Continuation of the older threads. Please scan those (even briefly) to see whether your point has already been dealt with. Let me know if there is something worth pulling from the comments to the main post.
In the meantime, read about why peer-review is a necessary but not sufficient condition for science to be worth looking at. Also, before you conclude that the emails have any impact on the science, read about the six easy steps that mean that CO2 (and the other greenhouse gases) are indeed likely to be a problem, and think specifically how anything in the emails affect them.
Update: The piece by Peter Kelemen at Columbia in Popular Mechanics is quite sensible, even if I don’t agree in all particulars.
Further update: Nature’s editorial.
Further, further update: Ben Santer’s mail (click on quoted text), the Mike Hulme op-ed, and Kevin Trenberth.
David B. Benson (1181)
Actually, he does neither, DBB.
He rationalizes (with a bit of clever wording and some smoke and mirrors) why the observed cycles cannot truly be cycles and why the recent observed cooling cannot really be cooling.
Max
manacker wrote in 1201:
Tamino provides actual, detailed statistical analysis. In contrast, your argument consists of, “It looks cyclical to me,” and, “The IPCC report specifically mentions two of these cycles, well, no, actually two half cycles.”
Tamino’s qualifications? Professional statistician who has published a number of peer reviewed papers in professional journals, including two papers each of which received over a hundred citations. You on the other hand… What grade are you in?
Timothy Chase (1202)
Sorry, Timothy, you don’t have to be a statistician to see a trend of multi-decadal warming and cooling cycles in our long-term temperature record or that it happens to be cooling right now.
Analyzing why this is so is another story.
Max
manacker wrote in 1203:
You “see” it. I don’t.
What is the court of appeal if it isn’t mathematics and statistical significance? You might want to recite the, “For those who understand, no further explanation is necessary…” line over and over but I won’t buy it.
By that logic we don’t even have to get out our thermometers. Someone like you can come along and just claim to know. And then what happens when someone else comes along and just claims to know the opposite?
Sorry, but between your “just seeing” what others like myself do not see and Tamino’s objective mathematical analysis…
Cyclical? Not.
December 22, 2009
http://tamino.wordpress.com/2009/12/22/cyclical-not/
How Long?
December 15, 2009
http://tamino.wordpress.com/2009/12/15/how-long/
… there just isn’t any choice.
Somebody believes statistical tests are “smoke and mirrors”.
Being a competent statistician helps to avoid being fooled into purely speculative conclusions by superficial appearances.
So, Max, since you are convinced that every hint of an oscillation must be significant, what is the cause of the oscillations in the digits of the base of the Napierian logarithms, e:
1-2
2-7
3-1
4-8
5-2
6-8
7-1
8-8
9-2
10-8
11-4
Timothy Chase (et al?), some people look at the global temperature graph and notice that is goes up a little for a while, then goes down a little for a while, then, maybe strangely, goes up again for a while, then, still maybe strangely, goes back down for a while, then says, “Hmmm. the temperature did a little wiggling up and down in quasi periodic fashion.” Others look at the same chart, take the 2nd derivative of the 3rd integral, calculate the delta y-squares, add up the difference, plot its deviations, and take the line integral and say, “Straight line.” Odd how that pedantic sophistication can screw things up so badly.
Two questions:
In January 1981 the GISS/NASA data seems to have taken about a 0.20 degree C jump in temperature over a one month period. Is a SUSTAINED 0.20C change in the Earths temperature over a one month period a significant event?
Also, in January 2001 the same data took what looks like a 0.15C SUSTAINED jump in temperature over a 1 month period. Is a SUSTAINED 0.15C change in the Earths temperature over a one month period a significant event?
If they are not significant then the question – What causes the Earths temperatures to make these huge SUSTAINED leaps – is insignificant.
Bruce Williams (1208)
You ask a valid question about the two observed sustained jumps in temperature, which apparently occurred on January 1981 and January 2001, resulting in a total of 0.35C temperature rise, according to your observation.
