Musings about models
With the blogosphere all a-flutter with discussions of hundredths of degrees adjustments to the surface temperature record, you probably missed a couple of actually interesting stories last week.
Tipping points
Oft-discussed and frequently abused, tipping points are very rarely actually defined. Tim Lenton does a good job in this recent article. A tipping 'element' for climate purposes is defined as
The parameters controlling the system can be transparently combined into a single control, and there exists a critical value of this control from which a small perturbation leads to a qualitative change in a crucial feature of the system, after some observation time.
and the examples that he thinks have the potential to be large scale tipping elements are: Arctic sea-ice, a reorganisation of the Atlantic thermohaline circulation, melt of the Greenland or West Antarctic Ice Sheets, dieback of the Amazon rainforest, a greening of the Sahara, Indian summer monsoon collapse, boreal forest dieback and ocean methane hydrates.
To that list, we'd probably add any number of ecosystems where small changes can have cascading effects - such as fisheries. It's interesting to note that most of these elements include physics that modellers are least confident about - hydrology, ice sheets and vegetation dynamics.
Prediction vs. Projections
As we discussed recently in connection with climate 'forecasting', the kinds of simulations used in AR4 are all 'projections' i.e. runs that attempt to estimate the forced response of the climate to emission changes, but that don't attempt to estimate the trajectory of the unforced 'weather'. As we mentioned briefly, that leads to a 'sweet spot' for forecasting of a couple of decades into the future where the initial condition uncertainty dies away, but the uncertainty in the emission scenario is not yet so large as to be dominating. Last week there was a paper by Smith and colleagues in Science that tried to fill in those early years, using a model that initialises the heat content from the upper ocean - with the idea that the structure of those anomalies control the 'weather' progression over the next few years.
They find that their initialisation makes a difference for a about a decade, but that at longer timescales the results look like the standard projections (i.e. 0.2 to 0.3ºC per decade warming). One big caveat is that they aren't able to predict El Niño events, and since they account for a great deal of the interannual global temperature anomaly, that is a limitation. Nonetheless, this is a good step forward and people should be looking out for whether their predictions - for a plateau until 2009 and then a big ramp up - materialise over the next few years.
Model ensembles as probabilities
A rather esoteric point of discussion concerning 'Bayesian priors' got a mainstream outing this week in the Economist. The very narrow point in question is to what extent model ensembles are probability distributions. i.e. if only 10% of models show a particular behaviour, does this mean that the likelihood of this happening is 10%?
The answer is no. The other 90% could all be missing some key piece of physics.
However, there has been a bit of confusion generated though through the work of climateprediction.net - the multi-thousand member perturbed parameter ensembles that, notoriously, suggested that climate sensitivity could be as high as 11 ºC in a paper a couple of years back. The very specific issue is whether the histograms generated through that process could be considered a probability distribution function or not. ('Not' is the correct answer).
The point in the Economist article is that one can demonstrate that very clearly by changing the variables you are perturbing (in the example they use an inverse). If you evenly sample X, or evenly sample 1/X (or any other function of X) you will get a different distribution of results. Then instead of (in one case) getting 10% of models runs to show behaviour X, now maybe 30% of models will. And all this is completely independent of any change to the physics.
My only complaint about the Economist piece is the conclusion that, because of this inherent ambiguity, dealing with it becomes a 'logistical nightmare' - that's is incorrect. What should happen is that people should stop trying to think that counting finite samples of model ensembles can give a probability. Nothing else changes.
20 August 2007 at 6:57 PM
All good. So how do we get to realistic probability distributions of outcomes? They are needed…
20 August 2007 at 7:21 PM
Are there any model predictions (simulations?) for temperatures round 1800 and before?
20 August 2007 at 7:22 PM
Do we ask too much of models?
I think it’s fair to say that we’ll never see a perfect one except the planet system itself. That doesn’t mean or imply that models are not helpful, or needed. They may, however, never meet all the demands that have been placed on them, including by the debunkers who want all action delayed until the perfect model or ensemble is at hand.
Actually, despite limits demonstrated for accuracy of rate and extent of change, the models deserve some cheers for pointing in the direction we’re headed. And that should be warning enough to set us on a course correction.
20 August 2007 at 7:49 PM
Re 1
The realistic, probability-distribution models will come after we have made our decisions the old-fashioned way - on the basis on incomplete and mostly wrong information.
There is so much social inertia and so many lags and delays in climate systems that we may already have made critical decisions; and not yet realize that we have already past those decision points.
Here, I would cite Beyond the Limits by Meadows, Meadows, and Randers, & earlier works by Jay Forester, Meadows, and Meadows going back into the Club of Rome Report and Limits to Growth.
(Dynamo was not a good language to program in, but it was better than Formula Translation Language.)
20 August 2007 at 8:02 PM
His definition adds unnecessary confusion and misses the main point of a “tipping point”, which is that it’s a value where the system you’re describing abruptly shifts from negative feedback to positive in some range of conditions.
If you have a normal thermostat, for example, the heater goes on when the temperature falls and turns off as it rises (”negative feedback”, a feature which tends to keep things stable.) If there were a bad design flaw in a thermostat, such that temperatures over 100 F turned the furnace on, that room’s climate would have a tipping point ~100 F and the room would get hard to cool whenever temperatures rose over that (”positive feedback,” at least for awhile.) It wouldn’t necessarily get hotter & hotter until the place burned down; the furnace would have limits & eventually a cold enough night would bring things back to normal, but that 100 F mark would be well worth avoiding…
20 August 2007 at 8:03 PM
Regarding the Sahara and the Sahel, this news article addresses that in some depth, and even provides a good example of the model ensemble business, and why a ‘model outlier’ might actually be correct.
In particular, Isaac Held’s group produced model results that indicated that the Sahel wouldn’t be greening but instead would be facing a period of continued drying. They also have a more recent follow-up paper with a statistical approach.
On the other hand,
“Last year (2005) US-based researchers Martin Hoerling and James Hurrell looked at all of the most recent climate models, averaged them out, and came to the conclusion that the Sahel’s recent fate would be reversed in the 21st century.” (Note that their analysis predicts increased drought for southern Africa, however).
The article also finds yet another way to bring tipping into the discussion:
“To complicate matters, the relative importance of factors affecting the Sahel’s climate is tipped in different directions by the different models.”:)
Unfortunately, this is a topic that sites like Sherwood Idso’s Western Fuels Association-linked CO2science have jumped on (guess which outcome they’re promoting: greening or drying?). That site seems to do more deliberate distortion of scientific publications than any other.
Given all this uncertainty, what should policy makers do? There must be something in the ‘policy makers guidebook’ that relates to serious uncertainty - something like : hedge your bets and start some contingency planning for the worst-possible-outcome scenario - just to be on the safe side. There are some more obvious steps - since deforestation in the region has played at least some role, one goal should be to do everything possible to halt and reverse that trend (saving forests appears to be more important than producing biofuels, as well).
20 August 2007 at 8:04 PM
Very interesting article by Tim Lenton on tipping points. I note that Tim sees the loss of the Greenland Ice Sheet as the most likely Tipper - giving us 7m sea level rise over the next 300 years or so.
While he discusses the interaction between the GIS and the WAIS, in his summing up he does not tie the loss of GIS to the WAIS in the way he does in the body of his report. But it seems he is saying that it is most unlikely we will be able to avoid the loss of the GIS (+7m rise), and he means that we will then loose WAIS (4-6m rise) as well - the two will be trundling into the ocean together, as we frantically withdraw our civilisation from the coast.
With the prospect of 11 to 13m rise over 300 years, it makes well over +1m rise this century seem very very likely, doesnt it? (13m/300 years comes to over 4m/100 years on average. I know it wont be linear, but its going to go with a hiss and a roar, eh!)
http://www.nasa.gov/vision/earth/lookingatearth/arctic-20070515.html
And isnt this well above the politically-correct IPCC predictions?
20 August 2007 at 8:49 PM
The skeptics of GW and AGW often say: processes in nature always try to return to equilibrium instead of runaway amplification, so nature will be take care of it. That is simply false. Look at gravitational collapse, stability of objects in flight unless specially made with canard wings etc., the rust process (more rust makes rusting even easier by opening up surface pits) etc.
20 August 2007 at 9:44 PM
In message 7 above, Nigel Williams expresses something of the cognitive dissonance I’ve felt in trying to sink my teeth into this issue: who is addressing the disconnect between IPCC projections and ice-sheet observations? Luckily for lost, confused souls such as myself, James Hansen (who is a great guru not only among scientists but also among philosophers) has done a fine job, in my humble opinion.
http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf
This review, entitled “Climate Change and Trace Gases” cuts to the chase with remarkable frankness. The “Albedo Flip” Hansen et al warn of is, substantially, what’s going on now (a decade or four ahead of schedule) in the Arctic. So there we are, I suppose.
But, you say, this article only demonstrates Hansen’s singular genius in his chosen field of climatology. What of my claim that Hansen is also a philosopher of unique insight?
http://pubs.giss.nasa.gov/abstracts/2007/Hansen.html
This paper, called “Scientific Reticence and Sea-Level Rise” is one of the more thoughtful treatments you’re likely to see of the problem: why is a large, consensus organization (such as the IPCC) more likely to underestimate the scope of future disasters?
