Guest Post by Bill Illis
This post is the first of what will likely be a series on the PaleoClimate.
In this part, we are just going to go through the various estimates for Temperature, CO2 and Sea Levels in the PaleoClimate. This post is also about making the data available to everyone so that others can use it. All of the data presented in this post is available for download at the end in easy to use Excel spreadsheets which also incorporates direct links to the actual data sources used.
PaleoClimate Temperature Estimates Over the Past 570 Million Years
There are various sources we can use for estimates of Temperatures in the PaleoClimate.
We have the ice core dO18 isotope data going back 800,000 years. James Zachos has a high resolution database of dO18 isotopes going back 67.0 million years. Jan Veizer has accumulated an isotope database that goes back 526.5 million years. Dana Royer and Robert Berner applied a ph-correction factor to Veizer’s database and Christopher Scotese has developed Temperature estimates that extend back into the pre-Cambrian.
For the most part, the Temperature estimates are based on dO18 isotopes and these have proven to be reasonably reliable, or more accurately, to be the most reliable temperature estimation method that is available.
The isotope data does require a number of different transformations and smoothing to make it useful as a Temperature proxy. Nobody is really sure what the proper way to carry this out is.
For one, it must be detrended as the data becomes older. The dO18 declines over time due to the radioactivity of the Earth. The above estimates are based on a simple linear detrending formula. The rationale is that the radioactive conditions would have remained reasonably constant over the last 530 million years. Others have used a second order polynomial but this does not result in much difference.
It has been noted that the dO18 isotope data should also be corrected for ice volume, sea level, the concentrations of CaCO3 in the oceans and -ph conditions of the oceans. Royer and Berner applied a ph-correction factor based on Berner’s GeoCarb III CO2 estimates. Again, this doesn’t make much difference except that Royer and Berner’s numbers are now lower than Veizer’s original database would point to.
Effectively, any transformation carried out has still got to match the record that we know about. It is still going to have to show a Carboniferous ice age, an Ordovician ice age, a hot Permian Pangea climate, a hot Cretaceous period, an Antarctic glaciation and the recent ice ages.
In other words, no matter what corrections are applied, one should just end up with something very similar to the above chart.
Detailed Temperature Estimates Over the Past 530 Million Years
Veizer’s database contains over 16,600 individual dO18 isotope data points extending back 526.5 million years. There is sufficient resolution throughout the database that we can be reasonably certain about any specific period.
The above chart has been constructed using Veizer’s data with two different smoothing parameters; a shorter one which preserves more detail and then one that emulates the Phanerozoic Climate Change chart by Robert Rohdes of Global Warming Art. It is likely that both are reasonably accurate and sometimes less smoothing is preferred to more smoothing so that more information can be extracted.
In this case, there really is more information available from the shorter Gaussian smooth. Immediately evident is that certain large temperature changes coincide with some of the large Mass Extinction events in the planet’s history.
The really unusual one is the Permian Extinction event in which 96% of marine species and 70% of large land animals died out in a very short period of time about 251.4 million years ago. Previously this was thought to be due to exceptionally hot conditions or even ocean chemistry changes.
But now one can see that temperatures actually declined by about 5.0C in a very short period of time (something that is that well-known). This temperature drop exactly coincides with the dating of the Siberian Traps volcanic events at 251 to 250 million years ago which is the largest series of volcanic events known in history. An area nearly the size of Australia may have been covered by volcanic magma flows hundreds of metres deep (some places have been measured at 4 kms deep). The volcanoes lasted for about 1 million years and, not surprisingly, temperatures fell.
The other event is the Ordovician extinction event of 443 million years ago in which 50% of the new Cambrian genera of life disappeared. This was always known to be caused by a cooling climate. But now, one can see that there is a very significant drop in the smoothed temperature estimates exactly at 443 million years ago.
The Devonian Extinction seems to be caused by a rapid increase in temperatures, as much as 10.0C in just a few million years.
Notice how the Cretaceous Period, 95 million years ago, is 2.0C to 3.0C higher than the Paleocene Eocene Thermal Maximum. The climate scientists are always talking about how unusual the PETM was but just a few million years earlier, temperatures were quite a bit higher. Dinosaurs even lived in Alaska at the time, and it was a little farther north in the period than it is now. The PETM event does not even look unusual enough in the record to spend much time on.
