The Search for a Short Term Marker of Long Term Climate Sensitivity
By Dr. Roy Spencer. October 4th, 2009
[This is an update on research progress we have made into determining just how sensitive the climate system is to increasing atmospheric greenhouse gas concentrations.]
While published studies are beginning to suggest that net feedbacks in the climate system could be negative for year-to-year variations (e.g., our 2007 paper, and the new study by Lindzen and Choi, 2009), there remains the question of whether the same can be said of long-term climate sensitivity (and therefore, of the strength of future global warming).
Even if we find observational evidence of an insensitive climate system for year-to-year fluctuations in the climate system, it could be that the system’s long term response to more carbon dioxide is very sensitive. I’m not saying I believe that is the case – I don’t – but it is possible. This question of a potentially large difference in short-term and long-term responses of the climate system has been bothering me for many months.
Significantly, as far as I know, the climate modelers have not yet demonstrated that there is any short-term behavior in their models which is also a good predictor of how much global warming those models project for our future. It needs to be something we can measure, something we can test with real observations. Just because all of the models behave more-or-less like the real climate system does not mean the range of warming they produce encompasses the truth.
For instance, computing feedback parameters (a measure of how much the radiative balance of the Earth changes in response to a temperature change) would be the most obvious test. But I’ve diagnosed feedback parameters from 7- to 10-year subsets of the models’ long-term global warming simulations, and they have virtually no correlation with those models known long-term feedbacks. (I am quite sure I know the reason for this…which is the subject of our JGR paper now being revised…I just don’t know a good way around it).
But I refuse to give up searching. This is because the most important feedbacks in the climate system – clouds and water vapor – have inherently short time scales…minutes for individual clouds, to days or weeks for large regional cloud systems and changes in free-tropospheric water vapor. So, I still believe that there MUST be one or more short term “markers” of long term climate sensitivity.
Well, this past week I think I finally found one. I’m going to be a little evasive about exactly what that marker is because, in this case, the finding is too important to give away to another researcher who will beat me to publishing it (insert smiley here).
What I will say is that the marker ‘index’ is related to how the climate models behave during sudden warming events and the cooling that follows them. In the IPCC climate models, these warming/cooling events typically have time scales of several months, and are self-generated as ‘natural variability’ within the models. (I’m not concerned that I’ve given it away, since the marker is not obvious…as my associate Danny Braswell asked, “What made you think of that?”)
The following plot shows how this ‘mystery index’ is related to the net feedback parameters diagnosed in those 18 climate models by Forster and Taylor (2006). As can be seen, it explains 50% of the variance among the different models. The best I have been able to do up to this point is less than 10% explained variance, which for a sample size of 18 models might as well be zero.
Also plotted is the range of values of this index from 9 years of CERES satellite measurements computed in the same manner as with the models’ output. As can be seen, the satellite data support lower climate sensitivity (larger feedback parameter) than any of the climate models…but not nearly as low as the 6 Watts per sq. meter per degree found for tropical climate variations by us and others.
For a doubling of atmospheric carbon dioxide, the satellite measurements would correspond to about 1.6 to 2.0 deg. C of warming, compared to the 18 IPCC models’ range shown, which corresponds to warming of from about 2.0 to 4.2 deg. C.
The relatively short length of record of our best satellite data (9 years) appears to be the limiting factor in this analysis. The model results shown in the above figure come from 50 years of output from each of the 18 models, while the satellite range of results comes from only 9 years of CERES data (March 2000 through December 2008). The index needs to be computed from as many strong warming events as can be found, because the marker only emerges when a number of them are averaged together.
Despite this drawback, the finding of this short-term marker of long-term climate sensitivity is at least a step in the right direction. I will post progress on this issue as the evidence unfolds. Hopefully, more robust markers can be found that show even a stronger relationship to long-term warming in the models, and which will produce greater confidence when tested with relatively short periods of satellite data.
