Comment on unproven models

Coby,

I am not impressed by your assumption that I am quoting some site. I did not read about this at that site. That appears to be labeling.

Serreze et al (2006) can be found:
http://marine.rutgers.edu/~francis/pres/AA_final.pdf

Polyakov et al (2003) can be found:
http://ams.allenpress.com/archive/1520-0442/16/12/pdf/i1520-0442-16-12-…

These are the full papers.

For starters, I would recommend reading more than just the first few lines of Serreze 2006 as he actually seems to come to the opposite conclusion that Vernon seems to take.

In summary, we conclude that: (1) In sharp contrast to the high-latitude warming
in the earlier part of the 20th century, the recent warming is part of a global signal,
suggestive of external forcing; (2) Arctic amplification of this SAT signal, as well
the observed decline in the sea ice cover, has been strongly influenced by lowfrequency
climate variability, especially that associated with the NAM and PDO;
(3) The NAM and PDO cannot neatly explain all of the changes.
How do conclusions drawn from available observations align with model predictions?
For the intermediate (2040â2059) and mature (2070â2089) greenhouse
states, the ensemble mean of the five models used in the ACIA shows the largest
warming over the Arctic Ocean during autumn and winter. This projected change
is due to the retreat and thinning of sea ice, along with increased ocean heat
content, which is consistent with theory (Section 2). We submit that the projection
is correct in its overall direction and location of change, a conclusion
that finds further support from the simulations summarized by Holland and Bitz
(2003).

And the final conclusion:

The observed trajectory of the Arctic system over the past several decades appears
to be in overall agreement with model projections. This conclusion must of
course acknowledge uncertainties in model projections (in particular, model-tomodel
scatter) as well as uncertainties in trend assessments of the relatively short
time series of observed SAT and sea ice. Our synthesis of the available evidence
points to the Arctic as in a state of preconditioning, less advanced than that shown
in the ACIA simulations for 2010â2029, but setting the stage for larger changes
in future decades. This preconditioning is characterized by general warming in all
seasons, a lengthened melt season, and an initial retreat and thinning of sea ice, all
accompanied by strong expressions of decadal-scale climate variability. The present
sea ice cover is still sufficient to act as an effective insulator between the ocean and
atmosphere. Before Arctic Ocean SAT changes can show the seasonality and magnitudes
predicted by models for intermediate and mature greenhouse states, more
ice must be removed from the system. This will allow enough additional absorption
of solar radiation in summer to limit ice growth during the following autumn
and winter, initiating a large-scale ice-albedo feedback. The overall consistency
between observations and near-future model predictions supports the concept of
Arctic amplification. We expect that the fingerprint of enhanced warming over the
Arctic Ocean will soon emerge from the noise of internal low-frequency variability,
at which time a new state of the Arctic will come into clearer focus.

As for the Antarctic, parts of it are cooling, due to the unique local phenomena of the ozone hole causing circular winds to isolate the interior. As for the Southern Ocean around Antarctica, it's warming at a rate higher than the rest of the oceans of the world.

On further reflection, Serreze 2006 puts the regional changes observed in Polyakov 2003 in a wider context:

In sharp contrast to the high-latitude warming in the earlier part of the 20th century, the recent warming is part of a global signal, suggestive of external forcing

In other words, the Arctic showed big swings in temperature in the 30's as well as now. The big difference between then and now is that in recent decades, the whole planet is warming. This indicates the whole planet is in energy imbalance. Eg - an external forcing, the planet is overall absorbing more energy than it's releasing back into space.

Here is more:

Bitz et al (2006)

http://www.atmos.washington.edu/~bitz/bitz_goosse.pdf

Amplification of Arctic surface warming is a well known feature of climate model predictions for the mid and late 21st century. However, as of 2004, observed Arctic surface warming is not yet significantly higher than the whole northern hemisphere. ⦠Using historical runs and future scenarios to estimate trends and internal variability, we predict Arctic warming won't be significantly greater than the northern hemisphere until at least 2020.

So like Serreze, there is no Arctic amplification now but there will be some in the future.

Oh, and there is still no warming in the Antarctic.

JohnCook,

Serreze et al (2009)http://66.102.1.104/scholar?hl=en&lr=&scoring=r&q=cache:75rom87kSU4J:ww…

That the sea ice cover is responding to the effects of GHG loading finds strong support from analysis of the IPCC-AR4 simulations (e.g., Stroeve et al., 2007). Whether the warming seen in the NCEP and JRA-25 data is still within the expected range of natural variability is unclear. That the Arcticis home to strong variability is well recognized. For example, a period of strong high-latitude warming occurred from about 1930 to 1940 (Polyakov et al., 2002; Overland et al.,2004). While likely in part associated with reduced ice cover(Bengtsson et al., 2004), sparse data precludes drawing firm conclusions.

Which is his teams on going position, that polar amplification is coming but it is not here yet. That we cannot tell. So while he wants there to be polar amplification he is honest enough to admit that it may be coming but there is no proof on any now.

It's odd to see someone quoting the Serreze and Francis 2006 paper to conclude that there's no Arctic amplification. The authors themselves make no such conclusion.

Polyakov et al. 2003 examine surface air temperatures at high latitudes, and conclude (among other things) that there is a large amplitude low-frequency (50-80 year) variability to Arctic surface air temperatures. By that time, it was already no surprise that such variability exists. I recall John Walsh discussing it about a decade earlier. Serreze and Francis note this (and Polyakov et al) as well.

Both papers also are aware of the fact that there is interannual weather variability, so it takes time to establish a mean or trend even without having to worry about the low-frequency variability.

Serreze and Francis also note that the different models have different sensitivities. In their study, they used only 5, which is pretty small (say I) to get a good handle on the inter-model variability. Even when the same model is run, slightly varying initial conditions will give markedly different instantaneous or short term. (See the IPCC AR4 model ensemble.)

Between the interannual, low frequency, inter-model, and model initial condition issues, one has to be pretty careful about what conclusions one draws. Polyakov et al, and Serreze and Francis do so, but then Vernon draws conclusions outside what the authors do.

There's an additional point Vernon seems to have missed. Namely, the models that Serreze and Francis looked at were run in a mode with 1% per year increase in atmospheric CO2. In fact, the increase has been more like 2/3rds %. Consequently, the time for the atmosphere to reach the levels of the models is off to the future of current dates. It seems to be their allowance for this that results in his comment about cherry-picking start dates. As Mark and Jennifer note, the 1% time varying run, and looking at the early period of it, is much more realistic with respect to recent conditions than the previously standard things to do -- look at equilibrium response to doubled CO2 (goes back to Arrhenius), or to examine the 2100 or so values.

