation propagation….for instance, from American Thinker, Jan.29,1011,…..http://www.americanthinker.com/2011/01/greenland_is_going_to_be_ok.html
I am keeping these bogus articles in a folder for now…but am hoping someone thinks it would be a good idea to put this and others like this into a public domain to which others maybe able to add to.
Comment by lucien p. locke — 29 Jan 2011 @ 8:07 PM
In fact you should. All members of AGU get Physics Today,
so far as I know. You just need to enter your data on the PT web page to get an account that gives you
electronic access. –raypierre]
Ah. Indeed I now do. I hadn’t realized I needed to set-up an account–the original email link that should have set me up just led to a “too many redirect” loop. They just sent me a new link and that works. Thank you.
I could see it [Warming Papers] on an iPad, but the large format pages probably would be hard to read on a Kindle, unless they have a new large-format version out. –raypierre]
If it was too difficult to read on my Kindle, I could view it on the downloadable Kindle for PC. That is how I read my Climate Change Biology e-book when I want a better look at some of the pictures, or want to see more of the page.
I wasn’t too worried about the cost of The Warming Papers either–it is a matter of convenience in that I like being able to carry numerous books/papers with me when I’m away. The Kindle 3 seems to have worked out the pdf viewing bugs that plagued Kindle 2, so I’ve loaded a number of pdfs too.
Comment by Daniel J. Andrews — 30 Jan 2011 @ 10:47 AM
I just read raypierre’s radiative transfer primer on one. Took a fair bit of panning and zooming to get all of figure 2, and of course the excellent fit between modeled and observed spectra in fig 3a was all but invisible in graytones. Otherwise it was great; the column width fits the screen width at 200% magnification for large, legible letters. It’s becoming my favorite platform for keeping up with comments here, and though I won’t often be typing a comment this long on it, it is now capable of getting past recaptcha.
Great primer — I’ve absorbed some understanding of the subject from this blog, but this reading broadened the tails considerably. Saturation is still a long way off, though…
1. The reporting of the Greenland glaciers Nature paper that I saw was sadly along the lines of #2, not #3, sigh!
2. Whenever I visit a book shop I check the climate science shelves and if there are any denialist books I move them to the fiction section.
Comment by calyptorhynchus — 30 Jan 2011 @ 6:24 PM
calyptorhynchus @36 —
:-) for part 2; right on!
Comment by David B. Benson — 30 Jan 2011 @ 7:48 PM
An interesting thing I see on the Atlantic water hockey stick is that most of the warming appears to have occurred between 1800 and 1900. The two possibilities I can think of are that natural variability played a large part, or that there has been a very non-linear response to Co2 increases (or both). Perhaps a non-linear response could be due to albedo feedbacks, if during the 19th century a small warming due to small increases in Co2 (280ppm > 300ppm) melted quite a large amount of ice in the far north Atlantic. In comparison since 1980 the ice edge in summer has hardly moved on the Atlantic side, and mostly retreated in the Arctic basin on the Pacific side.
Re the Greenland ice sheet (I don’t have access to the paper), is there a discussion of why we would expect the channels to be able to handle large increaes in the volume of meltwater? Coming at it from another direction, what would an eventual bulk melting process look like? I wonder in particular about the handful of major discharge channels that run all the way inland. To the extent that these would act like river drainages, would we expect to see at some point enough water in them to destabilize the overlying glaciers, and if so how would things proceed?
# 42, worth checking your local library though to see where they are putting denialist science, years ago our library was placing creation science in with science, managed to convince librarian to put them into theology,
These often lie around somewhere on the web pages of one of the authors. Browsing for them takes time, emailing an author to ask can be daunting. The following trick is sometimes a shortcut:
Locate a characteristic phrase from the paper — a sequence of say 6-8 words that would not be likely to show up in a whole lot of other documents. Paste into your favorite search engine and surround with quotation marks to search for the exact phrase.
To avoid wading through a lot of hits that don’t contain an actual offprint, it’s best to avoid using a phrase from the abstract, or from the main conclusion, as these tend to bring up too many hits. (You can get a phrase from the article body if someone quotes from it, or if the paywalled site displays the first page of the article. Of course, it’s easiest for those who can access the full text to begin with.) Using Advanced Search options to search only for PDFs may help narrow it down.
For Steve Bloom, I recalled where Mauri Pelto answered when I asked that question:
“… Ice under pressure would deform and flow into this void. This happens to much of the seasonal hydrology system each winter. Without water flow to keep tunnels open, they close, then in spring maximum water pressures often occur befor the conduit system redevelops. Once opened the flowing meltwater can maintain these narrow conduits. However, the meltwater does not have enough heat to melt much…. I still see a persistent misconception about the ability of meltwater to melt glacier ice and riddle the glacier with holes. I work on glaciers with lots of melt and they are not weakened by all the meltwater drainage….”
Thanks for your response. That is pretty much what I remembered from your draft.
Interestingly, Hansen addresses your point that a runaway should have happened in the past first on pp 231-232:
“At earlier times, when atmospheric carbon dioxide was more abundant, the sun was dimmer. For example, 250 million years ago the sun was 2% dimmer than now. A 2% change of solar irradiance is equivalent to doubling the amount of carbon dioxide in the atmosphere. So if the estimated amount of carbon dioxide in the atmosphere 250 million years ago was 2000 ppm, it would only take about 1000 ppm of carbon dioxide today to create a climate equally warm, assuming other factors are equal…. In other words, the fact that some scientists have estimated the carbon dioxide was much larger earlier in Earth’s history, perhaps even by a few thousand parts per million, does not mean that we could tollerate that much carbon dioxide now without hitting runaway conditions, becuase the sun is brighter now.”
