Buy

Books
Click images for more details

Support

 

Twitter
Recent comments
Recent posts
Currently discussing
Links

A few sites I've stumbled across recently....

Powered by Squarespace

Discussion > Feedbacks and Forcings

RKS, It is clear the ho ho BBD has no intention of answering the questions raised and instead feeds off people's responses by spinning out further and further distractions.

Best of luck pinning his slipperiness down.

Aug 3, 2012 at 11:14 PM | Registered Commentershub

typo: open systems are not predictable (i.e. unpredictable)

Aug 3, 2012 at 11:11 PM | September 2011>>>>

The eco-loons found that out in the 1980's when they tried to model the eco-system.

The more data they put in, the more chaotic was the result.

A whole generation of students had to go back to the drawing board.

Aug 3, 2012 at 11:16 PM | Unregistered CommenterRKS

suggests that BBD is the Barbara Cartland of climate science...heavily made-up and totally vacuous

Aug 3, 2012 at 11:16 PM | Unregistered Commenterdiogenes

RKS, It is clear the ho ho BBD has no intention of answering the questions raised and instead feeds off people's responses by spinning out further and further distractions.

Best of luck pinning his slipperiness down.

Aug 3, 2012 at 11:14 PM | shub>>>

Quite right as usual.

I tried to respond to Rhoda's post on Mike Jackson's reference to N&Z.

Of course, the BBD entity jumped in and diverted the discussion.

Thanks for your timely interjection.

regards.

Aug 3, 2012 at 11:20 PM | Unregistered CommenterRKS

One reiteration/clarification and I'm done. There is no quick average number which can be applied for forcing/feedback estimation for the globe. Those numbers like x degrees per doubling are misleading over-simplifications. Those cycles they tell you about are deceptive too. There are numerous proposed cycles. Solar, Ocean, orbital, whatever. The result is that interactions between them and the land use and GHG forcings produce effects which need never be repeated or predictable. To think otherwise is hubris. To ask for sixty million quid to buy a better computer which is SURE to finally do it is, well, cheeky. I am inclined to ask for my pound back.

Aug 3, 2012 at 11:55 PM | Registered Commenterrhoda

Rhoda

One reiteration/clarification and I'm done. There is no quick average number which can be applied for forcing/feedback estimation for the globe.

Perhaps the aggregate effect might show up if we look at regional temperature change over time? Go here, scroll down to 'Global surface temperature' and have a play with the 'Time series 1884 - 2010' visualisation. Slowly drag the slider below the window to the right. What do you see?

Aug 4, 2012 at 12:21 AM | Unregistered CommenterBBD

rhoda, BBD is not helping and his counterquestions are, well, cheeky. You'd almost think BBD hasn't heard of the so called Little Ice Age. (Sorry BBD, since you never answer my questions I have lost the interest for the moment to speak to you directly.)

Aug 4, 2012 at 1:20 AM | Unregistered CommenterSeptember 2011

BBD links to the 'Time series 1884 - 2010' at NASA's web site. How many thermometers were, for instance, in the Arctic?

Aug 4, 2012 at 1:29 AM | Unregistered CommenterSeptember 2011

BBD:"Oh dear. Look, the large carbon isotopic excursion is the *fingerprint* of what was quite possibly a huge release of methane from clathrates. You are horribly confused, aren't you?"

Well yes I am confused. First of all our resident know-it-all tells us that the Eocene warming was produced by a release of CO2 caused by the collision of India with Eurasia. So I go to the text books which tell me that the conventional wisdom is that the rise in temperature of the late PETM and early Eocene was likely caused by methane calthrates, from which I deduced the the consequent rise in CO2 was caused by the rise in temperature, as you would expect from the ice cores.

I also pointed out that the India had not begun its collision with Eurasia at the start of the Eocene so could not have been responsible for for the rise in CO2, as you had indicated. I don't recall what mechanism you invented for the production of the CO2, but either way it doesn't fit with the explanations in the text books.

So yes, I am confused, confused by your explanation of the CO2 rise causing the Eocene warming when the text books tell us they believe it was methane calthrates and confused by the explanation you gave for the rise in CO2 being India's collision with Eurasia an event which took place millions of years after the rise in temperature at the beginning of the Eocene. Of course you could just be making it up, (like your explanation for why the positive feedback is dampened - the conservation of energy!), but I doubt it, probably information gleaned from Skeptical Science.