The GISS record shows a linear warming from 1980 to 2005 of 0.4C, so these two “jumps” account for almost all of the warming since 1980.
This makes your question all the more pertinent.
But maybe the two jumps simply did not occur, since they cannot be explained mathematically or statistically.
Max
I’m wondering what is the statistical probability of post 1208 and 1209 appearing so narrowly separated in chronological order?
Bruce Williams (1208), I don’t see anything strange around january 1981:
http://www.woodfortrees.org/plot/gistemp/from:1970/to:1990
nor in january 2001:
http://www.woodfortrees.org/plot/gistemp/from:1990/to:2009
Notice how, in both graphs, a 0.2C temperature difference between adjacent months is quite common.
1210: “Notice how, in both graphs, a 0.2C temperature difference between adjacent months is quite common.”
Aren’t those differences what the AGW alarmists call “seasons?”
John E. Pearson (1212) “Aren’t those differences what the AGW alarmists call “seasons?” ”
Those graphs show anomalies (differences from a reference period), so seasonal effects are removed, unless winters and summers were changing in different ways.
John E. Pearson (1212):
“Aren’t those differences what the AGW alarmists call “seasons?””
You might want to read up on Temperature Anomaly graphs. The key word is “Anomaly”.
Rod B: “Others look at the same chart, take the 2nd derivative of the 3rd integral, calculate the delta y-squares, add up the difference, plot its deviations, and take the line integral and say, “Straight line.” Odd how that pedantic sophistication can screw things up so badly.”
Who are these others? You’re making up crap and you know it. Funny how science and math are suspect when you don’t like what they tell you… I’m sure you must be a unibomber type, avoiding all technology and science, right? Except for the time you spend on your computer. Oops!
Bruce, Given that on a timescale of a month you are dealing with the relatively small thermal reservoir of the atmosphere, and given that the Sun can raise the atmospheric temperature 20-30 degrees in a day, I’d say that you are not looking at anything too significant. There are several such jumps in the record as Alfio’s links show.
Now will somebody please help max get the hook, line and sinker out of his throat…
> John E. Pearson says: 28 December 2009 at 10:0 AM
…
>
> Aren’t those differences what the AGW alarmists
> call “seasons?”
Nope, they’re anomalies.
John, you’ve wondered why people mock the copypasters who come here with stuff they could easily have checked themselves, throw it into the comment threads here, and make themselves and their sources look like ignoramuses.
Please, we need better skeptics. Try harder.
1214:1215 WHen I wrote my “seasonal” remark it was meant as a joke, but I can’t think of any reason that there ought not to be seasonality in the anomaly. Are you saying that if you consider dT(t) = T(t)-Tbar where Tbar is the temperature averaged over some suitably long period of time that dT(t) can’t exhibit the same time dependence as T(t)? Heat flows in and out of the oceans. I’m no climatologist but I’d be surprised if there weren’t a seasonal component to these heat fluxes. Whether seasonality can be teased out of globally averaged climate data or not I have no idea.
Hank Robert’s wrote:
“John, you’ve wondered why people mock the copypasters who come here with stuff they could easily have checked themselves, throw it into the comment threads here, and make themselves and their sources look like ignoramuses.
Please, we need better skeptics. Try harder.”
Huh? I’ve never wondered any such thing. Now I’m a skeptic? It’s news to me.
Yesterday I attempted to post a suggestion that Max von Anacker learn some statistics. Either the software failed, as it does once in awhile, or I was too intemperate. But I don’t think I was as outright unkind as Max’s comment #1201.
John E. Pearson (1218) — One could take the seasonal data from the temperature reporting stations and globally average that. That product might be available from one or more of the four major temperature product producers; try the data sources on the siderbar.
Doug Bostrom wrote (1210)
4 hours and 9 minutes is “narrowly separated in chronological order”?