20 August 2007 at 10:50 PM
There are some important distinctions between Bayesian and Frequentists statistics. What I find refreshing about casting an answer to a question in terms of Bayesian statistics is that one’s assumptions are explicitly part of the answer. Some questions are better answered without pretending there is an absolute probability of being right or wrong. For the problem of climate model parametric uncertainties, one should regard the resulting Bayesian probability as a relative likelihood given the parameters considered and one’s prior assumptions. If one wanted to express no particular preference for a prior for a parameter x, a uniform probability may suffice. However, if the parameter were 1/x then a more appropriate prior (that expresses no particular preference) should be a Gamma distribution. Climate model ensembles can be constructed to reflect exactly what we mean to express in terms of sources of uncertainty.
21 August 2007 at 1:14 AM
The problem is genetic. The average human is just not good enough in math to survive the next 200 years. My browser can’t read the Economist web site, but my guess is, you shouldn’t expect accountants to do math. The problem with democracy is, we all get the government the average deserves. The average may “deserve” extinction, or “deserve” is a bum concept.
I think I know why ET hasn’t arrived yet. His planet died because of global warming before he could get off of it. The end-Permian extinction made it into NASA’s Astrobiology zine. See:
http://astrobio.net/news/modules.php?op=modload&name=News
&file=article&sid=2429&mode=thread&order=0&thold=0
The Astrobio article refers to the end-Permian as a carbon cycle problem.
The points Gavin makes are mathematical and way beyond the comprehension of not just the average, but all but the top 0.1%. Even the top 0.1% can’t understand it unless they received the proper training. Gavin is talking to physicists and mathematicians but publishing to the world. Everybody needs to understand what he says. This is an impossible bind. We need to do a million years worth of evolution in the next 5 years.
21 August 2007 at 2:02 AM
Hi Gavin,
I certainly don’t want to belittle anyones models but I had an interesting conversation last week in California. A computer modeler was explaining to me how models can be wrong. I acknowledged that he is right and computer models can be wrong.
Then I said, forget all the computer models. They are becoming increasingly irrelevant to the argument of global warming. They are important for understanding things and predictive quality but it’s getting warm outside. Everyone feels it. Everyone says hey this weather seems quite different than when I was young.
For myself, I remember in Big Bear Lake when they could ice skate on the lake in winter and skiing went until July 4th (that was only around 37 years ago).
People are arguing about whether the glaciers are melting. Well, the pictures don’t lie. http://www7.nationalgeographic.com/ngm/0706/feature2/
When I’m in Switzerland I visit glaciers and its interesting that all these spots have picture of how big the glaciers were before. The amount of shrinkage is striking.
The fact is that we are getting more Category 5 Tropical Cyclones than ever before. I’ve been watching the SST’s lately and hearing everyone talk about how were not going to get to many hurricanes this year. But it is well known that sea surface temperature drives hurricanes. It takes temps over 28.5 C to get a hurricane but the temps in the gulf today are showing way above that averaging near 30 C. http://www.osdpd.noaa.gov/PSB/EPS/SST/data/FS_km50f100.gif
http://polar.ncep.noaa.gov/sst/ophi/Welcome.html
As far as the argument goes, I think we are getting beyond models. The sad thing is that if the exponent of acceleration continues as it seems to be doing in the real time data. When the policy makers wake up we will be facing the front of a wave that will seem overwhelming and it will be.
I continue to hope that we wake up faster as it no longer seems a matter of if it’s too late but rather that we are going to be in damage control for some time to come and all that that implies. I have this message for those that are questioning the veracity of reason or, by some fluke of neuro-chemistry, still doubting that global warming is real. Good luck!
21 August 2007 at 2:49 AM
“And isnt this well above the politically-correct IPCC predictions?”
I’m growing increasingly sceptical about the IPCC’s conclusions wrt sea level rise. Hansen et al think there is good evidence for a 7m rise by the end of the century unless urgent action is taken. Given that the IPCC’s report doesn’t factor in Greenland or the West Antarctic ice sheet owing to their complexity, Hansen’s report seems far more convincing - unfortunately. I’d be very interested to see a response from one of the climatalogists.
James Hansen et al, 2007. Climate Change and Trace Gases. Philiosophical Transactions of the Royal Society - A. Vol 365, pp 1925-1954. doi: 10.1098/rsta.2007.2052. http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf
21 August 2007 at 4:45 AM
Sorry I have not had time to read all the reactions above, and apologies in advance if this repeats anything. However, I think a lot can be achieved by noting the errors in our models (however calibrated), and ‘bootstrapping’ our forecasts. Thus we can include both our parameter (and indeed any other ratio factor) uncertainties and our calibration uncertainty, building ensembles of results for individual models, and hence ensembles of ensembles etc. There are lots of ways of dealing with being cautious with the prediction errors (include jackknifing with the bootstrap, for example - see Davison and Hinkley, 1997) and establishing the extent of equifinality (or convergence if you prefer), and hence to begin considering how much is model artefact, how much is error, and how much is at heart a forecast that we need to take notice of. Nick O.
21 August 2007 at 5:10 AM
Thanks for the article. Very interesting!
21 August 2007 at 5:41 AM
With regard to Tipping Points, is the 300 year timeline at 382 ppm of CO2 or the project(BAU)scenario of 550 ppm. Is there enough CO2 currently in the atmosphere for Greenland and WAIS to experience this non linear phenomena ?
Politically this 300 year time line is a joke.
21 August 2007 at 5:52 AM
For feedbacks capable of becoming tipping points, don’t forget greenhouse gases in melting permafrost.
21 August 2007 at 6:00 AM
I noticed the ‘tipping points’ were all localized. Calling them “large scale” is meaningless, they are either local or global. Often the tipping point proponents here will point to such local phenomenon and imply that the whole earth will get warmer. What they forget is there are negative feedbacks elsewhere, particularly in the weather in a wetter world. Tim pointed one out in the Sahara. That does not mean I believe that Gaia will magically regulate the climate, far from it. There will be local tipping points particularly at the poles where CO2 has the greatest warming effect. For the earth as a whole, doubtful.
21 August 2007 at 6:30 AM
Daniel, thank you for those pointers. I had read the first paper, and the one on Reticence is entirely pertinent. Im a transportation planner by trade, and I try and get other engineers to move towards using more sustainable modes of transport. Regrettably not too many are prepared to recommend to their clients that they use horses and carts to build their next skyscraper or dam.
Everything I have read of Hansen et al lately, and everything that the community is reporting in relation to our declining global climate’s critical parameters points to the same point: A very wet year 2100 for a huge part of humanity.
I notice that even Hansen is prone to ‘reticence’ as he tells us things will be fine if we sequester virtually all of virtually every greenhouse gas immediately. I think it was in the movie The Princess Bride where – presented with a total load of lies about his future (It was going to be bad) the hero said to his antagonists “We are all gentlemen here..” making it clear that he knew rubbish when he heard it, and thy all knew the truth.
Hansen has made the same observation among his peers. We ARE all gentlemen here. Frankly the time for being polite is past. So what we loose some funding, or loose out jobs if we speak out. Perhaps the more practice we get making do with less will stand us in good stead before too long!.
21 August 2007 at 7:47 AM
As always a cogent explanation followed by a rousing and intelligent discussion. Exactly why Real Climate is the best climate site around. Slightly off topic, news of this article “Heat Capacity, Time Constant, and Sensitivity of Earth’s Climate System,” by Brookhaven National Lab scientist Stephen Swartz soon to appear in the journal of Geophysical Research is already making the rounds on the skeptic blogs as the final nail in the coffin for AGW. No one has been able to tell me what it actually says though. Any insights from this learned crowd?
21 August 2007 at 7:54 AM
Re: my previous post: The paper in question is available in a preprint at http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf
Thanks for any comments. My skeptical friends are crowing that this kills the AGW theory. I’m not so sure..
[Response: You want http://julesandjames.blogspot.com/2007/08/schwartz-sensitivity-estimate.html - William]
21 August 2007 at 8:30 AM
Re #18 where Eric the Skeptic says:
There will be local tipping points particularly at the poles where CO2 has the greatest warming effect. For the earth as a whole, doubtful.
The problem is that the global climate is inter-connected. The atmosphere is like a water bed. If you increase the pressure in one place it will pop up somewhere else.
When the Arctic summer ice disappears, the sea will get warmer and the air will contain more water vapour. This makes it lighter and it will start rising instead of falling in the polar vortex. As a result the Northern hemisphere circulation pattern will be disrupted, and that will overflow into the Southern Hemisphere. Changes in the Arctic air flow could result in changes to the Indian and east African monsoons, El Ninos, and the ITCZ.
Of course all those changes might not be bad, but if it caused the west African Monsoon to restart and return the Sahara into a bread basket, how are we going to get the farmers and farm machinery from the new US Mid-West desert across to Africa quickly enough to prevent a famine?
21 August 2007 at 8:40 AM
RE #18 [I noticed the ‘tipping points’ were all localized.] Some of these “local” (but large-scale) events would have global effects. Among those mentioned in the article the Amazon die-off and the change in the amount of Arctic sea ice are the most obvious over the medium term: the first would lead to a large pulse of greenhouse gas emissions as trees burned and further emissions as soil carbon was released; the second to a change in albedo which would accelerate warming. The greening of the Sahara would presumably have a global effect in the opposite direction (though perhaps not if secondary effects are taken into account: Saharan dust is thought to have an important fertilising effect on the Atlantic and the Amazon). Although it falls outside the article’s definition of a “tipping point”, the release of methane from melting permafrost would have a global effect.