Notice that the timelines surrounding the Carboniferous Ice Age and the Ordovician-Silurian Ice Age are now clearly defined. These timelines match up very closely with the estimated alignment of the Continents during the periods. Even the short mid-Jurassic Ice Ages are now evident at a point in time when parts of EuroAsia were transiting the North Pole.
Detailed Temperature Estimates Over the Past 67 million Years
Zachos has developed another database of 14,800 individual estimates of dO18 isotopes that covers the past 67 million years with a resolution of less than 100,000 years in most cases.
The time period when Antarctica glaciated over (for the fourth time that is known about) is clearly evident. Temperatures reached as high as 6.0C during the PETM and the periods when Antarctica reglaciated and when Greenland’s glaciers started building occurred at 14 million years ago.
About 2.5 million years, the most recent cycle of ice ages began. In part II of the series, we may take a closer look at the ice ages in more detail.
PaleoCO2 Estimates
There are quite a few different estimates for CO2 in the PaleoClimate. We have the ice cores, we have Mark Pagani 2005 with high resolution estimates between 5.4 million years to 44.5 million years ago and we have Berner’s GeoCarb III estimates which go back to 570 million years ago.
There are others (and they have been included in the CO2 spreadsheet) but they are not as well-accepted as these. The other estimates come mainly from Stomata size (the cells that plants to use to absorb CO2), Paleosols (ancient soil deposits) and Phytoplankton among others.
Using the estimates that are most accepted and given the resolution is higher with the ice cores than with Pagani and then Pagani’s resolution is higher than Berner’s, they have been incorporated back-to-back-to-back as one series as follows.
As most of you are aware, CO2 goes as high as 7,069 ppm 520 million years ago and as low as 180 ppm during the height of the ice ages.
On the same timeline as the PaleoTemperatures Over 67 Million Years chart above, CO2 looks like this over the past 70 million years.
Paleo Sea Level Estimates
Sea level has also been included in the databases since it is not well-known that these high resolution estimates exist. In addition, sea level can certainly have an impact on the climate as well be an indicator for the climate.
There are many different sea level estimates and the most recent one covering the whole period, produced by the world-leading expert on sea level, Bilal Haq, is the most accepted version (Haq, Schutter, 2008).
Sea Level has varied by a large amount throughout history. Sea levels were as much as 265 metres higher than today 100 million years ago and have been as low as 120 metres lower than today during the Last Glacial Maximum.
Sea level seems to vary through three different mechanisms.
- Sea level falls when glaciers build up on land. Obvious enough.
- Sea level falls when continental land masses are concentrated together. Collisions and mountain building tend to squeeze the Earth’s landmasses together and there is less continental shelf area that can affect the average depth of the overall oceans. Related to the last reason, the ocean basins tend to be more mature and deeper in these situations. and,
- Sea level rises when new young ocean basins are opening. New ocean basins generally form at only 2,500 metres depth while mature ocean basins tend to deepen and reach a depth of about 6,000 metres after 100 million years. That means the overall average depth of the ocean is lower when new oceans are forming. This is particularly the case during the Cretaceous when the Atlantic Ocean was just opening up.
Sea levels rose so high during the Cretaceous as the Atlantic was just opening, that the ocean flooded North America from Texas to Inuvik, to Hudson Bay. Europe, the Middle East, North Africa and the central parts of Eurasia were also flooded by shallow oceans.
During the Carboniferous and the Jurassic, the land masses were collected together into the Supercontinent of Pangea. Sea levels fell in the earlier part as glaciers covered large parts of Gondwana, but then they stayed low as the glaciers melted and the continents moved together to form Pangea.
There are periods when there are rapid changes in sea level and these have been used by researchers to date the periods of glaciations. It appears Scotese has used earlier versions of the sea level data to date the glaciations used in his temperature reconstruction.
Conclusion
Putting all the best estimates together, here is a view of the Temperatures, CO2 and Sea Level throughout the past 526 to 570 million years.
