I thought this post on clouds and climate modeling below from Steve McIntyre’s Climate Audit was interesting, because it highlights the dreaded “negative feedbacks” that many climate modelers say don’t exist. Dr. Richard Lindzen highlighted the importance of negative feedback in a recent WUWT post.
One of the comments to the CA article shows the simplicity and obviousness of the existence of negative feedback in one of our most common weather events. Willis Eschenbach writes:
Cloud positive feedback is one of the most foolish and anti-common sense claims of the models.
This is particularly true of cumulus and cumulonimbus, which increase with the temperature during the day, move huge amounts of energy from the surface aloft, reflect huge amounts of energy to space, and fade away and disappear at night.
Spot on Willis, I couldn’t agree more. This is especially well demonstrated in the Inter Tropical Convergence Zone (ITCZ) The ITCZ has been in the news recently because early analysis of the flight path of Air France 447 suggests flying through an intense thunderstorm cell in the ITCZ may have been the fatal mistake. There is a huge amount of energy being transported into the upper atmosphere by these storms.
Here are some diagrams and photographs to help visualize the ITCZ heat transport process. First, here is what the ITCZ looks like from space. Note the bright band of cumulonimbus clouds from left to right.
Here is a pictorial showing a cross section of the ITCZ with a cumulonimbus cloud in the center.
And finally, a 3D pictorial showing ITCZ circulation and heat transport. Note the cloud tops produce a bright albedo, reflecting solar radiation.
And here is the post on Climate Audit
Cloud Super-Parameterization and Low Climate Sensitivity
“Superparameterization” is described by the Climate Process Team on Low-Latitude Cloud Feedbacks on Climate Sensitivity in an online meeting report (Bretherton, 2006) as:
a recently developed form of global modeling in which the parameterized moist physics in each grid column of an AGCM is replaced by a small cloud-resolving model (CRM). It holds the promise of much more realistic simulations of cloud fields associated with moist convection and turbulence.
Clouds have, of course, been the primary source of uncertainty in climate models since the 1970s. Some of the conclusions from cloud parameterization studies are quite startling.
The Climate Process Team on Low-Latitude Cloud Feedbacks on Climate Sensitivity reported that:
The world’s first superparameterization climate sensitivity results show strong negative cloud feedbacks driven by enhancement of boundary layer clouds in a warmer climate.
These strong negative cloud feedbacks resulted in a low climate sensitivity of only 0.41 K/(W m-2), described as being at the “low end” of traditional GCMS (i.e. around 1.5 deg C/doubled CO2.):
The CAM-SP shows strongly negative net cloud feedback in both the tropics and in the extratropics, resulting in a global climate sensitivity of only 0.41 K/(W m-2), at the low end of traditional AGCMs (e.g. Cess et al. 1996), but in accord with an analysis of 30-day SST/SST+2K climatologies from a global aquaplanet CRM run on the Earth Simulator (Miura et al. 2005). The conventional AGCMs differ greatly from each other but all have less negative net cloud forcings and correspondingly larger climate sensitivities than the superparameterization
They analyzed the generation of clouds in a few leading GCMs, finding that a GCM’s mean behavior can “reflect unanticipated and unphysical interactions between its component parameterizations”:
A diagnosis of the CAM3 SCM showed the cloud layer was maintained by a complex cycle with a few hour period in which different moist physics parameterizations take over at different times in ways unintended by their developers. A surprise was the unexpectedly large role of parameterized deep convection parameterization even though the cloud layer does not extend above 800 hPa. This emphasizes that an AGCM is a system whose mean behavior can reflect unanticipated and unphysical interactions between its component parameterizations.
Wyant et al (GRL 2006) reported some of these findings. Its abstract stated:
The model has weaker climate sensitivity than most GCMs, but comparable climate sensitivity to recent aqua-planet simulations of a global cloud-resolving model. The weak sensitivity is primarily due to an increase in low cloud fraction and liquid water in tropical regions of moderate subsidence as well as substantial increases in high-latitude cloud fraction.