21 August 2007 at 8:58 AM
Re #12
What is the source for more Cat 5 hurricanes? the Hurricane center has denied any such claim and frankly, they’d know.
As for computer models… for a decade people have been saying “the models are RIGHT”. now models don’t matter? why is that? because the models aren’t predicting the gloom and doom anymore?
as far as the 10% comment in the original story goes, if 90% of the models predict no change and 10% predict devastation, then something is wrong somewhere. while science isn’t dependent on consensus, the peer review process does work by developing consensus among knowledgeable people. yes, the 90% may be wrong, but rarely is that the case. when it is the case, i’ll admit that it’s very visible (Galileo comes to mind)
21 August 2007 at 9:01 AM
One thing I’ve noticed is that many of us use the oven analogy. One major flaw with this analogy is that our system isn’t temperature based, it’s time based. the oven’s on for a set amount of time. It makes a lot more sense to think of the world this way… it also is easier to envision the ‘tipping point’.
21 August 2007 at 9:29 AM
Eric,
A volcano like the Yellowstone eruption can be considered a point source, geologically. Yet it has global and long term effects.
Doug,
I haven’t had time to peruse the paper thoroughly, but it would appear to be quite full of questionable assumptions. The values for climate sensitivity and equilibrium response appear to contradict values determined from a variety of other lines of evidence. I would also question his treatment of climate relaxation using “fluctuations” about an equilibrium. Instead, we have a system disturbed from equilibrium by forcer that increases with time. He also conveniently ignores positive feedbacks (e.g. increased water vapor) and most of the actual physics of climate change. The goal of physics should be, we are told, to make a model as simple as it can be and no simpler. It appears he has gone overboard on simplification, so it is not surprising that he is getting absurd results. I’m kind of surprised this got published.
21 August 2007 at 9:29 AM
Doug Lowthian wrote at 21 Aug 2007,7:54 AM
>http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf
i looked at the paper and i see some simplifications:
1)the outgoing longwave emission is stated to vary as the fourth power of the
_surface_ temperature. Should this not be the temperature at the radiating surface at the top of the atmosphere ?
2)there is an assumption of linearity made in eq. 5. i am not sure this will hold
3)the para before eq 16. admits that there are significant changes in the heat content of the ocean, and posits that the only causes could be variation in planetary albedo or effective emissivity; this is not clear to me since there are other components to the climate system such as icesheets which can sink considerable amounts of heat as well.
it appears at first reading that some possibly important physics is left out of this model. Perhaps some of our resident climate modellers would care to comment ?
sidd
21 August 2007 at 9:42 AM
“Re: my previous post: The paper in question is available in a preprint at http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf
Thanks for any comments. My skeptical friends are crowing that this kills the AGW theory. I’m not so sure..”
I’m not so sure either. The paper never mentions feedbacks. He concludes that a doubling of CO2 will cause a temperature increase of ~1.1 degC and contrasts this with the IPCC report that gives an equivalent figure of 3 deg C. But didn’t that figure also take into account the several feedbacks?
21 August 2007 at 10:18 AM
Re 18, where Eric says there will be local tipping at the poles,particularly at the poles,but doubtful for the whole Earth.
Melting of Greenland and West Antarctic ice sheets will raise sea level globally. Melting of Greenland ice would dump large amounts of fresh water into the north Atlantic affecting the Atlantic thermohaline circulation pattern. As was pointed out earlier, the release of CH4 from melting permafrost would be distributed pretty evenly throughout the atmosphere and not remain local. A number of such area wide warming events,will have global consequences.
21 August 2007 at 10:21 AM
Re: #20, #21
Yes I’ve seen Schwartz’s paper.
He estimates the heat capacity of the global climate system, and uses historical temperature data to estimate the “characteristic timescale” of temperature change. Using these data, he claims to derive the climate sensitivity, getting a figure of 1.1 deg.C for a doubling of CO2. This is much less than the current “best estimate” of about 3 deg.C, and would imply that there is *not* any unfelt warming “still in the pipeline” from greenhouse gases we’ve already emitted.
Even if his result is correct (which it isn’t), it by no means “kills AGW theory.” It simply changes the numbers. In fact, Schwartz’s analysis implicitly assumes that the planet *is* warming, and that the primary cause is man-made greenhouse gases.
His work depends on (among other things) the assumption that there’s only *one* characteristic timescale for global climate. Physically this would seem to be impossible; each component of the climate system (atmosphere, ocean, cryosphere) will necessarily have a different characteristic timescale. Schwartz’s analysis depends on the fast response of the atmosphere to climate forcing, but quite ignores the slow response of oceans and other components.
The really odd thing, for me, is that mathematically, the data themselves contradict his hypothesis of a single timescale for climate response. I believe I can show, beyond doubt, that the data he presents *reject* the idea of such a simple behavior, but Schwartz presents an argument (which I regard as invalid) that they confirm it.
I’m considering writing it up for JGR, and also considering doing a blog post on the subject.
21 August 2007 at 10:22 AM
What are some examples of climate tipping points from the past that demonstrate what actually happens when a tipping point is reached?
21 August 2007 at 10:22 AM
Ooops, that’s a link to the original paper - James’ comments are actually here:
http://julesandjames.blogspot.com/2007/08/schwartz-sensitivity-estimate.html
21 August 2007 at 10:24 AM
That’s the same value for climate sensitivity I’ve seen from the string theory physics site and from knowledgeable climate sites as well — it’s the number people get this way: calculated in the absence of any feedback, on the hypothetical twinning of each molecule of CO2 in the atmosphere to make two where there were one, instantly, and having nothing else happen.
Nice in theory. Of course, if it were possible to cut the total amount of CO2 in the atmosphere by half without any other event occurring, this also would solve a lot of problems. Perhaps pulling on the strings in exactly the right way through the fifth dimension somehow would do it. Til then it’s just a hypothetical.
The rest of the climate sensitivity above the about 1 degree C is tied to the obvious questions: where does the CO2 come from, and where does it go, and over what time period.
21 August 2007 at 10:46 AM
As best I can read the tipping point defn. and comments (and I’m sure I haven’t quite got it), “crucial feature” 1) describes or defines a region of the global system that when subjected to a small change in the short run suffers a large change in the long run because of an abrupt shift in the sign of its feedback and 2) transfers the large change/long run effects to other regions, so as to significanly affect the larger global system.
Having my brain insisting that every “crucial feature” be something I can point to on a world map is probably not helping me understand. And I have no idea what to make of “parameters controlling the system can be transparently combined into a single control.”
Anyway, the whole reason I’m even interested in the defn. (which I assume is intended to be read by someone with technical knowledge of climate modeling jargon) is that I’ve started wondering about how climate models handle volcanoes or geology like the Yellowstone caldera–regularly emitting “point sources” that transfer their climate effects globally. And what (if anything) makes geological emissions from Yellowstone different from man-made emissions from Taiwan or L.A.?
21 August 2007 at 11:09 AM
So glad you’re getting around to talking about (I know you hate this :)) the Venus effect, runaway warming…(note, I did not say “permanent runaway warming”).
The Venus effect is meant to be an analogy (of course, we all know Earth is not Venus), and analogies are only similar in some aspects and to some extent. For the totally unrefined layperson, it is a way to grasp an idea that GW may not be linear (which I sorta think most people are assuming & that we have plenty of time), but may zoom up to big harm, before the climate gets back to today’s temps 1000s of years from now.
I think scientists prefer the term “hysteresis” for this, because that contains the meaning that the climate eventually levels off (after wiping out much of life) and cools back down again.
But, I think most people would be more focused on the upswing in GW than its eventual retreat. Except the denialists, who’d probably claim, “Well, that wasn’t so bad, some 30,000 people survived 100,000 years later, and now are back to repopulating the earth with all that great fossil fuel from the anthropocene die out.”
21 August 2007 at 11:29 AM
A.C.
A dynamical system will respond differently to a point source than it will to a diffuse system. Likewise, a steady perturbation will have a different effect than a delta function in time. Think of it this way: In the vicinity of a Yellowstone type event, the local changes will be drastic, and hence there may be a significant difference in how efficiently these changes are transmitted to the global system–e.g. you may have a significant local temperature drop that results in rainshowers that take at least some of the dust and sulfates out of the air, etc.
In addition, a volcano emits LOTS of sulfates, dust and other nasties in addition to the CO2. Finally, averaged over time, volcanos produce far fewer ghgs than do humans.
21 August 2007 at 11:43 AM
Regarding “Scientific Reticence” - Nigel Williams, in post 19 above, points out that Hansen et al engage in a bit of the same at the end of “Climate Change and Trace Gases,” where they conclude that sequestering emissions from biofuels is a means of drawing down atmospheric co2. This also strikes me as a bit pollyannish. It would work (if gradually) if the population of the earth were considerably smaller, I suppose. Nobody wants to be accused of being a doomsayer, and so reviews of this nature tend to search (if pathetically) for some ray of hope to grab onto, for some positive message to conclude with, no matter what the state of the evidence.
