A few items of interest this week.
Paleoclimate:
1. A new study by Spielhagen and co-authors in Science reconstructs temperatures of North Atlantic source waters to the Arctic for the past two millennia, adding another very long-handled Hockey Stick to the ever-growing league.
2. From last week, an article in Science Express by Buntgen et al reconstructing European summer temperature for the past 2500 years, finding that recent warming is unprecedented over that time frame, and providing some historical insights into the societal challenges posed by climate instability (listen here for an interview with mike about the study on NPR’s All Things Considered).
3. The team of ice core researchers at WAIS Divide reaches its goal of 3300 meters of ice. [WAIS Divide, central West Antarctica, is a site of significant warming in Antarctica, over at least the last 50 years, a result recently confirmed by the study of O’Donnell et al. (2010); Stay tuned for more on the that soon].
Other Miscellaneous Items:
1. More in Nature on data sharing.
2. A great primer in Physics Today on planetary energy balance from our very own Ray Pierrehumbert (link to pdf available here).
3. Now shipping are David and Ray’s The Warming Papers and Ray’s Principles of Planetary Climate.
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.
*sigh*
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]
> nonlinear
How could that be possible?
Oh, wait — little reported, an outbreak of “unprecedented mildness” —
http://www2.ucar.edu/currents/cold-comfort-canadas-record-smashing-mildness
hat tip to:
http://www.desmogblog.com/canadian-hotspot-hits-21%C2%B0c-378%C2%B0f-above-normal
http://watchingthedeniers.wordpress.com/2011/01/24/faster-climate-change-kill-kill-kill/
http://members.autobahn.mb.ca/~het/enviro/gwnews.html
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.
#48 JBL
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).
> bookstores
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 …”
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.
Hank:
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.
For the record, I’ve never done it.
OK enough on guerrilla book re-shelving. Thanks.
Yes,
The very idea that someone would try to hide books that highlight their opponent’s position, tells me that they believe they have very flimsy evidence to support their own case.
[Response: No more on it please. People are welcome to discuss ethical ways of addressing the issue of what books bookstores carry, and how to deal with issues therein, in the open thread.–Jim]
@5 Arthur Smith
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.
Chris Dudley, on Jim Hansen and the runaway
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?
raypierre (#47),
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.
Hansen, like you, is also talking about 4W/m^2 per doubling of carbon dioxide. I left that out of the quote at the ellipses. I think he is talking about burning more fossil fuels than you though. Probably about this much: http://www.theoildrum.com/files/long_term_oil_supply_cost_cruve.png
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]
Chris (#61),
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.
I saw a quote in a financial newsletter that I think applies to deniers.
“As Kindleberger, the well-regarded economics historian said, the efficient market people (like Fama, French, Cochrane, Lucas, and Malkiel) ignore the data in defense of a theory.”
Ray,
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]
Chris Dudley,
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.
How about this: “New Study Affirms Natural Climate Change” at http://www.enterstageright.com/archive/articles/0211/0211natclichange.htm
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 :)”
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
time to start banging heads together?
> 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.
Sigh.
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”.
.
Chris (#68)
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[1]. 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[2]. The paleoclimate evidence from the PETM shows essentially fresh surface water that supported seasonal Azolla growth during a period of high CO2.[3] 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?
[1] http://www.sciencemag.org/content/298/5601/2171.abstract
[2] http://www.agu.org/journals/ABS/2008/2008GL033614.shtml “the jet streams have risen in altitude and moved poleward in both hemispheres.”
[3] http://deepblue.lib.umich.edu/bitstream/2027.42/62499/1/nature04800.pdf
[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. ]
John,
You might want to check on the flood history of Australia. This year is nothing out of the ordinary.
http://www.bom.gov.au/hydro/flood/qld/fld_history/index.shtml
It seems like you are saying that rainfall will decrease, except when it increases.
Hank,
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
sign outside Hogs breath in Cairns
http://blogs.abc.net.au/.a/6a00e0097e4e6888330148c83e9698970c-popup
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]
Dan H (#76)
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?
Observations: Climate change cover-up? You better believe it
Hank Roberts @79 — Thanks for the link.
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 ,
Chris Dudley,
//”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.
Cyclone Yasi,
see 2:17 PM entry for live webcams set up between Cairns and Townsville
http://www.abc.net.au/news/events/cyclone-yasi/
#75 Dan H
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,
Hank Roberts,
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?
Raypierre and Chris,
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]
Dan H wrote: “You might want to check on the flood history of Australia. This year is nothing out of the ordinary.”
You might want to refrain from posting blatant and absurd falsehoods if you wish to be treated with anything but derision and contempt.
raypierre (#88),
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.
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.
Some more typos I found in The Warming Papers …
== 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