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Post by steve on Jan 6, 2010 18:10:10 GMT
Gradient of what? I don't understand how you can claim you ought to assume the possibility of no feedbacks when all the evidence of past climate change indicates that feedbacks are positive. Steve, can you give a reference on the the identity and magnitude of these feedbacks _required_ for past climate change? Well for some of them, the identity has to be speculative (hope icefisher isn't around to spot that I don't know). The climate has tended to warm and cool by more than can be explained by greenhouse gases and albedo effects. Some links here to estimates based on different methods: www.skepticalscience.com/Empirical-evidence-for-positive-feedback.htmlThere's also this: droyer.web.wesleyan.edu/climate_sensitivity.pdfWhere is your evidence that sensitivity is low? What explains the ice age cycles?
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Post by hairball on Jan 6, 2010 18:35:23 GMT
My evidence for sensitivity being low is that the Earth is inhabitable. IF water vapour is a much stronger GHG than CO2 then surely pure chance would have seen enough H2O in the atmosphere at some point to tip whatever point could be tipped.
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Post by hairball on Jan 6, 2010 18:56:55 GMT
While tipping points are up; the BBC haven't run a GW scare story for at least 10 days but they just put up a doozy. Apparently a guy who's job it is to monitor methane released from permafrost tells them "Methane release from the East Siberian Shelf is underway and it looks stronger than it was supposed [to be]," Guess we'll have to give him wads of cash to keep an eye on that then. The BBC imagines: "A worst-case scenario is one where the feedback passes a tipping point and billions of tonnes of methane are released suddenly, as has occurred at least once in the Earth's past. Such sudden releases have been linked to rapid increases in global temperatures and could have been a factor in the mass extinction of species." Since they don't provide any sources for this information, I'm gonna consider it to be a wild effing guess if not an outright lie.
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Post by sigurdur on Jan 6, 2010 19:04:50 GMT
While tipping points are up; the BBC haven't run a GW scare story for at least 10 days but they just put up a doozy. Apparently a guy who's job it is to monitor methane released from permafrost tells them "Methane release from the East Siberian Shelf is underway and it looks stronger than it was supposed [to be]," Guess we'll have to give him wads of cash to keep an eye on that then. The BBC imagines: "A worst-case scenario is one where the feedback passes a tipping point and billions of tonnes of methane are released suddenly, as has occurred at least once in the Earth's past. Such sudden releases have been linked to rapid increases in global temperatures and could have been a factor in the mass extinction of species." Since they don't provide any sources for this information, I'm gonna consider it to be a wild effing guess if not an outright lie. The methane thing is one guess for the Great Extinction. Other guesses are meteorite strikes, all kinds of things. No one knows, but I guess it makes for good press?
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Post by magellan on Jan 7, 2010 3:58:48 GMT
Steve, can you give a reference on the the identity and magnitude of these feedbacks _required_ for past climate change? Well for some of them, the identity has to be speculative (hope icefisher isn't around to spot that I don't know). The climate has tended to warm and cool by more than can be explained by greenhouse gases and albedo effects. Some links here to estimates based on different methods: www.skepticalscience.com/Empirical-evidence-for-positive-feedback.htmlThere's also this: droyer.web.wesleyan.edu/climate_sensitivity.pdfWhere is your evidence that sensitivity is low? What explains the ice age cycles? www.drroyspencer.com/2009/09/the-2007-2008-global-cooling-event-evidence-for-clouds-as-the-cause/But what is really curious is that the 9-year change in radiative forcing (warming influence) of the system seen in the last two figures is at least TWICE that expected from the carbon dioxide component alone, and yet essentially no warming has occurred over that period (see first illustration above). How could this be, if the climate system is as sensitive as the IPCC claims it to be? Now steve, can you provide data showing the upper Troposphere absolute water vapor content has increased along with CO2? I didn't think so. I'd also like to see the cloud feedback data (not GCM assumptions) supporting the purported high climate sensitivity. What's that, you can't find it? What a travesty! Now that Climategate has blown open the corruption of the so-called "peer review" process the Team has had control of, maybe Spencer will be able to get his large paper published as it was rejected ad hoc last year for no reason. Positive or negative feedback? Oh, and btw, since the advent of those papers cited in link to 'skepticalscience' (an oxymoron), what has been the real world test of their hypotheses? I don't assume any hypothesis is correct until it has been tested.