Compounding the clumsiness of this obviously inadequate suggestion, the paper concludes on a puzzling footnote, with a whiff of cloying, desperate patriotism:
Just goes to show that even geniuses experience lapses of judgment from time to time…
21 August 2007 at 11:58 AM
RE #12 (John P Reisman): With all due respect, I would disagree with your view that we should forget the models. Yes, the models are imperfect, but that does not mean they are worthless. They are useful, first, to show the causes of the current warming - the comparison of outcomes for natural vs. anthropogenic forcinigs is a powerful argument for AGW. They are also useful to point to what the effects of AGW probably would be. The predictive power of the models does depend on checking them against what is actually happening - and this will be more important when the feedbacks start kicking in (but by then maybe we won’t need the models to tell us we are bad off). I am concerned that the deniers/skeptics use the imperfection of the multiple lines of evidence as a tool to argue against an anthropogenic cause for GW - I see this happening in the current arguments against the surface data. Yes, we can acknowledge the limitations of each line of evidence and of the models, but it does not help us if climatologists abandon these useful tools.
21 August 2007 at 12:16 PM
Re: 35
Venus and run away global warming. Here’s a serious look at it:
http://personals.galaxyinternet.net/tunga/DefectiveGlobalWarming.pdf
“Why is the albedo of Venus important? When the albedo is at 0.80, the Global Warming Theory falls apart. . .
The carbon dioxide levels on Earth have risen from approximately 0.028% to 0.036% in the last few decades. It is a major stretch to compare this with Venus at a 96.500% carbon dioxide level and promote an uncontrollable runaway condition. Earth in its early history, 385 million years ago, had an atmosphere with 10 times the present carbon dioxide levels. Those elevated levels did not produce runaway global warming then, so why should we theorize that it would today?”
21 August 2007 at 12:19 PM
> cloying, desperate patriotism
Er, no. Belated acceptance of responsibility for cleaning up the mess that we profited from, by profiting from being the first to come up with the solutions, so we can sell them overseas.
He knows Americans want to do well by doing good.
21 August 2007 at 12:20 PM
Re #24
Hi Dean, while data in NHC, NOAA, NASA, NCAR and other .gov web sites is scattered, the NHC does have a nice paper on the subject including the following:
Research has shown that the sea surface temperature (SST) alone does not provide a good indication of whether a storm will intensify. (See, for example the SST/Intensity relationships of recent Atlantic tropical cyclones.) However, SST does provide an upper limit to storm intensity. In SHIPS, the Maximum Possible Storm Intensity (MPI) is related to the SST by the equation:
MPI = 55.6 kt + 108.5 kt exp[0.1813 * {SST - 30.0oC)]
http://www.srh.noaa.gov/ssd/nwpmodel/html/nhcmodel.htm
One of the strongest observed correlative facts is that we are getting more of those ‘rare’ cat. 5 hurricanes, and the water is warmer. Let me know if you have another good explanation for the increase of cat. 5 hurricanes. I’m all ears on that one!
Also, could you please show me a link where they claim that their own research is incorrect on this matter. Maybe there is a contextual dilemma?
“As for computer models…” What I said was: “They are becoming increasingly irrelevant to the argument of global warming. They are important for understanding things and predictive quality”
A lot of the models that are tracking reality pretty well are being attacked because of minute errors. This of course is silly as the models are generally correct and indicative and therefore a good way to indicate or predict probability in relation to human caused global warming. Minute errors are corrected as discovered and do not detract from the overall picture as modeling and measuring improves.
What I am saying is that it is pretty easy for some to get caught up in the minutia and maybe that is a reflection of individual thought process or bias of some nature, but that generally, it’s getting warmer and that is affecting the weather.
More heat translates to more moisture in the air so more rainfall, more snow (melting faster though) likely larger climate momentums causing droughts and floods as well as debilitating storms and crop failures.
This is all just common sense. The world is already experiencing these effects. It’s not like we need a model to see what is happening. Good models help us see what is coming and models are getting better all the time because lots more people are working on it.
21 August 2007 at 12:42 PM
Paul, you asked for examples of climate tipping points.
Your library should have this book:
http://www.powells.com/review/2007_06_09.html
If you don’t read the book, at least read the review.
21 August 2007 at 12:44 PM
# 9
I would like to thank Daniel for pointing out “Scientific Reticence and Sea-Level Rise”. I had not seen it.
21 August 2007 at 12:52 PM
Daniel C. Goodwin wrote: “Nobody wants to be accused of being a doomsayer”
I don’t mind being accused of being a doomsayer. So I’ll say it:
1. My take on the science is that the warming from the CO2 that humanity has already added to the atmosphere is probably more than sufficient to trigger multiple positive-feedback “tipping points” that will further increase and accelerate the direct anthropogenic warming — and we are already seeing evidence of these feedbacks kicking in; and
2. Anthropogenic CO2 emissions are presently increasing every year at an accelerating rate, and it is extremely unlikely that humanity will collectively do what is necessary to not only stop that growth in CO2 emissions, but reverse it, and then reduce emissions by 80 percent or more within 5 to 10 years, which is what mainstream climate scientists say is needed to avoid the worst outcomes of anthropogenic global warming. (And per point 1 above, they are probably mistaken to believe that we have that much time anyway.) So,
3. The rapid, accelerating and extreme anthropogenic warming of the Earth, reinforced by feedbacks, will not only cause the various “disaster scenarios” that will be catastrophic for human civilization (e.g. megadroughts that will wipe out most agriculture, loss of fresh water supplies for billions of people, inundation of heavily populated coastal zones including most of the world’s major cities) but will lead to a global ecological meltdown — a general biospheric collapse — and the mass extinction of most life on Earth.
So, we are, in a word, doomed. There, I said it.
21 August 2007 at 12:54 PM
Daniel, I dont think the Amber Waves comment is an error of judgement, It is a genuine image of how good ot could be if only we did what we know we shuld. If someone (like a president) took that vision to the nation it may work, but I wouldnt hang up my umbrella yet.
21 August 2007 at 1:01 PM
[[They (computer models-RO) are important for understanding things and predictive quality but it’s getting warm outside. Everyone feels it. Everyone says hey this weather seems quite different than when I was young.]]
There are really two other *scientific* ways to predict future global warming trends beside computer models.
1) Physics.
2) Paleoclimatology
I would be really careful on saying that people can observe GW so it must be happening. Remember certain parts of the Earth have been getting cooler…and this is expected….but the average surface temps are going up taken from 10s of thousands of locations world-wide.
I don’t mean to knock your comments down…but they are simply unscientific. They would not pass for a second in science peer-review journal.
21 August 2007 at 1:03 PM
Re #24
Hi Dean, here’s some more from NASA on the matter:
Take Warm Water, Stir:
Sea surface temperatures must be 82 degrees Fahrenheit (F) or warmer for tropical cyclone formation and sustenance.
http://www.nasa.gov/vision/earth/environment/HURRICANE_RECIPE.html
21 August 2007 at 1:16 PM
Re # 37 Daniel C. Goodwin: “Compounding the clumsiness of this obviously inadequate suggestion, the paper concludes on a puzzling footnote, with a whiff of cloying, desperate patriotism…”
They also appear to be mimicking the concluding statement of the famous Watson and Crick DNA double helix paper (Nature, 1953): “It has not escaped our notice that the specific mechanism we have postulated…” (http://www.nature.com/nature/dna50/archive.html)
21 August 2007 at 1:40 PM
re #13
Hi Bill, just a small note on the IPCC. It is a very large process and typically lags the leading edge of new data and modeling in order to process the large scope of data collected. It’s also in Switzerland and its a fairly conservative place. I know because ‘m over there a lot these days.
The IPCC will lag but lay down arguments that will be harder to argue with. In my opinion, that is helpful because it keeps furthering the leading edge of the research and giving basis for those new arguments, models, predictions and projections.
When you add the IPCC data with the leading edge, one can see the trends and potentials fairly well. Using both in our considerations I believe will help us formulate policy and reasonable perspective faster.
21 August 2007 at 1:58 PM
I’m no expert in these things, but it seems to me that when you rain on a desert you get mud, not a ‘breadbasket’. You still have no soil and no vegetation or animal life to spawn growth.
Of course those things would develop over time through some processes about which others probably know a great deal. What I do suspect is that we are talking about a very long time; generations, certainly.
As for those areas which suddenly get no rain, their long-term future will be even less certain, with this exception: those who relied upon the fertility of that habitat will be forced to relocate.
To the mud flats, perhaps?
21 August 2007 at 2:10 PM
#8 Neil B.
Be sure that any GW/AGW skeptics that push the “return to equilibrium” argument realize that it may not be (probably will not be?) the same equilibrium.
In a number of discussions I have had the term “equilibrium” is treated as it were an unchanging absolute state of a system. There are many equilibria and some may not be much fun for human existence.
#22 Alistair McDonald
Your meteorology is not on a sound scientific basis. Yes you can calculate the decrease of density of the lower atmosphere because of an increase in water vapor. However your statement implicitly assumes it will all stay near where it is evaporated, much will be advected (transported quasi-horizontally) away.
But a greater flaw in your argument is that the static stability of the atmosphere will be fundamentally changed by an expected increase in water vapor.
To a high degree of accuracy much of the atmosphere is in hydrostatic balannce - the downward gravitational force balances the upward-directed vertical pressure gradient. To get air to rise there must be a mechanism to upset this balance.
An increase of water vapor cannot do this (and create spontaneous upward motion as you imply) because the water vapor fraction of air is constrained by the amount of kinetic energy available to do the work of evaporation.