His next argument is that climate sensitivity is an increasing function of temperature. He claims that recent work on the PETM tends to confirm the model based estimates shown in fig. 30 on p. 227.
Finally he considers that burning all conventional fossil fuels is likely to destabilize methane hydrates and, I think, that additionally burning tar sands and shale oil makes that certain to happen. At that point he sees a runaway as inevitable.
On p. 225 he describes the Venus runaway as a water vapor runaway so I think that is what he means when he talks about ‘a runaway greenhouse effect that would destroy all life on the planet [Earth]‘ p. 236
On your point about low albedo high altitude clouds, it seems pretty clear that an atmosphere which is primarily water will have high altitude clouds. The droplet size will depend on the vertical stability of that layer. If it is playing a primary greenhouse role, I wonder of the three micron ice absorption feature would play any role in radiatively induced mixing by providing an opacity switch? Models of stellar pulsation sometimes rely on that kind of physics.
In any case, an atmosphere with say twice as much water vapor as nitrogen will be trying to sustain a steeper lapse rate and should be pretty convective for that reason leading to large droplets at high altitude I think. With a physically larger atmosphere (90% water vapor), things might settle down some since the temperature gradient would not need to be so steep.
[Response: Jim's insistence that a Venus-type runaway is a credible risk is an unfortunate distraction. The crux of the matter is that it is very hard to place any simple a priori bounds on how much
clouds could warm the climate. In order for cloud feedbacks to trigger a Venus-type runaway, however, the clouds have to do something so extreme that a tiny proportional change in the cloud feedbacks would enable that to happen even without any CO2 increase and even despite a slightly fainter Sun. Jim's argument about the dimmer Sun is not the least convincing. With the usual albedo estimate, a 2% dimmer Sun just amounts to 4.78 W/m**2 averaged over Earth's surface, and if you are going to argue for something like 30 W/m**2 of extra net cloud forcing to trigger a runaway then the difference that dim-Sun effect makes doesn't look so impressive; a slight further fluctuation in clouds could make up for it, or for lower CO2. Besides that, CO2 was probably already high in the Paleocene, and at that time, the Sun was less than a half percent dimmer. Talking about extra CO2 or methane release from feedbacks doesn't change the argument, since the OLR is determined by water vapor and water clouds in the runaway state. I actually think clouds make the runaway harder. As I argue in Chapter 5, clouds fairly deep in the atmosphere still increase the albedo, but in a steam atmosphere they need to be at altitudes well above the 100mb level to even have a chance to affect the OLR; otherwise their infrared effect is blocked by water vapor opacity. I also point out, however, why this argument isn't completely watertight. But basically, there is absolutely no credible cloud physics to suggest that clouds could make up the large energy deficit required for a planet in Earth's orbit to go runaway. You could worry that we can't absolutely rule it out, but that requires such extreme cloud feedbacks that you might as well say climate is so fragile it could do anything at all, with or without us poking it.
So maybe I've made you all feel a little better by saying there's a vanishingly small chance that increasing CO2 could evaporate away our oceans and turn the Earth into Venus. But that deafening sigh of relief I'm hearing
may just be drowning out the much more serious and credible threat I'm trying to tell you about -- that neither cloud physics nor any paleoclimate proxy can at present rule out a climate sensitivity as high as 8C for a doubling, while we might well go considerably beyond quadrupling if all the coal is burned and there are land carbon or sedimentary clathrate releases. That world wouldn't be as lethal to all life as Venus, but it would certainly pose an existential threat to human society. I don't view it as an especially probably outcome, but it doesn't require clouds to do anything nearly as farfetched as they would have to do in order to trigger a runaway greenhouse --raypierre]
JCH, are you thinking that paper rules out what Rahmstorf wrote not long ago? – Hank
Not at all. In the past, temperature changes and SLR have a relationship. From that, many sources have predicted ~1 meter by 2100. I’m presuming the melting described in the paper also happened in the same way in the past and is probably already in the ~1 meter number.
Hansen is describing ice-sheet disintegration, which he believes will add meters to the ~1 meter predicted by 2100. To model that, scientists need to much better understand ice-sheet dynamics, and it sounds to me like they have achieved a better understanding of the ice sheet with this study.
So the only way this paper can be “good news” would be if better understanding of ice-sheet dynamics eventually rules out nonlinear melting, which seems unlikely to me, but who knows.
Re: reshelving books, all you do is create more work for bookshop employees.
Right, of course. I suppose one should simply avoid looking at the climate “science” section, just as one avoids deniers’ blogs. Still, it’s an outrage when such crap outnumbers the genuine works on display.