They report the low end sensitivities noted in the workshop as follows:
We have performed similar +2 K perturbation experiments with CAM 3.0 with a semi-Lagrangian dynamical core, CAM 3.0 with an Eulerian dynamical core, and with the GFDL AM2.12b. These have λ’s of 0.41, 0.54, and 0.65 respectively; SP-CAM is about as sensitive or less sensitive than these GCMs. In fact, SPCAM has only slightly higher climate sensitivity than the least sensitive of the models presented in C89 (The C89 values are based on July simulations)…
The global annual mean changes in shortwave cloud forcing (SWCF) and longwave cloud forcing (LWCF) and net cloud forcing for SP-CAM are _1.94 W m_2, 0.17 W m_2, and _1.77 W m_2, respectively. The negative change in net cloud forcing increases G and makes λ smaller than it would be in the absence of cloud changes.
Wyant et al (GRL 2006) is not cited in IPCC AR4 chapter 8, though a companion study (Wyant et al Clim Dyn 2006) is, but only in the most general terms, no mention being made of low sensitivity being associated with superparameterization:
Recent analyses suggest that the response of boundary-layer clouds constitutes the largest contributor to the range of climate change cloud feedbacks among current GCMs (Bony and Dufresne, 2005; Webb et al., 2006; Wyant et al., 2006). It is due both to large discrepancies in the radiative response simulated by models in regions dominated by lowlevel cloud cover (Figure 8.15), and to the large areas of the globe covered by these regions…
the evaluation of simulated cloud fi elds is increasingly done in terms of cloud types and cloud optical properties (Klein and Jakob, 1999; Webb et al., 2001; Williams et al., 2003; Lin and Zhang, 2004; Weare, 2004; Zhang et al., 2005; Wyant et al., 2006).
(Bretherton 2006)
Dessler et al (GRL 2008) made no mention of strong negative cloud feedbacks under superparamterization, stating that sensitivity is “virtually guaranteed” to be at least several degrees C, unless “a strong, negative, and currently unknown feedback is discovered somewhere in our climate system”:
The existence of a strong and positive water-vapor feedback means that projected business-as-usual greenhouse gas emissions over the next century are virtually guaranteed to produce warming of several degrees Celsius. The only way that will not happen is if a strong, negative, and currently unknown feedback is discovered somewhere in our climate system.
There are a limited number of possibilities for such a possibility, but it is interesting that cloud super-parameterizations indicate a strong negative cloud feedback (contra the standard Soden and Held results.)
This is not an area that I’ve studied at length and I do have no personal views or opinions on the matters discussed in this thread.
References:
Bretherton, C.S., 2006. Low-Latitude Cloud Feedbacks on Climate Sensitivity. Available at: www.usclivar.org/Newsletter/VariationsV4N1/BrethertonCPT.pdf [Accessed June 12, 2009].
Wyant, M.C., Khairoutdinov, M. & Bretherton, C.S., 2006. Climate sensitivity and cloud response of a GCM with a superparameterization. Geophys. Res. Lett, 33, L06714. eos.atmos.washington.edu/pub/breth/papers/2006/SPGRL.pdf
Bretherton, C.S., 2006. Low-Latitude Cloud Feedbacks on Climate Sensitivity. Available at: www.usclivar.org/Newsletter/VariationsV4N1/BrethertonCPT.pdf [Accessed June 12, 2009].
Wyant, M.C., Khairoutdinov, M. & Bretherton, C.S., 2006. Climate sensitivity and cloud response of a GCM with a superparameterization. Geophys. Res. Lett, 33, L06714.
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It is my understanding that the clouds that are the main sensitivity issue are low clouds, not high Cn clouds.
REPLY: True, and Svensmark’s GCR premise says similar things, but what I’m expounding on here is a demonstration of negative feedback using the CB as an example as a way to help readers understand the reflectivity issue. The ITCZ does become quite a reflective band at times. Also I’ll point out that there are about two orders of magnitude more low level cumulus form that also have this heat transport turned solar shield character, that don’t make it to CB. status. Just look at the cumulus distribution around the CB in the top satellite photo from ISS. They have a significant reflective role also.