With an Arctic Ocean air/sea interface temperature of 0C the maximum amount of water vapor in the lower atmosphere at equilibrium (i.e. saturation), measured as the partial pressure of total atmospheric pressure would be less than 1% of total atmospheric pressure. At 30C, a tempeature no one expects even in an ice-free Arctic Ocean with a runaway greehouse warming scenario, the fraction of total atmospheric pressure at equilibrium is around 3%. Though the value triples the maximum of 3% is a value much too small to overcome the larger magnitude hydrostatic balance.
So an increase of water vapor because of increased evaporation created by GW/AGW “will not a tipping point make” by upsetting the hydrostatic balance.
The greater influence of water vapor increases will be once air is lifted, condensation has occurred and rainfall becomes more plentiful.
Steve Horstmeyer
21 August 2007 at 2:21 PM
Who were the referees that peer reviewed the cited article in the Economist?
21 August 2007 at 3:05 PM
Re the Schwartz article: I’m not technically qualified to critique something like this, and there’s very little point in my putting the effort into becoming qualified in that way, but let me describe how I lok at these things (for the benefit of Doug Lowthian in particular): Read the abstract, read the introduction, read the conclusion, and then skim the contents. The purpose of doing this is to not only understnad the basic thrust of the paper but to turn up the caveats, which will indicate how much weight the author thinks ought to be put on the paper.
In the case of this paper, the next to last paragraph tells the tale: It’s a thought experiment using a simple model that Schwartz does not expect will be correct, although he believes that the approach he takes may have some value. The denialists, it seems, never look for the caveats.
21 August 2007 at 3:07 PM
“If you evenly sample X, or evenly sample 1/X (or any other function of X) you will get a different distribution of results.”
Absolutely true, fits are forced to the end of decay components as data is normally taken on a timebase so you have very few data pints at the beginning, where change is the greatest, and very few at the end, where change is the smallest. There are ways around it. Typically, fits are done by comparing the data set to a model, and fit to get the smallest sum of squares Sum of (model-real)^2.
However, you can multiply the squares at time = t, with an exponential function so that the amount of information is reflected in the fit.
This is only a rough and ready solution, but it is possible to get good fits in enzyme kinetics using this methodology (using the M-M equation instead of an exponential).
Indeed, what should be fitted is the “information” in the system, but you need to do the fit before you know where the information is.
There is a lot of work in this area in information theory, but to be honest, I really do not understand it.
21 August 2007 at 3:12 PM
Re 24 Dean: “What is the source for more Cat 5 hurricanes? the Hurricane center has denied any such claim and frankly, they’d know.”
Georgia Institute of Technology and the National Center for Atmospheric Research for starters: http://www.gatech.edu/news-room/release.php?id=654
21 August 2007 at 3:14 PM
On Bayesian priors and probability distribution generation: doesn’t the work of Forest et al. (GRL 2006) and Webster et al. (Climatic Change 2003) address some of these issues? In the former paper input distributions are not generated arbitrarily but rather derived from historical data, and in the latter these distributions are used to generated pdfs of future climate in a consistent fashion. Of course, these generated pdfs don’t address issues like the probability of poorly understood tipping points, but they are certainly a step up from using climateprediction.net or model ensembles to define pdfs (note that I think that both model ensembles and the .net experiment are very useful, just not for pdf definition). (Disclaimer: I work with the authors I’m citing)
[Response: Indeed. The problem discussed in the Economist is not related to the use of priors per se, but to the assumption that an appropriate choice of priors allows you to sample model parameter space in a probabilistic way. Mind you, some of the discussion on the influence of priors in the Forest et al papers is a little overblown, since their importance reduces every time you add in new information (as Annan and Hargreaves 2006 showed). I too agree that the CPDN ensembles are interesting though. - gavin]
21 August 2007 at 3:22 PM
gavin, stupid question time.
I know somewhere here abouts you have explained “climate sensitivity ” Could you give a quick
definition. And then an explaination of how one estimates the varience of the metric
[Response: http://www.realclimate.org/index.php/archives/2006/03/climate-sensitivity-plus-a-change/ - gavin]
21 August 2007 at 4:08 PM
RE #39 & #35, and “the Venus effect.”
Well, a lot of people have trouble understanding analogies (and poetry, for that matter). But then again many people don’t have such trouble. I would guess most people grasp them. That’s why they’re in such heavy use.
21 August 2007 at 4:21 PM
re: #52 & The Economist
The Economist is not a peer-reviewed scientific journal.
However, from multiple firsthand experiences, IF you send a pleasant note (which doesn’t have to be intended as a letter to editor to be printed) to them that basically says:
1) “This is in error, facts…”
2) “OK article, but you need to know about XXX, see URL, a good source on this topic.”
THEN
a) Sometimes later articles show they go do more homework.
b) Sometimes you even get a person-generated email in reply.
c) and some.times they even invite you to stop by next time you’re in London.
I already took action 2) on this topic yesterday.
21 August 2007 at 4:44 PM
Re message 48 where Chuck Booth points out the playful allusion to Watson and Crick’s
What fun! Patriotism is dangerous medicine to fiddle about with, however, particularly in the current atmosphere where the percentage of American exceptionalism is increasing in toxicity, when calculations more fully account for biogeophysical feedbacks.
21 August 2007 at 4:48 PM
Re #38
Ref. #41
—–
Re #46
Dear Richard,
I agree with you. It is an unscientific assessment. But I travel around the world quite a bit and I am hearing this type of comment more and more. I did not wish to infer that it was scientific assessment, merely an observation that has a modicum of relevance to the discussion.
Besides the certain places that are getting cooler are fewer than the places that are getting warmer
Beyond that, the physical evidence in the melting of the glaciers is pretty much the smoking gun. Combine that with the observed increase in SST and stronger storms, et cetera…
By the way, I am not submitting the comments for peer review.
Thanks for the input,
21 August 2007 at 5:05 PM
Eric (skeptic) says: “What they forget is there are negative feedbacks elsewhere, particularly in the weather in a wetter world. Tim pointed one out in the Sahara.”
I think you’re entirely missing the point - there is significant uncertainty in the regional predictions, and much less uncertainty in the global predictions. Look at the observations and forget about the models for a second:
http://www.sciencemag.org/cgi/content/abstract/312/5777/1179
There, they look at the tropospheric and stratospheric temperature trends for 1979-2005 and find that there is a poleward shift of the tropospheric jet streams and their associated subtropical dry zones.
Other measurements show the increasing trends in Indian, Atlantic and Pacific seas-surface temperatures. The notion that higher sea-surface temps means more evaporation means more precipitation over Africa is just too simplistic.
As yet another contributing factor, the deforestation in West Africa means less evapotranspiration over land surfaces and a possible related decrease in precipitation.
Any honest person would include all these factors - the anthropogenic CO2 forcing, the intrinsic natural climate variability, and the effects of deforestation. What the denialists are doing is just picking those factors that support the notion of ‘beneficial natural global warming uninfluenced by humans’ and ignoring all the others.
If you really want to understand what’s going on, you can’t leave anything out. If you want to promote a certain position, than you only include evidence that supports that position - which is the difference between scientific work and public relations work.
Note - people are just now starting to come up with physical models that explain the formation of jets in the atmosphere. One concept here is ‘jumping jets’ - a possible example of a planetary-scale transition or tipping point. It refers to the tendency of some jets to reposition themselves (and their associated climates) suddenly when the climate forcing reaches some threshold level. The change in jet stream positions over the US and the Atlantic during El Nino / La Nina is an example of this phenomenon. This helps explain the apparent contradiction between high sea surface temperatures and expanding dry regions. The drying American Southwest is another example of this effect.
21 August 2007 at 5:07 PM
Re 30: “His work depends on (among other things) the assumption that there’s only *one* characteristic timescale for global climate. Physically this would seem to be impossible; each component of the climate system (atmosphere, ocean, cryosphere) will necessarily have a different characteristic timescale.”
You’re understating the wrongness of Schwarz’s assumption, Tamino. Each of these components on the climate system has a whole range of time scales. Specifically the ocean (which is the component that is most relevant here) has a time scale for absorbing heat in its top metre or so, a longer time scale for mixing this heat down to the maximum seasonal mixed layer depth, a longer time scale again for subducting heat into the permanent thermocline and a very long time scale for warming up the whole thing. Thus between 1961 and 2003, global average SSTs increased by about 0.45 degC (AR4 WG1 Fig 3.4a), the average temperature of the layer to 700 m increased by about 0.1 degC (AR4 WG1 chap5 Sec 5.2.2.1 & Exec Summary) and the average temperature of the entire ocean increased by 0.037 degC (AR4 WG1 chap5 Sec 5.2.2.1).
Sorry this is a bit off-topic
21 August 2007 at 5:53 PM
I understand that permafrost thawing has sometimes been presented as a “tipping point”, even though it’s one of several contributing feedbacks. But the question is whether we have a good idea of the maximum likely carbon release (both existing methane and organics decay). With significant outgassing, perhaps it could become a stronger feedback despite being “globally well-mixed”? Along with oceanic methane spurts and other effects, we presumably still have the possibility of acceleration events tipping other elements in the system. Since we can’t determine how everything will play out, this is all quite an experiment.
21 August 2007 at 6:07 PM
Ike (#62), it’s a very good point to take into account all evidence. I believe Alistair (#22) does not. There are many potential warming and cooling effects as Steve (#51) points out. They all have to be taken into account and that’s when the tipping point tends to disappear. I agree with Ike, Nick (#23), Ray (#26), and Lawrence (#29) that the effects of the local tipping points will be global in many cases and difficult for life. But that does not make them global tipping points, just global effects. In a world with lots of local tipping points the global balance will certainly start to be affected, plus the effects may be messy enough that nobody will care what the global average is anymore. But the negative feedbacks, negative tipping points and numerous positive global side effects will be just as real.