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Post by icefisher on Jan 7, 2010 5:17:05 GMT
Well for some of them, the identity has to be speculative (hope icefisher isn't around to spot that I don't know). The climate has tended to warm and cool by more than can be explained by greenhouse gases and albedo effects. Heck I have no problem with you admitting you don't know. In fact, I don't even mind if you plug in religious belief where you don't know. I only get antsy when that religious belief seeks being officially established. As a sworn defender of my nation's constitution I don't take lightly to the violation of it.
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Post by steve on Jan 7, 2010 10:17:09 GMT
Magellan,
Surely what Spencer needs to show is this bit:
Some of the papers looking at sensitivity *are* real world tests of the theory - obviously Spencer hasn't yet done his real world test on his hypothesis of century scale internal radiative forcing. Despite observations of his phenomenon three times in ten years, there is very little sign of it cancelling out the warming of the 1980s and 1990s, or the warming of the early 20th century.
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Post by sentient on Jan 7, 2010 14:24:20 GMT
I spent quite some time looking into methane gas hydrates and the Clathrate Gun Hypothesis. One of the main proponents of this avenue of thought is Dr. James P. Kennett of UC Santa Barbara. Occasionally you will find one of his students, Dr. Richard Behl (CSU Long Beach) as co-author. They have done some remarkable work on this phenomena in many parts of the world, and particularly in the Santa Barbara Channel, notably Ocean Drilling Project (ODP) 893.
They even developed some remarkable short coring techniques using the complex structure of the offshore ridges to stair-step their way through the stratigraphic column pushing back over a million years into the sedimentary record offshore California.
I haven't the time this morning to dredge up citations for you, but if you search on Kennett in scholar.google.com advanced page being creative with your boolean search strings you will likely find many of his papers on the subject.
From memory of the SB channel work, they have been able to tune their sediment cores to the Greenland ice cores fairly well, providing Pacific Basin signatures of the D-O events (also known as stadials) suggesting that increases in methane concentrations, which quickly follow these thermal events, are more likely due to melting of clathrates than continental wetlands.
The various lines of evidence point to accelerated effects of clathrate instability, particularly since the Mid Pleistocene Transition. In one paper especially, clathrate "bombing sites" are clearly visible in high resolution sonographs of the channel floor where rapid melting where explosions of methane are believed to have occurred after transiting the pressure/temperature boundary of the frozen boundary layers releasing the not frozen gas beneath.
There is considerable evidence to suggest that this source of a far more potent GHG than CO2 has indeed aided and abetted whatever is causing the thermal excursions, which remains to be identified.
What is well worth considering here is that an ocean-temperature "tipping point", with respect to methane instability, has an evidentiary signature in the paleo record. The fact that these clathrate excursions have occurred repeatedly in association with the stadials and terminations, their signatures clear in both ice and ocean sediment records, provides a fairly noisy record of natural climate instability.
Again, we are faced with a signal to noise ratio of natural climate change of considerable range, very likely aided and abetted by a potent GHG, the thermal trigger for which remains the greatest mystery in climate science. In terms of alarmism, should anthropogenic forcing ever be capable of raising ocean temperatures to the clathrate boundary condition, there is reason to anticipate a potentially strong methane pulse. The problem, as ever, is this natural envelope of thermal and CH4 noise has been so large during the latter half of the Pleistocene that it would be unusual for this not to happen entirely due to natural causes.
Balancing atmospheric concentrations of CO2 to attempt to regulate temperature is likely to be problematic due to its relatively low forcing on climate regardless of concentration. What we should be concentrating on is what causes the thermal excursions that cause the clathrates to melt, re-freeze, and melt again etc.
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Post by magellan on Jan 7, 2010 14:44:41 GMT
Magellan, Surely what Spencer needs to show is this bit: Some of the papers looking at sensitivity *are* real world tests of the theory - obviously Spencer hasn't yet done his real world test on his hypothesis of century scale internal radiative forcing. Despite observations of his phenomenon three times in ten years, there is very little sign of it cancelling out the warming of the 1980s and 1990s, or the warming of the early 20th century. I'll note you did not respond directly to the quote by Spencer. It's a very simple yet relevant observation the earth has not warmed despite the climate system being flooded with far more "radiative forcing" than CO2. Explain please. Since when is a climate model a test? Testing a hypothesis with a hypothesis. How does that work? There was limited data available for the cited papers you provided, so how can you say they were based on real tests? I, and no doubt others, are more interested in observational data, not more links to hypotheses. Once again: Can you provide evidence supporting the CO2 amplification hypothesis or not? The upper troposphere should be increasing in absolute water vapor content. Belly up to the bar. Can you provide evidence for cloud feedback supporting the CO2 amplification hypothesis? If you can't, then both points render the high climate sensitivity mantra neutered, and the entire house of cards is based on untested assumptions unrelated to real world processes. Also, there was no warming through 1997, but rather a step change as a result of the 97-98 El Nino. Sorry, it is what it is.
