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Saturday, March 12, 2016

Uncertainty in uncertainty

I may seem to pick on Marcott et al. 2013, but that paper came out while I was playing with ocean paleo-reconstructions in the tropics.  Marcott used a number of tropical paleo reconstructions that I didn't use because they were too coarse (ultra low frequency) and had a unknown uncertainty in the samples.

The unknown uncertainty is "natural" averaging.  Most of the proxies are based on plankton of some sort and the biological temperature proxies would go through boom bust cycles.  You can have more depositing of a particular type of plankton during either.  So if you have a core sample say one inch thick that spans say 300 years, one particular good growth period would dominate the sample or one massive die off could.  The published accuracy of the sample is based on how well a lab can count something not how well biological life fits a normal distribution assumption.

At the time I was using the Oppo et al. 2009 and the Mohtadi et al. 2010 aka Anand on the legend was the low frequency reconstruction I didn't use.  There is a large difference between the two, especially near the end.  The lower frequency reconstructions have more uncertainty in dating which is pretty well know plus the natural averaging of the samples isn't known and the impact isn't discussed as far as I know.

Most of the criticisms of Marcott, Mann and other paleo re-constructors deal with just about everything other than the "effective" averaging produced "naturally" by the organisms and unintentionally by "novel" methods.

My curiosity might be misdirected, unfounded or irrelevant, especially since I am a Redneck and not a part of the "scientific" establishment, but since just about every higher resolution "cap" reconstruction diverges from lower resolution reconstructions, I am a tad stubborn about wanting a few answers.

It is a bit frustrating to me since in Redneckville such an obvious issue would dealt with something profound like, "What the F__ is going on!" but in climate scienceville some dweeb starts babbling about standard error when this is pretty much a non-standard situation :)

Technically, the error is only about a degree or about equal to the estimated amount of warming during the instrumental period and you can massage or polish all you like, but the result should always consider the absolute magnitude of the potential error if it is never specifically addressed.  In order to reduce the error you have to do more digging and less assuming.  It is very unlikely the error is "normally" distributed uniformly over the entire time frame of the reconstruction which is part of the assumptions made to get those unbelievably tight error margins in the published literature.

Inquiring Rednecks want to know what's the deal Lucille?

Friday, March 11, 2016

How to make history disappear as if by magic

Greg Goodman has a nice post on basic issues with Ordinary Least Squares regression analysis at Dr. Curry's place.  Someone asked about what impact it would paleo reconstructions of sea level.  While I don't have a specific sea level example I do have a sea surface temperature example.

The yellow curve is from the Mohtadi et al. 2010 paper reconstructing temperatures of the Indo-Pacific Warm Pool which has an sample rate of about 400 years and the blue curve is from Oppo et al. 2009 from the same area but it has a sample rate of about 50 years.  With more samples and higher resolution you get a clearer picture.  The Mohtadi reconstruction was one of many reconstructions used in the seriously flawed Marcott et al. paper of 2013.

If you regress Oppo with respect to Mohtadi you would have oranges on the x axis and apples on the y axis.  If you just average the two, the coarser Mohtadi would smooth out the information in the finer Oppo.  Either way you end up with a flatter than it should be past history and a sudden pop, either up or down when the influence of the coarse Mohtadi data ends.  If you pick coarse data or make higher resolution data coarse by inappropriate or "novel" averaging, you can make the details of the past disappear, as if by magic.  Even though Oppo et al. 2009 was available for Marcott and company it was not included in their "ground breaking" paper.

This is like the most basic of basics screw ups, so someone with a bit of knowledge would assume ignoring the obvious has to be deceptive instead of frigging stupid, if the mistake is made by a "professional" and published in a peer reviewed journal.  Unfortunately, since nearly everyone has access to canned statistic packages, stupidly using extremely powerful statistical tools is more likely than intentional deception.

With only the options of dishonest or stupid, tact becomes a bit of an issue.  Most engineers are not know for excessive amounts of tact, generally expect professionals to know what they are doing and have close to anal attention to detail, so they lean toward the dishonest accusation.  Hey!  It is an honest mistake and no one really likes being called stupid.

Back in the day, scientists had plenty of time to ponder prior to responding through snail mail or journals, so they were a lot more creative in parsing their insults.  Now a days, time is money and profanity is more socially acceptable.  Deal with it.