Aug 4, 2012 at 8:10 AM | Unregistered Commentergeronimo

The whole forcing and feedback situation should hopefully get much clearer from the data over the next few years. As I believe the majority of temperature changes are due to solar and ocean circulation changes and the forecasts for these are generally for no change or falling changes I would be surprised if temperatures increased this decade. If temperatures significantly went up I would review what may be the cause of it.

With the data as it stands there is still too much ambiguity that can be read either way if trying defend a single point of view.

Aug 4, 2012 at 10:18 AM | Unregistered CommenterRob Burton

Second, who says it's warming on Mars? There's a common misconception based on albedo change, but it's one of those sceptic memes that turns out to be nonsense.

(2005) According to a September 20 NASA news release, "for three Mars summers in a row, deposits of frozen carbon dioxide near Mars' south pole have shrunk from the previous year's size, suggesting a climate change in progress." Because a Martian year is approximately twice as long as an Earth year, the shrinking of the Martian polar ice cap has been ongoing for at least six Earth years.
The shrinking is substantial. According to Michael Malin, principal investigator for the Mars Orbiter Camera, the polar ice cap is shrinking at "a prodigious rate."
The images, documenting changes from 1999 to 2005, suggest the climate on Mars is presently warmer, and perhaps getting warmer still, than it was several decades or centuries ago.

(2002) Pluto is undergoing global warming, as evidenced by a three-fold increase in the planet's atmospheric pressure during the past 14 years, a team of astronomers from Massachusetts Institute of Technology (MIT), Williams College, the University of Hawaii, Lowell Observatory and Cornell University announced in a press conference today at the annual meeting of the American Astronomical Society's (AAS) Division for Planetary Sciences in Birmingham, AL.
The team, led by James Elliot, professor of planetary astronomy at MIT and director of MIT's Wallace Observatory, made this finding by watching the dimming of a star when Pluto passed in front of it Aug. 20. The team carried out observations using eight telescopes at Mauna Kea Observatory, Haleakala, Lick Observatory, Lowell Observatory and Palomar Observatory. Data were successfully recorded at all sites.

Suggestive correlations between the brightness of Neptune, solar variability, and Earth's temperature, Hammel & Lockwood (GRL) 2007

(1998) We're not the o nly ones experiencing global warming. A Massachusetts Institute of Technology researcher has reported that observations obtained by NASA's Hubble Space Telescope and ground-based instruments reveal that Neptune's largest moon, Triton, seems to have heated up significantly since the Voyager space probe visited it in 1989. The warming trend is causing part of Triton's surface of frozen nitrogen to turn into gas, thus making its thin atmosphere denser.
While no one is likely to plan a summer vacation on Triton, this report in the June 25 issue of the journal Nature by MIT astronomer James L. Elliot and his colleagues from MIT, Lowell Observatory and Williams College says that the moon is approaching an unusually warm summer season that only happens once every few hundred years. Elliot and his colleagues believe that Triton's warming trend could be driven by seasonal changes in the absorption of solar energy by its polar ice caps.
"At least since 1989, Triton has been undergoing a period of global warming. Percentage-wise, it's a very large increase," said Elliot, professor of Earth, Atmospheric and Planetary Sciences and director of the Wallace Astrophysical Observatory. The 5 percent increase on the absolute temperature scale from about minus-392 degrees Fahrenheit to about minus-389 degrees Fahrenheit would be like the Earth experiencing a jump of about 22 degrees Fahrenheit.

Admittedly only one of those was a peer-reviewed journal publication and the rest were press releases but it seems like a good starting point.
Question: If two-thirds of measuring stations show a rising trend and one-third show a falling trend, on what basis is the warming truly "global"?

Aug 4, 2012 at 10:36 AM | Registered CommenterMike Jackson

Aug 3, 2012 at 7:31 PM | BBD

Sorry, but I don't buy the random walk stuff because it violates conservation of energy.

A random walk is very easy to generate in the presence of white noise. It even occurs in the simplest energy balance model, the one often used to justify Δ F = λ Δ T. Of course, it only appears to be a random walk, because it eventually flattens out after a few days into a white noise: nonetheless, prior to this transition it is barely distinguishable from a proper random walk.