His comments don't look like a 'co2science'-style hash of the papers. On the other hand, they do look like what happens when someone who doesn't really know the science in an area hits original papers while carrying a conclusion he wants to find.

In reading Serreze and Francis, I was struck by the last sentence of their abstract (published, remember, in 2006):

Given the general consistency with model projections, we are likely near the threshold when absorption of solar radiation during summer limits ice growth the following autumn and winter, initiating a feedback leading to a substantial increase in Arctic Ocean SATs.

The next year, fall 2007, showed extreme shifts in atmospheric temperatures and sea ice cover over the Arctic. Fall 2008's sea ice cover (and, even more so, thickness) did not recover to anywhere near the pre-2007 levels.

Robert,

The current sea ice level is within one SD of the 1979-2000 mean per NISDC. This year has more sea ice that last year, which is way to soon to determine a trend. However, this graphic shows that current sea ice is closer to the mean that the 2007 extreme.

http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png

The issue is there is not enough data to know if what we are seeing is unusual or not. We know it was warmer in the Arctic in the 30s-40s. We know it is not warmer now than it was then. We do not know the extent of sea ice then, so saying the present is exceptional is baseless.

That is the issue, some day in the future, if some thing happens, polar amplification may happen. These papers all show that it is not happening now, regardless of what it may be in the future.

Vernon, I have pointed this graphic to you on two other blogs and you still repeat your incorrect statements:

http://data.giss.nasa.gov/gistemp/graphs/2009+2005+2007.pdf

Where are the areas with the largest temperature anomalies? The ones which are the darkest colour in the graphs. They are in the polar area. Why do you refuse to accept any data which contradict your wrong interpretation of climate science?

I am a bit confused, first we are told the arctic is melting but then it appears that the ice extent is almost on the average (post 7). If so then what is all the fuss about?

Are we debating this issue simply to justify the errors in another IPCC model?

Ian,

For that last time. I have explained those graphics every time you toss them out. The Arctic was in one of the two cold periods during the 20th century during the years that GISS picked to be the baseline; 1951-1980. The warming in the Arctic will look exceptional when it is actually not significantly greater Northern Hemisphere warming. Bitz et al (2006) states it clearly "However, as of 2004, observed Arctic surface warming is not yet significantly higher than the whole northern hemisphere."

Why do you refuse to learn why the pretty pictures show what they show?

Like the denialist you are Crakar, you bring up again for about the 10th time this same fallacious argument. The ice extent of a single month tells you nothing about the trend.

You are not sincerely interested in climate science.

Coby,

If i am a denialist then how do you explain this

This article states all Arctic ice will be gone in 23 years thats 2030

http://www.stopglobalwarming.org/sgw_read.asp?id=745049102007

This article states all Arctic ice will be gone in 34 years thats 2040

http://www.ucar.edu/news/releases/2006/arctic.shtml

This article states all Arctic ice will be gone in 56 years thats 2070

http://www.guardian.co.uk/science/2004/nov/03/environment.environment

Do the above links fill you with any confidence that these so called scientists are acting in good faith, do you honestly believe these scientists are speaking the truth or do you think maybe they are embellishing the truth somewhat to further their own agendas? Or do you think that neither of them really have any idea of what they are talking about?

Then we have this article by NASA which casts doubt on the 3 above alarmist claims

http://www.jpl.nasa.gov/news/news.cfm?release=2007-131

And we also have this by Igor V. Polyakov

http://www.frontier.iarc.uaf.edu/~igor/research/pdf/50yr_web.pdf

The interesting thing here is that he uses 135 years of ice extent data to say that natural variations drive Arctic climate not AGW.

But here you are using less than 30 years to claim AGW is melting all the ice, do you not the irony in what you accuse me of doing Coby?

I see three articles that come to the same general conclusion, differing only in the time-frame. This is a fair analogy to to rebut common contrarian arguments. There is a general consensus on the direction we're headed. The debate on certain, specific aspects is not over within the science community.

The NASA article contradicts nothing of the 3 above. It's loking at a different facet of the science - specifically, whether temperature trends in the 90s are mostly naturally derived or more a product of anthro global warming. No mention whatsoever of projections or how projections might be impacted.

The 135 year record in the study is Nordic Seas only, not the entire Arctic sea ice cover. I cannot speak to the reliability of extrapolating for the region using only a part of it (sea ice cover changes geographically year-to-year and decadally). I can say that the 30 year record is most referenced because it has unprecedented (satellite) coverage. Data gets sparser the further back in time you go.

Finally, I don't understand this reliance on single paper to come to any strong conclusions (unless the contributor is only interested in buttressing a prior conviction). A proper analysis would synthesise a range of reports, establish the quality of each, and defer, usually, to the mean result.

The current near-average anomoly in Arctic sea-ice area is an artefact of weather. To refer to a couple of months of data as a signal component when speaking about climate trends is statistically prepsterous.

Seeing as sea-ice extent is getting mentioned here (as different from area), the anomalies of the past two months on that metric are clearly below the average (-250 000 sq km). Much the same as last year. Even 13 months of data is way too short to confirm a climate trend change, never mind that the 2008 minimum, "only" the second lowest area/extent for the last 30 years, actually increased the overall trend for the satellite period.

A short course in statistics should alleviate these misconceptions.

Crakar,

You forgot the scare quotes, it is not 'so called scientists' it is 'so called "scientists"'. Much more effective!

barry,

I agree, a course in statistics would help. So statistically, how much should we rely on future predictions when the only data we have is for one thirty year warming period? Additionally, that warming period was not the warmest the Arctic was during the last 100 years. What is the basis for suspecting that the sea ice change in extent is exceptional?

Actually if you want to see how much real warming there is in the Arctic go to GISS: http://data.giss.nasa.gov/gistemp/maps/ and run the program with the ocean data set to HR2SST and the baseline set to when the Arctic was the warmest, 1925-1955. All the warming goes away except for some asian warming smeared into the Arctic. Odd that.

Vernon said: "For that last time. I have explained those graphics every time you toss them out. The Arctic was in one of the two cold periods during the 20th century during the years that GISS picked to be the baseline; 1951-1980".

That has nothing to do with arctic amplification. All that means is that the total change over a long period of time is greater because you started at a lower temperature

Arctic amplification refers to rate of change of temperature. That means it is the slope of the graph showing temp versus time not the distance from top to bottom that is critical.

All decent reports and papers show arctic amplification if you only stopped cherry picking one report out of many.

I've been trying to get you to read good and honest papers for some time now.