Thursday, March 10, 2016

Error Cascade

Judith Curry had a post on Error Cascade back in 2012.  There are tons of ways to screw up and one not so big screw up can lead to a progression of more screw ups that end in pretty spectacular failures.

There is some fairly new hysteria online about Arsenic in rice, water, apple juice and just about everything, since Arsenic is common if soils.  Some of the "Organic Gurus" primed the pump with Arsenic in poultry.  OMG!  Chicken farmers are feeding Arsenic to chickens then you eat them!!  Damn, that has to be bad, right?

I was bored and Googled a few things.  It appears the Arsenic deal started in Bangladesh in 1994.  Water wells had a higher than normal level so the WHO stepped in to set a few standards a limit Arsenic in water to about 50 ppb.  Since most places do not have as high a level, the WHO set somewhat arbitrarily a 10 ppb standard for every place else.  Once the drinking water standard was set and set pretty low, the US EPA requested research into field testing kits that were cheap and could read down to close to zero to include the 10 ppd water standard.

I haven't found out everything I want about the timing of Arsenic sample testing, but it appears that 5 ppb with any real accuracy is a pretty new development.  Consumer Reports got some on the new test kits and started testing whatever blew wind up their skirts and had a "block buster" discovery that some rice crop could have up to around 160 ppb Arsenic content.  This got the US "health food" guys going.

In the mean time, scientists with WHO recommended that Bangladeshi folks switch from deeper wells to shallow wells and surface water to reduce exposure to the killer Arsenic.  Surface water and shallow wells are not know to be great water sources in areas with poor sanitation, lots of people and lots of diseases.  So a MIT study found that the water source switch was killing more children that the Arsenic.

The FDA, concerned with the US food supply, basically took the position that there is no evidence that Arsenic in low ppb amounts is doing any harm.  The Arsenic in chicken haters pretty much forced the FDA to set limits on Arsenic in poultry even though that Arsenic was "organic" and posed a much lower health risk than Inorganic Arsenic.

All the time this was going on, "Organic Food" fans were developing pseudo-scientific remedies for Arsenic poisoning that has never been determine to really be a problem.  I stumbled on "Seattle Organic Restaurants" website and they recommended a "cleansing" using bananas and coconut milk to flush the deadly toxin from your pristine bodies.  Coconut milk and bananas can have as much or more Arsenic as some rices and both are an order of magnitude greater that the frigging chicken which has mainly organic arsenic to begin with :)

I am extremely grateful to Dr. Curry for enlightening me with error cascade because the terminology I was used to was "Cluster Fuck".

Throwing the Baby out with the Drinking Water: Unintended Consequences of Arsenic Mitigation Efforts in Bangladesh,

Update: More cascade potential fun.  Flint City has started replacing lead pipe run outs with new copper run outs to the meter.  Toronto, Canada did the same and noted that partial replacement, city to meter but no owner change out tended to make the lead situation worse.  Most northern cities do not like using PVC for run outs mainly because of union plumber concerns.  Using non-conductive PVC instead of copper would reduce at least part of the issues with partial replacement.  So catastrophe fans, things should get interesting.  Toronto's lead pipe replacement program questioned.

Sunday, March 6, 2016

That Danged Mid-tropospheric Hot Spot Deal

The blogosphere is alive with talk about the troposphere.  I borrowed this chart from wattsupwiththat via Climate Etc., RSS's new paper indicates that the troposphere is warming at a rate of 0.125 C per decade!  There is a discussion on the changes at Climate Etc.titled, End of the satellite data warming pause?  Imagine that?  No sooner than I finished my Raising the lid on models post.

In my opinion, the Tropical Troposphere Hot Spot has issues because of pole ward advection not being properly simulated in the models.  It is really more a a northern hemisphere mid to low troposphere warm spot because Arctic Winter Warming and Sudden Stratospheric Warming are not all that easy to model nor is the break down in the Arctic polar vortex during high "wall energy" transfer.  A stable vortex helps retain heat and an unstable vortex releases lots of heat and that heat is what should be causing the warming of the tropical middle troposphere.

This dovetails with my concerns about how useful "average" surface temperature anomaly is when small amounts of energy can cause a large change in temperature anomaly during the extremely cold winter months at the poles.  We are stuck with the data we have but we really don't have to hype things that are spurious.