And I’ll point out in on of the papers you reference, the title contains the word “low latitude”, which point directly at the ITCZ. The ITCZ does create a lot of low level cumulus. – Anthony
OT, but you guys might get a kick out of this header at the top of the “debate message board” at “GoodPlanet.org”
“Leave scepticism to others and take action. And let’s make this forum a space that is 100% positive.”
LOL!
Pamela Gray (06:39:48) :
Every day the NWS predicts high 80’s here in Pendleton, Oregon. And every day the thunder clouds swoop it all up into the heavens and we stay cool (and very damp)
This summer is starting look similar to the summer after the eruption of Mt. Pinatubo except for the lack of a major eruption.
I have done some parametrization in the molecular dynamics field but I wouldn’t say I am an expert molecular modeller.
The word ‘superparametrization’ intrigues me. By reading the post it is not clear to me what the authors of the study mean by ‘superparametrization’ Could anybody who has read the original study explain what is the difference between this and the ‘normal’ parametrization?
Usually, when some parametrization is done in the computational chemistry field, a ‘reality check’ is needed to verify the values you are using. Sort of validation of the parameters. Long story short, you run some computational jobs with the new parameters and you compare the results of the model with the ones obtained empirically. I have always wondered how climate models are validated. How do they validate the ‘climate sensitivity to CO2 doubling’ parameter? It seems to me that the only thing you can do is to wait for 30 years and see if your 30 years long climate model was right or it deviates from reality.
I just hope this ‘superparametrization’ thingy doesn’t mean that these parameters don’t need to be validated.
OT, but get a load of this guy using a school project to prove why he believes that CO2 is the cause of Global Warming. He seems to forget that there is more involved than adding a some co2 to a bottle. But this can explain the computer models way of testing. No wind, no clouds, etc.. Any way read it you may laugh.
http://www.bbc.co.uk/blogs/climatechange/2009/06/the_unpredictable_weather.html
28. At 07:44am on 11 Jun 2009, SheffTim wrote:
#26. “I put a link simply to save people time and trouble; Wikipedia is just one site/page. Use Google / Bing / or whatever search engine you prefer on the same topic:
Paleocene Eocene Thermal Maximum
Can it be demonstrated that additional CO2 can affect temperature in the atmosphere?
A small experiment any high school lab can do.
Take two airtight glass tanks, each with a thermometer inside, and a means of introducing a gas into one without breaking the airtight seal. (An intake pipe etc.)
Each box to contain ordinary air. Seal both tanks and place both in sunlight so that both are receiving approx. equal amounts. The thermometer readings of both should match at this point.
Introduce a small amount of additional CO2 into one tank; its thermometer reading will rise above that of the other box.
For those that read books and want to become more informed I suggest: (Try your library service.)
‘Ice, Mud and Blood’ by Chris Turney.
A summary of key discoveries by scientists about past climate change going back deep in time and the implications for the present.
‘An Ocean of Air: A Natural History of the Atmosphere’ by Gabrielle Walker.
A history of some of the major discoveries about air, gasses and the atmosphere from Galileo to the present day together with explanation as to their importance for life on Earth.
‘Earth: The Power of the Planet’ by Iain Stewart & John Lynch.
An accessible introduction to earth systems and earth’s history.
‘Earth’s Climate Past And Future’ by William F. Ruddiman.
An account of known factors that have influenced climate change over earth’s history”
Pamela Gray (06:39:48) :
It reaches for 80 here, but then up go the cumulo-nimbus, down comes the temp and the monster raindrops. Very damp here, too, just 450 miles to your south. Supposedly, by middle of next week we will go back to sunny.
Guys, it’s just a model result. It may turn out that this new parametrization brings us closer to reality-I suspect so myself-but models are models and it is not clear how solid their results are. They are hypotheses which must be tested. I’ll believe the model results when they agree with observations-which is why I think Roy’s work is so important, he is looking for observational evidence of feedbacks and isolating the effects from natural variations.