[Response: That's for damn sure--and it should not be allowed to stand; it represents a decision by that store to present a completely unbalanced selection of information to the public. If I found that situation, I would immediately take it up with the store manager (or at higher levels of a corporate chain), presenting a list of legitimate climate sci books that should be carried, and/or links to sites where legitimate reviews of various books are provided, first inquiring as to whether they are just out of stock on the legitimate stuff. This is something that everyone can do. Same applies--even moreso in fact--to public libraries--Jim]
Congratulations and many thanks to R. Pierrehumbert for such a lucid article on radiative transfer (Physics Today). I hope this article proves instructive to anyone curious about how planetary temperatures are what they are and how they respond to perturbations. Perhaps it will (yet again) set the stage for coherent and quantitative dialog amongst those who are interested in or question climate models. I wish your book had been available when I took my graduate courses in planetary atmospheres in the mid-70s. It would have saved me (and my fellow graduate students) interpreting our pages of scribbled notes.
Reshelving denialist books in the fiction section doesn’t create more work for bookshop employees. Both my sons have worked in bookshops (different chains) and both confirm that if a book is relocated to another section it is effectively lost, no great search is mounted for it if requested, and it would only be located back to the original section if an employee happened to notice it and decided to move it back (an unlikely event in their view).
Comment by calyptorhynchus — 31 Jan 2011 @ 5:55 PM
Don’t screw up bookstores. Don’t screw up libraries either. It’s a game nobody wins and more and more people will play if you start that stuff.
Try instead adding a Post-it in the section that lists a few recent “Climate science books recommended by climate scientists …”
Reshelving denialist books in the fiction section doesn’t create more work for bookshop employees.
Plus they’re typically paid by the hour here in the US, and they could use the extra work even if the claim were true.
Don’t screw up bookstores. Don’t screw up libraries either. It’s a game nobody wins and more and more people will play if you start that stuff
While neither condoning nor condemning the behavior, people have been doing that with creationist and ID books that have shown up in bookstore science sections for at least a couple of decades, and I doubt you can find any evidence that more and more people have been playing the game as a result.
I’ve noticed something similar at Barnes and Noble, though I’d say there was about an even number of mainstream and skeptic climate change books. And like you saw at Borders, Skeptical Environmentalist was displayed with the cover out. They also had Cool It, and McGibbons book, Hansen’s book and Al Gore’s book etc. I have approached the help desk at two Barnes and Nobles and questioned why there were so many skeptic books and why they didn’t have The Lomborg Deception.
I also asked at one store in LA, why they didn’t have Climate Cover-Up or Merchants of Doubt, and was told that if enough people ordered it, they would stock it. Which brings up the question, how do all the skeptic books get there?
Is this another case of conservative books being bought by their sponsors to up their ratings and maybe be best sellers?
One lady who waited on me was sympathetic, saying anyone can get a book published these days. Maybe people should write to both companies and let them know that they are not doing the public a service with these practices.
I forget where I found this information, but most skeptic books on climate change, 78%, are funded or published by conservative think tanks, resulting in 64 skeptic books on climate change.
The argument about the 2% increased solar irradiance makes very little sense. Offsetting that much sunlight would be equivalent to moving the Earth’s orbit by a factor of 1 A.U.*sqrt(0.98/1)~ 0.99 AU, which is well within the realm of planetary habitability by most (all?) estimates, and the inner edge of the habitable zone is usually defined by the runaway threshold. As for the CO2, I would look at Kasting and Ackerman (1986) and Kasting (1988) which shows that Earth’s atmosphere would not experience a runaway greenhouse even with a 100-bar CO2 atmosphere, more than the reservoir tied up in carbonate rocks. Another constraint on this is that the planetary albedo increases to well over Earth’s modern albedo in a dense H2O or CO2 atmosphere due to Rayleigh Scattering, which helps prevent a full runaway even down to orbital distances less than 0.9 A.U. There are situations where CO2 can cause a runaway greenhouse effect, but you need the right conditions in other parameters as well, and Earth isn’t in that domain.
I’d also be skeptical that climate sensitivity increases as a function of temperature. It could of course (or decrease as well) and scaling sensitivity estimates over different climate regimes (or under different forcings) is not always a good idea due to non-linearities in feedback behavior (e.g., Crucifix, 2006) but the derivative of the sensitivity with respect to T is rather small over the anthropogenic perturbation scales of interest. The water vapor feedback should increase in warm climates but the lapse rate (negative) feedback does as well, and surface albedo does to in the limit of minimal ice cover. Some modeling studies (e.g., Colman and McAvaney, 2009, GRL) found sensitivity decreases somewhat in warm regimes, so it’s not really easy to say with high confidence if sensitivity “increases in warm climates.” There’s too much uncertainty in the proxy reconstructions and forcings to say that from paleoclimate records.
On a more practical note, there’s enough worry about anthropogenic climate change without the need to worry about runaway greenhouses. Temperature changes of 5-10 C over the next couple hundred years can be catastrophic in certain regions, so we don’t need to think about 500 C rises if it’s not physically realizable. The latter can be reserved for interesting astrophysical or planetary habitability topics, but if the Earth were very sensitive to runaway greenhouses in a reverse-Budyko sense it would probably have happened already. Burning all the coal and envisioning worse-case carbon cycle feedbacks from permafrost or the deep ocean could make life nearly impossible for humans and certainly kill off countless other species which are more sensitive to change (I really don’t think you can stretch sensitivity to 8 C, even on the high ends of Earth System sensitivity timescales it’s pushing it, but it’s still high enough to matter quite a bit).
If anything, the climate sensitivity should decrease as temperatures increase due to the larger radiative imbalance that would occur between the Earth and space.
Longer term effects arising from albedo effects and such would be harder to model.