In subsequent posts, we may look at the Milankovitch Cycles and the recent ice ages, Continental Drift through time and how that may have affected the climate and then the empirical evidence surrounding the CO2 doubling sensitivity in the PaleoClimate.
The main purpose of this post was to just make the data available to everyone. Others are free to use to use this data in any manner they see fit.
The data is available in three different easy-to-use Excel spreadsheets and can be downloaded at this link. The Paleo Temp Database is a very large file and may be a slow download.
[Paleo Temp CO2 Sea Level Data]
PaleoClimate Temperature, CO2 and Sea Level Estimates
Guest Post by Bill Illis
This post is the first of what will likely be a series on the PaleoClimate.
In this part, we are just going to go through the various estimates for Temperature, CO2 and Sea Levels in the PaleoClimate. This post is also about making the data available to everyone so that others can use it. All of the data presented in this post is available for download at the end in easy to use Excel spreadsheets which also incorporates direct links to the actual data sources used.
PaleoClimate Temperature Estimates Over the Past 570 Million Years
There are various sources we can use for estimates of Temperatures in the PaleoClimate.
We have the ice core dO18 
isotope data going back 800,000 years. James Zachos has a high resolution database of dO18 isotopes going back 67.0 million years. Jan Veizer has accumulated an isotope database that goes back 526.5 million years. Dana Royer and Robert Berner applied a ph-correction factor to Veizer’s database and Christopher Scotese has developed Temperature estimates that extend back into the pre-Cambrian.
For the most part, the Temperature estimates are based on dO18 isotopes and these have proven to be reasonably reliable, or more accurately, to be the most reliable temperature estimation method that is available.
The isotope data does require a number of different transformations and smoothing to make it useful as a Temperature proxy. Nobody is really sure what the proper way to carry this out is.
For one, it must be detrended as the data becomes older. The dO18 declines over time due to the radioactivity of the Earth. The above estimates are based on a simple linear detrending formula. The rationale is that the radioactive conditions would have remained reasonably constant over the last 530 million years. Others have used a second order polynomial but this does not result in much difference.
It has been noted that the dO18 isotope data should also be corrected for ice volume, sea level, the concentrations of CaCO3 in the oceans and -ph conditions of the oceans. Royer and Berner applied a ph-correction factor based on Berner’s GeoCarb III CO2 estimates. Again, this doesn’t make much difference except that Royer and Berner’s numbers are now lower than Veizer’s original database would point to.
Effectively, any transformation carried out has still got to match the record that we know about. It is still going to have to show a Carboniferous ice age, an Ordovician ice age, a hot Permian Pangea climate, a hot Cretaceous period, an Antarctic glaciation and the recent ice ages.
In other words, no matter what corrections are applied, one should just end up with something very similar to the above chart.
Detailed Temperature Estimates Over the Past 530 Million Years
Veizer’s database contains over 16,600 individual dO18 isotope data points extending back 526.5 million years. There is sufficient resolution throughout the database that we can be reasonably certain about any specific period.
The above chart has been constructed using Veizer’s data with two different smoothing parameters; a shorter one which preserves more detail and then one that emulates the Phanerozoic Climate Change chart by Robert Rohdes of Global Warming Art. It is likely that both are reasonably accurate and sometimes less smoothing is preferred to more smoothing so that more information can be extracted.
In this case, there really is more information available from the shorter Gaussian smooth. Immediately evident is that certain large temperature changes coincide with some of the large Mass Extinction events in the planet’s history.
The really unusual one is the Permian Extinction event in which 96% of marine species and 70% of large land animals died out in a very short period of time about 251.4 million years ago. Previously this was thought to be due to exceptionally hot conditions or even ocean chemistry changes.
But now one can see that temperatures actually declined by about 5.0C in a very short period of time (something that is that well-known). This temperature drop exactly coincides with the dating of the Siberian Traps volcanic events at 251 to 250 million years ago which is the largest series of volcanic events known in history. An area nearly the size of Australia may have been covered by volcanic magma flows hundreds of metres deep (some places have been measured at 4 kms deep). The volcanoes lasted for about 1 million years and, not surprisingly, temperatures fell.