“This is particularly true of cumulus and cumulonimbus, which increase with the temperature during the day, move huge amounts of energy from the surface aloft, reflect huge amounts of energy to space, and fade away and disappear at night.”
I was watching this happen last night. (In an earlier comment on another thread I’d point out the odd “hazy cloud” turning into cumulus late in the day). But I had not watched it through the night. But something had to change to let the cycle repeat… So last night I spent a few (cold) hours in a lawn chair watching the night sky. It was clear.
Little did i know that this was an understood behaviour. So here I am with clear starry nights radiating away what little thermal energy we got for the day, then turning back into overcast cumulus days “protecting” me from all that solar heat…
I may not like it, but at least now I have a clue why it’s so cool here.
Spot on Willis, I couldn’t agree more. This is especially well demonstrated in the Inter Tropical Convergence Zone (ITCZ) The ITCZ has been in the news recently because early analysis of the flight path of Air France 447 suggests flying through an intense thunderstorm cell in the ITCZ may have been the fatal mistake. There is a huge amount of energy being transported into the upper atmosphere by these storms.
When I was taking ground school, it was strongly emphasized that we were, when confronted with “weather”, to simply avoid a “thunderhead”. The received wisdom was that you could not go over it, going through it was lethal, and even around the edges the downdrafts could be extremely violent. I’ve been in commercial aircraft that were weaving their way between convection cells, so some of the pilots do this. I suspect some of the folks flying jumbos may be forgetting that a bigger airplane is not any stronger WRT thunderstorms.
Also, my personal speculation still in the “is this even worth looking at?” stage: With an increase in GCRs, we get an increasing shower of particles. Modern memory cells have gotten small enough that a single cosmic ray can cause a “bit flip” so we have gone to ECC – Error Correcting Code memory. Extra parity bits are stored so you can repair a flipped bit. This has been used on larger computers for 20-40 years, but is still “new” in the smaller machines. The Speculation:
Could it be that the ECC memory was developed in a lower cosmic ray field and now, with higher than “spec” bit flips is being overwhelmed? Especially if the GCRs are not smoothly distributed in time and space? (i.e. if they are very “bursty”).
The Airbus is a highly automated airplane… The pilot basically makes requests of the flight computers and the computers decide what to do with them. Given the reports of a cascading electrical failure reported by the in flight avionics, this would be “bad news” to say the least. (Why I like aircraft with mechanical backup systems – my favorite being the A10 Warthog with a few hydraulic flight controls AND a cable control system – but they don’t do commercial flights 😉
There were a couple of years, near the top of the solar output, with NO major airline accidents. Now we’ve had a couple of crashes on the double quick. Could be statistical noise, or it could be that convection has picked up, or GCRs are causing computers to sporadically get flakey. But the trend is real and the statistics are public.
FWIW, the NYSE had a server outage today that took down trading on 250 major stocks. These folks have some of the best, most redundant, most outage resistant systems in the world. Literally $Billions of dollars depend on them so money is no object. And it went down. (This isn’t a single computer like most folks think of it, it’s a high availability cluster. A couple or a few computers working in tandem and if one goes flakey the rest keep on keeping on… for one of these clusters to go down is, er, odd. Not unheard of, but very rare.)
So I’m now watching my patch of sky and thinking about a dynamic system that is valving the heat out at night but shutting down the warmth in the day; and wondering just how many cosmic rays it takes to swamp the ECC memory in an airliner… So little time, so much to contemplate…
Thom Scrutchin (07:22:53)
Thanks Thom.
Nowadays the greatest problem with new ideas is not protecting them but getting anyone to take them seriously.
As a non scientist I have an uphill struggle despite the fact that my suggested description of the climate system complies with both observations and basic physical principles.
Mind you, I do have 50 years obsessive interest in the subject with just as many years of reading and observation to inform me. Add to that a professional life of analysis and weighing of evidence.
As to the logic (or otherwise) of my conclusions, that can be followed through various articles prepared by me over the past 15 months and first published here:
http://climaterealists.com/index.php?tid=37
The worldwide response has been unexpected and rewarding.