Furthermore, it is also straightforward to construct scenarios in which a similar pattern results from the accumulation of small variations in albedo and emissivity, and in which the eventual flattening out happens only after thousands of years. I have no idea whether any such scenario occurs in reality, but if it did it would go some way to explaining the observed background spectrum.

Such a scenario does not violate conservation of energy, because the changes to albedo and emissivity modify the amount of energy entering and leaving the system (as also mentioned earlier by Rhoda).

I'm aware that you want to find a way to argue that a random walk pattern cannot be responsible for the continuum. However, I think that to do this you need to demonstrate that such small changes in albedo and emissivity either cannot or do not occur naturally.

Ah, no. You may find this interesting...

OK, I see where you are coming from and agree I may have read too much into your earlier comment. To clarify my own position, I do accept that the orbital cycles are likely to play some kind of "pacemaker" role in the glacial cycles. However, they cannot by themselves explain the background spectrum (not even including all four of the cycles you mention).

One of the authors of your citation (PH) wrote a year later that "variations would presumably still exist" even in the "absence of annual or Milankovitch variations" (echoing Swanson's comments). In the same paper, he conjectured that "the climate system has a memory associated with the oceans that causes high-frequency variability to accumulate into progressively larger and longer-period variations, and a Milankovitch-driven low-frequency response that transfers spectral energy toward higher frequencies, possibly involving nonlinear ice-sheet dynamics."

From these comments, the background is at least partially explained as a response to orbital and annual forcing which moves spectral energy towards higher and lower frequencies respectively. In this picture, the movement of spectral energy is (at least partially) responsible for the variability over the 1000 yr time-scale. But if so, this means that the same 1000 yr variability cannot also be entirely a direct result of forcing.

A similar conclusion is made in the L&S paper I referenced earlier. Forcing over millenial time scales is not by itself able to explain millenial variability. Instead, the long-term climate system response must be invoked, and this is itself a scaling function, and not necessarily directly correlated to forcing: "the usual definition of climate sensitivity is only valid if there is a causal link: the fluctuations ΔT and ΔRF must have the same underlying cause such as a change in solar output". So what is the direct cause of the variability? I imagine explanations might include recycling of energy through the deep ocean and accumulated small natural changes in albedo and emissivity.

Aug 4, 2012 at 10:57 AM | Registered CommenterPhilip Richens

Aug 2, 2012 at 7:09 PM BBD

This is the point I keep on trying to make: *if* feedbacks net neutral or negative *then* the kind of variable climate we know we have would be a physical impossibility. Simple deductive reasoning demonstrates that feedbacks must, therefore, net positive. We might not know the detail about cloud feedbacks, but we can infer that your assumption above is incorrect. Do you accept this?

I think this ["negative feedback stabilises things" - to paraphrase] oversimplifies things.

Things with complicated dynamics and negative feedback can exhibit all sorts of unexpected behaviour, including instability.

Any electronics engineer who has had to use high gain amplifiers with large amounts of negative feedback (= any electronic engineer) knows that you can have unexpected effects where, due to phase shifts at high frequencies, the feedback becomes positive at some frequencies, even though it was intended to be negative feedback - and remains negative feedback at low frequencies. The more there are time lags in the system, the more extreme these effects become.

Unexpected amplification of random noise at high frequencies (= short timescales) is entirely consistent with negative feedback in systems with complicated dynamic behaviour. So far as climate is concerned, I am not sure what constitutes "short" timescales - decades? centuries?

Incidentally, feedback stability theory makes clear the validity of Rhoda's point that averaging feedbacks gives something that is utterly meaningless.

Aug 4, 2012 at 11:01 AM | Registered CommenterMartin A

Mike Jackson: You don't think for one minute do you that BBD is going to accept the paper or the news announcements as evidence that Mars, or any other body in the universe is simultaneously warming with the Earth do you?

As we speak he'll be scouring past copies of Skeptical Science to produce a repudiation, complete with a bafflingly long list of peer-reviewed papers from the usual suspects.

Good luck, but I don't think the point will be conceded.

Aug 4, 2012 at 11:09 AM | Unregistered Commentergeronimo

A new, pay walled paper by A.E. Dessler, obviously concerning the "net negative feedbacks" (cf. f.ex. also BBD's and matthu's points here), titled: "Observations of climate feedbacks over 2000-2010 and comparisons to climate models".