Hmmm…
Max
> I can’t think of any reason that there ought not to
> be seasonality in the anomaly
http://www.google.com/search?q=climate+change+seasonal+anomaly
In fact it’s among the early predictions, borne out by observation. You really can look this stuff up.
I always do try to look up even the simplest such question — rather than trying to answer from memory — because I have “a poor sort of memory that only works backward” — so I should always check what has happened since I last learned about something. Stuff happens fast these days.
Here’s a nice new tool:
http://www.geoplace.com/ME2/dirmod.asp?sid=&nm=&type=MultiPublishing&mod=PublishingTitles&mid=13B2F0D0AFA04476A2ACC02ED28A405F&tier=4&id=DE0C0B03714348ECAAEA632C4742453F
1219: I’d really like to know which of my posts on this site you think were “copypasted”. You can actually do it. You can type “John E. Pearson” into the RC search tool and tell me which of the 100 or so posts I’ve made over the past 4 or 5 years were copypasted from elsewhere. I’ll wager not a single post I’ve made on this cite was copypasted without attribution.
Here’s me “copypasting” and looking like an ignoramus yet again:
http://www.washingtonpost.com/ac2/wp-dyn/comments/display?contentID=AR2006033101707
John, you apparently made up an entirely original joke, and it sounded to me like you’d just posted the kind of misinformation people often bring here without checking it first. Fooled me once, shame on me.
David B. Benson
You wrote:
You apparently believe that I have personally invented the concept of multi-decadal oscillations in the global temperature record as well as the notion that the global temperature has cooled after 2000.
This is not correct.
For Dr. Syun Akasofu on the multi-decadal oscillations as well as the current cooling see:
http://wattsupwiththat.com/2009/03/20/dr-syun-akasofu-on-ipccs-forecast-accuracy/
To quote:
So you see that the multi-decadal oscillation is not an invention of mine, but something that others (including a well-known climate scientist) have observed.
Max
Dr. Syun Akasofu, “well-known climate scientist”. Not so much, not matter how hard you squint at his CV. Still, a real comfort in certain quarters because he’s published many papers, is respected in the particular arena of his expertise and has since gone outside his realm of competence to lend much-needed support to Senator Inhofe et al. He’s definitely an exceptionally quality pick from Senator Inhofe’s collection of 700 contrarian dentists, veterinarians, chiropractors etc. in that he’s an actual scientist but he’s got the same problem as Dr. Easterbrook: Octogenarian Emerititus is clouding his thinking.
Notable publications:
* Akasofu, S.-I., Polar and Magnetospheric Substorms, D. Reidel Pub. Co., Dordrecht, Holland, 1968, (also a Russian edition).
* Akasofu, S.-I., B. Fogle, and B. Haurwitz, Sydney Chapman, Eighty, published by the National Center for Atmospheric Research and the Publishing Service of the University of Colorado, 1968.
* Akasofu, S.-I. and S. Chapman, Solar-Terrestrial Physics, Clarendon Press, Oxford, England, 1972, (also a Russian and Chinese edition).
* Akasofu, S.-I., The Aurora: A Discharge Phenomenon Surrounding the Earth, (in Japanese), Chuo-koran- sha, Tokyo, Japan.
* Akasofu, S.-I., Physics of Magnetospheric Substorms, D. Reidel, Pub. Co., Dordrecht, Holland, 1977.
* Akasofu, S.-I., Aurora Borealis: The Amazing Northern Lights, Alaska Geographic Society, Alaska Northwest Pub. Co., 6, 2, 1979, (also a Japanese edition).
* Akasofu, S.-I. (ed.), Dynamics of the Magnetosphere, D. Reidel Pub. Co., Dordrecht, Holland, 1979.
* Akasofu, S.-I. and J.R. Kan (eds.), Physics of Auroral Arc Formation, Am. Geophys. Union, Washington, D.C., 1981.