Proper climatology died 20 years ago when the CO2 idea was found to be a source of unlimited taxpayer funding.
The professionals have had their eyes off the ball for so long that modern instrumentation and real world observations are discrediting them day by day.
Fixing on a simplistic, fixed, climate explanation in return for money was as good an idea as assuming that we had come to the end of ‘boom and bust’ in the commercial world.
smallz79,
No one doubts that CO2 in a sealed box will do what it does.
The question is how is this manifested on the vastly larger, vastly more complex, Earth climate system?
AGW has made the case for an apocalyptic climate future from CO2 driven change, and it is not happening.
Skeptics point out that is not happening, and are correct.
A diagnosis of the CAM3 SCM showed the cloud layer was maintained by a complex cycle with a few hour period in which different moist physics parameterizations take over at different times in ways unintended by their developers. A surprise was the unexpectedly large role of parameterized deep convection parameterization even though the cloud layer does not extend above 800 hPa. This emphasizes that an AGCM is a system whose mean behavior can reflect unanticipated and unphysical interactions between its component parameterizations.
For folks not into geek speak, what this says is roughly:
The computer program does some really interesting things that never happen in nature and goes into a runaway fantasy mode with strange results you will never see in the real world. This happens because the hard coded guesses about how things work that the computer programmer made (the prameterizations) have little to do with reality and interact with each other in strange unexpected ways. What most programmers would call “a bug”…
Or in short form: The circulation models are bogus and busted and give you bad results because the prameterized code is bogus and flakey in strange ways.
smallz79 (10:10:17) :
Each box to contain ordinary air. Seal both tanks and place both in sunlight so that both are receiving approx. equal amounts. The thermometer readings of both should match at this point.
Introduce a small amount of additional CO2 into one tank; its thermometer reading will rise above that of the other box.
LOL! Apparently, the Ideal Gas Law is now an Inconvenient Truth.
Annabelle, David Ball, John Galt,
Regarding transparency: I altered an XKCD comic to illustrate the point:
http://cuppacafe.com/if-xkcd-did-a-global-warming-comic/3652
“”” Urederra (10:06:46) :
I have done some parametrization in the molecular dynamics field but I wouldn’t say I am an expert molecular modeller.
The word ’superparametrization’ intrigues me. By reading the post it is not clear to me what the authors of the study mean by ’superparametrization’ Could anybody who has read the original study explain what is the difference between this and the ‘normal’ parametrization?
Usually, when some parametrization is done in the computational chemistry field, a ‘reality check’ is needed to verify the values you are using. Sort of validation of the parameters. Long story short, you run some computational jobs with the new parameters and you compare the results of the model with the ones obtained empirically. I have always wondered how climate models are validated. How do they validate the ‘climate sensitivity to CO2 doubling’ parameter? It seems to me that the only thing you can do is to wait for 30 years and see if your 30 years long climate model was right or it deviates from reality.
I just hope this ’superparametrization’ thingy doesn’t mean that these parameters don’t need to be validated. “””
Su-per-pa-ra-met-ri-za-tion is an eight syllable word for fudge-ing, which is two syllables.
It amounts to writing an expression with a big enough array of adjustable fudge factors to get it to fit any observed set of data. So it is curve fitting ala King.
Doesn’t mean there is any causal physics associated with any of those parameters.
Scientists have proved before that you can fit observed measured data to as close as eight significant digits of precision; by doing nothing more than playing around with numbers.
Superparametrization is just as bogus; it is not going to realize any advance in climate physics; just make for prettier looking video games.
Cloud feedback is 8th grade high school meteorology science; more sun, more heating, more evaporation, more clouds; more clouds, less sun, less heating, less evaporation. QED
You don’t need a Cray computer to model cloud feedback.
George
Peter Hearnden (05:14:49) :
“How do they get away with ignoring clouds negative feedback?”
Who is? No one.