Here are a couple of reports which show that you are wrong:

http://downloads.climatescience.gov/sap/sap1-2/sap1-2-final-report-all… (read chapter 4 in particular)

http://www.arcticwarming.net/science (click on "rapidly warming Arctic climate and the large projected changes")

These two reports, and many others show that arctic amplification is well underway and is not confined to models.

Vernon, we do know what the ice cover was like in the Arctic in the 1930s and 1940s. Indeed, back to the later 1800s. At no time was the fall melt back anywhere near what happened in 2007 and 2008. Do more looking at NSIDC and you'll see the records.

In the mean time, do explain why it is that you consider your opinion to be scientifically more meaningful than the authors of the papers you cite and disagree with as to their own conclusions. Better, of course, is for you to write up your conclusions properly and submit it to the scientific literature. Mark and Jennifer did, and you're saying here that they're wrong. The progress of science comes from people showing such things openly and will full documentation, not hiding off in comments of a blog somewhere.

Robert,

Are you refering to the HadISST1, the only data set that covers the periods you are describing? If so, did you miss the warming on the site that says:"Users of HadISST1 are cautioned that the interpolation and adjustments used to make the sea ice data homogenous and to extend them into data sparse areas may also make them inappropriate for studies of observed climatic trends or variability (Rayner et al., 2003)."

"The progress of science comes from people showing such things openly and will full documentation... ." This the funniest thing I have ever heard from the pro-AGW side. In light of your position, try finding what stations Jones uses to produce the HadCRU data sets. How long did it take to get Mann to release his data and processes. What was the process used in Stieg et al (2009) to removed clouds from the satellite data. Should I go on? Most the issues I have seen in climate science are due to the scientist not making the data or methodologies available.

But, back on topic. All those papers say that there is no Arctic Amplification signal now. I happen to agree with that. What comes next is conjecture, Arctic Amplification will happen in the future. What I am saying is that the models call for Arctic Amplification. AGW is been going on since at least the 70s, yet no Arctic amplification.

As I pointed out, there is no "accurate enough for trend analysis" sea ice data for the entire Arctic prior to the satellite era. While Serreze and Francis think that the loss of sea ice will start the polar amplification, there is not enough sea data from the other warming periods to support the claim. Bitz on the other hand, does not think polar amplification will happen till 2020, or about 50 years. All the models predict Arctic amplification with the warming, not some unknow time in the future.

I'm not referring to HadISST.

Regardless of that, however, accuracy requirements for deciding about trends to within plus or minus 1% or less per decade are one thing. Deciding about whether we've previously experienced coverage 40% less than a 20 year mean has much less rigorous data requirements. Data more than adequate for that purpose exists (and, for that matter, the HadISST is sufficient for that purpose).

Robert,

You may be right, point me to a study that shows ice trends prior to the satellite age.

Scare quotes Coby?

We have 3 independant studies of future Arctic climate trends which all come to the same conclusions albeit over differing time scales. If you read the articles you will find that all the studies are based on the same criteria.

That criteria is the data gleaned over a handful of years going as far back as 1979.

Coby, you your self have used this very same criteria to make your own assumptions and opinions.

I have therefore used the same criteria to come to a different opinion than yourself, and you decide to call me a denier. As we both use the same criteria one can only surmise that i am a denier because my opinions differ from yours.

I have shown you research from the AARI which concludes that Arctic ice is being subjected to natural climate variables, this study was rejected by you based not on scienticfic grounds but on your beliefs.

I have shown you a NASA study which came to the same conclusions which was once again rejected by you not based on scientific grounds but on verbal gymnastics.

And now we have the third study by Igor V. Polyakov which goes back 135 years and once again agrees with the AARI and NASA findings, i assume this study was rejected by you based on your silence. All you have is faith and sarcasm, i wonder how long it will be before you start calling me an athiest?

Why, I though arctic amplification was a direct result of CO2 being heavier than air, floats to poles by coriolis forces by definition. Of course there is the issue of ice melting but I thought that was the effect, not the cause. Of course it's more complicated than that.

Vernon,

"All the warming goes away except for some asian warming smeared into the Arctic. Odd that."

I haven't used this page before, so I'm hoping I get this right. Correct me where I'm wrong.

By changing the baseline to the one you specified (1925 - 1955), we've picked a fairly (averaged) warm period in the Arctic. Not necessarily the warmest (I think spatialization in the studies above is too sparse), but certainly warm.

Set SSTs - fine. Set to polar. Fine. Smoothing radius at 1200km. Fine.

Leaving April 2009 - 2009 as set means we are comparing the middle of winter in the Arctic in a relatively cold year to an averaged baseline that was warm. We are comparing a weather anomaly (one months data) not a climate trend.

Do I have this right so far?

So, let's choose annual instead of April, and lets do it for the last year of data 2008. Now we are comparing annual temps to annual temps, yes? Instead of singling out the winter month.

With the baseline as you set it, the warming has returned, and we have a fairer (if still not statistically robust) anomaly measurement.

Set the time interval to 1998 - 2008, and the warming is even clearer. Basically, the last 10 years (averaged) have been noticably warmer than the baseline period, even though we've selected the earlier baseline to be a warm one.

The more we stretch the time interval, the less warming, because we're selected (cherry picked?) a warm baseline. Make the baseline 1900 - 2000 and I think we'll have a fairer construction. Make the time interval 1925 - 1955, and then compare that with a range of recent temps to date.

I kept the field set to anomaly rather than trend, by the way.

How did I do?

Well, April isn't a winter month. It's the month after sea ice minimum, though.

[coby here - I assume you meant to say "sea ice maximum", no? Minimum is of course in September]

Another perspective.

The early twentieth-century warming trend in the Arctic was nearly as large as the warming trend for the last 20 yr, such that some researchers (e.g. Polyakov et al., 2002) regard them to be part and parcel of the same natural low-frequency oscillation. However, our spatial comparison of these periods reveals key differences in their patterns (Fig. 2). The 20-yr SAT trends for the 1920sâ1930s warming period (Figs 2a and b) and the subsequent cooling period (Figs 2c and d) have remarkably similar patterns, thus suggesting similar underlying processes. In the winter half-year, the high-latitude warming (Fig. 2a) and cooling
(Fig. 2c) patterns are organized symmetrically around the
pole, while in the summer half-year, the warming (Fig. 2b) and cooling (Fig. 2d) appear to reflect the positions of the latitudinal quasi-stationary wave structure, predominantly wavenumber three and four. However, the warming trend for the last 20 yr is more widespread and has a markedly different pattern from the earlier periods in both winter (Fig. 2e) and summer (Fig. 2f). Both the 1920â39 and 1980â99 warming are most pronounced during winter for the high Arctic. In addition, in the latter period, there is pronounced warming in the Eurasian midlatitudes, especially in summer.

https://bora.uib.no/dspace/bitstream/1956/2728/1/tellus_omj.pdf

Yes, maximum is what I meant, Coby, ta.