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Post by steve on Jan 7, 2010 16:09:45 GMT
Magellan A number of the papers are not based on climate models It's not quite the full story. Ocean heat content went up about 0.7W/m^2 averaged over the 9 year period (based on a rise of 7e22 Joules between 2000 and about 2005).
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Post by icefisher on Jan 7, 2010 16:22:31 GMT
Magellan A number of the papers are not based on climate models But they are based upon the presumption we understand all the drivers of climate. . . .when we now know very clearly we do not. It's not quite the full story. Ocean heat content went up about 0.7W/m^2 averaged over the 9 year period (based on a rise of 7e22 Joules between 2000 and about 2005). A single paper that splices to inconsistent data sets together without adequate ground truthing or an extended period of calibrating the two sets of data. And right at the splice we see an very uncharacteristic jump in temperatures that accounts for essentially all that heat gain. But with 90,000 red flags flying Steve bites like a cod on a clam.
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Post by magellan on Jan 7, 2010 17:33:23 GMT
Magellan A number of the papers are not based on climate models It's not quite the full story. Ocean heat content went up about 0.7W/m^2 averaged over the 9 year period (based on a rise of 7e22 Joules between 2000 and about 2005). (based on a rise of 7e22 Joules between 2000 and about 2005)
Comment From Josh Willis On The Upper Ocean Heat Content Data Posted On Real ClimateThere is still a good deal of uncertainty in observational estimates of ocean heat content during the 1990s and into the early part of the 2000s. This is because of known biases in the XBT data set, which are the dominant source of ocean temperature data up until 2003 or 2004. Numerous authors have attempted to correct these biases, but substantial difference remain in the “corrected” data. As a result, the period from 1993 to 2003 still has uncertainties that are probably larger than the natural or anthropogenic signals in ocean heat content that happen over a period of 1 to 3 years. However, the decadal trend of 10 to 15 years seems to be large enough to see despite the uncertainties. Because Argo begins to become the dominant source of temperature data in about 2004, the period from 2000 to 2005 is especially worriesome because of the transition from an XBT-dominated estimate of ocean heat content.
It would appear there are not enough data compiled from ARGO to quantify OHC yet. A few more years maybe. I wouldn't classify Josh Willis as a "skeptic", and he is the principle analyst for the ARGO data. His analysis of top 700m of OHC (where 85% of heat is and best measured) shows a slight decrease from 2003 onward. Craig Loehle shows more. Levitus 2009 shows a slight increase. Take your pick. Those now digging into 3000m OHC are hardly reliable. More interesting is now that surface and LT temperatures aren't following the AGW talking points, OHC has become the new "proof" for human caused GW. So how does 10 ppm CO2 account for any increase in SST and OHC increases? It's absurd, especially when you cannot tell us what changes in cloud cover have contributed which could account for 100% of any increase/decrease in OHC or global surface temperature for that matter. In any case, the OHC even using your preferred reference is less than half that cited by IPCC for claimed human contributions.
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Post by steve on Jan 7, 2010 18:02:42 GMT
Icefisher,
Glad to see you are continuing to fight the good fight against truth.
1. "A single paper": There are papers by Willis, Levitus, Ishii and Dominguez. They all show a rise.
2. "without adequate ground truthing": They are supported by observations and assessments of sea level rise taking into account both thermal expansion and glacier/ice cap melt.
3. "Extended period of calibrating the two sets of data": Argo came on stream in about 2001 and has ramped up. Since then, the number of XBTs has reduced, but not massively so. There is a reasonable calibration period. The data is available for analysis.
Anyway, whatever you or I think, claiming that the earth hasn't warmed in 9 years because he's failed to acknowledge or deal with at least 4 peer reviewed papers that say that it has could be the reason why Spencer's paper gets rejected for the umpteenth time. Let me predict that if he gets published his final submission doesn't include this claim, but he will allow people without subscriptions to JClim to assume that it does.
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Post by steve on Jan 7, 2010 18:24:23 GMT
Magellan
When you are subtracting two large but similar uncertain numbers, a factor of two is quite a good margin of error. The Forster Gregory paper had an error bar of 56%. But even Spencer points out that the method he has applied has been questioned when used by other scientists such as Forster and Gregory.
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