The "warming" is caused by latent "cooling" where warming or cooling really depends on your frame of reference.  If the tropical troposphere "warming" stays in the tropical troposphere then it would be real warming of the system but if it advects to the poles that "warming" is actually "cooling" since there isn't any heat uptake associated with it.  You could argue that it reduces the rate of cooling, but that is wrong because the outward flow increases, i.e. it is a heat loss from the system.  I don't expect many people to understand that since it would require changing one's frame of reference or "looking at the puzzle" differently.

However, the mid-troposphere should warm at a faster pace than the "surface" based on the models and the increase in the rate should be in the 70% faster range.  So the indicated 0.125 C/dec. should be scaled down to about 0.0875 C per decade at the "surface", in this case the lower troposphere which isn't really the same as the "surface" based on land and sea direct measurements.

Land "surface" temperature anomaly should be higher than satellite derived lower troposphere temperature because land is based on Tmax minus Tmin and lower troposphere is based on a "fixed" time of day.  The adjustments being made by RSS are adjustments to the "effective" time of day because the satellites can change speed a bit over time and there is also an internal calibration issue with the older satellite platforms.  I still think it is a pretty remarkable feat of engineering for the satellite data to be as good as it is, but there is no such thing as "prefect" data.

There could be better agreement if the "time of day" was made to be roughly the same.  The land surface temperature guys like local midnight while the satellites are closer to 7:30 AM local if I read the comments correctly.  Don't expect that to be discussed anytime soon either.  IMHO though, the less adjustment required the better.

Unfortunately, the RSS adjustment this time may have a little miscue similar to the Karl et al. miscue of leaning towards less "state of the art" data which happens to be a great reason to defund projects if the Climate Gurus are going to ignore billions of dollars worth of advanced remote sensing investment.  I love the space program but absolutely despise the way some are thumbing their nose at space based technology.  It is going to take a while for all this to get sorted out and I doubt that corrections if coming, will get much in the way of high dollar, high impact press.

This is where firing folks gets to be a requirement if you want progress, but of course "firing" is just so capitalistic and leaving no scientist behind is so progressive.  Funny, you cannot progress because of progressives :)

Friday, March 4, 2016

Raising the Lid on Climate Models

This is something that I missed that I found interesting.  I have used a pot lid rattling to describe the situation with the stratospheric Brewer-Dobson Circulation and Sudden Stratospheric Warming events that tend to impact the stability of the polar vortexes. I was pretty critical of people using "lazy" tropopause TOA reference when there is a lot of important dynamics up to an including the Turbopause at nearly 100 kilometers.

With the huge differences in the Northern and Southern Hemispheres temperature wise and roughness wise there are all sorts of interesting dynamics which somewhere along the line have to conserve angular momentum.  During my brief foray into the PETM situation and the indications that sea levels might be hundreds of meters higher than today I wondered how you would have to model potential variation in Earth's rotation velocity to see if it was worth considering.

This dissertation, The Earth’s Atmospheric Angular Momentum Budget and its Representation in Reanalysis Observation Datasets and Climate Models by Simon Driscol at the University of Reading popped up.  I haven't digested it all yet, but there is a mention of raising the lids on Hadley Center climate models to roughly 85 km from 40 km which was interesting.  Since climate models basically suck at emulating most of the common "oscillations" and some even get reversed flows for know ocean currents, it is pretty obvious that they have had some issues with what should be very basic physics.  Granted, modeling climate is a monumental task but not even coming close matching the difference between hemispheres to the point that they don't even want to discuss the differences between the hemisphere is pretty sad.

This is the second dissertation from the University of Reading that has caught my eye, the other being Andrew Barrett's recommended changes to liquid top cloud parameterization entitled, "Why can't models simulate mixed-phase clouds correctly."  Barrett's conclusion was that properly parameterizing mixed-phase clouds could reduce modeled sensitivity to about 1.6 C per doubling which is right in line with most current estimates.  I haven't followed up on how well is dissertation was received, but mixed-phase clouds was one of my pet peeves since increased relative humidity should impact the types of clouds being formed.  This peeve goes all the way back to the issues with the Kiehl and Trenberth etc. Earth Energy Budget incorrect assumptions about the atmospheric window from the "real" surface when their assumption actually was for the top of the atmospheric boundary layer "surface".