21 August 2007 at 6:29 PM
Re #11: “The problem is genetic. The average human is just not good enough in math to survive the next 200 years.” Not true.
While we’re discussing Bayes Theorem and other areas of probability and statistics, others
out there are working on developing and improving alternatives to fossil fuels, such as fuel cells, solar panels, wind turbines, plug in hybrids and the like. Models are important much as Paul Revere was important in telling us what’s coming. The next step is to react. People in other developed countries have already made important changes.
See http://ec.europa.eu/energy/index_en.html.
Here in the U.S., we’re coming around to realize that energy efficiency is critical and that conservation is not just a “personal virtue” in the words of a very influential political figure. A penny saved is a lot more than a penny earned,especially when environmental effects are considered. You don’t have to look much farther than the record profits of oil companies and oil exploration companies in the past few years to see the cynicism in those words.
We don’t need to know tensor calculus or matrix or probabitiy theory to put a halt to what’s becoming more and more obvious with each passing year.
21 August 2007 at 8:04 PM
The way to handle the problem of parameterzation dependence of sampled estimates in statistics is pretty much along the same lines as Jeffreys’ prior; oddly enough Harold Jeffreys was a geophysicist.
21 August 2007 at 10:04 PM
The point of the butterfly effect in chaotic systems is that the resulting probability distribution IS independent of the distribution with which you started. Provided that you allow enough time to elapse in the model, the results from neighboring samples will be entirely independent. Both you and the Economist appear to be assuming that model output will vary smoothly with the input parameters, which is generally not the case for chaotic systems.
It is important not to confuse the probabilites that something will happen in a model with the probability that it will happen in real life. When X% of the ensamble elements of a model predict that something that means that that is the chance that it would happen providing that the initial starting condition is correct, that the model accurately captures the physics, and so forth. The chance that it will actually happen in real life must take into account these errors as well, which is sufficiently complicated that estimates of real life chances are not usually published.
21 August 2007 at 11:07 PM
I guess I don’t understand something at the end of this article. If the probability of any particular path in the simulation is not proportional to the probability of this path actually occurring, then why is it valid to average the ensemble of paths and claim that the average value of the (say) temperature increase is the same as the likely value of the actual temperature increase? What does the distribution of paths actually mean?
[Response: Fair point. The reason why the multi-model mean is used is because it empirically shown that it works the best at getting other observables correct. That implies that at least some of the errors are random and not systematic. But it doesn’t imply that there are no systematic errors remaining. - gavin]
22 August 2007 at 12:10 AM
Eric (skeptic): Seems like the “numerous” positive (”global”?) side-effects discussed by “skeptics” are often rather dubious or leave out caveats, and don’t appear to outweigh the negatives associated with the situation getting out of hand. And I’ve yet to see any successfully reviewed study suggesting negative feedbacks or “negative tipping points”(?) are strong enough to prevent that from happening. Seems that on timescales important to humanity, amplifying feedbacks are likely to rule.
22 August 2007 at 12:46 AM
I don’t know, I am only an old, near retiring age, bumbling general practitioner. I have no more qualifications to discuss AGW, tipping points or GIS melting than the next person, though I have studied these issues extensively on this site and others, I have John Houghton’s book, even read Fred Pearce’s book in 1989, but regrettably put that information in the back of my mind for the next decade. But having said that, I think my age, and my experience of life, and in particular, my experience of other people’s lives, and the normal course of physiology and the abnormal course of pathology, has gained me some insight into the how living systems do function and how they go wrong. Although James Lovelock doesn’t possess a clinical medical degree, he has worked in many medical fields and has a PhD in medicine. He certainly knows his physiology, and has applied that breadth of view in his theories about Gaia. I would suggest that this view point is of inestimable value when examining complicated issues like AGW.
My comments both about tipping points and Bayesian projections, and so much about AGW would be the same. I think we need, like a good physician, at the times you have something wrong with you and you don’t quite know what’s going on, to stand back a bit and look at the whole organism and the totality of its functioning. If the world was my patient, I would be very apprehensive about the prognosis, and the patient should be justifiably frightened.
For instance, take the comments about tipping points, are they local, are they global? This is not the issue. The loss of the Indian monsoon might not affect me here in New Zealand, but there are a billion people on the planet that it would. The loss of ice in the Arctic, (and this year surely brings us to the realisation that the tipping point in the Arctic is almost upon us - what chance no summer ice within ten years, or five years?) again might be remote to me, but to the Inuit and to those living in northern climes in Europe, who number many millions, it could be very troublesome. Increasing heat and dryness in the south-western USA would again adversely affect tens of millions directly and in the “breadbaskets” of the world, affect hundreds of millions in their food supplies. One thing we must understand is that the whole planet is local, we are all co-dependent on one small globe whizzing through the ether. We are several orders of magnitude larger than Easter Island, but we are just as isolated and just as vulnerable. I very much doubt there is such a thing as a “local” or “regional” tipping point. We are all in this together and too many such arguments seems to me the sort of thing that Rana temporia might have croaked on about in the heating pan of water.
Similar also are my comments on Bayesian predictions. This is all so esoteric, and seems almost to come down to the same sort of arguments that once exercised the best brains in Christendom as to how many angels can dance on the head of a pin.
So let’s stand back, and things become so much clearer.
There is, as far as we know, only one planet in the universe that can support life, and it is the one that supports us, and if something goes wrong with this planet, we cannot escape anywhere else.
We are called Homo sapiens sapiens, which supposedly should mean that we have the intelligence, properly directed, to deal with the sort of problem that besets us.
We have now almost all of us accepted the reality of AGW.
We are ourselves the direct cause of these problems. We know the world’s climate can change due to other factors not involving human agency, but for the moment, the threat of the heating world arises from our own actions.
It is, even with present technology and the power of many thousands of expert people’s minds, impossible to precisely predict the future but whatever the future, it is definitely going to be very different from today, perhaps as different as the ice-age planet was ten thousand years ago. We haven’t yet reached a one degree C rise in global temperature, but this year brings warning of the complete loss of arctic summer ice and the imminent collapse of the normal arctic climate. If less than one degree can do this, what will 2 degrees or even more accomplish?
Humanity has thrived in its present environment, which includes a relatively constant climate in the Holocene, hardly varying at all for ten thousand years. Humanity has come to occupy every ecological and climatic niche over this time. It is almost certain, because we have prospered in a relatively constant climate, that any change in that climate will bring many more problems than benefits. All our infrastructure, our housing, where we live, whether by rivers, lakes or coasts, our water supplies, our farms and farming practices, our industry, our fishing, our forests, are adapted to those niches and, almost by definition, any change in prevailing climatic conditions will mean that this infrastructure will not be best suited for the new climate.
We are now so numerous, and have already occupied all the most favourable areas of the Earth’s surface, that we won’t be able to move to avoid these climate difficulties, but will have to adapt our present investment and infrastructure to cope. The expense and the difficulty of this obviously is going to be massive, and has the capacity to severely reduce our wealth. It is likely that there will be some areas that this will in fact be impossible, e.g., the Ganges delta, Florida, flood plains, dry areas dependent on aquifers or glacial water feeds etc. It is likely that many areas, already full to the brim with humanity, will need to cope with tens of millions of climate refugees. Imagine New Orleans magnified a hundred-fold or more, even in a best-case scenario. .
We talk about 2 deg C of warming with some equanimity, as if this is not really going to be an issue, and of course we are already committed to at least 1.5 deg C of warming. Yet even this amount of warming could prove quite disastrous to some areas of the world, and there may be major climatic changes that we haven’t even envisaged. It is likely that the melting of the summer ice in the Arctic will be the first example of major climate change to cope with. Will the jet stream move south, north or stay where it is? Will increasing atmospheric moisture cause major increases in summer rainfall in northern latitudes, including North America and most of Europe. Will the floods the UK has seen this year become the norm and how could we cope if it did? We shall shortly find out.
Is anything that I have written under any serious dispute? Yet this last few weeks have seen Russia planting small flags on the Arctic Ocean floor, Denmark asserting territorial claims off the Greenland coast, and Canada promising to station hundreds of soldiers in its Arctic Territories, all with the object of securing sovereignty over the possible resources of the Arctic. These resources include of course, oil and gas; the Arctic is one un-explored region where large amounts of such fossil fuels could be found.
There is some sort of supreme cosmic joke here, though I don’t find it particularly humorous. That humanity should so poison our atmosphere as to permanently damage one of the Earth’s major climatic control mechanisms, then take advantage of this damage to damage our climate even more, is just so absurd, so stupid, so cosmically cretinous, as to beggar belief. It is the positive feedback mechanism to beat them all.
And yet, looked at from our present perspectives, it is hardly surprising. The vast majority of humanity hasn’t even noticed or commented. Here in New Zealand we are proposing to spend over a billion dollars in oil and gas exploration in the oceans to our south. Our commitment to continued economic expansion is almost total, and even threats to the health of our planet doesn’t cause us to waver in this.