Sorry for not answering sooner but I was on vacation. Anyway, to address the issues barry raised. First, the global warming predicts that there will be polar amplification. What Hansen, Serreze, Bitz, and Polyakov all show is that the warming in the current period started at the lower latitudes and moved only to the North Pole. In the warming in the 30-40s the warming started at the poles, both Arctic and Antarctic, and move towards the equator. Current theory says that for real global warming, the warming will be amplified at the poles and move to the equator. That did happen in the earlier warming but not in the current warming. In the current warming we have warming in the Arctic but cooling in the Antarctic.

Now as to the GISS model. First, of you go and read up on how they do the magic, you would know that there is nearly no record of what the SST was for the Arctic. While Hansen has shown that met stations on land so correlation within 1000km, he makes no claim about land met stations and SST. In fact, he uses Hadley Centers SST data until he switched to another source. However, there is not enough met stations or ships to know what the SST was. This can be seen if you do a polar view and set the smoothing to 250km.

What the GISS tool does clearly show is that warming started in the low latitudes and moved North. It also shows that the warming is on the land and not SST of the Arctic.

If I was unclear expressing this, then I am sorry.

Have a read of this article, and then asked yourself why people believe the models are unproven.

http://wattsupwiththat.com/2009/05/25/global-warming-of-7c-could-kill-b…

The latest model predic...sorry guess is

"MIT predicts âa 90% probability that worldwide surface temperatures will rise at least 9 degrees by 2100.â

Now in 2003 it was less than half this so what has changed? There has been no empirical evidence that has come to light to suggest this large jump in temps, but what has changed is the model, thats right they now have a new model to play with which guesses even more warming than previously guessed.

This is light of the fact that;

Global temps have dropped (ok stayed the same) since 2003

Arctic ice extent is at the highest late May levels in the AMSR-E satellite record

Antarctic ice has broken the record for greatest extent ever recorded.

January, 2008 broke the record for the most snow covered area ever measured in the Northern Hemisphere.

And yes of course all of the above is just weather i know, but how do these computer programmers come to their startling conclusions with a 90% confidence level just by peering at a computer screen?

Here is the version the general public will see

http://www.reuters.com/article/mnCarbonEmissions/idUS148975034620090522

Crakar -

but how do these computer programmers come to their startling conclusions with a 90% confidence level just by peering at a computer screen?

This might be the most staggeringly nonsensical thing I've yet to read by you, Crakar. I don't know if you're just trying to be cute, or if you're fundamentally ignorant of what modeling (and not just climate modeling) entails.

That being said, Mr. Watts' post is (yet another) exercise in cherry picking start and end dates, and you correctly identify his mistake. Good for you, Crakar, there may be hope for you yet.

Adam,

What do you think maybe the reason why they are only 90% sure of their shiny brand new computer? The ignorance is in simply accepting what these people have to say not questioning them, do you accept that the IPCC is completely wrong and these people from MIT are 100% well lets say 90% right?

Crakar -

Considering that this study doesn't contradict anything in the IPCC (the 9 degree increase falls into the high end of the range given by that report), it's not an issue.

FYI, yet another study that finds the climate models are not working.

Maslowski et al (2008), Title, Eos Trans. AGU, 89(53), Fall Meet.
The inability of climate models to reproduce the recent warming and ice melt in the Arctic Ocean diminishes their accuracy of future climate predictions. Some of these limitations include: northward oceanic heat fluxes, distribution and variability of sea ice in the Arctic Ocean, and its export into the North Atlantic. The general tendency in those models is to transport warm Atlantic Water via the Barents Sea, with Fram Strait experiencing mostly outflow to the south. In reality, the West Spitsbergen Current flowing along the eastern part of Fram Strait delivers the majority of heat into the Arctic Ocean, while most of the heat entering the Barents Sea is released to the atmosphere before entering the central Arctic. More importantly, the heat advected by Summer Pacific Water through Bering Strait is distributed by local currents and eddies over the Chukchi Shelf and into the Beaufort Sea and is readily available for melting sea ice in the western Arctic, where most of the ice retreat has taken place.

So with no polar amplification yet, no equatorial upper troposheric hot spot, and now a failure to actually model the Arctic, what have the GCMs gotten right.

CO2 level increases, but even that will be wrong in about 12 months time.

Well, as further proof the GCMs are wrong. Sea level rise has slowed back down since the warming stopped.

A few more studies that address the GCMs problems:

Spencer et al (2008)
http://www.drroyspencer.com/Spencer-and-Braswell-08.pdf
Nevertheless, since FGâs observational estimates of total (SW LW) feedback already represent a lower climate sensitivity than that produced by any of the 20 coupled climate models analyzed by Forster and Taylor (2006), our results suggest the possibility of an even larger discrepancy between models and observations than is currently realized.

Andrews et al (2008)
http://homepages.see.leeds.ac.uk/~earpmf/papers/AndrewsForster2008.pdf
Previous estimates of climate feedbacks are unlikely to have taken these semi-direct effects into account and so misinterpret processes as feedbacks that depend only on the forcing, but not the global surface temperature. We show that the actual cloud feedback is around half of what previous methods suggest and that a significant part of the cloud response and the large spread between previous model estimates of cloud feedback is due to the semi-direct forcing.

Bony et al (2005)
http://www.met.sjsu.edu/~tesfai/RESULTS/Journals/how%20well%20do%20we%2…
Based on recent studies, no substantive evidence suggests that the weak relative humidity response of climate models, and thus the large magnitude of the water vaporâlapse rate feedback under climate change, are an artifact of climate models. However, as the water vapor feedback represents the strongest positive feedback of the climate system, uncertainties about how small relative humidity changes should be, or how accurate the magnitude of the correlation between humidity and temperature should be, can matter for the spread in water vaporâlapse rate feedback and for the magnitude of climate sensitivity.

However, recent comparisons of the observed and simulated variations of water vapor and relative humidity in the current climate reveal biases in GCMs (sections 3c, 3d, and 3e), and there is still a nonnegligible spread in the model estimates of the water vaporâlapse rate feedback under climate change (Fig. 1). This spread is likely to result from intermodel differences in the meridional patterns of surface warming and in the magnitude (albeit small) of relative humidity changes.

Bennhold et al (2008)
http://66.102.1.104/scholar?hl=en&lr=&scoring=r&q=cache:-QFJipqUrooJ:ea…
As a primary result of this work, we have documented the mean biases between models and productsderived from satellite observations, namely, upper-tropospheric humidity, precipitable water, and net cloud radiative forcing, which are too high, too low, and too strong, respectively, in all models. In addition, we have documented several significant and systematic discrepancies between modeled and observed relation-ships among cloud- and moisture-related variables.