The other event is the Ordovician extinction event of 443 million years ago in which 50% of the new Cambrian genera of life disappeared. This was always known to be caused by a cooling climate. But now, one can see that there is a very significant drop in the smoothed temperature estimates exactly at 443 million years ago.
The Devonian Extinction seems to be caused by a rapid increase in temperatures, as much as 10.0C in just a few million years.
Notice how the Cretaceous Period, 95 million years ago, is 2.0C to 3.0C higher than the Paleocene Eocene Thermal Maximum. The climate scientists are always talking about how unusual the PETM was but just a few million years earlier, temperatures were quite a bit higher. Dinosaurs even lived in Alaska at the time, and it was a little farther north in the period than it is now. The PETM event does not even look unusual enough in the record to spend much time on.
Notice that the timelines surrounding the Carboniferous Ice Age and the Ordovician-Silurian Ice Age are now clearly defined. These timelines match up very closely with the estimated alignment of the Continents during the periods. Even the short mid-Jurassic Ice Ages are now evident at a point in time when parts of EuroAsia were transiting the North Pole.
Detailed Temperature Estimates Over the Past 67 million Years
Zachos has developed another database of 14,800 individual estimates of dO18 isotopes that covers the past 67 million years with a resolution of less than 100,000 years in most cases.
The time period when Antarctica glaciated over (for the fourth time that is known about) is clearly evident. Temperatures reached as high as 6.0C during the PETM and the periods when Antarctica reglaciated and when Greenland’s glaciers started building occurred at 14 million years ago.
About 2.5 million years, the most recent cycle of ice ages began. In part II of the series, we may take a closer look at the ice ages in more detail.
PaleoCO2 Estimates
There are quite a few different estimates for CO2 in the PaleoClimate. We have the ice cores, we have Mark Pagani 2005 with high resolution estimates between 5.4 million years to 44.5 million years ago and we have Berner’s GeoCarb III estimates which go back to 570 million years ago.
There are others (and they have been included in the CO2 spreadsheet) but they are not as well-accepted as these. The other estimates come mainly from Stomata size (the cells that plants to use to absorb CO2), Paleosols (ancient soil deposits) and Phytoplankton among others.
Using the estimates that are most accepted and given the resolution is higher with the ice cores than with Pagani and then Pagani’s resolution is higher than Berner’s, they have been incorporated back-to-back-to-back as one series as follows.
As most of you are aware, CO2 goes as high as 7,069 ppm 520 million years ago and as low as 180 ppm during the height of the ice ages.
On the same timeline as the PaleoTemperatures Over 67 Million Years chart above, CO2 looks like this over the past 70 million years.
Paleo Sea Level Estimates
Sea level has also been included in the databases since it is not well-known that these high resolution estimates exist. In addition, sea level can certainly have an impact on the climate as well be an indicator for the climate.
There are many different sea level estimates and the most recent one covering the whole period, produced by the world-leading expert on sea level, Bilal Haq, is the most accepted version (Haq, Schutter, 2008).
Sea Level has varied by a large amount throughout history. Sea levels were as much as 265 metres higher than today 100 million years ago and have been as low as 120 metres lower than today during the Last Glacial Maximum.
Sea level seems to vary through three different mechanisms.
· Sea level falls when glaciers build up on land. Obvious enough.
· Sea level falls when continental land masses are concentrated together. Collisions and mountain building tend to squeeze the Earth’s landmasses together and there is less continental shelf area that can affect the average depth of the overall oceans. Related to the last reason, the ocean basins tend to be more mature and deeper in these situations. and,
· Sea level rises when new young ocean basins are opening. New ocean basins generally form at only 2,500 metres depth while mature ocean basins tend to deepen and reach a depth of about 6,000 metres after 100 million years. That means the overall average depth of the ocean is lower when new oceans are forming. This is particularly the case during the Cretaceous when the Atlantic Ocean was just opening up.
Sea levels rose so high during the Cretaceous as the Atlantic was just opening, that the ocean flooded North America from Texas to Inuvik, to Hudson Bay. Europe, the Middle East, North Africa and the central parts of Eurasia were also flooded by shallow oceans.