I think we solve this quandary by looking at AGW in an entirely different way. To go back to my introduction, when I introduced myself as a physician, standing back, and taking the overview, not only has the physician a professional obligation to you and your welfare, and your family and children, but he has a moral obligation, which actually transcends this professional obligation. Furthermore, and this is the important point, this moral obligation is in fact no different in kind or degree to the moral obligations that we all have to each other in any case. It would be my contention that AGW is, as much as anything, a moral issue, the supreme moral issue of our times. Our moral obligation to our planet arises from our moral obligation to each other. Whilst we can certainly examine AGW from a scientific, political, economic, environmental or societal viewpoint, I don’t think we are going to get very far until we admit this moral perspective.
And this is why I believe that we should be looking at the morality of what we are doing. It brings everything back into focus. We continue to make the most appalling errors by treating this issue as one of pure logic. It would be nice to think that humanity could be guided by logic but, generally, this doesn’t happen. It is not logical to damage our planet any further, but it is not entirely illogical to try and sustain our present standard of living either, it has brought humanity many undoubted benefits. But by simplifying all these discussions and arguments to a simple moral perspective we avoid these pointless and irresolvable arguments. What we are doing to the planet and ourselves is immoral, here are some reasons why.
I could go on, I often do. But I will end with observing that there is now something distinctly Darwinian in what we are doing – in fact I think Darwin would have a good chuckle at our expense, if, as a humane man, he wasn’t weeping. We are the universe’s first species, as far as we know, intelligent enough to have discovered the theory of evolution, the principle of natural selection and survival of the fittest. What is now so ironic is that we seem determined also to be the universe’s first species to deliberately set out to prove it.
22 August 2007 at 3:05 AM
I know this is off topic, however Philip Stott wrote a letter into the Telegraph today which included this line:
‘First, new research indicates that our climate may be only one third as sensitive to C02 as has been assumed.’
What research is he talking about??
link to the letter - http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2007/08/21/nosplit/dt2101.xml
thanks
22 August 2007 at 5:32 AM
So the distribution of model results isnt a pdf of the climate system.
Then what does it tell us?
Should values, like the 11 degrees simulated by climateprediction.net, be considered ‘possible’?
Or is even the range meaningless?
[Response: Personally, I don’t consider 11 deg C possible. It’s interesting to see that a model can generate something like that, but whether it matches with the real world is key. Many of the subsequent analyses of the CPDN runs show that even modest requirements of TOA radiation balance for instance, none of the high end numbers survive the cut. - gavin]
22 August 2007 at 6:10 AM
“The way to handle the problem of parameterzation dependence of sampled estimates in statistics is pretty much along the same lines as Jeffreys’ prior; oddly enough Harold Jeffreys was a geophysicist.”
The problem is how to find the Jeffrey’s prior when the likelihood function isnt available analytically as a function of the parameters.
22 August 2007 at 6:34 AM
[[The really odd thing, for me, is that mathematically, the data themselves contradict his hypothesis of a single timescale for climate response. I believe I can show, beyond doubt, that the data he presents *reject* the idea of such a simple behavior, but Schwartz presents an argument (which I regard as invalid) that they confirm it.
I’m considering writing it up for JGR, and also considering doing a blog post on the subject.]]
I wish you would do the former (the latter would also be good). I’d love to see a paper in JGR from a regular poster here (other than the professional climatologists, that is).
22 August 2007 at 6:39 AM
[[http://personals.galaxyinternet.net/tunga/DefectiveGlobalWarming.pdf
“Why is the albedo of Venus important? When the albedo is at 0.80, the Global Warming Theory falls apart. . .]]
I looked at your reference. I’ve never seen a clearer example of pseudoscience. The paper starts getting things wrong right at the start, by saying global warming theory was invented “a few decades ago” — try 1896. It then goes on to say that airborne carbon dioxide “reflects thermal energy” — no it doesn’t, it absorbs it. And so on and so on. The author of your reference is a crackpot, clear and simple.
22 August 2007 at 9:51 AM
Re: #71
John,
Very interesting post, well stated. I approach the problem slightly differently. The problem with the morality argument is that there are those who will argue the immorality of needlessly disrupting societies and economies to chase a ’solution’ to a ‘non-existent problem’, or to a problem about which not enough is known to wisely choose a credible solution. There is a point to be made there.
The problem with the Darwinian argument is that many people do ‘get it’. Those who argue in favor of a BAU approach are not necessarily oblivious to the self-detructiveness of that stance; they simply understand that it will be others, not themselves, who will face those consequences. At its base, this approach can be defended as practical and rational, at least as far as it serves the near-term interests of those who hold it.
My approach is this: man has greatly accelerated his ability to alter his environment (Gore’s “bigger shovel” example in AIT). Man has not necessarily accelerated his ability to understand the consequences of these alterations. To some extent this blindness is useful, because we don’t know enough about future conditions and capabilities to choose too far in advance.
AGW is clearly a new paradigm. Each of us contributes the tiniest increments to the overall problem, but the comnbined, sustained contribution is a real problem. We don’t feel that, though: it’s a mighty chilly August here in Pennsylvania, for example. We don’t see it: CO2 is invisible and mostly odorless. We can’t always take specific measures to reduce our contribution, and when we do, we don’t always understand the consequences of THOSE choices.
Complex stuff.
Much too soon to judge our ability to learn from this experience. We are still in the bubbling cauldron of competing ideas.
I do not necessarily disagree with your views vis-a-vis morality and Darwinism, but I do not believe they are the root issues which confront us. I believe that the root issue is simply, man learning how to sort through myriad sources of information in order to make perceptive judgements. It’s almost impossible to imagine this process as something that can be done with any degree of rapidity, or as something with any sort of definable end-point.
22 August 2007 at 10:01 AM
re Dominic #72
Just to avoid any confusion, the Stott who wrote to the Telegraph is not the same person as Peter Stott, the climatologist at the Hadley Centre, who wrote the recent paper linking changing patterns of rainfall to Global Warming.
(I am also not the same person as # 70!)
22 August 2007 at 10:02 AM
RE 57.
Thanks Gavin.
22 August 2007 at 10:44 AM
RE # 45
Nigel, you said, [I dont think the Amber Waves comment is an error of judgement, It is a genuine image of how good ot could be if only we did what we know we shuld.]
The American diet relies upon that Amber grain (and the amber lager we love so well)and exports the surplus stock of those Amber Waves of grain.
Here is where I disagree with Dr. Hansen and all the ethanol advocates.
It is self-destructive to use the global grain basket to fuel our vacation trip to the beach. And, the ethanol industry is betting the farm on predictable climate conditions during the growing season in a world of record Arctic sea ice meltback and its conseguences for Western North American temp and precip.
22 August 2007 at 12:04 PM
Re John L. McCormick in post 80
I doubt that McCormick’s characterization of Hansen as an “ethanol advocate” is accurate, though I can understand how the footnote I quoted might lead one to that impression.
Regarding not what Hansen personally advocates anyhow, but what Hansen et al advocate in “Climate Change and Trace Gases:” their conclusion is: (1) That some means must be found to draw down atmospheric co2 concentrations. (2) If emissions from combustion of biofuels are sequestered (and sequestering looks like a tractable engineering problem), the result of such activity on a large scale would be to draw down atmospheric co2.
There are many interesting things about this proposal. One of them is that, where co2 extraction technologies are concerned, Hansen et al found none more efficient or promising than those which life has already developed: photosynthesis and respiration. Another interesting thing is this proposal’s implicit blithe dismissal of problems like the price of tortillas in Mexico.
Please remember, the point here isn’t “look how full of crap Hansen is,” the point is that even the most thoughtful people around (Hansen, for his courage through the decades, really is a personal hero of mine) make some intellectual blunders occasionally. I’ve even been known to stumble myself, believe it or don’t.
22 August 2007 at 12:40 PM
RE # 81, Daniel, I share your respect for, and appreciation of, Dr. Hansen and his contribution to our understanding AGW.
22 August 2007 at 1:03 PM
Re 71- I fully agree with this posting by John Monro.
I would add a growing concern that the stance of some denialists may include a hidden agenda. That agenda is basically this: “When things really begin to hit the fan and hundreds of millions or billions are in great distress, we will have to be strong enough to fend them off and let them die. Otherwise, they will overwhelm us and we will all go down together. So we have to push for continuing development and ward off any any action that might compromise our hegemonic position, even if that means accelerating the crisis.”
A note to denialists - I know this does not represent most of you, but please take care that this sort of idea does not creep into your thinking.
22 August 2007 at 1:32 PM
RE the “reticent scientists” thread (#7, 9, 19, 37, 44), I did my thesis on “Environmental Victimology,” and came to realize there are several perspectives:
(1) THE NAYSAYERS (often industrialists), who would prefer not to accept that a problem is happening, and would require more than 95% confidence it is (99, or even 101%
).
(2) THE SCIENTIFIC MODEL: Scientists usually require 95% or greater confidence to make a claim. They need to protect their reputations, so that people will go on believing them — so making false claims (alpha error) is much worst for them as professionals, than failing to make true claims (beta error). They cannot be the boy crying wolf. If they are, they get cut out of the loop.
(3) THE MEDICAL MODEL: Victims and potential victims of environmental harm, and environmentalists, and the general public (you’d think), would like to avoid environmental harm in the first place. They would be reticent to continue a practice that MIGHT be harmful to them or others. They would be greatly averse to failing to avoid a true harm (beta error). As are doctors and their patients when viewing test results — the doctor will not tell his patient he/she is are only 94% confident the lump is cancerous, so they won’t operate, and to come back next year to see if it’s made the 95% confidence interval.
