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Post by socold on Oct 30, 2009 0:38:03 GMT
Akasofu's projection is nothing more than curve fitting. He's just assumed the background trend must be linear and assumed that there is an exactly repetitive cycle over the top. Neither of those is necessarily the case. And as Steve points out Akasofu's graph contains too much warming in the early 20th century, without which the linear trend plus repetitive cycle wouldn't fit the data. To fit the actual surface temperature records Akasofu would require a linear trend plus a non-repetitive cycle. Swanson and Tsonis recently attempted to derive (not assume, like Akasofu) the contribution of natural variation on the temperature record and they found the background warming trend is not linear, but resembles an exponentially increasing curve. And that natural variation is not a repetitive cycle. I am certainly not assuming the Swanson and Tsonis result is correct, it might not be. But I think it is certainty more credible than the Akasofu graph. Also has the PDO contributed warming or cooling in the past 30 years? www.woodfortrees.org/plot/jisao-pdo/plot/jisao-pdo/from:1980/trend
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Post by icefisher on Oct 30, 2009 3:12:36 GMT
Akasofu's projection is nothing more than curve fitting. He's just assumed the background trend must be linear and assumed that there is an exactly repetitive cycle over the top. Neither of those is necessarily the case. And as Steve points out Akasofu's graph contains too much warming in the early 20th century, without which the linear trend plus repetitive cycle wouldn't fit the data. To fit the actual surface temperature records Akasofu would require a linear trend plus a non-repetitive cycle. Swanson and Tsonis recently attempted to derive (not assume, like Akasofu) the contribution of natural variation on the temperature record and they found the background warming trend is not linear, but resembles an exponentially increasing curve. And that natural variation is not a repetitive cycle. I am certainly not assuming the Swanson and Tsonis result is correct, it might not be. But I think it is certainty more credible than the Akasofu graph. Also has the PDO contributed warming or cooling in the past 30 years? www.woodfortrees.org/plot/jisao-pdo/plot/jisao-pdo/from:1980/trendTo get your graph you have to switch to the Jim Hansen enhanced version of history and his GISS "value added" temperature line. But even then the curve is not fit well with a big bump on the inside of the curve a little teensy bumps on the outside. We are aware of those manipulations. Akasofu's graph apparently uses a smoothed Hadcrut record it appears as you can plant it right on top of the smoothed data provided by Hadcrut and get almost a perfect fit. But you are right the trend may well not be linear but thats precisely Akasofu's point. We need to better understand natural variations. Just running around and offering quadratic equations for better fits does not provide us much more information over a linear fit. The LIA recovery may well have been an accelerating phenomena driven by the solar grand maximum which accelerated in the last half of the 20th century. . . .and so far both the Farmers Almanacs have been doing a better job of forecasting the seaons than either NOAA or the Met.
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Post by sigurdur on Oct 30, 2009 3:29:05 GMT
Oh Icefisher: We all know that the Farmers Almanac has at leastttttt 40 times the budget of NOAA. Why they have numerous satillites, a huge data base of thermometers which are accurate to the 100th degree. With that kind of data base and funding....how could they be wrong most of the time?
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Post by sigurdur on Oct 30, 2009 3:30:04 GMT
Oh Icefisher: We all know that the Farmers Almanac has at leastttttt 40 times the budget of NOAA. Why they have numerous satillites, a huge data base of thermometers which are accurate to the 100th degree. With that kind of data base and funding....how could they be wrong most of the time? oops......."How could they not be RIGHT most of the time"
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Post by kiwistonewall on Oct 30, 2009 4:36:56 GMT
Back onto this thread's topic: The greenhouse effect is "approximately" constant. This doesn't mean that it is EXACTLY a constant, but any changes in greenhouse effect are unlikely to produce "runaway" heating.
Looking at this in another way,
the critical input is the TSI (mostly a constant!). This will be balanced by outward radiation (of all types). The outward radiation from thermal energies (the greenhouse effect operates in the thermal) is dependent on the fourth power of temperature. Thus any tiny increase in the temperature of the atmosphere is going to lead to a massive increase in outward radiation.