Hockeyschtick writes:

A paper published this week in the Journal of Climate finds from observations that the global climate stabilized from 2000-2010 due to net negative feedbacks. The IPCC erroneously assumes net feedbacks are positive resulting in a 'runaway greenhouse effect'. The net negative feedback of -1.15 W/m^2/K found by this paper is almost the same as the positive forcing alleged to occur from a doubling of CO2 levels [1.3 W/m^2/K], which would take over 200 years to occur at the present rate.

Aug 4, 2012 at 12:22 PM | Unregistered CommenterSeptember 2011

Good luck, but I don't think the point will be conceded.
You surely don't really think I'm that naive, geronimo, do you?
But it makes me feel better.<;-))

Meanwhile ...... Dessler has either come up with something interesting or got himself in big trouble with The Team.
If the global climate stabilised in the first 10 years of this century — which most of us on this side of the fence believe but this is the first time I've heard someone from the main stream admit it — and this was the result of "net negative feedbacks", then we really do need to know what those negative feedbacks were. If they turn out to be increased clouds I am definitely going to demand my Nobel Prize!
The question, of course, is whether there were any positive feedbacks which have now been overturned by these negative ones or whether, as has been suggested but not as yet proven, the feedbacks lways were negative.
Or whether there is any truth in the (increasingly popular) hypothesis that CO2 is not and never was guilty of the charge against it.

Aug 4, 2012 at 2:21 PM | Registered CommenterMike Jackson

If the temp didn't move over the last ten years you would not expect to see a temp feedback, positive or negative. You'd have to look further back. Unfortunately the albedo record is mixed and you'd need to be able to work out the lag in response. I would guess the usual data/noise problem would prevent attribution. As it always does, even if the met say they can see past that. They are only fooling themselves.

Aug 4, 2012 at 3:37 PM | Registered Commenterrhoda

In a casual trawl around my favourite sites (I'm waiting for the heptathlon 800 metres, you understand), I came across this on Matt Ridley's 'Rational Optimist' blog. It's from part 3 of a series of articles under the general title The perils of confirmation bias

It isn't just models, but the interpretation of real data, too. The rise and fall in both temperature and carbon dioxide, evident in Antarctic ice cores, was at first thought to be evidence of carbon dioxide driving climate change. Then it emerged that the temperature had begun rising centuries earlier than carbon dioxide. Rather than abandon the theory, scientists fell back on the notion that the data jibed with the possibility that rising carbon dioxide levels were reinforcing the warming trend in what's called a positive feedback loop. Maybe-but there's still no empirical evidence that this was a significant effect compared with a continuation of whatever first caused the warming.
There is nothing unfamiliar in there; it has been understood for several years that — coming out of ice ages at least — CO2 lags temperature by up to about 800 years. Some interesting hypotheses have been trailed as a result of this discovery, none perhaps more so than those aired here by spartacus (or mydog, or whatever name he's using these days). Whether he is right he is certainly not wrong when he says that, having had the CO2 rug pulled from under their pet theory, the 'climate change enthusiasts' (H/T to Grant B for that phrase - see Unthreaded - one which I plan to use in future) simply shrugged their shoulders and seamlessly carried on with a new piece of science fiction since, as Ridley points out, they simply declared — in the face of no empirical evidence — that at a certain point the CO2 that was caused by warming suddenly started to cause warming. Neat one!
Now if we think about that in the context of the work of Nikolov & Keller and really concentrate hard on what has happened we can ask the question and hope for an answer (from BBD for a start, perhaps).
Until better evidence came long it was assumed that temperature and CO2 rose in something resembling lockstep. The discovery that CO2 lagged temperature —even by a day (ok, I exaggerate) — drives a massive hole in the climate change enthusiasts' (not to mention the eco-activists) argument for the anthropogenic aspect of global warming.
Remember, the idea that CO2 causes warming was initially proved to be false and reinstated by fiat with no empirical evidence to support the concept. As Ridley concludes: where is the evidence that continued warming is not the result of continued activity by what caused the warming in the first place?

Aug 4, 2012 at 9:36 PM | Registered CommenterMike Jackson

geronimo

Well yes I am confused. First of all our resident know-it-all tells us that the Eocene warming was produced by a release of CO2 caused by the collision of India with Eurasia. So I go to the text books which tell me that the conventional wisdom is that the rise in temperature of the late PETM and early Eocene was likely caused by methane calthrates, from which I deduced the the consequent rise in CO2 was caused by the rise in temperature, as you would expect from the ice cores.