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Govidan et al, “Global climate models violate scaling of the observed atmospheric variability,” arXiv:cond-mat/0206040v1 [cond-mat:stat-mech] 4 Jun 2002.
These authors show that (as of 2002 anyway) AOGCMs do not exhibit the same statistics of fluctuations as the real atmosphere. The comparison data is atmospheric temperature, which the authors state shows correlation power law coefficient of about 0.7 for decadal time scales, and shows no evidence for any break from this behavior at longer time scales. It appears to be universal behavior.
In summary the climate models show excessive persistence for time periods up to about two years, and then the power-law characterizing persistence in these models goes much too flat indicating a lack of longer range correlation.
The authors suggest that the parameterization at sub-grid scale seems to be the source of the flaw, but it is interesting to me that the failure to replicate the power-law persists to the longest time-scales available to analyze in the model output. The observations suggest, I believe, that feedback processes are self-similar at long, and perhaps all time scales.
Peter Taylor (04:20:34) :
On my reading list.
Well, I suspect I know what Spencer’s secret line of research is but he need not worry about me stealing it out from under his nose since 1. I wouldn’t begin to know how to analyze that and 2. I’m just an amatuer anyway.
But watch out Roy, I’m on to you!
The estimate given hear also lines up fairly well with Nicola Scafetta’s second time constant:
http://www.fel.duke.edu/~scafetta/pdf/2007JD009586.pdf
as well as the estimate from aerosol data by Chylek et al. :
http://www.agu.org/pubs/crossref/2007/2007JD008740.shtml
Roy Spencer (05:03:12) :
to Frank Lansner: “Yes, I agree that the NCEP reanalysis data going back to 1940 are intriguing. Actually, the reanalysis plots you refer to DO show an increase in total atmospheric water vapor (most of it is in the boundary layer, below about 900 mb, where it HAS increased)…but the fact that it has decreased above 700 mb is more important for water vapor feedback. If those data reflect reality, then water vapor feedback probably has been negative during the warming of the last 50 years.”
Brilliant. Also its “nice” that the its only in the very lowest part of the atmosphere that water content in the atmosphere is slightly slightly bigger today than 1940, because according to Svensmark, its specifically the clouds in these lowest layers that has a cooling effect… nice.
K.R. Frank
Roy
Look forward to your final paper.
If you have not already, may I recommend evaluating the changes in global optical depth Ta as measured by satellites vs climate models.
Ferenc Miskolczi predicts a very low sensitivity of global optical depth Ta with the climate showing small variations about a thermodynamically stable value of Ta = 1.87. See the popular presentation/explanation: The new climate theory of Dr. Ferenc Miskolczi See figure 13:
Miskolczi predicts a DECLINE in optical depth with water vapor (which counters the CO2 increase). Conversely conventional climate models predict a high sensitivity of global optical depth with increase in greenhouse gases increasing optical depth, especially by water vapor.
I understood your earlier models to imply an optical depth closer to Miskolczi’s value. Recommend a joint experimental/theoretical effort with Miskolczi.
Leif Svalgaard (05:08:51) :
Perhaps Piers Corbyn will beat him to it.
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It’ll be seaweed, I reckon. 🙂
I have a question that indirectly links to this. We hear about the missing sink for about half the anthropogenic CO2 that goes into the atmosphere. Mainly you hear that it is likely absorbed in the ocean but the ocean would seem to be so big that any measurement of ocean CO2 would likely have a Margin of Error larger than the sink. Not to mention whether we could detect it and how quickly CO2 gets used up by the aquatic plants.
With this ambiguity in mind it seems we might have a measure of the other possible sink of terrestrial plants. If the sink were plants would it not show up in the magnitude of the seasonal fluctuation in Atmospheric CO2? Would we get a deeper breathing biosphere?