The greenhouse effect is thus a "Stable equilibrium" - which is an equilibrium state which is hard to displace in either direction.
Warm the atmosphere - radiation outwards rises as T^4. Cool the atmosphere, and the opposite happens. The chance of the greenhouse effect becoming unbalanced is infinitesimally small.
The BIG energy factors (at the high energy UV, Vis & near IR - i.e. non greenhouse EMR) are going to drive climate change - Albedo, clouds etc.
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Post by steve on Oct 30, 2009 10:18:06 GMT
No, the IPCC case does not rely on just that mid-70s to mid-90s period. And the Akasofu graph is a distortion because it exaggerates the lenght and height of the 1940s warmer period (try printing off HadCRUT3 and drawing the line yourself), it includes a fantasy that prior to 1880 it was cooler (it wasn't) and that post 2008 it will cool (2009 is warmer and 2010 will be warmer as well). I think you will find that Akasofu's trend lines from peak to peak very closely approximates the smoothed data provided by the Hadcrut website. Clearly its within a tenth of a degree and we have that much divergence between the various temperature records. So the argument that Akasofu's data is proven wrong by the Hadcrut dataset is essentially a non-starter within the observed data window. And you will need to provide some credible evidence that there was no LIA to support your contention that it was not colder prior to 1880 otherwise the extensions drawn by Akasofu fits Occams Razor rather nicely. Occams razor suggests that since greenhouse gases keep us warm, more greenhouse gases will keep us warmer. And since climate has been quite sensitive to change in the past, it will be quite sensitive to change now. I think I have already found that Akasofu's image is bonkers. Print it off and have a go yourself. My Akasofu-like line was -0.7 on the left to 0.2 on the right (same gradient as Akasofu). My "best fit" line was from -0.5 on the left to 0.2 on the right. Neither line would support the various delusions represented by the Akasofu image. What line would you like me to draw? (bottom plot - or find a plot of your own)
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Post by steve on Oct 30, 2009 10:45:05 GMT
steve writes "If 2010 happens to be a strong El Niño accompanied by strong warming (I have no expectation that it will be) then I will be looking forward to the days when people say "dontca know that global warming stopped in 2010"." Push is coming to shove. As I have noted before, future global temperature data hangs like a Sword of Damacles over the warmaholics. The Sword has already skewered the sceptic case numerous times, but they're like zombies. Just when you think it is safe to point out that 9 of the 10 warmest years have happened this century...
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Post by steve on Oct 30, 2009 11:01:54 GMT
Kiwistonewall
So it's not constant then. We agree. Good start. It doesn't logically follow that runaway heating *won't* follow, but I also agree with that too (if you mean oceans evaporating, and a Venus effect).
An increase of 1C will lead to an increase of about 3.6 Watts. Words such as "tiny" and "massive" depend on the circumstance, so can we put them to one side?
The 3.7W increase would be just enough to balance a doubling of CO2 assuming nothing else changes.
How is a 1C temperature rise a stable equilibrium? There is a logical step missing from your argument.
If there is such a stable equilibrium, how come we've had ice ages and hot temperatures across the whole of the earth's geological time.
"Infinitesimally small"? Out of 9 planets, one of them has suffered a runaway greenhouse effect. One in nine is not infinitesimally small. The circumstances required to cause runaway warming can be roughly calculated. It will happen within about a billion years assuming the Sun continues to warm at its expected rate. The amount of greenhouse gas forcing required to cause it now would likely mean the gas kills us before the warming happens.
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Post by stanb999 on Oct 30, 2009 14:03:06 GMT
"Infinitesimally small"? Out of 9 planets, one of them has suffered a runaway greenhouse effect. One in nine is not infinitesimally small. The circumstances required to cause runaway warming can be roughly calculated. It will happen within about a billion years assuming the Sun continues to warm at its expected rate. The amount of greenhouse gas forcing required to cause it now would likely mean the gas kills us before the warming happens. Steve tho I'm a skeptic.... I really like the level of alarm-ism in this post.