The PETM was a geologically short-lived spike of super-warming on the temperature up-slope leading to the peak of the Eocene hothouse climate. It *isn't* the Eocene hothouse. Argument as to what caused the PETM continues, but a large carbon isotopic excursion is associated with the initial warming. Seafloor methane hydrates are a key suspect for the source, arguably warmed to instability by the general increase in GAT. The PETM was was a consequence of the ongoing tectonic forcing, not the thing itself.

H&S12:

India was the only land area located far from its current location at the beginning of the Cenozoic. The Indian plate was still south of the Equator, but moving northward at a rate of about 20 cm per year (Kumar et al., 2007), a rapid continental drift rate. The Indian plate moved through the Tethys Ocean, now the Indian Ocean, which had long been the depocenter for carbonate and organic sediments from major world rivers.

The strong global warming trend between 60 and 50 My ago was presumably a consequence of increasing atmospheric CO2, as the Indian plate subducted carbonate-rich ocean crust while traversing the Tethys Ocean (Kent and Muttoni, 2008). The magnitude of the CO2 source continued to increase until India crashed into Asia and began pushing up the Himalaya Mountains and Tibetan Plateau.

The 'until' addresses your next point:

I also pointed out that the India had not begun its collision with Eurasia at the start of the Eocene so could not have been responsible for for the rise in CO2, as you had indicated. I don't recall what mechanism you invented for the production of the CO2, but either way it doesn't fit with the explanations in the text books.

And no, this information was not gleaned from Skeptical Science :-)

Aug 4, 2012 at 11:47 PM | Unregistered CommenterBBD

Philip Richens

Forcing over millenial time scales is not by itself able to explain millenial variability. Instead, the long-term climate system response must be invoked, and this is itself a scaling function, and not necessarily directly correlated to forcing: "the usual definition of climate sensitivity is only valid if there is a causal link: the fluctuations ΔT and ΔRF must have the same underlying cause such as a change in solar output". So what is the direct cause of the variability? I imagine explanations might include recycling of energy through the deep ocean and accumulated small natural changes in albedo and emissivity.

While I agree with much of what you say, let's let the subtext rear its ugly head. If the heat is coming from the ocean the deep water should be cooling. Observations show warming to 2000m so unless the ocean is being heated from below it is being warmed from above.

Aug 5, 2012 at 12:09 AM | Unregistered CommenterBBD

Re: Aug 5, 2012 at 12:09 AM | BBD

Given the know preference for positioning heat monitoring devices next to air conditioning units and at airports I wouldn't be surprised if they were similarly positioned in the oceans - ie over underwater volcanoes!!!

Aug 5, 2012 at 9:41 AM | Unregistered CommenterMarion

My apologies for mis-naming Zeller as Keller last night. I couldn't for the life of me remember the other half of Nikolov and ... and relied on a post that had also evidently had a senior moment! The argument still holds, however!

Aug 5, 2012 at 11:35 AM | Registered CommenterMike Jackson

My apologies for mis-naming Zeller as Keller last night. I couldn't for the life of me remember the other half of Nikolov and ... and relied on a post that had also evidently had a senior moment! The argument still holds, however!

Aug 5, 2012 at 11:35 AM | Mike Jackson>>>>

That was my fault Mike, I've even called Ned 'Nick' at times.

I've already offered my apologies to Chris M on Unthreaded.

Aug 5, 2012 at 12:27 PM | Unregistered CommenterRKS

It was indeed you, RSK or KRH or whatever your name is! But since we all make mistakes I didn't see any reason to tell everyone.
I assume that this blatant error doesn't change the basic science in any way? [:—)

Aug 5, 2012 at 2:32 PM | Registered CommenterMike Jackson

It was indeed you, RSK or KRH or whatever your name is! But since we all make mistakes I didn't see any reason to tell everyone.
I assume that this blatant error doesn't change the basic science in any way? [:—)

Aug 5, 2012 at 2:32 PM | Mike Jackson>>>

The science remains as solid as ever Myke.

regards :-)

Aug 5, 2012 at 2:57 PM | Unregistered CommenterRKS