You are absolutely right. The models do not ignore cloud feedbacks, as the prior geek speak translation shows, they make up a fictional non-physical positive feedback and ignore the negative feedbacks. That’s hardly ignoring them. It takes hard work to make a decent bit of coded fiction…
Walt Stone (10:46:47) : I used to read XKCD, but then his politics started to slip into the comics, greatly diminishing their quality IMHO.
Got a kick outta that one though. Hehe…
Water acts as the “working fluid” for natural convective refrigeration system. It isn’t that hard to grasp and I can’t understand why the warmers are such “denialists” in this regard.
Anthony,
Re Thom Scrutchin (07:22:53)
How about it ?
If I’m wrong then the sooner someone tells me the better. I’ve got an alternative life to pursue if I’m wasting my time.
REPLY: “I’ve got an alternative life to pursue…”
As do I. I can’t be on this blog 24/7 to answer every question, challenge and request. I’m a finite resource. I’m only online now because it is noon PST and I’m at work break.
I’ll review it, but I have other stories that are scheduled in the que right now, most importantly the CO2 freezing on Antarctica story – Anthony
Dave (05:56:29) : I would still like to know though, if, as Ice core samples suggest, that the earth, from time to time, sees sudden temperature movements (5 degrees C or more) happening in less than a year, and those changes are discrete, then what is the mechanism for this?
The short answer is: Unknown.
There are many “maybe”s:
Their is evidence for a major ‘rock fall’ from space onto the ice sheet causing the rapid change 13,000 years ago. We get hit with about 2 “small nuke” sized explosions each year high in the sky mostly over nowhere. Junk from space is a big issue. Sometimes it’s bigger and reaches the ground and all hell breaks loose…
There is also the explanation of volcanic cycles. There are times when the earth just makes a whole lot more volcanoes than at other times. We’ve been in a “quiet time” and seem to be heading back into a more “active time” with Chaiten and Redoubt both picking up activity (along with about 20 others…). If Chaiten blows at a supervolcano scale, we will be seeing snowfall in Phoenix in August… and it will be dark at high noon. (Hyperbole, but you get the point…)
There is also “antipodal focusing” that means when a big rock hits, the energy travels around the globe and you get a matching “whack” on the far side of the planet. This would explain the constant bickering between rock fall and volcano folks. Both come together. (big rock hits near Mexico, we get massive lava flows near India…).
Finally, there are a couple of speculative “positive feedback” possibles:
Right now we are water phase moderated, but what happens as we get very very cold and the global surface water phase approaches solid? Less moderation… One could have a catastrophic change in cloud cover… Basically, part of that historical record may be from non-stable regimes.
Or what happens as the ice accumulates and ocean levels fall? At some point a few gigatons of Methane Clathrate on the ocean bottom catastrophically destabilize and we get an immense methane flood. Talk about your “greenhouse gas warming”! These clathrate destabilizations on a small scale have been observed and can lead to massive releases. Enough that the frothy ocean would not support a ship and it sinks. This may explain ships disappearances in some places with high incidence of both ship losses and clathrate boils on the ocean bottom.
And then there is the possibility of a plant mediated cyclicality. As ice forms in an ice age, fewer plants. Less CO2 removed from the air and it accumulates over thousands of years (from volcanos). Eventually enough to cause warming, that causes an albedo feedback along with releasing methane and CO2 from plant matter trapped under the global glaciers for who knows how long. This leads to a rapid albedo / gas feedback the other way as the glaciers runaway melt. Eventually the planet is warm and wet enough for an explosion of plants that rapidly sequester the CO2 leading to another plummet into cold.
http://chiefio.wordpress.com/2009/06/02/of-trees-volcanos-and-pond-scum/
And there is also the possibility that it is just the interaction of a bunch of independent oscillating systems. Rather like the “rogue wave” effect (that was thought to be bunk by the scientific community despite many sailors telling the same tale for generations – never dismiss anecdotal evidence out of hand.) until an interesting bit of computer work and some satellite photos showed it to be the natural result of wave interference patterns… So PDO flips and AMO flips and a Solar flips and sometimes they converge into an Oh My God hot year like 1998 that comes fast, and just as fast evaporates. And sometimes they converge into a Big Blue Blob of cold air sitting on my head 8-{
There is also the possibility that it has to do with our place in the cosmos or other larger changes in the planet. Volcanic cyclicality has an eery correlation with sunspots (on a very long time scale) and climate cycles that both have an eery correlation with planetary positions.