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Post by steve on Oct 30, 2009 14:44:41 GMT
I was hoping to live for a billion years, so *I* find it alarming.
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Post by kiwistonewall on Oct 30, 2009 17:30:53 GMT
And steve misses the point about stable equilibrium:
Energy in is from the Sun. Long wave out increases at T^4, so any tiny increase in Earth's temp will rapidly reestablish radiation equilibrium with a negligible change - and ditto for lower temps.
Ergo, Climate change is fundamentally NOT caused by the greenhouse effect, which is effectively a constant.
No amount of greenhouse gas is going to cause a runaway temperature effect. The T^4 law makes that impossible.
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Post by steve on Oct 30, 2009 18:13:03 GMT
And steve misses the point about stable equilibrium: And Kiwistonewall misses the point as to why I am questioning his meaning! Are you saying that the rise to the new temperature is a return to a stable equilibrium. Or are you saying that a stable equilibrium exists already (ie. the powerful T^4 relationship) which acts against the rise. There is a bit of mixing and matching of the two propositions in what you write. There is a bit of truth in both propositions, I would say, but in this case the devil is in the detail and the detail is what you are intent on ignoring by your uses of words such as tiny, negligible and so forth. Where did the ergo come from? The first sentence ignored the greenhouse effect, so how can you draw a conclusion about the greenhouse effect from it. But as it happens, climate change *can be* caused by *changes* in the "greenhouse effect", not by the "greenhouse effect" per se. Using the T^4 formula you have referred to, the earth only needs to be about 250 Kelvin to radiate enough to remain in balance with absorbed solar. Yet the earth's surface is more like 280-odd Kelvin. So what keeps the earth warm? If it isn't the "greenhouse effect", what is it? If it is the "greenhouse effect", why are you sidestepping the question as to whether the observed effect of 30 or so degrees could go up to 34 or so degrees, or down to 26 or so degrees if the amount of greenhouse gas that is present is changed. The runaway effect happens (in my book) when the oceans start evaporating away such that the rate of increase in the greenhouse effect from the water vapour stays ahead of even the T^4 relationship. The runaway effect can alternatively be applied to other situations where a new and sudden change caused by the warming (ie. different to the water vapour related feedbacks that are researched in the basic GCMs) leads to more warming which leads to more of the change (and other changes). Eg. the idea that methane clathrates could be released leading to more warming and more methane, and more permafrost melt which causes more warming which causes more ice-melt which causes more solar absorption which causes more warming which causes Amazon die-back which causes more CO2 which causes more warming... The T^4 law does not make either of these things impossible, it just makes it harder.
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Post by kiwistonewall on Oct 30, 2009 19:16:57 GMT
Steve, you obviously do not have a grasp on what a stable equilibrium is: The only constant (more or less) is the inward TSI.
This must be balanced by outward radiation. The T^4 means that a small change in Earth's surface temp leads to a huge change (in either direction) of outward radiation.
This the greenhouse effect is a STABLE equilibrium, in that any tendency to move away from the equilibrium position is an uphill battle. Thus the greenhouse effect (controlled by the Sun's constant TSI- or nearly constant) is the only driving factor.
OTHER effects (Albedo changes from the Earth's surface, Ice, clouds etc) are going to have a HUGE effect, as these operate at much higher energy wavelengths.
The greenhouse effect ISN't a climate change driver.
If man has changed the climate (and I believe he has) it has been with the Axe, fire and the desert creating goat!
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Post by toughluck on Oct 30, 2009 19:39:20 GMT
Any comments/explanations on the virial theorem, kirchoff's laws or the predicted drop in humidity due to increased CO2 in miskolczi's theory?
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Post by Ratty on Oct 31, 2009 0:51:16 GMT
[Snip] The Sword has already skewered the sceptic case numerous times, but they're like zombies. Just when you think it is safe to point out that 9 of the 10 warmest years have happened this century... Ten warmest years? Over what period?
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