So I might just have a bit more reading ahead of me.  Both of these get into more intensive modeling that I am willing to pursue but worth a look.

Thursday, March 3, 2016

Notes on PETM stuff

Constantly being updated aka a work in progress

I am probably going to never finish this because it is really a waste of time, but there are a few interesting things about the Paleocene-Eocene period.  This is inspired by a CO2 done it versus the impact of plate tectonics on climate smack down at And There is Physics which tends to devolve into an there there is bullshit when the usual suspects get involved.  

First there was no glacial area of any significance.  The "high" plateaus by and large didn't exist and since there was no Antarctic or Greenland ice mass there is a significant lapse rate issue because the PETM "surface" doesn't compare easily with today's surface.  The Antarctic would be nearly 30 C degrees warmer just due to the lower altitude.

Second, the ratio of ocean area to land area was very different.  As a rough estimate, there was closer to 80% ocean area.  Oceans of course have a higher heat capacity and the average temperature of the oceans is about 18 C degrees.  So assuming "pre-industrial" average temperature was about 15 C degrees, the average land surface temperature should be about 9 C degrees.  Just changing the ratio of ocean and land would make the average temperature about one degree warmer.

The atmospheric CO2 during the PETM was close to 1200 ppmv and assuming just the no feedback sensitivity the temperature should have been 2 to 3 degrees warmer than preindustrial depending on what values you like for initial condition and "benchmark" forcing.

These are pretty basic issues with the "Global Mean Surface Temperature Anomaly" being used as an "index".  Since there are huge differences between today's surface and the likely surface 55 million years ago you have a apples to oranges situation that requires a lot of consideration.  Even the elevation of the ocean surface was different enough to consider nearly half a degree of cooling caused by lapse rate.

The lack of ice covered poles, reduced average surface elevation and reduced land surface area would nearly eliminate polar/land amplification.  Since I saw one poster that confidently stated that PETM temperatures were 16 C warmer than today but noted that ocean temperatures were only about 5 C warmer, that would indicate that land temperatures were close to 50 degrees warmer, however the tropics appear to have only been one to two degrees warmer.

Interestingly,  the deep oceans had the greatest warming (Kenneth and Stott 1991) and species extinction events were limited to the deep oceans for the most part.  Today, the deep oceans are below 4 C degrees due to more dense cold water sinking near the poles.  That would change should the Antarctic Circumpolar current stopped since that is the primary source of deep ocean water.  Losing that cooling feature by itself would cause a 3 to 4 C rise in average ocean surface temperature.  Without some means to mix the oceans you would not have a significant temperature gradient moving poleward so the oceans would be in a sort of permanent El Nino condition.  With the deepest ocean temperatures above 4 C, the maximum density temperature of fresh water, you would have less of a thermocline that is an important feature of today's ocean thermodynamics.

As I mentioned before one of the largest sources of uncertainty is the exact placement of the land masses and potential gaps for ocean circulation. The simplest explanation for the rather abrupt change during the PETM would be plate tectonics closing and then opening a minor ocean gateway and the associated marine volcanic activity that would likely be a part of that process.  However, we are dealing with selective use of Occam's razor and optimistic force fitting of pet theory.

This chart borrowed from Zachos et al. 2001 has a lot of information, note though the orientation.  Since 55 million years ago is a fairly long time relative to actual instrumental of up to a few hundred years, we are comparing tenths of degrees and mm per year to tens of degrees and meters.  That is what we have to work with so here we go.  IF all land based ice melted we could experience 50 to 70 meters of sea level rise.  According to this chart the PETM sea level might have been 200 meters higher than that.  The PETM temperature spike was about three degrees and only about one degree higher than the Eocene maximum.  Today, sea level rise is a bit debatable even with current state of the art measurements that allow for rising and falling of land mass and it is accepted that 55 million years ago there was a great deal variation due to tectonic plate movement that appears to be several order of magnitude greater than today.  If the data used for this chart is reasonably accurate, either billions of tons of water vapor were lost to space or the average elevation of the land mass varied by a 100 meters or so without the benefit of melting ice mass.