http://www.schulphysik.de/klima/landscheidt/iceage.htm
Ice epochs have a fairly strong correlation with our position in the galactic spiral arms (that changes over time).
http://www.sciencebits.com/ice-ages
Our magnetic field oscillates and we don’t really know what happens when it “goes to zero” mid flip. And our sun is a variable star. We don’t really know what happens as it varies nor what the bounds are on that variation. We like to think that it is stable, but we have only really watched it for less than a fraction of a millisecond on a solar clock time scale.
There is a known 1500 year climate cycle called the Bond Event. Clearly seen in the geologic record. Nobody knows why, but every 1500 years we get a big cold snap. Last one was about 1500 years ago… It is most remarkable for it’s periodicity. Until we are talking about 3000 year spans of data, we are not talking about climate (IMHO) and all the folks getting excited about this or that fantasy cause of change may just be making stuff up to explain their current position on a known 1500 year cycle (or a 176 year solar cycle, or a 30 year PDO cycle, or…). To talk about “stability” we really need the context:
http://chiefio.wordpress.com/2009/04/06/bond-event-zero/
And there are more, but I’m going to stop here. (Too many links and I’ll end up in the spamfilter que for a few hours…)
The bottom line is that nobody knows. But some folks think “the science is settled” and you caused it with soda fiz (and it only goes one way). Such hubris. But just take a minute to look at the chart of ice and cold during an ice age cycle and notice that we are this little tiny flat shelf of about 1 mm on the left side of gigantic plunges and soaring rises. That little shelf is 10,000 years long and encompasses all the “extreme” climate we know as long as history records.
http://en.wikipedia.org/wiki/File:Ice_Age_Temperature.png
We think the system is stable because we have only seen it in the narrowest of bands. In the longer run, the system is stable, but as an ice ball with sporadic moments like now when the Milankovitch Cycle is just right…
” Stephen Wilde (06:17:18) : ”
Was reading a paper recently about a very dry spell that seems to have happened in East Africa a few thousand years ago. It mentions that it appears that the entire ITZ shifted South by a couple of hundred miles greatly altering precipitation patterns over much of Africa.
And what you say is consistent with evidence of changes in precipitation patterns uncovered over time by studying lake sediment for pollen content and lake level (shoreline) histories. Journals such as Quaternary Research are filled with such papers each month.
Ramanathan has some interesting thoughts on Cloud radiative forcing.
Cloud radiative forcing (CRF) is defined as the difference between the radiation budget (net incoming solar radiation minus the outgoing long wave) over a cloudy (mix of clear and clouds) sky and that over a clear sky. If this difference is negative clouds exert a cooling effect, while if it is positive, it denotes a heating effect. Five-year average of the cloud radiative forcing [1] is shown in Fig. 2. The global average forcing is about –15 to –20 W m-2 and thus clouds have a major cooling effect on the planet.
The enormous cooling effect of extratropical storm track cloud systems
Extra-tropical storm track cloud systems provide about 60% of the total cooling effect of clouds [2]. The annual mean forcing from these cloud systems is in the range of –45 to –55 W m–2 and effectively these cloud systems are shielding both the northern and the southern polar regions from intense radiative heating. Their spatial extent towards the tropics moves with the jet stream, extending farthest towards the tropics (about 35 deg latitude) during winter and retreating polewards (polewards of 50 deg latitude) during summer. This phenomenon raises an important question related to past climate dynamics. During the ice age, due to the large polar cooling, the northern hemisphere jet stream extended more southwards. But have the extra tropical cloud systems also moved southward? The increase in the negative forcing would have exerted a major positive feedback on the ice age cooling. There is a curious puzzle about the existence of these cooling clouds. The basic function of the extra tropical dynamics is to export heat polewards.