STEPHENS (2005)
http://irina.eas.gatech.edu/EAS_spring2006/Stephens2005.pdf
While GCM climate and NWP models represent the most complete description of all the interactions between the processes that establish the main cloud feedbacks, the weak link in the use of these models lies in the cloud parameterization imbedded in them. Aspects of these parameterizations remain worrisome containing levels of empiricism and assumptions that are hard to evaluate with current global observations. For example, the relationship between convection, cirrus anvil clouds, and SST is a recurring theme in many feedback hypotheses (section 5) yet the connections between convection and cirrus in parameterization schemes is highly uncertain, in many cases empirical, and difficult to evaluate with observations.

Ringer et al (2006)
http://luv.dkrz.de/publications_2006/pub_362_402.pdf
Consistent with Senior and Mitchell [1993] we find that in any given model the sign of global mean net cloud feedback, and of its shortwave and longwave components, may differ between ±2K and 2 CO2 experiments. The relative strength of the cloud feedbacks across GCMs is also likely to be different. However, the most important conclusion of the original Cess et al. [1990] study, namely that the variation of the total climate feedback across an ensemble of GCMs depends primarily on the variation in the cloud feedback, holds in both cases.

Williams et al (2007)
http://cosis.net/abstracts/EGU2007/01305/EGU2007-J-01305.pdf
It is shown here that evaluation and subsequent improvement in the simulation of the present-day regime properties has the potential to reduce the variance of the global cloud response, and hence climate sensitivity, amongst GCMs. For the ensemble of models considered in this study, the use of observations of the mean present-day cloud regimes suggests a potential reduction in the range of climate sensitivity of almost a third.

Happy reading.

The current sea ice level is within one SD of the 1979-2000 mean per NISDC. This year has more sea ice that last year, which is way to soon to determine a trend. However, this graphic shows that current sea ice is closer to the mean that the 2007 extreme.

No it doesn't. Neener-neener!

If this doesn't underscore the stupidity of the denialist's tendency to focus on short-term phenomena, what will?

Urgggh I busted that link.

Improved neener-neener link

dhogaza -

Wow, according to that graph, global warming started in Feb. 2009, stopped in April 2009, and then started up again this month!!!! If only there wasn't so much conflicting data, we'd be able to the truth!

dhogaza,

you are just being a troll. The quote even says that it is too soon to determin a trend, but then as I also pointed out, only 30 years of data from on short warming period is not enough to say the ice is going away either.

NSICD is no longer posting a graph since they finally admitted that the sensor is going bad, just like the other sensor in January.

I notice that your ignoring all the issues, like lack of polar amplification and that the models have a host of issues, not the least being clouds.

Your just in denial. The warming has stopped and temperatures are dropping, the sea level trend has gone back to the pre-warming level of 2.5mm, the climate reconstructions have been show to have serious issues with low frequency variability. Basically, the whole justification for the current warming being something unusual is proving to be false.

We still have this one;

w.w.w.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

Does not go back as far but beggars cant be choosers.

Cheers

Crakar

Does not go back as far but beggars cant be choosers.

You have summarized the denialist position perfectly. Using data that doesn't support your preconceived conclusions is bad argumentation, but, hey, beggars can't be choosers!

NSICD is no longer posting a graph since they finally admitted that the sensor is going bad, just like the other sensor in January.

Yes, they are, they've finished the calibration work that they've been working on for months in anticipation of the older satellite reaching the end of its life span, and are now updating daily.

And if you go to the site, you'll see the data for the two sensors for the last year graphed on top of each other. As close to a perfect fit as you can imagine.

Ironic, though, that you posted a link the the graph triumphantly in May and now swear it's meaningless today.

Typical denialist crap.

We still have this one;

Which shows 2009 sea ice extent to be identical to that in 2008, the second lowest minimum on record.

NSICD is no longer posting a graph since they finally admitted that the sensor is going bad, just like the other sensor in January.

And actually, it was the same satellite/sensor in both cases.

Gee, Vernon, display your ignorance in public much?

hog,

still nothing to actually address the model problems yet, huh?

Wake me up when there are model problems that need addressing.

They're doing fine.

It will be fun to watch your spin when El Niño later this year, using the standard denialist cherry-picking technique, "proves" that the models really are wrong and that it's warming 2x or 3x as quickly as they "predict".

Oh, and there is still no warming in the Antarctic.

Actually, RyanO's problem-filled "debunking" of Steig, so proudly flaunted by the denialsphere, shows LESS WARMING not NO WARMING in the Antarctic.

Refer post 42

You are a complete twit Adam.

I was merely posting a link that shows current ice extent for the posters, but you spin the thing into another verbal attack against someone. Adam grow the F..K up.

Crakar -

I was merely posting a link that shows current ice extent for the posters, but you spin the thing into another verbal attack against someone. Adam grow the F..K up.

Don't take it so personally, Crakar. I have nothing against you. I take issue with your quality (or lack thereof, more appropriately) of argumentation, and complete unwillingness to understand the science. If it sounds like I'm attacking you personally, well, I apologize, but I'm attacking your arguments (which are rather poor). For all I know, you might be a great person in real life, and it's only your blog commenting personality that is a complete muppet.

You posted that link to Arctic sea ice in an attempt to show that it's not decreasing. It's been explained to you over and over why this is wrong, by several people. So, my comment was perfectly appropriate. You can't find any data that actually supports the position you've taken, so hence, "beggar's can't be choosers."

Get over yourself, pal.

For the last time Adam i posted it because the only other source of sea ice data was not working, if you honestly beleive i posted it in an attempt to cloud the debate then you obviously see the world very differently to most others.

Crakar -

Very well. I apologize for misinterpreting your intentions. I hope, given your previous comments, that you understand why I would misinterpret what your point was.

I think at times all (myself included) need to step back and take a deep breathe.

I am pretty thick skinned so i dont mind if you or anyone else for that matter disagrees with me (re you above posts, muppet etc).

I do not intend to deliberately mislead the debate by claiming things as fact when i know they are not.

The term "beggars cant be choosers" meant we cant see the entire 30 year record because the sat was broke but we can still see the current ice levels.

I hope this clears up a few things.

Yet a few more studies that have identified climate factors that the models fail to capture.