On a shorter time, I do not see how a climate sensitivity of anywhere near 8C can be assigned. Past temperature data would argue for lower climate sensitivities than posted (especially here), and that the Earth is significantly less sensitive to greenhouse gases than some propose. In fact, past temperature data would indicate that the climate sensitivity is ~1.8C, assuming that all the observed warming is due to an increase in atmospheric CO2. This would argue the case that the Earth is less sensitive to CO2. I know that many posters here will object to that value, but until temperatures begin to rise at a much higher rate, we have to accept the possibility that the Earth is much more resilient that we think.
[Response: Piffle. Words are not physics. Your pseudoscientific phrase about why you think climate sensitivity goes down with temperature is just meaningless verbiage. You have to do the physics -- and the math. Climate sensitivity is inversely related to the steepness with which infrared cooling to space increases with surface temperature. For clear sky physics, the increasing role of water vapor as temperature gets warmer makes the slope flatten, increasing climate sensitivity. When you get to very high CO2, you also start to pick up additional absorption bands, which can increase the radiative forcing (which also increases the climate sensitivity if it is expressed in terms of the usual "per doubling" metric.) When you bring in clouds, there is no longer any simple thermodynamics that connects the feedback with temperature, since clouds depend on occurrence of saturation, which can either increase or decrease with temperature; their radiative effects involve both the albedo and infrared influences, and the balance of the two depends on particle size and cloud height. WIth all that leeway, clouds have a considerable latitude to substantially increase climate sensitivity, and also have latitude to reduce it. Essentially all climate models based on credible cloud physics yield a cloud effect that is between neutral to climate sensitivity and a moderately strong increase. So, physics doesn't rule out high climate sensitivity. The main reason paleoclimate data fails to rule out a climate sensitivity as high as 8C is that the lower end of CO2 in various past warm climates is not well constrained But the Pliocene gives us a lot to worry about regarding climate sensitivity, since the whole Northern Hemisphere was essentially ice free, a permanent El Nino locked in, and the world was substantially warmer -- and all that with a TOP CO2 estimate of around 450ppmv. --raypierre]
Oh, Dan, you are so lost. First off, when you say “past temperature data”, you need to specify which epoch. Second, there are several dozen analyses out there that get values from 0.1 (Sellers) to ~9.6(Moller). Even since 2000, estimates range from about 1.8-4.5 (excluding the BS from Shaviv and Vizier). These are best-fit point estimates. The confidence intervals would be skewed right. The average of all the estimates is about 2.8 degrees per doubling, and the distribution pretty closely follows a Weibull with shape parameter 2 (except at the high end).
The thing is that sensitivity could be higher, especially if we are warming the deep oceans more than we think. And changes in albedo are among the easiest to model, especially at the poles. So my question, Dan, is where are you getting this crap?
Thanks for another valuable response. I should have made more clear where I was attempting to report from Hansen’s book and where I was kibitzing myself. The comments on clouds are mine and not really about staring a runaway since that would already be going on with a primarily water vapor atmosphere.
I agree with him that tar sands and oil shale are viable resources. I think this is the case because low cost renewable energy will make the poor energy return on exploiting these unimportant and their value as an easy path to liquid fuels will be the most important thing. I think he is thinking of over 2000 ppm carbon dioxide and a 6 C per doubling equilibrium sensitivity. So, we’d see about 70 C on the warmest days in the hottest places. That is not boiling and water vapor should be less than a third of the atmosphere so this is where your first principles argument seemed like it would be relevant. I have not seen him invoke clouds specifically, just fast and slow feedbacks generally. If you read the whole chapter without my (somewhat cloudy) filter, maybe it would be better.
[Response: Chris, you're just running around in circles because you're not making any progress in understanding the basic physical issue, which Chris Colose and I have both explained to you. The basic physical issue is that you need a certain threshold amount of ABSORBED SOLAR RADIATION to sustain a runaway. Earth's orbit is nowhere near where you get enough for that, and no amount of climate sensitivity changes and no amount of released CO2 will change that. CO2 does not change the threshold because in the runaway limit the upper atmospheric opacity is completely determined by water. The only way you could make up for that is if the net of cloud OLR effects and and cloud albedo effects changed in such a way as to give a very substantial net warming influence on the top-of-atmosphere radiation budget, and I have argued why that is very, very hard to do in a runaway situation. So, you can just stop worrying about the runaway, and start worrying about what happens if we release 5000 Gt of carbon and the climate sensitivity turns out to be 8C per doubling. The latter is somewhat farfetched, but not nearly as farfetched, by far, as a cloud-induced runaway. --raypierre]
Thanks for your response. It is good that you raise the habitability zone question. Hansen spends the beginning of his chapter on this. While he uses a different estimate for the amount of fossil fuels available to burn (see my response to raypierre) he also says that increasing the brightness of the Sun by 10% (a 25 W/m^2 forcing) ‘is surely enough to push the Earth into a runaway greenhouse effect.’ So, his habitable zone appears to be narrower than yours. There seem to be some estimates in line with his: http://en.wikipedia.org/wiki/Habitable_zone#Habitable_zone_edge_predictions_for_our_solar_system
I am having a little trouble understanding Hansen’s fig. 30. If sensitivity increased with temperature, then it does not do so much if I am reading it correctly so why is it important?
It is worth mentioning too that it was raypierre who brought up 8 C per doubling. I’ve seen Hansen use 3 C for fast feedbacks and 6 C for equilibrium sensitivity recently.