During the Carboniferous and the Jurassic, the land masses were collected together into the Supercontinent of Pangea. Sea levels fell in the earlier part as glaciers covered large parts of Gondwana, but then they stayed low as the glaciers melted and the continents moved together to form Pangea.
There are periods when there are rapid changes in sea level and these have been used by researchers to date the periods of glaciations. It appears Scotese has used earlier versions of the sea level data to date the glaciations used in his temperature reconstruction.
Conclusion
Putting all the best estimates together, here is a view of the Temperatures, CO2 and Sea Level throughout the past 526 to 570 million years.
In subsequent posts, we may look at the Milankovitch Cycles and the recent ice ages, Continental Drift through time and how that may have affected the climate and then the empirical evidence surrounding the CO2 doubling sensitivity in the PaleoClimate.
The main purpose of this post was to just make the data available to everyone. Others are free to use to use this data in any manner they see fit.
The data is available in three different easy-to-use Excel spreadsheets and can be downloaded at this link. The Paleo Temp Database is a very large file and may be a slow download.
[Paleo Temp CO2 Sea Level Data]
Let’s take Hansen’s ice age forcing estimate and put some perspective to it.
Today, the solar forcing is 1366 W/m2 * (1-0.298) /4 = 239.7 Watts
Hansen’s ice age would be 1366 W/m2 * (1-0.3083) /4 = 236.2 Watts
Or -3.5 watts less.
If one used the Stefan Boltzmann equations for these forcings.
You would get:
=> Today = (1366 * (1-0.298)/4/Stefan Boltzmann Constant)^0.25 = 255K (the estimated solar irradiance only temperaure).
=> Ice Age = (1366 * (1-0.3083)/4/SB Constant)^0.25 = 254.1K
… or just a reduction of 0.9C due to Albedo in the ice ages (far, far too low). So you can know that Hansen’s -3.5 watts is just sliced and diced in a climate model and the standard way of thinking about how solar irradiance warms/cools the Earth is not taken into account.
A question that has interested me and I have been unable to find an answer to is how the irrigation of surrounding land from melting glaciers were incorporated into the models when determining paleoclimatology. Should this irrigation cause regional warming then, in my mind, you would have a higher climate sensitivity when the glaciers were actually in the process of melting and this sensitivity would slowly be reduced as the source of the irrigation decreased. I was hoping since many with an interest in paleoclimatology were reading this post that perhaps someone could point me to a paper on this topic. Thanks.
Bill Illis says:
What you point out here is that in the absence of any atmospheric feedbacks then the proposed forcing is too small to account for the changes in climate. That is indeed correct, which is why the best estimate of forcings and temperature changes from the LGM strongly implies that the atmospheric feedbacks (i.e., all the feedbacks beyond the direct radiative feedback due to Stefan-Boltzmann) must be positive.
Or it means that Hansen, the IPCC and you are grossly underestimating the effects of albedo.
“Or it means that Hansen, the IPCC and you are grossly underestimating the effects of albedo.”
Yup, that’s right.
The validity of strong positive feed-backs rests (in large part) on the accuracy of the albedo effect of man-made aerosols. Without substantial “cancellation” of the pretty well know radiative forcing from well mixed GHG’s in all climate models, the sensitivity to radiative forcing must be substantially lower than assumed by those models (that is, in the absence of strong aerosol cancellation, the feeds-backs would have to be much smaller). Since both estimates of ice age albedo and man-made aerosol effects are highly uncertain, equally uncertain is the claim of strong positive feed-backs and high climate sensitivity.
Is there a significant warming effect from well mixed GHG’s? Almost certainly. Are extreme temperature increases as projected by climate models certain? For sure they are extremely uncertain. The wide range of climate sensitivities in the various IPCC climate models ought to give you pause Joel Shore. They certainly are not all correct, and their wide range of implied climate sensitivities means that most of them must (of course) be quite far away from correct about sensitivity. I suggest that you consider the most basic conclusion one can draw for the wide range of model sensitivities: these models most certainly could all be quite wrong about climate sensitivity.