So it’s usually potential/actual victims, environmentalists, and the public who are well in front of the false-claim-avoiding, reticent scientists in clammering for ameliorative action.
But this time it’s different (as scientists have themselves pointed out…and are scratching their head over); the scientists are the ones out in front clammering, while the public switches the dial to some entertainment channel.
I’ve been thinking for over 17 years (since I became active on the GW issue), that we’d reach some societal “tipping point,” and go into a very different state, a revitalization (or social) movement to address this issue (e.g., the 60s anti-war, civil rights, and feminist movements). I’ve been waiting…..
Of course, there is industry/government/media complex obstructionism, and a social movement’s need for many to perceive future/current harm to themselves, and the issue of GW being a bit slow-moving.
But now I’m thinking that there are these other socio-cultural-psychological negative feedbacks that are stalling this flip into action. For one thing, it’s a lot easier if there are single, identifiable perpetrators against which to rail. But it is we ourselves who are the perpetrators, though on the whole the greater perps will suffer the least, and the least (or non-perps) will suffer the greatest. The very poor, who are and will be suffering the most, tend to lack social mobilization resources….though the movement might come alive with them — or become a big world clash.
I’m thinking what this issue of mitigating global warming will take (at least on the part of the higher end perps, like us Americans) is very difficult, introspective work, self-examination, and humility. You’d think religions would be in the forefront, since that’s their province….but some of the greatest resistance I’ve seen is from the “religious,” and it seems religions (in addition to many good things they do) have this dsyfunction of helping people become self-righteous and impervious to acknowledging they might be doing something wrong. The religious do join social movements……against other people’s sins.
This is a tough nut to crack. But a great opportunity for some deep and true improvement in the (inner and outer) human condition. Like a real conversion to goodness and caring.
22 August 2007 at 1:36 PM
Re: #81
I have been thinking about the biofuels as sequestration idea for a while (not very deeply I admit!) but here is my noodling.
Suppose we come up with a scheme like that proposed by some UNH researchers to use green algae in closed tanks to produce biodiesel fuel stock. One could apply this technology in a number of ways.
One would be to hook it up to municipal waste water systems and have localities produce fuel stock that they could sell to refineries. This would be great for a number of US policy problems like improving balance of trade, removing the funding sources for unstable/repressive/hostile regimes, funding local government (imagine if your city ran at a profit like the State of Alaska) and so on.
But suppose for a moment that one could make the technology very simple and cheap. Tanks built from discarded plastic beverage bottles, feed stock from seaweed or other local biomass (think tropics where there is much poverty). storage in discarded steel drums or even the bottles themselves, a cottage industry of picking up the produce with circling trucks. This would become (for a while) an easy way to make money and if the technology is simple/viral enough, we get sequestration out of the deal too. Once we have reached break-even on energy generation, we could continue to buy the fixed carbon for sequestration, energy supply buffering (think strategic petroleum reserve) or even maufacturing (plastics). If it gets too out of control, the market will drop the price too low for even poor Indonesian farmers and they will be left with a system that simply makes them self-sufficient in energy.
Anyway, just an idea.
22 August 2007 at 1:44 PM
I’m also thinking there’s probably a difference among different types of scientists. A geologist won’t be losing his/her focus of scientific interest for billions of years, but biologists may be losing their species of scientific focus, and might be more vocal in their speaking out against GW.
The death of an organism (a person, animal, or plant) is not only a tipping point, but a tipping point of no return (as opposed to climate “hysteresis” (#35), which is more like an extreme fever that eventually goes back down).
So is extinction of species.
22 August 2007 at 2:00 PM
Re #71 Where Doc Munro ended:
We are the universe’s first species, as far as we know, intelligent enough to have discovered the theory of evolution, the principle of natural selection and survival of the fittest. What is now so ironic is that we seem determined also to be the universe’s first species to deliberately set out to prove it.
It is highly unlikely that we are the Universe’s first species, which leads to Enrico Fermi’s Paradox - Where are they? See:
http://en.wikipedia.org/wiki/Fermi_paradox
The paradox is easily resolved if we assume that any species that developed intelligence would inevitably be aggressive, since it would have developed through the process of the survival of the fittest. Like us, they too would burn their planet’s fossil fuels as if there was no tomorrow. They too would not only cause the end of their civilisaton, but also the end the prospect of any new civilisation because the natural resources needed to advance beyond the stone age had already been squandered.
22 August 2007 at 2:02 PM
Here’s something re what to expect from 2100 temps — no ice cap (I guess this is another nail in the denialist arguments):
22 August 2007 at 2:37 PM
Lynn, that’s apparently referring to something now in Nature.
I followed their link back as far as Reuters.
http://uk.reuters.com/article/scienceNews/idUKL2286724920070822
“… In the period his team studied, the earth had about as much carbon dioxide in the atmosphere as scientists predict may be present in 100 years, so the findings also offer clues as to how rising greenhouse gas levels may affect the planet, Wilson said.”
22 August 2007 at 4:02 PM
I think the world is naive if they continue to blind themselves towards our environmental issues. It’s time we open our eyes and see all of the symptoms that occur every day. The symptoms for the “tipping point” are happening as we speak.
Whether or not there is a tipping point, we need to act as if we are drawing near the tipping point. Politicians twiddle their thumbs at the mercy of corporations. We have no time to wait, our world is in a dire state and something needs to get done, now.
www.globalwarminglife.com
22 August 2007 at 5:36 PM
Eric says:”But the negative feedbacks, negative tipping points and numerous positive global side effects will be just as real.”
That statement would be more believable if you were to attempt to give some (any) examples of such “positive global side effects” or “negative tipping points”.
A number of comments above point to the need to ‘do something’, but let’s just spell it out - we need to end the use of fossil fuels on a global scale, and we need to put an end to deforestation, particularly in the tropics.
Doing this creates a big problem - what source of energy will humans use in the future? Solar and wind are huge energy sources that are largely untapped. If we start with replacing all fossil fuels used in agriculture with solar / wind power (coupled to efficient energy storage systems, of course), than you can get agriculture off fossil fuels. Once that is done, you can examine the issue of sustainable biofuel production.
The basic point is that a blend of renewable energy sources will be required. A lot can be learned from traditional energy sources - i.e. synergy matters. For example, you can use solar thermal heating to provide a good deal of the energy needed for ethanol distillation. As many have pointed out, one acre of biofuel crops provides enough fuel to work that field for decades. Put all these energy sources and storage mechanisms together - sunlight, wind, photosynthesis and improved technology - and you have enough energy for all, with no need for nuclear power or coal carbon sequestration.
If one includes human activity within the ‘Earth system’, then a rapid transition to a renewable economy would be an example of a ‘negative tipping point that counters the projected long-term effects of global warming’.
22 August 2007 at 6:41 PM
I’m pretty much convinced now that the climate is changing due to CO2 polution.
I’d like to be pointed a reasonable site discutting prospective :
- what could be done
- what will likelly be done (my personnal bet is : too little too late, starting in 10 to 20 years when politicians feel the anger of Joe Sixpack the voter who finally got flooded or desertified)
- who will loose
- who will win
anyone can point to such a site ?
[Response: Try http://www.climatepolicy.org/ or http://www.cleantechblog.com/ - gavin]
22 August 2007 at 6:52 PM
re 83: “a growing concern that the stance of some denialists may include a hidden agenda… ”
I’m positive this is true, as it is for many proponents of the AGW theory. Might be best to just leave the factions of both camps alone, though I have to admit their cacophony sometimes just can’t be ignored.
22 August 2007 at 7:01 PM
Actually there has been a set of environmentalists that for some time now have the survival and enhancement of the human species way way down on the priority list. Granted they’re the fringe, but they’re fun to talk about…
22 August 2007 at 7:09 PM
“Politicians twiddle their thumbs at the mercy of corporations. We have no time to wait, our world is in a dire state and something needs to get done, now.
www.globalwarminglife.com
Comment by Heigi Blume ”
I have in my hands a photocopy from Science 10 February 1989 pp 771-781. “The Greenhouse Effect: Science and Policy” Stephen H. Schneider.
“Within the past year (1988) cover stories of both time and Newsweek have featured global warming from the green house effect and ozone depletion from industrial chemicals. The intense heat, forest fires, and drought of the summer of 1988 and the observation that the 1980s are the warmest decade on record have ignited an explosion of media, public, and governmental concern that the long debated global warming has arrived-and prompted some urgent calls for actions to deal with it. For example, the National Energy Policy Act of 1988 to control carbon dioxide emissions was introduced by Senator Wirth in August 1988, and hearing were held on 11 August. At that hearing,, there were sharply conflicting views about whether policy actions are premature given the many remaining scientific uncertainties. Whether some amount of scientific uncertainty is ‘enough’ to justify action or delay it is not a scientific judgment testable by any standard scientific method. Rather, it is a person value choice that depends upon whether one fears more investing present resources as a hedge against potential future change or, alternatively, fears rapid future change descending without some attempt to slow it down or work actively to make adaptation to that change easier.”
So although the science has improved during the past 18 years, the politicians and corporations haven’t. They and the media are not guilty so much of lying in what they say, they are guilty of lying by NOT saying things to the general public.
Business as usual.
I wish our resident skeptics and denialists could see this article and research what is contained in the footnotes. Then they’d begin to understand the science behind climatology and that very little of Realclimate is ‘new’. And that delay of action was ALWAYS the game plan. (And I wish archived issues of Science were available online to non-subscribers.)