* Akasofu, S.-I. and Y. Kamide (eds.), The Solar Wind and the Earth, Geophys. Astrophys. Monographs, Terra Scientific Pub. Co., Tokyo, Japan, and D. Reidel Pub. Co., Dordrecht, Holland, 1987.
* Akasofu, S.-I., Secrets of the Aurora Borealis, Alaska Geographic Society, Banta Publications Group/Hart Press, Vol. 29, No. 1, 2002.
* Akasofu, S.-I. Exploring the Secrets of the Aurora, Kluwer Academic Publishers, Netherlands, 2002.
Also notable, mostly because of Dr. Akasofu’s assertions about models:
http://www.webcommentary.com/docs/2natural.pdf
Another ringer, lots of conclusions supported by 3 citiations:
http://people.iarc.uaf.edu/~sakasofu/pdf/global_temperature_change.pdf
Here, Dr. Akasofu claims that sea level has ceased rising, heat content of the oceans is decreasing, and that Arctic ice is now recovering post 2007. These are controversial assertions, to say the least:
http://people.iarc.uaf.edu/~sakasofu/pdf/Natural_Components_of_Climate_Change.pdf
Yes, anomalies can be seasonal, but it’s not as straight-forward as you suggest.
The global surface station temperature anomalies (GISTEMP, HADCRUT, JMA, etc) are calculated as follows:
– weather stations report monthly temperatures: “how warm is it in Rutland in November 2009?”;
– monthly mean temperatures are calculated over some fixed period, e.g. 1950-1990: “how warm is it normally in Rutland in November?”;
– monthly anomalies – differences from the monthly mean – are calculated: “how much warmer than normal was Rutland in November 2009?”;
– some adjustments are applied (e.g. peri-urban adjustments, station change adjustments, etc);
– these monthly station anomalies are combined with sea-surface anomalies (calulated in a similar way) to make regional or geographical anomalies: “how much warmer than normal was central england in November 2009?”;
– geographical anomalies across the world are combined: “how much warmer than normal was the world in November 2009?”.
As you can see, most seasonality is removed in an early stage: for our purposes we don’t care so much how warm November was, rather we want to know how much warmer it was, compared to an average November. The anomaly that remains can still be seasonal. For instance latent heat keeps the Arctic ocean in summer very close to the melting point of sea ice. So every August in that area has the same temperature, so every August has zero anomaly – whereas the weather in winter does not constrain the temperature so February anomalies can vary.
Maxie says, “You apparently believe that I have personally invented the concept of multi-decadal oscillations in the global temperature record as well as the notion that the global temperature has cooled after 2000.”
No, Max. We know you aren’t smart enough to come up with all this on your own. It is the same crap many denialists have been peddling, including Singer, Akasofu… It’d be nice if y’all could agree on one periodicity, but, hey, to each his own hallucination. Our brains are wired to spot patterns whether they are really there or not. It takes proper statistical analysis to determine whether the patterns are really there and significant or merely coincidence. Hey, by the way, how’s that number theory on oscillations in e coming? There’s a Fielding medal in it for you if you find something there.
Ray, what’s the trend of a sine wave for, say, four cycles? Actually the trend is quite clear: it’s the average of a sine wave — zero — and with 99+% confidence it will project zero for many many periods. Ergo you would say either the sine wave wiggles do not exist, or they are insignificant, or both. I sure hope you don’t do much electronic circuit design.
Rod, We aren’t talking about a sine wave. We are talking about whether a sine wave fit to a bunch of data carries with it any predictive power. For this to be so, it must give us information about the data. Again, I ask you–how’s that number theory problem I gave you comong along. You’ve got 5 periods there. That must be signfiicant, right? Just because you SEE a pattern doesn’t mean it’s really there.