While the baroclinic systems are efficient in transporting heat, the enormous negative
radiative forcing (Fig. 2) associated with these cloud systems seems to undo the
poleward transport of heat by the dynamics. The radiative effect of these systems is working against the dynamical effect. Evidently,we need better understanding of the dynamic-thermodynamic coupling between these enormous cooling clouds and the
equator-pole temperature gradient, and greenhouse forcing.
1 Ramanathan V, Cess RD, Harrison EF, Minnis P, Barkstrom BR, Ahmad E and Hartmann D 1989. Cloud-radiative forcing and climate: results from the Earth radiation budget experiment. Science 243, 57–63.
2 Weaver CP and Ramanathan V 1997. Relationships between large-scale vertical velocity, static stability, and cloud radiative forcing over Northern Hemisphere extratropical oceans. Journal of Climate 10, 2871–2887.
The importance of changes in CRF and Downward shortwave radiation can be seen quite clearly in ENSO dynamics.eg
http://i255.photobucket.com/albums/hh133/mataraka/dsrenso.jpg
Could that be where the “missing heat” is going? Squeezed out of the system like toothpaste out of a tube?
“The ITCZ does become quite a reflective band at times. Also I’ll point out that there are about two orders of magnitude more low level cumulus form that also have this heat transport turned solar shield character, that don’t make it to CB. status.”
One of the observational problems I remember when I was an observer was affixing the correct cloud code to the 6 hour observations. If I remember correctly, the code 1963 stood for Low Cloud -9 (CB), Mid Cloud 6 (Altocumulous) and HIgh Cloud 3 (Cirro-Stratus). High Cloud 3 could be providing a 10/10ths overcast, but no one doubted that the high level cirrus came from the CB. My time spent at the JTWC as a tropical sat analyst saw many weeks where entire regions of the Pacific were covered in a thick CS shield, which orginated from multiple storm clusters.
One other point concerning dirurnal cooling in the tropics: since the tropics (at least over the oceans) are at near saturation, the night time lows are fairly consistent. Even the presence of high clouds do not change this consistency that much. Radiative cooling and the attendent night time temp inversion are not that pronounced -especially when compared to the deserts. On the other hand, overcast skies during the day block insolation, and do have an pronounced effect on daytime highs.
E. M. Smith (11:51:17)
Excellent post indicating just how little we can know and putting it in a universal perspective.
On the scale of a human lifetime (or even a couple of centuries) it seems that our environment is reasonably stable or at least the prospect of a major natural disruption seems too small to consider. For day to day living that is fine.
The trouble is that there is a huge number of unknown variables that can whack us at any time and the chances of one or other of those variables giving us a whack during any single human lifetime is probably higher than ongoing stability for more than a couple of centuries.
People who lived during major and rapid past climate and other changes may just have been less lucky than those of us alive today but the fact is that no one alive today can be sure that there will be no major natural (and not anthropogenic) worldwide event within our remaining lifetimes.
Even the climate change from 1600 to date if reversed would have a devastating effect on our current hard earned civilisation whatever it’s flaws.
We have the privilege of being at the top of a rising curve of increased average individual prosperity ( despite the fact that many are not yet sharing in it) and it would take but a minor blip in any number of natural phenomena to take the whole of the benefits of the past 500 years away from us.
Yet so many are so cavalier about our hard earned progress against natural depredations that they now tell us that abandonimg all that has been achieved is the sole route to moral and material nirvana.
We are engaged in a desperate battle against an anti human (indeed an anti life ) natural environment yet we are attacked on all sides by fuzzy minded individuals and organisations (usually funded by us) who think that nature is our friend.
There lies the decadence and destruction of our species. Rot starts from within and nature revels in it.
A bit off topic but relevant to the general tenor of climate catastrophism.
George E. Smith (10:49:04) :
The superparameterization replaces the regular cloud parameterization with a (higher-resolution) cloud-resolving model in each column of the GCM. The cloud-resolving model is better physics and more verified for small scale processes and short timescales, so the idea is to find out it does anything different when it’s embedded in the GCM (it does).