A proper theory should explain everything.  Rapid changes in plate tectonics that would up lift land mass and increase the average depth of the oceans while releasing energy to the deep oceans while plates drift apart would kill a number of birds with one stone. Deep ocean warming greater than surface warming would be related to geothermal energy and convective mixing induced by volcanic activity.  Methane and carbon dioxide along with sulfuric acids would also be release in large amounts, ocean currents could easily reverse direction and you would have a reduction in sea level relative to land elevation without land based ice accumulation.  I am not going to attempt to go into great detail and try to make estimates of the impact because the data available is much too coarse for anything meaningful.

One of the problems with the data is that CO2 is to a certain extent estimated based on temperature and ocean pH making that circular and another is the dating uncertainty in the range of +/- 9,000 years that makes impossible to determine timing of CO2 rise relative to sea level and temperature.  Because of these you cannot eliminate potential cause you are stuck with the preponderance of evidence situation where in my opinion, tectonic activity has an advantage.

That tectonic activity could have been influence by an impact event, by CO2 mega forcing, by orbital instability, internal core dynamics or any combination, but if the data available is accurate, obviously there had to be huge changes in the configuration of land mass in three dimensions.

If you pick any single "cause" you are subject  theory bias meaning you should be your own toughest critic.  Unfortunately, with "post modern" science you can not include any number of issues much like a lawyer in court forcing you critics to waste time you should have devoted to your own research.  In Redneckese that is half-assed science.

Plate Tectonics and Climate Change by DeConto at the University of Massachusetts has a more formal discussion on all the issues.  Of particular note would be the ocean dynamics:

"Because changes in the physiognomy of ocean basins and/or the opening or closure of gateways alters both the winddriven (surface) and density-driven (deep) components of the ocean’s meridional overturning (Bice et al., 1998; Poulsen et al.,2001), it may be reasonable to assume that tectonically-forced changes in ocean circulation can have profound climatic consequences (Covey and Barron, 1988). Conversely, theoretical arguments suggest the potential effects of ocean circulation
on total poleward heat transport are inherently limited. It has been hypothesized that the total energy transport by the atmosphere-ocean system remains roughly unchanged, so if the efficiency of either the atmosphere or ocean is reduced, the other compensates (Stone, 1978). Furthermore, ocean heat transport is proportional to the product of the temperature change and mass transport of water advected into a given region. Thus, the ocean’s potential to transport heat would have been limited during times in the past when the temperature difference between low and high latitudes (and surface and deep waters) was much smaller than today, such as during the Cretaceous and early Eocene (Hay and DeConto, 1999; Sloan et al., 1995). "

Oh, I have to add the concluding paragraph: "Lastly, while tectonic processes are usually associated with slowly evolving environmental change, there are important exceptions. Volcanism’s essentially instantaneous effect on the atmosphere provides one example. Less obvious is the climate system’s potential to respond non-linearly to the most gradual tectonic forcing, with sometimes sudden and extreme consequences. Thus, plate tectonic processes should be considered a potential climate forcing mechanism on all timescales."

My interests mainly reside in the ocean and ocean dynamics since I am after all a fishing guide.  The oceans do produce a number of pseudo cyclic patterns that impact my catch and due to sea level variations certain depths that correspond to ancient shorelines are more productive that others.  So if anyone needs a reason for my apparent bias towards oceans, there ya go.

Continental Drift and Ocean Currents

This is a bit bizarre.  The Paleocene-Ecocene Thermal Maximum (PETM) was a bizarre event some 55 million years ago.  Based on core samples, temperatures were 5 to 8 C higher than today, the oceans were "acidic" meaning 0.3 units or so lower pH, which should require several thousand gigatons of methane and or carbon dioxide to be released rapidly over roughly 10,000 years.  The core samples also indicate some changes in bio and geomagnetic orientation along with some indication of a possible impact event.  At 55 million years of age, the accuracy of the core dating is pretty good, ~ +/- 9,000 years, but since the event rapidly progressed over about the same period as the sample data dating error and lasted some 40,000 to 75,000 years, the dating uncertainty is a bit of an issue.

The PETM isn't my typical cup of tea.  Once you get back to about 12,000 years the uncertainty in dating and magnitude of paleo data is large enough you can draw several "conclusions" from the same data.  Since I was drawn into a discussion of ocean dynamics, I mentioned that condition that may have existed during the PETM are pretty much irrelevant to today because of events like the closure of the Isthmus of Panama roughly 3 to 15 million years ago and the opening of the Drake Passage some 15 to 49 million years ago.  Since the PETM predated both, there is no way the same ocean dynamics could be repeated in any meaningful time frame.  Of course a few hundred million years from now things could drift to a similar configuration, but I really don't care.