I do think that if we are capable of setting off a runaway, it is important to know. The nature of war changed once we understood the destructive power of nuclear weapons. Churches became involved in disarmament efforts. There is a moral agency aspect to utter annihilation. But, while we have tested hydrogen bombs and are pretty sure what they can do, there seems to be less certainty about the runaway greenhouse.
Yes, the sensitivity could be higher. It could also be lower. As far as past temperature, I was referring to the CRU data for the past 150 years. Many of the estimates are climate models as raypierre pointed out earlier.
The bottom line is that the surface temperature data does not indicate such high climate sensitivity. At some point, the modeled climate sensitivity needs to match the observed temperature data. Otherwise, it is just verbiage (as raypierre says). We have no data about warming of the deep oceans, only the recent realization that the top 700m has not warmed recently (see previous RC thread). The upper ocean temperature data matches the surface temperature data from 2002-2010 with amazing precision. Neither is showing the expected warming. Gavin deflected this question earlier, and Roger Pielke picked up on it on his site. http://pielkeclimatesci.wordpress.com/2011/01/25/comment-on-gavin-schmidts-statement-of-jan-21-on-real-climate-regarding-upper-ocean-heat-content/
[Response:Response (and please stop repeating the same point over and again - it's extremely boring). - gavin]
[Response: I'm with Gavin here. And also, remember that a proper analysis of the instrumental record is fully compatible with a high climate sensitivity, largely because of uncertainty in the aerosol component of radiative forcing (see Knutti and Hegerl). Moreover, at best you get an estimate of transient climate response, not equilibrium sensitivity. TCR is well below the equilibrium, due to effects associated with ocean heat uptake (see Winton, Takahashi and Held's recent J. Climate paper). Moreover, even if you manage to estimate equilibrium sensitivity, there's still the longer term Earth System Sensitivity (land carbon release, reduction in ocean carbon uptake, ice sheet melting, vegetation changes,...) which is likely to boost the temperature response another 50%, based on estimates from the Pliocene. --raypierre]
Unfortunately I don’t have the book so I can’t follow what figure you’re looking at.
Please see the last figure in my second post on feedbacks here (which I pulled from Pierrehumbert, 2002). This clearly shows a flattening out of the OLR curve at higher temperatures in an atmosphere with a condensable greenhouse gas, and eventually the OLR is independent of T which sets up conditions in which a runaway can ensue. Sensitivity is practically infinite in this domain until the water reservoir is depleted (note in my previous comment about sensitivity changing with temperature, I was thinking much more narrowly to conditions of modern Earth such as doubling CO2 from a modern state vs. doubling it in a Pliocene initial state).
On the habitable zone, the inner edge is likely a lot more sensitive than the outer edge, but there’s still some wiggle room to move a planet closer to the sun, especially if the albedo is high enough. Orbits less than 1 A.U. show a large sensitivity in the surface temperature to distance because of the IR opacity increase with a water vapor feedback (and also due to a decrease in albedo caused by solar absorption). If you add clouds though in this domain their greenhouse effect is less important (because of the very high opacity due to water vapor) so a good amount of cloud cover can move the habitable zone inwards if you get the albedo high enough (e.g., Selsis et al., 2007). The key to the runaway though is to get the absorbed solar radiation high enough to sustain it, and I don’t see a way to do that on Earth currently.
I didn’t even have time to read it, but gave the response on a blog “Looks like bunk-bunk-bunk-bunk-bunk [said rapidly] to me, esp since it’s done by the usual denialist suspects. I’ll ask some real climate scientists about it, but meanwhile don’t forget to turn off lights not it use :)”
Comment by Lynn Vincentnatnathan — 1 Feb 2011 @ 3:28 PM
In Australia the right wing coalition have come out with a massive campaign to distort the science and oppose any tax on carbon,
meanwhile in Far North Queensland,
Details of Severe Tropical Cyclone Yasi at 4:00 am EST:
.Centre located near…… 15.7 degrees South 151.7 degrees East
.Location accuracy…….. within 20 kilometres
.Recent movement………. towards the west southwest at 30 kilometres per hour
.Wind gusts near centre… 295 kilometres per hour
.Severity category…….. 5
.Central pressure……… 924 hectoPascals
This still has about 14 hours, moving over the record warm Coral Sea with over 200,000 people in its path when it makes landfall
> At some point, the modeled climate sensitivity needs
> to match the observed temperature data.
Dan H. hasn’t read the definition of climate sensitivity: the temperature change measured once the “equilibrium response” point is reached. Not now. Not soon. We hope the great-grandchildren will measure it.
People like Spencer try to make a strawman of this.
He’s calling the definition a “dirty little secret” on his blog.
Emergency services are describing “Yasi” ” A monster unprecedented in Australia’s history”
2007 Garnaut Report
“Climate change is likely to affect extreme rainfall in SE QLD, Abbs et al (2006}, projections indicate an increase in 2 hour, 24 hour and 72 hour extreme rainfall events for large areas of SE QLD especially in the Mcpherson and great dividing range west of brisbane and the gold coast .Projections also indicate that the regions of east Australian cyclone genesis could shift southward by two degrees latitude (approximately 200 km) by 2050, Leslie et al (2007), while the average decay location could be up to 300 km south of the current location. Models estimate that the number of strong cyclones reaching the Australian coastline will increase, and ‘super cyclones’, with an intensity hitherto unrecorded on the Australian east coast, may develop over the next 50 years Leslie et al(2007).Therefore despite a projected long term decrease in rainfall across most of Queensland, the projected increase in rainfall intensity could result in more flooding events”.