Bony et al (2005)
http://www.met.sjsu.edu/~tesfai/RESULTS/Journals/how%20well%20do%20we%2…
Based on recent studies, no substantive evidence suggests that the weak relative humidity response of climate models, and thus the large magnitude of the water vaporâlapse rate feedback under climate change, are an artifact of climate models. However, as the water vapor feedback represents the strongest positive feedback of the climate system, uncertainties about how small relative humidity changes should be, or how accurate the magnitude of the correlation between humidity and temperature should be, can matter for the spread in water vaporâlapse rate feedback and for the magnitude of climate sensitivity.

However, recent comparisons of the observed and simulated variations of water vapor and relative humidity in the current climate reveal biases in GCMs (sections 3c, 3d, and 3e), and there is still a nonnegligible spread in the model estimates of the water vaporâlapse rate feedback under climate change (Fig. 1). This spread is likely to result from intermodel differences in the meridional patterns of surface warming and in the magnitude (albeit small) of relative humidity changes.

Bennhold et al (2008)
http://66.102.1.104/scholar?hl=en&lr=&scoring=r&q=cache:-QFJipqUrooJ:ea…
As a primary result of this work, we have documented the mean biases between models and products derived from satellite observations, namely, upper-tropospheric humidity, precipitable water, and net cloud radiative forcing, which are too high, too low, and too strong, respectively, in all models. In addition, we have documented several significant and systematic discrepancies between modeled and observed relation-ships among cloud- and moisture-related variables.

STEPHENS (2005)
http://irina.eas.gatech.edu/EAS_spring2006/Stephens2005.pdf
While GCM climate and NWP models represent the most complete description of all the interactions between the processes that establish the main cloud feedbacks, the weak link in the use of these models lies in the cloud parameterization imbedded in them. Aspects of these parameterizations remain worrisome containing levels of empiricism and assumptions that are hard to evaluate with current global observations. For example, the relationship between convection, cirrus anvil clouds, and SST is a recurring theme in many feedback hypotheses (section 5) yet the connections between convection and cirrus in parameterization schemes is highly uncertain, in many cases empirical, and difficult to evaluate with observations.

Ringer et al (2006)
http://luv.dkrz.de/publications_2006/pub_362_402.pdf
Consistent with Senior and Mitchell [1993] we find that in any given model the sign of global mean net cloud feedback, and of its shortwave and longwave components, may differ between ±2K and 2 CO2 experiments. The relative strength of the cloud feedbacks across GCMs is also likely to be different. However, the most important conclusion of the original Cess et al. [1990] study, namely that the variation of the total climate feedback across an ensemble of GCMs depends primarily on the variation in the cloud feedback, holds in both cases.

Williams et al (2007)
http://cosis.net/abstracts/EGU2007/01305/EGU2007-J-01305.pdf
It is shown here that evaluation and subsequent improvement in the simulation of the present-day regime properties has the potential to reduce the variance of the global cloud response, and hence climate sensitivity, amongst GCMs. For the ensemble of models considered in this study, the use of observations of the mean present-day cloud regimes suggests a potential reduction in the range of climate sensitivity of almost a third.

have fun reading.

Sorry for the delay in posting but I was busy with RL for the last month+.

Anyway, yet another nail in the coffin of GCM modles being unproven. None of the models show why there would be 20-30 periods of warming or cooling that is not related to CO2 or volcanic activity.

Basically, as was in a current RC post, there is current cooling and warming is not expected to resume till 2020. Please point to any GCM's that predicted that?

None of the models show why there would be 20-30 periods of warming or cooling that is not related to CO2 or volcanic activity.

Models generate noisy up-and-down results just like the real world, imposed on a trend of increasing temperature.

You've been told this approximately 527,987 times in the past, Vernon.

Basically, as was in a current RC post, there is current cooling and warming is not expected to resume till 2020.

June, according to NOAA and GISTemp, was the 2nd warmest on record. The piece posted on RC was by Swanson, who was explaining a controversial paper he co-wrote.

Note that his prediction and analysis aren't accepted by the climate science community. For one thing, they only hold for one dataset, HadCrut. For another, the supposed "current cooling" isn't statistically significant and indeed is only "cooling" if you carefully cherry-pick starting points over the last decade. Other starting points yield a rising trend. Neither is a statistically valid trend.

Please point to any GCM's that predicted that?

Basic understanding of statistics will tell you that a noisy signal imposed on a rising trend will yield a curve where short-term downward portions would appear.

Digustingly, someone had to actually write a paper in a journal to point out with graphics why this is true, and Tamino did the same with his "wiggles" post over at Open Mind.

Disgustingly, because anyone whose studied statistics for even a few hours knows this.

Anyone who's ever gambled knows this.

The obvious only needs to be pointed out to denialists whose ignorance is unbounded.

yet another nail in the coffin of GCM modles being unproven.

Oh, and I'm sure you meant to say "proven", not "unproven". Regardless, no one claims GCMs are "proven". They're *useful*. They're not complete; no "modle" will ever be complete.

However, research is always being done to make them better.

For instance, this paper you reference above:

It is shown here that evaluation and subsequent improvement in the simulation of the present-day regime properties has the potential to reduce the variance of the global cloud response, and hence climate sensitivity, amongst GCMs. For the ensemble of models considered in this study, the use of observations of the mean present-day cloud regimes suggests a potential reduction in the range of climate sensitivity of almost a third.

have fun reading.

You're right, it *is* fun reading, the abstract, at least.

They claim to be on to something that will allow them to tighten up the range of climate sensitivity by 1/3 by improving modeling of cloud-related phenomena, an area that all modelers openly state is the most poorly modeled bits of climate.

In other words, rather than the current range of climate sensitivity computed by model of say 2-4.5C, they say their work might enable modelers to tighten up that range around the 3.0C mark, to say about 2.5-4C.

This constitutes "victory" for denialists, in your eyes?

Or is this just another case of Vernon reading a paper and totally misunderstanding what the authors are saying?

dhogaza,

The point of this discussion is not what is the climate sensitivity to CO2 but rather, have the GCM models been shown to be accurate enough to base future policy on. My point is that they have not been.

If we can get proven GCM models that accurately project future climate, then they could be used as a basis for policy decisions. GCM's have not reached that point yet.

That is the point of this discussion.

Vernon -

The point of this discussion is not what is the climate sensitivity to CO2 but rather, have the GCM models been shown to be accurate enough to base future policy on. My point is that they have not been.

You have stated this numerous times, and yet cannot show anything that demonstrates that the models are way off base. What data do you have to show that the models make poor representations of the climate?