Steve: I agree that there are still quite large uncertainties on climate sensitivity…and also the possibility of some surprises in store! Unfortunately, those uncertainties go in both directions (and, in fact, estimates of the probabilities for climate sensitivity tend to be pretty skewed, with a sharper cutoff on the low side and a long tail on the high side).
I think that the probability both that climate sensitivity turns out to be low and that ocean acidification turns out to be no-big-deal is pretty small. We might be so lucky, but it would be quite foolish to bet on it.
Joel,
The ocean acidification argument is so over-played.
The Cambrian explosion of (marine) life occured when CO2 was 7,000 ppm. Corals evolved when CO2 was 20 times higher than today. Carbonate-shell based organisms like Trilobites and Ammonites (as big as 8 feet across) dominated the world’s oceans when CO2 was 20 times higher than today.
The uncertainties of the temperature impact per doubling cannot go higher than 3.0C per doubling. Temperatures would have been 20C in the distant past at the upper uncertainity limit of 4.2C per doubling when maybe 8.0C to 10.0C higher are the estimates.
The greenhouse effect is 33C. 11 halvings of CO2 puts CO2 level at effectively Zero – so even mathematically, it cannot be higher than 3.0C per doubling.
Joel Shore,
The ‘bet’ that you frame does not reflect the situation. The bet is to expend a lot of (very real) capital today, and in the process reduce global wealth development, in the hope of reducing projected warming, which may very well not be nearly as extreme as projected. A much safer bet is to let the dust settle long enough that the range of uncertainty is much lower…. Let say until all the models all pretty much agree on the sensitivity, that they can make reasonably accurate decade length estimates of ocean warming in response to CO2, and the uncertainty in aerosol effects are reduced by a factor of three to five.
There really is a sharp cut-off on the low sensitivity side: close to the SB sensitivity of ~1C per doubling of CO2. There is no surprise here, since there is essentially no upper limit to the net sensitivity you can postulate based on a positive feed-back value that approaches the thermal run-away point, while it’s a bit mad to suggest that SB doesn’t apply to the Earth.
With regard to ocean acidification, I have taken the time to read several studies on the effect of increasing CO2 on marine life. The reports of (future) coral deaths are (to paraphrase Mark Twain) greatly exaggerated. In fact, most credible studies seem to show little or no negative effect on corals until at least 500-600 PPM CO2, and only somewhat slowed growth above these levels, not coral death. Aragonite shelled organisms in very cold water really would be in trouble (not able to form shells) when CO2 reached ~1300 PPM, but no credible projection shows this level ever being reached during mankind’s age of fossil fuels.
I do believe that most of the uncertainty about GHG warming effects will be eliminated in the next 10-15 years, if only because there will be a lot more data available to validate or invalidate model projections. (And, yes, I do expect that the existing models will be shown to substantially overstate future warming, though I can’t be certain.) Modest steps to encourage emissions reductions, like replacing many coal fired power plants with nuclear, minimizing non-CO2 GHG emissions, and applying a low, uniform, across-the-board carbon tax probably make sense at present.
But policies that are both useless and destructive (like Waxman-Markey C&T) or extremely draconian (like trying to mandate 50% CO2 emissions reductions in 20 years) seem to me to be the real fool’s bet.
Steve Fitzpatrick (20:09:08) :
re ocean acidification.
I can find no paper where CO2 has been titrated into actual ocean water to measure the pH change. All I can find is models.
Can anyone point to a reference?
Bill…
You might want to incorporate Jevrejeva et al., (2006) into your paleo sea level series…
Global Sea Level Reconstruction since 1700
Bill Illis says:
The issue isn’t one of absolute CO2 levels but rather how fast CO2 levels are changing relative to the rate at which CaCO3 can be dissolved from rocks to neutralize the acidification.
This isn’t really true. For one thing, there is no reason to believe that the rise per doubling is constant over so large a range. Also, that 33C number is with our current albedo…A “snowball earth” could be more than 33C colder. Hopefully, the climate sensitivity isn’t any higher than 3 C per doubling but I don’t think there are any mathematical guarantees that this is so.
Here’s a typical example of how the alarmist crowd moves the goal posts every time their latest panic attack is debunked by reality:
It used to be: “CO2 will cause runaway globaloney! Everybody panic!!”