The CO2 could cause some desert areas to be turned more tropical as CO2 contributes to both plant growth and efficient water use and retention. So would additional CO2, create a more robust biosphere that would change landcover so as to effect the Diurnal cycle by not letting heat escape at night. Would the more active biosphere be an example of a feedback that changes overtime?
hmmm. I wonder if there is information in the wriggle pattern. I have often noticed similarities in the relatively unsmoothed shapes. The flat areas , rising trend shapes, and falling trend shapes may have some regularity, some non-random predictive value in them. Maybe a consequent temperature correlation occurs depending on the pattern just prior to the temperature trend change? Cosmic ray wriggles have a pattern as well (flat-pointed-flat-pointed) that corresponds with the polarity and position of the butterfly pattern of spots (if I remember correctly).
I we don´t really know the laws operating behind climate we can´t make any models whatsoever, and if we should know them we shouldn´t need any models.
Now if you like to play models seek wherever there are right forecasts, perhaps there are true laws behind which you can use for a succesful climate game.
interesting comments. i can’t help but suspect Roy’s marker is in my pet area of interest on cloud cover fractions and albedo as that is ultimately the mechanism that determines the energy balance although i suspect i might not even understand this marker concept when finally presented.
Personally, I don’t like end of season tv series cliff hangers and this sort of thing is somewhat akin. Consequently, I agree for the most part on Leif’s comment that perhaps such things shouldn’t be mentioned until they are ready to be fully disclosed. I think though that while the blog might provide the fastest approach to being able to lay claim to something by publishing which may be important in some potential race between competing groups to be first, the blog might become problematic with peer reviewed journals claiming the information was already published. Of course the ideas in the blog will be reviewed, even practically shredded.
I really look forward to seeing Roy’s full presentation – even though I wish he had not tortured me with a “preview of coming attractions” first.
So let me get this right,
Dr. Spencer is listening to that tiny tick-tick-tich sound of a well-used car motor and deciding if it’s just an out-of-adjustment lifter or a rod bearing announcing its imminent catastrophic death.
From his message – I’d put tax dollars on that – who knows what it might deliver about climate?
Mike
Claude Harvey (05:09:08) :
I must have missed something along the way. Where might I find the Arctic ice measurements of “volume” I’m seeing so confidently referenced in some of these responses? We know “extent” from the satellite readings, but all I’ve seen on “thickness” has been a bit a core sampling here and there, a few U.S.Army buoy readings and the results of a radar skid recently flown over a swath of the ice.
————————–
Has any data on this been published (the radar skid data) ??
RR Kempen, as Claude says, in order to compare ice volumes it would help to have numbers expressed as cubic meters (or kilometers), not a link to a map showing square meters (or kilometers).
PS RR Kampen …. sorry !
OT – Anthony, thanks for your policy of cutting off religious remarks (pro or con). It maintains a certain decorum for the site.
/OT off
I have often wondered about the uncanny ability of animals to sense when there is going to be a bad winter. During the late summer here in the mountains of New Mexico, we have had a bear (about a 300 lb bear!!!) wander through the neighborhood, the raccoons have been desperately trying to get into the house (succeeding on several nights, which caused our dog great consternation), and I have seen deer, coyotes and skunks freely roaming about in broad daylight along the main thoroughfares of our small town. The hummingbirds have been migrating south already, emptying the feeder within 24 hours several times, the normal birds have been munching up the bird food as if there is no tomorrow, and the ravens are getting into trash bins with a ferocity not usually seen. In addition, my norwegian elkhound is shedding for the second time this year, meaning that her coat is growing in even heavier than usual.
Then I hear that there is a possible new marker for short-term change. So I wonder if the marker is based upon something biological. We so often hear that people are somehow changing climate, but couldn’t the opposite be true? What if climate changes cause certain biological processes to be slightly different? Some of the actions of the local fauna might be explained by something switching on or off in their biology, thus precipitating what appears to be abnormal actions. The scientists who are studying climate are looking at the “big picture” and ignoring a lot of the small markers, because weather is not climate.