Thanks for another reply. It looks like Hansen’s book is available at the UW-Madison Library.
On the figure you pointed me to, I think I am getting a little stuck on the concept of RH when water vapor is becoming a substantial fraction of the mass of the atmosphere. I suppose we talk about dry steam but it seems to me as though some physics may be slipping away. Could we end up with a lower wet atmosphere and an upper more familiar atmosphere but the surface temperature is now really the temperature of the top of the wet atmosphere?
[Response: I appreciate your attempts to understand this, but at some point you have to sit down with a textbook and work through the equations, rather than spinning your wheels and making do with words alone. Learn something about Clausius Clapeyron, and about the vertical structure of water vapor mixing ratio on the moist adiabat. "steam" is just another word for water vapor -- the gaseous form of water. Relative humidity is perfectly well defined even for a pure water vapor atmosphere -- it is the ratio of the pressure of an air parcel having temperature T to the saturation vapor pressure at that pressure given by Clausius-Clapeyron. I can't make sense of your final sentence, but perhaps after learning a bit more you will be able to reformulate it. In a runaway situation, the mixing ratio (concentration) of everything besides water vapor is very low right up to the top of the troposphere (which is practically the whole atmosphere) because you have a whole ocean's worth of water in the atmosphere which swamps everything else. --raypierre ]
On runaway global warming – my naive qualitative guess is that the axial tilt of the earth also produces a negative feedback to runaway. During polar winter, the only heat input to balance outward radiative loss is latent/sensible heat transport in the atmosphere. The latent heat transport is a giant sink for water vapor, and a source for liquid ocean water, which is observed to increase with increased global T and humidity. As the water vapor increases, more latent heat is available to drive convection in the upward branch of the Ferrel & polar cells, and more precipitation. The poleward motion results in more of that precip falling in basins that drain to the arctic, and over the Arctic itself. The paleoclimate evidence from the PETM shows essentially fresh surface water that supported seasonal Azolla growth during a period of high CO2. That fresh water represents a lot of latent heat transport, radiated to space; and a lot of water vapor removed from the atmosphere as a result. Off the top of my head, this means that at PETM temperatures, water vapor feedback might decline, because its transport to cold winter polar regions would increase. As long as minimum arctic temperatures supported precipitation, water would be removed from the atmosphere. I wonder how much water could rain out on an annual basis, and how warm it would have to be to preclude antarctic glacier accumulation?
[Response: Wrong at the end there. Rainfall does not determine relative humidity. You're confusing stock and flow. Relative humidity is the stock, evaporation/precipitation is the flow. The argument for climate sensitivity going up in a warmer, wetter climate is, as chris colose noted, in the OLR curve in my 2002 paper (also various places in Chapter 4 of my climate book). If anything, relative humidity tends to go up in warmer climates because temperature gradients get weaker, and that increases the feedback. As for your other point, I wouldn't call the tilt a "stabilizing feedback," but the need to transport heat from the tropics to the pole does have an effect on the runaway greenhouse threshold. In the standard estimate, it is assumed that the heat transport is perfectly efficient so that the planet becomes horizontally isothermal. There is some effect of the residual temperature gradient on the threshold, but I don't think it's a very big effect. I'm working on refining the answer to that question now. --raypierre. ]
That is the real hiding point isn’t it. That we will see an equilibrium sometime in the future, and depending on what timeframe the moideler choses for his equilibrium, the higher the climate sensitivit that can be obtained. At some point, we ahve to realize that the climate equalizes must faster than some think. The water cycle is rapid, and so is the carbon cycle. This is just a ploy to create every growing values for climate sensitivity, and claim that it is mandated by physics.
If the climate sensitivty was 2,3, or higher, then natural variation would not be able to overcome the warming as easily as we have witnessed. The forcing would simply be too strong.
[Response: Dan, are you running for candidacy for the Borehole? This comment is devoid of scientific content. --raypierre]
#75 Dan, reread the Garnaut extract
.Therefore despite a projected long term decrease in rainfall across most of Queensland, the projected increase in rainfall intensity could result in more flooding events”. sorry if that confuses you
62, raypierre in comment: WIth all that leeway, clouds have a considerable latitude to substantially increase climate sensitivity, and also have latitude to reduce it.
Does it not also matter where and when the clouds form, viz. daytime vs. night time, ocean vs. land?
And before I forget, thank you for your other comments in this thread.
[Response: Yes, all of that matters. That's what makes clouds hard. Clouds do have the potential to reduce climate sensitivity to zero, but paleoclimate if anything suggests climate sensitivity at the high end of the IPCC range, so that's unlikely. No climate model has clouds producing a significant stabilizing feedback. And if we are going to be open about cloud uncertainties, the key thing is that they have an almost unbounded possibility to make climate sensitivity really, really high -- though I think a true runaway can be almost certainly excluded. --raypierre]
I’m sorry but your posts are nonsensical. The real world has a deep ocean, mountain glaciers and sea ice, ice sheets, forests, etc. These various components of the climate system all have their own characteristic response times to an external perturbation. Why wouldn’t they? It takes longer to melt an ice sheet away than it does to make the Arctic sea ice retreat. Modelers don’t keep bumping up the “timeframe” to define sensitivity, it’s just that people find it rational to define various timeframes for which to account for these different characteristic time scales.