The closure of the Isthmus of Panama "most likely occurred" about 3 million years ago based on "climate" data.  The closure may have occurred 17 million years ago based on DNA sequencing data.  So there is a large range of uncertainty due to competing earth science fields.  The dating of the Drake Passage opening is even more uncertain.  There is a huge amount of literature speculating on the huge impact that both of these events had on climate.  I generally reference Brierley and Fedorov 2010 for the potential impact of the Closure of the Isthmus of Panama.

"During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the
tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and
subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable to the modern about 2 Myr ago (as estimated on the eastern side of the Pacific). The zonal SST gradient along the equator, virtually nonexistent in the early Pliocene, reached modern values between 1 and 2 Myr ago. Here, we use an atmospheric general circulation model to investigate the relative roles of the changes in the meridional and zonal temperature gradients for the onset of glacial cycles and for Pliocene‐Pleistocene climate evolution in general. We show that the increase in the meridional SST gradient reduces air temperature and increases snowfall over most of North America, both factors favorable to ice sheet inception. The impacts of changes in the zonal gradient, while also important over North America, are somewhat weaker than those caused by meridional temperature variations. The establishment of the modern meridional and zonal SST distributions leads to roughly 3.2°C and 0.6°C decreases in global mean temperature, respectively. Changes in the two gradients also have large regional consequences, including aridification of Africa (both gradients) and strengthening of the Indian monsoon (zonal gradient). Ultimately, this study suggests that the growth of Northern Hemisphere ice sheets is a result of the global cooling of Earth’s climate since 4 Myr rather than its
initial cause. Thus, reproducing the correct changes in the SST distribution is critical for a model to simulate the transition from the warm early Pliocene to a colder Pleistocene climate."

Moving from a permanent El Nino state i.e. "the warm ocean water extended over most of the tropics." to the alternating ENSO state should be a pretty big deal "climate change" wise.  Roughly 3.2 to 3.8 degrees C cooler could be called a new climate regime.  To figure out how much impact CO2 would have in the former regime would require a near perfect knowledge of the location of the land masses so that ocean circulation could even be roughly modeled.  Since we are pretty confident that ocean circulation changes can have a huge, greater than 3 C impact, ignoring ocean dynamics is in Redneck terms F'ing stupid.  Since it is an impossible task I will avoid it like the plague.  Drawing firm conclusions without that knowledge is a bad joke.

During the PETM the Antarctic Circumpolar Current (ACC) most likely did not exist.  Toggweiler and Bjornsson 2000 is my go to reference for the ACC and Drake Passage.

"The effect of Drake Passage on the Earth’s climate is examined using an idealised coupled model. It is found that the opening of Drake Passage cools the high latitudes of the southern hemisphere by about 3°C and warms the high latitudes of the northern hemisphere by nearly the same amount. This study also attempts to determine whether the width and depth of the Drake Passage channel is likely to be an important factor in the thermal response. A deeper channel is shown to produce more southern cooling but the magnitude of the effect is not large. Channel geometry is relatively unimportant in the model because of a haline response that develops when the channel is first opened up. Published in 2000 by John Wiley & Sons, Ltd."

Again, ocean dynamics changed with continental drift producing a new climate regime.

The video I have linked is one of several animations of the possible timing of continental drift and any opening or closing of a path for ocean circulation could have similar impacts on climate.  When ocean circulation is weak you have more of a solar pond situation where the oceans can get much warmer and increased ocean circulation would reduce the solar pond effect.  That is a pretty simple but likely accurate explanation.  According to Toggwiler and Bjornsson, it doesn't take much of a opening to have a significant impact.

Since we live on a planet that is mainly water, about 70%, and that water has about 1000 times the heat capacity of the atmosphere, ignoring the impact of changes in "mixing" of the oceans is in Redneckese, F'ing Stupid.

That said, could CO2 during the PETM have had much higher impact that today.  F'ing A yes it could, but there is no rational way to compare the PETM sensitivity to today's sensitivity since ocean and atmospheric circulations would respond differently with different configuration of the ocean and continents.

Now if "believers" want to completely ignore the dynamics and the "complexity" they use to sell their agenda, they can go for it, but the over simplifications are starting to bite them in the butt.