> electronic circuit design
People fool themselves in many fields, including that one:
http://www.nuscam.com/pdf/garbage_physics.pdf
Seriously, Rod, have you taken the time to watch this yet?
http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml
Ray, therein lies the difficulty. On numerous occasions it has been clearly stated that the question has little to do with predictability and trend significance (“little” stemming from a secondary level). My basic question (and probably Max’s) is why temperature oddly goes down one year or some such short period when CO2 shows virtually no such deviation. Your (and many others’) adamant insistence on answering a question that wasn’t posed might be good politics (Rule #3 for news briefings: “Never answer the question they asked; answer the question you wanted them to ask”) but doesn’t advance the science much.
1233 wrote: “My basic question (and probably Max’s) is why temperature oddly goes down one year or some such short period when CO2 shows virtually no such deviation. ”
Is this meant to be a serious question? I’m having a hard time believing you’re serious.
John E. Pearson (1234)
Rod B. has raised a question (which you have a hard time taking seriously, but have not answered).
In my case the question is not a year-by-year question (although the lack of apparent correlation between human CO2 emissions and atmospheric CO2 concentrations and either of these and globally and annually averaged land and sea surface temperatures on an annual basis is also an interesting question).
Here is my question: I wonder why we have had record CO2 emissions as well as increase in atmospheric CO2 after 2000 with no resulting observed increase of 0.2degC in global temperature as projected by the climate models, but rather a significant linear decrease of around 0.1degC.
Now I realize that the Met Office has explained this dilemma, citing “natural variability” (a.k.a. natural forcing) for the cooling, which temporarily overwhelmed the underlying warming trend.
I can accept this explanation, but it raises a new question: if natural forcing was strong enough to overwhelm record increases in CO2 in the 21st century could these same natural forcing factors not have been strong enough to cause a significant part of the observed 20th century warming?
And, yes, this IS a serious question (which Dr. Akasofu has also raised BTW).
Max
1235 wrote:
“the lack of apparent correlation between human CO2 emissions and atmospheric CO2 concentrations”
“we have had record CO2 emissions as well as increase in atmospheric CO2 after 2000”
I am experiencing cognitive dissonance.
Doug Bostrom (1227)
You refer to a paper by Dr. Akasofu and state:
Let’s take a closer look. In the paper which you cited, Dr. Akasofu claims
Data from NSIDC show
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135
end-September Arctic sea ice extent
2007 4.28 million square km
2008 4.67
2009 5.36 (up 25% from 2007)
Does an observed 25% recovery in late summer Arctic sea ice extent from 2007 to 2009 indicate that Dr. Akasufo’s statement is correct? Probably.
Does it mean that this is the beginning of a new longer-term trend of recovery? Probably not, but that is anyone’s guess for now.
Data from Argo buoys, operating since 2003, show
http://cbdakota.wordpress.com/2009/07/05/ocean-heat-content/
These data show that sea temperatures have decreased slightly since Argo measurements started in 2003, but it is hard to say that this is really the beginning of a trend.
This is true for now, according to all temperature records, but it is also too early to claim that this is the beginning of a new long-term trend.
The tide gauge record shows considerable multi-decadal swings over the 20th century, with a net linear rising trend of 1.74 mm per year, and a slightly lower rate of increase (1.45 mm/year) over the second half of the 20th century (1954-2003) than recorded (2.03 mm/year) over the first half (1904-1953)
http://www.agu.org/pubs/crossref/2007/2006GL028492.shtml.
(For a graphical depiction see)
http://farm4.static.flickr.com/3206/3144596227_545227fbae_b.jpg
So Dr. Akasofu is not correct in saying that “global sea level increased almost linearly from about 1800 to 2000”, since there were significant observed multi-decadal swings in the rate of increase, but he is correct in saying that there was no discernible long-term trend of acceleration.
The 60-day smoothed Jason satellite altimetry results show that sea level did level off since 2005, but it is premature to claim that this is the start of a new trend.
http://sealevel.jpl.nasa.gov/science/scientific-investigations-2008/nerem.html
So the claims made by Dr. Akasofu on current observations are correct per se, but any conclusions drawn on longer-term future continuation of the short-term changes seen are conjectural, and thus (as you say) “controversial”.