Thus we have a “transient climate response” which is most relevant for the upcoming century’s climate change, the so-called “Charney estimates” (which haven’t changed much at all for several decades, despite all those modelers and their tricky ploys) which lets the TOA balance come back to order, and only recently did people start to to expand this thinking to let ice sheets and other very slow components to change. Why shouldn’t people have the right to study the long-term effects of climate change, or do you just not like the answers?
Comment by David B. Benson — 1 Feb 2011 @ 11:04 PM
Dan H “You might want to check on the flood history of Australia. This year is nothing out of the ordinary”.
So far Australia sept 2010/ feb 2011
QLD 40 towns and cities flooded
QLD Area the size of Germany and France combined flooded
QLD “Biblical” flood surges on
QLD “YASI” unprecedented , Prepare for 24 hours of terror
Vic One in 200yr flood threat
Vic Floods for second time in six months
Vic 51 towns flooded
Vic worst flood in Western Victoria, in their history
I live in Queensland and you are telling me that this is nothing out of the ordinary, This my friend is exactly what we have been told will occur due to Global warming ,
//”Could we end up with a lower wet atmosphere and an upper more familiar atmosphere but the surface temperature is now really the temperature of the top of the wet atmosphere?”//
I also can’t see what you’re asking. Keep in mind that when the ocean is gone and you have lack of latent heat release by condensation in a runaway greenhouse, the lower atmosphere is on a dry adiabat until higher in the atmosphere when condensation can still occur. There’s also an almost-runaway case when the stratosphere gets pretty wet, see again Kasting (1988).
See raypierre’s response on the definition of RH. Relative humidity is just a good quantity to look at here because if you look at things in constant RH space, it means the total water vapor content goes up with temperature following Clausius-Clapeyron. C-C is just an upper bound (the atmosphere is not fully saturated!) and RH doesn’t need to stay the same, and in general it doesn’t (Tapio Schneider has a fair amount of work on this) but it turns out to be pretty hard to hold the vapor pressure increase against the C-C scaling. That’s also a pretty robust result for modern changes.
It seems you have a different dictionary to mine. My dictionary defines ordinary as
1. of no special quality or interest; commonplace; unexceptional.
2. plain or undistinguished,
3. somewhat inferior or below average; mediocre.
If you had actually read the website you quote, you would come across the Special Climate Statement which says such things as
“It was the wettest December on record for Queensland and for eastern Australia as a whole, the second-wettest for the Murray-Darling Basin, the sixth-wettest for Victoria and the eighth-wettest for New South Wales. For Australia as a whole it was the third-wettest December on record. This followed an extremely wet spring, the wettest on record for Queensland, New South Wales, eastern Australia and the Murray-Darling Basin, meaning many catchments were already wet before the flooding rain. It was Australia’s wettest July to December on record.”
“The rains of late 2010 have taken place during a strong La Niña event in the Pacific Ocean. The December Southern Oscillation Index (SOI) was +27.1, the highest December value on record and the highest monthly value since 1973, whilst other indicators of La Niña also indicate the strongest event since at least the mid-1970s, and one of the four strongest events of the last century. Previous strong La Niña events, such as those of 1973/74 and 1955, have also been associated with widespread and severe flooding in eastern Australia. Sea surface temperatures off the northern Australian coast in recent months have also been at or near record levels.”
“In Brisbane it was the second-highest flood of the last 100 years, after January 1974.”
Now you, Dan, may have your house inundated every year or so, but most people don’t expect that. So given the statistics, I think most people would not consider the events as ordinary.
As for your last sentence, have you heard about ‘averages’? You do realize, do you, that the long term average is, um, well, an average (or you might know it as the mean) (of the values over time). So an increase in extreme rainfall events does not necessarily mean an increase in the average taken over several decades. ie. the long term average.
Cyclone Yasi will make landfall within 150Kms of where the modeling projected it would from the time that Yasi entered the Australian BOM area, this remarkable achievement has allowed early preparation and resources to be placed where needed and will result in lives saved, without models its all guesswork,
Did you notice the massive influx of idiots posting to that editorial? It is enough to make one wonder whether “Scientific American” is a virtual oxymoron. I mean do these idjits think that readers of the site will be unaware of the overwhelming consensus throughout the scientific community? How do people read a magazine dedicated to science and manage to utterly ignore a mountain of scientific evidence?
Thanks for further responses. Yes, RH is well defined.
Digging into Kasting (1988) I realize that the moist greenhouse is sensitive to carbon dioxide concentration in his view in a manner that the runaway greenhouse isn’t and one might produce a non-dry stratosphere in Hansen’s all in scenario. This would lead to some hydrogen loss. If the hydrogen loss can be completed before the carbon dioxide concentration is brought down through weathering, so that the oceans are lost, then a path to current Venus conditions through uncompensated release of carbon dioxide from volcanoes is open.
This is why Kasting puts the edge of the habitable zone at 0.95 AU rather than requiring 1.4 times the current solar constant. And, Hansen does seem to be able to come up with that level of forcing in a reasonable manner.