Most people with any knowledge in the field would say that to 'valid' a model, you compare the model results to observations. Given that, using the 20th century to test models is an appropriate dataset, because we know both the outputs and the inputs. We can see that the models do a decent job of reproducing 20th century temperatures.
http://blogs.edf.org/climate411/wp-content/files/2007/07/hindcasts_vs_m…

Also see here: http://scienceblogs.com/illconsidered/2006/03/models-are-unproven.php

Sure there are parameters or factors going into the model that we [well, not me, but climate scientists in general] don't know well enough to reproduce very accurately. But we don't need perfection, not every little thing affects the general output of the model. No model is perfect, and we sacrifice accuracy for simplicity where we can (the law of diminishing returns applies to models as well as anything else, so we can, at some point, make this trade without losing too much accuracy).

As an example, we can safely ignore relativistic effects when modeling earth-bound, human scale mechanical systems. Strictly speaking, the model is 'incorrect.' But, we don't need to add that complexity, because we get good results without it.

But, this isn't new information to you. You know all this, and have heard it all before. So I have a question for you, Vernon. What test do you propose would determine the models' validity? What would Dr. Vernon, Climatologist, do to test his own climate model before releasing the results for scrutiny? What would Dr. Vernon need to see before he was comfortable basing future policy on his model?

Adam,

Why don't you try to answer peer reviewed studies with something other than opinion pieces. I have presented peer reviewed studies that address the problems with the models. You have presented opinion and links to other peoples opinions. Why not try to use current peer reviewed science.

So, peer reviewed studies vs your opinion.

Sorry, but I have seen nothing that shows the were the models are good enough to use as a basis for policy. I have listed many studies that have found problems. RC has posted a study that shows that there is major dynamics and processes that the models do not capture because we have not figured out what they are or how they work.

I am presenting studies, arm waving is not equivalent.

I have presented peer reviewed studies that address the problems with the models.

Yes, and I showed that one is meant to narrow uncertainty, meaning the "best estimate" of 3.0C forcing to a doubling of CO2 is strengthened.

Do you always shoot yourself in your (private member)?

Sorry, but I have seen nothing that shows the were the models are good enough to use as a basis for policy.

No one gives a shit about your opinion, in science, or outside science.

I'm sure this is frustrating to you, as you're so certain that you know more about the science, math, etc than thousands of professionals.

But - that's life!

Vernon -

Sorry, but I have seen nothing that shows the were the models are good enough to use as a basis for policy.

Again, you're avoiding the question. What would Dr. Vernon do to test his own climate model, what data would he input into it, and what would he look for. You make a lot of claims without much substantiation, and shit on actual scientists quite a bit, so why don't you stick your own neck out and say straight up what results would convince you.

I have listed many studies that have found problems.

Again, the ability of the models to hindcast the 20th century accurately demonstrates that, despite whatever problems they have, they are largely accurate. The real question is, if we fix all these problems, will it fundamentally change the modeling results? Ask dhogaza points out to you, this is pretty unlikely.

Why not try to use current peer reviewed science.

The first link I provided is a graph taken directly from the IPCC 4th assessment, which is the synthesis of the peer reviewed research as of 2007. And again, of the very few references you actually make, none of them actually, erhm, say what you wish they said.

Why don't you try to answer peer reviewed studies with something other than opinion pieces.

The only opinions I expressed was a discussion on the relationship between complexity and accuracy when constructing mathematical models and how to test model validity. Nothing I said is particularly controversial. Anyone who has ever constructed a model of anything will tell you this. You can never be perfect, but you can be good. Also, Coby's post has links to a subset of the successful modeling predictions, if you had bothered to read it you might know that.

dhogaza,

to bad you have nothing to contribute to the discussion other than ad hom attacks. Coby indicates your a smart person that must have much to offer, yet I rarely see more from you than personal attacks.

Adam,

I have list listed around seventeen studies, most that are after the IPCC 4th AR which all address problems with the models. Even over on RC there is a discussion of how there may be no warming till 2020.

When the models can explain how we get into and out of a period of glaciation, can explain periods like the MWP, RWP, LIA, etc. then I would consider them good enough to make policy decisions on.

to bad you have nothing to contribute to the discussion other than ad hom attacks.

Once upon a time, upon first meeting you on the internets, I was nice to him and tried to point out his errors regarding climate science.

So did many others, including professionals like those at RC and Tamino's Open Mind.

Your response was to continue making the same claims, repeatedly, in many venues, over and over.

So I stopped being nice to you. So did many others ...

Well, you do not like it when I point out the flaws so how about some one else:

http://scienceblogs.com/illconsidered/2008/07/how_to_talk_to_a_sceptic…

I already answered your post on that, Vernon.

Once again you're interpreting a scientist saying that current models don't capture some of the ways in which things might be MUCH WORSE (ocean model, in this case) as being supportive of your notion that there's nothing to this AGW stuff.

Vernon said:

Well, you do not like it when I point out the flaws so how about some one else

Vernon, you are obviously not a biologist since you keep on mixing apples and oranges. Do you really think that Terrence Joyce is discussing GCM's in that article?

Just to save you the embarrassment of repeating it on other blogs, he is discussing ocean circulation models not GCM's. They are much further behind than GCM's since there is a paucity of data on the oceans unlike the atmosphere. The introduction of the ARGO system and the exploration of the abyssal depths for temperature and salinity data will greatly improve these models in the future.

Just to save you the embarrassment of repeating it on other blogs, he is discussing ocean circulation models not GCM's.

Both HadCM3/4 and GISS GCM Model E include dynamic, gridded ocean models coupled to the atmospheric models. They can be turned off (for instance when the HadCM model's run in UK weather forecasting mode - they use the latest observed ocean "weather" data and run the atmospheric model with that representation of the ocean). Well, actually apparently at the moment Model E has five different ocean models to choose from, depending on what questions are being asked of the model.

So the criticism of ocean circulation models is fair since they get coupled to the atmospheric models.

But Vernon's still missing the point ...

Dhogaza, I think we are talking about two different kinds of ocean circulation models. The GCM's are linked to surface circulation whereas the models Joyce is working with involve overturning circulation involving thermo-saline conditions.

Here are two quotes from Joyce:

A 3-4 meter, high latitude buildup of fresh water over this time period has decreased water column salinities throughout the subpolar N. Atlantic as deep as 2000m. At the same time, subtropical and northern tropical salinities have increased.

The degree to which the two effects balance out in terms of fresh water is important for climate change. If the net effect is a lowering of salinity, then fresh water must have been added from other sources: river runoff, melting of multi-year arctic ice, or glaciers. A flooding of the northern Atlantic with fresh water from these various sources has the potential to reduce or even disrupt the overturning circulation.

Whether or not the latter will happen is the nexus of the problem, and one that is hard to predict with confidence. At present we do not even have a system in place for monitoring the overturning circulation.