But the planet laughed at their presumption, and cooled as CO2 rose.
So now they re-frame the argument, just like Joel Shore does above. Forget the fact that the biosphere expands when more plant food is available. Only rocks matter now.
And they wonder why we laugh at their nonsense.
That’s not entirely accurate. The Carbonate Compensation Depth (or Lysocline) is the depth at which carbonate shells dissolve faster than they accumulate. That depth is primarily determined by several factors…
Dave Middleton (06:29:12) :
You might want to incorporate Jevrejeva et al., (2006) into your paleo sea level series…
Global Sea Level Reconstruction since 1700
Looks like a good study. I’ve said before that you need as many sea level datasites as possible to carry out a decent review of sea level since there is so much post-glacial rebound, local land uplift/subsidence and even plate tectonics to take into account.
I’ll put it in but I should note that I am just focussing on the PaleoClimate starting about 10,000 years ago. There are lots of people looking at the more recent temperature trends and there is lots of easily available data so there is not as much rationale for earlier periods.
@ur momisugly Bill Illis
What are some of the better sea level reconstructions over the last 2,000 years?
I’d like to compare Jerejeva to the period from the Roman Warming through the Little Ice Age.
Scale is a “funny thing”. I appended Jerejeva onto the last 150,000 years of Miller… 1700-2003 was a dot on the graph. 😉
Dave,
I don’t have better reconstruction of sea level for the more recent periods.
The sea level spreadsheet does have a link to an NCDC archive of sea levels that goes back 9,000 years or so for many locations around the world. It is not in an easy to use format (would probably take a long time to turn it into something useful).
It is interesting though to see how much sea level change has varied by location over the recent past. For example, James Bay Canada has seen sea level fall by a huge 250 metres over the past 7,000 years (due to post-glacial rebound) while the Thames river area has seen sea level rise by 16 metres over the same period (due to post-glacial rebound of Scotland which has tilted southern England downward). These are the two extremes I believe.
Now you see the problem with simply picking a few sea level gauges for an estimate (one might need all of them).
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/paleocean/relative_sea_level/sealevel.dat
Thanks, Bill. Great work!
I’m looking forward to your future essays on paleoclimatology.
Yes, great work, Bill Illis. When I have time will look at all of this in more detail — essay plus comments printed out. Very much look forward to the next installment, plus Paul Dennis’s 101 primer on stable isotopes, etc. Poor Joel Shore. He keeps swinging away but the long arm of scientific experimental evidence shows him to be fundamentally ignorant even though well read in climate computer modelling. He keeps himself impotent. Thanks again to you and to the commenters who add their scientific expertises. We are light years ahead of where we would be without WUWT.
It appears that “Apollo 13” may have been worse propaganda for CO2 than “an inconvenient truth”:
http://blog.scienceinsociety.northwestern.edu/2009/06/why-michele-bachmann-should-watch-apollo-13/
But clearly this guy’s idea of CO2 “pollution” is so far off base as to be laughable.
I hope you will revise the discussion of the trend in oxygen isotopes in the article as suggested in several other comments. The trend is not due to radioactivity, and it’s not settled as to whether they represent a primary signal or diagenetic overprint, so the data should not be detrended.
In addition, there’s a plethora of data on current ocean acidification.
Paul Dennis (00:08:52) :
Should you write such an article, might you please be quite specific about how a qualitative observation (heavy oxygen isotopes are disproportionately left behind during evaporation) becomes a quantitative equation linking delta-O with temperature? If you do a frequency plot of a large number of diverse isotope ratios used in climatology, is the median displaced from the reference standard? It seems to me that there are many more reported isotope ratios attributed to heating than to cooling. Have you found limits to the amount of differentiation that can happen in nature? Overall, is the distribution centered, skewed and/or bounded?
Roberta Hotinski (10:43:19) :
“In addition, there’s a plethora of data on current ocean acidification”.
Virtually all of the pH calculation is done from phase diagrams involving carbonate, bicarbonate, calcium and so on.
Do you know of any references where ordinary sea water has been titrated with CO2 and the pH measured?
[snip – invalid email address, policy violation, see policy page]