Anyway, I’m probably way off course here, but wanted to post just in case I’ve stumbled across some vague something that is related to the new finding.
RR Kampen (05:09:15) :
“It might and it might all disappear next year and more, just like 2008 saw more than half of the multiyear ice from previous year disappear.
About two thirds of melting happens from below. Right now, even.”
Repeat this often, then cite yourself even more and you’ll get published in Nature and Scientific American! Two well known eco-theist publications.
RR Kampen (05:50:56) :
C’mon, admit it. You just made that up.
Re: hunter (06:12:45) :
“The AGW true believers are hoping that by moving the goal posts, from ice extent to volume, they can distract people from the fact that
1 – ice volume was never an issue in earlier years”
—
I might have been the first to pay attention to thickness of ice. Rest followed finally after the disaster of 2007.
Reason: in late summers 2005 and 2006 there suddenly appeared huge holes on the eastern (Siberian) side of the pack. Suddenly? Yes: a matter of days from pack to open areas the size of Britain.
The explanation is easy enough. Thickness of the ice determines its vulnarability to break-up and fast melt. When that sea-ice is reduced to half a metre it WILL break up and disappear very fast.
The same process could be witnessed on a great scale in 2007.
This is why ice volume is the only parameter that counts. Extent hides it. It means that coming spring the extent could be close to normal, while three months later all that ice might disappear in a matter of only two weeks; that is when this threshold thickness has been crossed and wholesale breakup occurs – like half the Arctic Sea showed in 2007.
Anyone living in a climate that sometimes puts ice on lakes can see the same phenomenon for himrself.
Extent is only interesting ref albedo and weather.
Measures of ice thickness have been increased bigtime autumn last year. But they have been done since at least 1921: by the Soviets, by landing planes on the ice (in places where there is sea today) and drilling.
Average thickness over more than half the Arctic Sea was 3-4 metres, today it is 1.20m. The disastrous reduction in extent followed, of course.
RR Kampen (05:50:56) :
From about a third of the climbing trajectory to interglacial maximum this CO2 becomes the dominant driver for further warming. The lag has then disappeared and temp and CO2 appear to rise simultaneously then – but in fact temp lags CO2 by a small time.
And the evidence supporting this story can be found where?
Janice (07:31:12) :
Speaking as a geologist – I know nothing about anything that isn’t a rock – I think you might have something there!
RR Kampen (07:47:22) :
C’mon, admit it. You just made that up.
Kampen,
We can discuss the AGW tactic of moving goal posts later.
INGSOC, Smokey and Smokey again – I would love to respond in unscientific kind, but I will keep to the rules on this forum which I happen to like (the rules ánd the forum). Which means I will pay no attention at all to any comment like yours here in future. Please spare your finger tips – or make yourself ridiculous.
Peter Taylor (04:20:34) :
If we are now entering a longer term cooling, then we should look for a signal that shows a) depletion of the northern gyres’ warm water pool; b) changes in cloud, storm tracks and wind patterns in relation to those gyres (especially the track of the jetstream). Ultimately, i suspect that it is the latter, which the work of Drew Shindell at NASA (I keep mentioning this but nobody seems to know what happened to the line of research) showed was correlated with a variable of solar output (UV light), that determines the long term pattern of build-up and depletion of upper ocean heat stores.
a) The slowing down of sea level rise as measured by satellite altimetry indicates ocean heat content is diminishing.
b)The jet stream is shifting back equatorwards, and the arctic ice extent recovery is indicative of this. The planet is gathering it’s cloak around it vital regions.
> “I might have been the first to pay attention to thickness of ice. Rest followed > finally after the disaster of 2007.”
> C’mon, admit it. You just made that up.
78% of all message board statistics are made up on the spur of the moment.
Yarmy (07:04:33) :
Leif Svalgaard (05:08:51) :
Perhaps Piers Corbyn will beat him to it.
–
It’ll be seaweed, I reckon. 🙂
I use tea-leaves meself.