Models of the overturning circulation are very sensitive to how internal mixing is parameterized. Recall that internal mixing of heat and salt is an integral part of overturning circulation. One recent study shows that for a model with constant vertical mixing, which is commonly used in coupled ocean-atmosphere climate runs, there is only one stable climate state: our present one with substantial sinking and dense water formation in the northern N. Atlantic.

---------------------------------------------

For the ocean, our data coverage is wholly inadequate. We canât say now what the overturning circulation looks like with any confidence and are faced with the task of predicting what it may be like in 10 years!

http://www.whoi.edu/page.do?pid=12455&tid=282&cid=10046

Dhogaza, I think we are talking about two different kinds of ocean circulation models. The GCM's are linked to surface circulation whereas the models Joyce is working with involve overturning circulation involving thermo-saline conditions.

That could be, I was just looking at the surface-level (pun intended) claim that GCMs don't include dynamic circulation models. They do, but as to how close they are to what Joyce is working on, I don't know. Maybe I'll spend some time looking, this week.

However, we're both agreed, I think, that ...

1. Vernon misrepresents Joyce's comments in regard to the utility of GCMs

2. He's either too uneducated to realize it, or dishonest.

3. And well maybe it's just me, not you, but I think he's a member of the Unteachable Caste.

Oh, and this quote you provide backs up what I was trying to tell Vernon, at least:

One recent study shows that for a model with constant vertical mixing, which is commonly used in coupled ocean-atmosphere climate runs, there is only one stable climate state: our present one with substantial sinking and dense water formation in the northern N. Atlantic.

He's saying that accurate modeling might show that possible response to AGW will be a second stable state, different than ours. Which, regardless of the change in average global temps, means hugely different regional climates based on shifting warm/cold water currents, etc.

In other words, as I've been trying to tell Vernon, THINGS MIGHT BE MUCH WORSE THAN WE IMAGINE.

Since the whole thrust is in the context of "response to AGW", there is no comfort there for Vernon etc denialist camp. Far from stating that AGW isn't real, or the response might not be important, they're saying "HOLY SHIT! We have no *effing* idea because the models aren't capable of modeling a state flip in the ocean!"

Vernon - the measured statement cited by you is how scientists respond when they're worried.

dhogaza,

You and Forrester are a trip. The WHOI clearly say that GCMs must include the oceans, since they are the major driver after the sun, which they do not do now. Just taking sea surface temperature does not work. To have you and Forrester say that that page has nothing to do with GCMs is an complete lie. I guess that is ok but I suggest that anyone that doubts what I quoted go read the whole thing at:

http://www.whoi.edu/page.do?pid=12455&tid=282&cid=10046

The WHOI clearly say that GCMs must include the oceans, since they are the major driver after the sun, which they do not do now.

You've been told you're wrong, and you're repeating it again.

That makes you a liar.

HadCR3:

"The ocean model has a resolution of 1.25Ã1.25 degrees and a timestep of 1 hour. Thus there are 6 ocean grid points for every atmospheric one."

GISS GCM Model E has several available models, including:

"GISS Dynamic ocean model (Russell)

This model is a fully dynamic, non-Boussinesq, mass-conserving free surface ocean model (Russell et al, 1995, 2000, Liu et al 2002). The dynamics is based on a modified Arakawa scheme on the C-grid, with a linear upstream scheme for advecting tracers. Vertical mixing uses the KPP scheme of Large et al (1996). Momentum mixing is modelled as a spatically varying laplacian as in Wajsowicz (1993). The effects of mesoscale eddies and isopycnal diffusion are parameterised as in Gent and McWilliams (1996), but using variable coefficients (Visbeck et al, 1997), and coded as in Griffies (1998).

The model contains up to 12 variable depth subgrid scale straits which contect ocean grid boxes, which would not be connected at the resolution used. In particular, the Straits of Gibraltar, Hormuz, and Nares straits are so modelled. All ocean components are fluxed through these straits as a function of the end to end pressure gradients, balanced against a drag proportional to the straits 'width' which serves as a tuning parameter to get reasonable fluxes."

they are the major driver after the sun

And this deserves a emphatic WTF?

So how is the ocean generating energy? Cold fusion of water molecules?

dhogaza,

Once again... The sun is the only source of energy of any significants. The oceans store almost all the energy (~99%) that runs the climate. Do you disagree with this? The atmosphere does not warm the oceans, rather the oceans hold and release heat for reasons that I have not seen answered yet.

That was Joyce and Keigwin are saying. That a GCM that does not incorporate a model reflecting the total oceans circulation will not work. They further say we do not know enough at this point to create one.

Yet another study that finds problems with the current GCMs.

Hunt (2005)
http://www.springerlink.com/content/677kx61w6812gx81/

It was therefore concluded that these fluctuations were generated by stochastic processes intrinsic to the nonlinear climatic system. While a number of characteristics of the MWP and the LIA could have been partially caused by natural processes within the climatic system, the inability of the model to reproduce the observed hemispheric mean temperature anomalies associated with these events indicates that external forcing must have been involved. Essentially the unforced climatic system is unable to sustain the generation of long-term climatic anomalies.

Well, I have presented a lot of studies that have found problem with the models. S&T's new study shows that natural climate drivers are much stronger than CO2 based warming.

Coby,

ready to concede that the models are not ready for prime time? Since I have not seen anyone actually showing that the models do not have the problems which I have presented.

Umm Vernon #96, what problem do you think your link reveals?

blueshift

Vernon probably won't reply, because his previous post was two years ago. But it does beautifully show how deniers have no idea about science.

Note how his link and his quote make this statement:

"..... Essentially the unforced climatic system is unable to sustain the generation of long-term climatic anomalies...."

There has never been a clearer statement about the idiocy of the 'natural variation' claim. That paper very clearly states that the climate MUST have some sort of external forcing mechanism if it is to sustain long term anomalies. It doesn't just change on its own.

It proves - once again - that deniers don't read science. They rely on others to give them their opinions. And those others are equally bad at understanding science and rely on ideology rather than evidence for their views.

Mandas,

There was some sort of spam comment that made me think it was an active thread. After I submitted I realized my mistake.

You are of course right, Vernon's post illustrates the ignorance of the deniers.

That was Joyce and Keigwin are saying. That a GCM that does not incorporate a model reflecting the total oceans circulation will not work. They further say we do not know enough at this point to create one.

So have they worked out what the "error" this introduces is worth?

I.e. it could be that the model UNDERESTIMATES warming because of that lack. It could be that the error makes the mean 2.95C per doubling rather than 3.0C per doubling.

What we observe now indicates that any sensitivity below the lower end of the IPCC projections is proven false.

Also, if all those other scientists have it wrong, what about Joyce and Keigwin?