Looks like we agree in principle here, Doug, as strange as that might seem.
Max
John E Pearson, when you say “AGW alarmists” you show you’re a copypaste ditto.
> monicker
> Does it mean that this is the beginning of a new
> longer-term trend of recovery? Probably not, but that is
> anyone’s guess for now.
Anyone isn’t stupid enough to fall for that.
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
http://nsidc.org/images/arcticseaicenews/20091207_Figure3.png
“November 2009 had the third-lowest average extent for the month since the beginning of satellite records. The linear rate of decline for the month is now 4.5 percent per decade.”
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.jpg
Oh, hell, I fell for the tag-team Rod/monicker red herring routine. Sorry, folks. No need to help them through yet another round of repetition of “gee I dunno, how could anybody know, seems to me it looks like what it looks like.”
You know the answer Max. If you don’t, perhaps an Alzheimer check-up would be in place, as you have been told this again and again and again (and again).
Don’t you ever get tired of this nonsense? (No, don’t answer that.)
1238: Do you have any suggestions as to where I should go for more of my material? I’m running out.
Martin Vermeer says: 30 December 2009 at 5:32 PM
It may well be that arguing with you is only indirectly the point, even more that you’re not the intended audience.
One way of understanding such remarkable intransigence is to consider that each ball successfully batted back across the net is another opportunity for your opponent to choose another from a bottomless bucket of misinformation and then serve it up.
RE #1242, John, I’ve found Hansen’s book STORMS OF MY CHILDREN to be quite helpful in filling in various lacunae I have re climate science. In addition to all sorts of tilt, orbit, solar irradiance, GHGs, albedo, the “sloshings” of el nino/la nina & such, etc impacting global average temp, there are lots of “known unknowns,” such as the very complex aerosol direct and indirect effects.
One of the reasons some of these latter factors are “known unknowns” is bec NASA funding went a lot more to studying outer space and less for studying earth, and we missed opportunities to get the data we needed to understand their aerosols and their effects. If aerosols are only slightly suppressing the amount of warming, we’re not as bad off than if it is greatly suppressing the warming, which will be like flying blind and smashing into the side of a mountain.
The book also reveals how various non-science factors, such as politics and media issues, suppress information and knowledge about global warming. The reader also gets an inside look at the anguish scientists feel by coming to understand the very serious threats of global warming, but unable to adequately communicate these.
If you don’t trust the models, then you’ll be glad to know that Hansen puts paleoclimatology and actual observations before the models.
I never had to understand much about global warming. I just trusted the scientists, bec I know how conservative science is (false-positive avoiding) and I’m even aware of some scientists working for industries falsifying science or doing it in a way that deflects concern about dangerous chemicals, etc (see TOXIC DECEPTION). So if scientists say there’s a problem, then I REALLY believe them.
However, I’m also glad now to be boning up on climate science by reading Hansen’s book, so I’ll be better able to inform others about it.
Martin Vermeer (1241)
Being told something that “ain’t necessarily so” over and over again does not make it “necessarily so”.
Met Office has acknowledged the observed 21st century cooling and explained it with “natural variability”, and I can accept that.
Can you?
Max
MetOffice has pointed out that climate skeptics claim recent events show global cooling, and that they’re wrong. You’ll find people making that kind of claim here. Note they never provide a citation to back up their assertion.
Why? Because …. well, you figure it out. You can do it.
The MetOffice makes a note that pauses occur in any long time series during a warming trend.
They have updated their colorful chart,adding 2009 (light pink, near the left side) — have a look at this page:
http://www.metoffice.gov.uk/climatechange/policymakers/policy/slowdown.html?
“… Many climate sceptics point to the fact that 1998 was the warmest year on record, and say that because no year has topped that since, there must have been global cooling. However, to look at one year in isolation is effectively seizing on an extreme of natural variability and using that to judge long-term climate. It’s the underlying trend that is important, which is why you can only make judgements over longer periods of time.