Within the uncertainties in Kasting’s paper, Venus need not have experienced a runaway so long as hydrogen was lost from the top of the atmosphere quickly enough. With the faint young Sun, it was borderline. A moist greenhouse followed by the carbon dioxide greenhouse of current conditions might be a viable path for Venus’ evolution. Accretion heat may well be a sufficient additional forcing to make the Venus water-based runaway inevitable but I don’t think Kasting takes that step.
If we accept Kasting’s structural change to the atmosphere at 1.1 times the current solar constant, it seems to me that perhaps the main question for the viability of Hansen’s ‘dead certainty’ assessment is the rate at which weathering can remove carbon dioxide from the atmosphere compared to rate at which hydrogen can be lost to space from a non-dry stratosphere. Do we stay past the inner edge of the habitability zone long enough to lose the oceans?
[Response: No. It takes a hundred million years, probably more, to lose an ocean in wet quasi-runaway conditions, which is far longer than the time required for silicate weathering to draw down CO2. Further, though the OLR is not as completely dominated by water vapor as it is in the true runaway, it is still comparatively insensitive to CO2. But more to the point, even going to 8X pre-industrial CO2 doesn't get you anywhere near the conditions that give you the wet runaway. Note also that there is no sharp transition to the "wet runaway" in contrast to the classic runaway. The warmer it gets (by one means or another) the moister the upper atmosphere gets, and the more it is subject to photodissociation and hydrogen loss. I don't think you can rescue Hansen's nonsensical "dead certainty" claim by invoking a wet runaway. The most you can say is that it is hard to put an a priori upper bound by basic physics on how warm clouds could make things, but both paleoclimate evidence and what we know about the general behavior of clouds make it extremely unlikely that we would get into Venus-like conditions -- or indeed even much beyond 8C per doubling -- as a result of anthropogenic CO2 increase. Even that 8C is pretty generous, but I'm leaning on the "extremely" here. I can't say the probability is exactly zero, but it's small enough that it would be more constructive to think about what happens at the 8C range instead, which offers plenty of extreme damages to worry about. But "dead certainty" of runaway? That's nonsense. There's no other word for it. --raypierre]
Indeed I remember calculating that it would take some time to remove hydrogen back in graduate school. At least the Earth and Venus are not the only experiments around now. We may be getting empirical information about the extent of the habitable zone with a bit of astronomy. Lots of candidates now.
Thanks again for your responses. Hope you will get a chance to read the chapter in question. I remember Martin Rees putting things in a similar way on a different topic. Not sure if that issue has been resolved yet.
RE #76, and coming to a climate equilibrium, I suppose you could say the Venus climate eventually came to an equilibrium, but not one amenable to life — and the water gone gone gone. But then again, some just like it hot, very hot.
Comment by Lynn Vincentnatnathan — 3 Feb 2011 @ 9:58 AM
I suppose this is an old and recurring complaint, but it gets really tiresome to see an interesting link and then find out it is hidden behind an expensive paywall. I suppose this never even occurs to those who are plugged into positions were institutions and/or grants pay for all this stuff, but it makes it difficult for others.
> John McCarthy
Paste the info into Scholar and look at the list, often an author has put a text copy online; your public library, if you’re in a country that has those, can provide a borrowed copy for you; and most modern journals list a “corresponding author” who can be asked for an offprint.
Reading my fresh new copy of The Warming Papers. I’m noticing a fairly surprising number of typographic errors. The first “real” one though I found on page 68 in Arrhenius’ article.
Formula (3) for the temperature of the ground is reproduced from earlier, to be shortly followed by Formula (4), which is supposed to be the ground temperature including corrections for clouds. But the Formula (4) given is identical with Formula (3) immediately above! So the following paragraph doesn’t make sense.
Is there a plan to make errata available?
Perhaps not “real” ones in Bret Burns’ expression, I also would like to inform some typos to that I have found in The Warming Papers. (Curiously to myself, I am quicker in finding typos than in reading.)
** Bibliographic note at the bottom of the first page of each paper
* Fourier 1927, p. 7
Fourier, J.-B. F. -> Fourier, J.-B. J.
* Budyko 1969, p. 116
Tellus 611-619 -> Tellus 21:611-619
* Kennett and Stott 1991, p. 385
Palaeoscene -> Palaeocene
** Callendar (1938)
* p. 261 (right), Heading of section 1
ATMOSPHKRIC -> ATMOSPHERIC
* p. 262 (right), Heading of section 2
INURA-RED -> INFRA-RED
* p. 262 (right), section 2, line 4
IO$\mu$ -> 10$\mu$
* p. 264 (left) text line 6
Hettncr -> Hettner
* p. 270, in Fig. 5, with “Funchal”
Madeisa -> Madeira
* p. 272 (left)
Mr. L. II. G. DINKS -> (probably) Mr. L. H. G. DINES (cf. “In reply to Mr. Dines,” in p. 272 (right))
* p. 273 (bottom right), References
Radcliffc Observatory -> Radcliffe Observatory (cf. p. 273 top left)
… I am not sure whether these typos existed in the original publication or happened during automatic character recognition.
== Chapter 12 introduction ==
* p. 259, 3rd paragraph, near end
Suiss -> Suess
* p. 260, last paragraph
John Callendar -> Guy Callendar
== Chapter 14 introduction
* p. 298
Moana Loa, Moanna Loa -> Mauna Loa
== Chapter 18 introduction
* p. 402
Moana Loa -> Mauna Loa