…. the projections for global climate do not include continual warming year-on-year. Instead they more closely reflect the reality we would expect, with some years warmer than others and even some series of years cooler than a preceding year.
Recent Met Office research investigated how often decades with a stable or even negative warming trend appeared in computer-modelled climate change simulations.
Jeff Knight, lead author on the research, says: “We found one in every eight decades has near-zero or negative global temperature trends in simulations. Given that we have seen fairly consistent warming since the 1970s, the odds of one in eight suggest the observed slowdown was due to happen.”
Our decadal forecast predicts an end to this period of relative stability after 2010. We project at least half of the years after 2009 will be warmer than the 1998 record. Climate researchers are, therefore, reinforcing the message that the case for tackling global warming remains strong.
… “Decades like 1999–2008 occur quite frequently in our climate change simulations, but the underlying trend of increasing temperature remains….”
Hank Roberts
Here is my “take home” from the slide show by Richard B. Alley, which you cited (1232).
“Biggest Control Knob – Carbon Dioxide in Earth’s Climate History”
I will post this in installments, since the spam filter does not accept the whole post.
All-in-all, Alley gives a very spirited argument in this 50 minute presentation for the concept that CO2 has been the primary (if not the only) driver of climate in Earth’s history, and that the 2xCO2 climate sensitivity is likely to be around 3°C.
Biggest argument for his thesis is “we cannot explain it any other way beside CO2 being causal”.
At the same time, agrees there are several other factors, which drive our climate, some of which may not be known as yet.
Discusses cosmic ray / cloud hypothesis rather superficially, but claims its effect is minor.
Part 2 to follow
Hank Roberts
Part 2 on Alley presentation
Alley claims Cretaceous temperature average was 37°C (most estimates put this at 20°-25°C). At that time atmospheric CO2 was over 1500 ppmv, due to breakup of Pangea and volcanic mid-ocean ridges emitting massive amounts of CO2 (and SO2). Claims we could reach this level if all fossil fuels were consumed (this is an exaggeration; there are not enough optimistically estimated fossil fuels on Earth to reach even 1000 ppmv, or 615 ppmv over today’s level, let alone 1500 ppmv, or 1115 ppmv over today’s level). Did not attempt to explain the long-term temperature decline, which began at the end of the Cretaceous despite very high starting CO2 level, and which played a significant role in ensuing mass extinctions due to extreme cold.
Part 3 to follow
Hank Roberts
Part 3 on Alley presentation
Uses Paleo-Eocene Thermal Maximum extinction as proof of CO2 as cause for rapid temperature increase estimated at around 6°C, during which period an estimated 6,800 Gigatons of carbon were released into the ocean and atmosphere as CO2 (roughly five times the amount contained in all fossil fuels on Earth today), but is unable to explain why temperatures began to drop again as atmospheric CO2 levels had reached their highest levels.
By the way, the PETM does not really support a 2xCO2 climate sensitivity of 3°C upon closer examination. Atmospheric CO2 rose by a factor of around 9 (by 2400 ppmv), assuming all of the carbon released was CO2, while temperature rose by 6°C. This would translate into a 2xCO2 climate sensitivity of below 2°C, all other things being equal. Since the carbon release is also estimated to have occurred largely in the form of methane (from clathrates), which has a much higher GH impact than CO2, the calculated 2xCO2 climate sensitivity estimate is even more suspect.
Part 4 to follow
Hank Roberts
Part 4 on Alley presentation
Weakest point is his explanation of the several hundred years time lag between temperature and CO2 in the long-term record (back to 450,000 years BP). [This had been mentioned at the start, where a writer asked that this be explained, which he never did directly] Uses a strange comparison of spending and interest to attempt to explain this time lag, but is unable to answer why CO2 lagged temperature by several hundred years, and why temperature started to cool at same time as CO2 level was very high or started to warm at other times when CO2 level was much lower.
Part 5 to follow