Dec 4, 2009

Misconceptions about global warming

Key misconceptions:

1) Sceptics or denialists are a single homogenous group
This is clearly wrong, but this does not stop anyone who is sceptical in any way being lumped into this group and being attacked continuously. For the record the following are just some types of sceptisism:

  • Those who fully accept dangerous global warming but think that an ETS system is a bad policy (e.g. James Hansen of NASA);
  • Those who accept that the world has warmed and will continue to warm in a serious way due to human contributions, but think there are a combination of human causes, not just CO2 (e.g. Prof. Roger Pielke Sr);
  • Those who accept that the world has warmed and will continue to warm significantly, primarily due to CO2 emissions, but don't accept the predictions of catastrophe (e.g. Tom Fuller);
  • Those who accept the world has warmed to some degree, partly due to human influence, but don't accept that human influence is dominant or likely to lead to dangerous warming in the future;
  • Those who do not accept there has been any warming in the last 50-100 years and deny that humans can influence the climate at all.
Only the last group above could possibly be called denialists, though it is very hard to find people who actually hold that view. I would say that most sceptics fall within the middle three categories, with the highest concentration probably in the second last category.

2) Sceptics are sceptical of climate change
This is a language trick. Very few people are sceptical of the fact that the world's climate is changing. The sceptisism is directed at the extent and causes of changes to climate. Natural variations in climate have always occured. So this misconception may be convenient shorthand, but it is inaccurate and misleading. The sceptisism is most often directed at human CO2 emissions being the most significant driver of dangerous global warming.

3) The evidence for CO2 driven dangerous climate change is overwhelming
This is obviously contentious. There is certainly overwhelming evdience that CO2 operates as a greenhouse gas. If you fill one glass container with air, and another with air plus extra CO2, then shine a light on both containers, the one with extra CO2 will get warmer. This is not where most sceptics find problems. The real problems that sceptics have include the following (courtesy of

  • Claim A: Nearly every scientist, skeptic and alarmist alike, agree that the first order warming from CO2 is small. Catastrophic forecasts that demand immediate government action are based on a second theory that the climate temperature system is dominated by positive feedback. There is little understanding of these feedbacks, at least in their net effect, and no basis for assuming feedbacks in a long-term stable system are strongly net positive. As a note, the claim is that the net feedbacks are not positive, so demonstration of single one-off positive feedbacks, like ice albedo, are not sufficient to disprove this claim. In particular, the role of the water cycle and cloud formation are very much in dispute.
  • Claim B: At no point have climate scientists ever reconciled the claims of the dendroclimatologists like Michael Mann that world temperatures were incredibly stable for thousands of years before man burned fossil fuels with the claim that the climate system is driven by very high net positive feedbacks. There is nothing in the feedback assumptions that applies uniquely to CO2 forcing, so these feedbacks, if they exist today, should have existed in the past and almost certainly have made temperatures highly variable, if not unstable.
  • Claim C: On its face, the climate model assumptions (including high positive feedbacks) of substantial warming from small changes in CO2 are inconsistent with relatively modest past warming. Scientists use what is essentially an arbitrary plug variable to handle this, assuming anthropogenic aerosols have historically masked what would be higher past warming levels. The arbitrariness of the plug is obvious given that most models include a cooling effect of aerosols in direct proportion to their warming effect from CO2, two phenomenon that should not be linked in nature, but are linked if modelers are trying to force their climate models to balance. Further, since aerosols are short lived and only cover about 10% of the globe’s surface in any volume, nearly heroic levels of cooling effects must be assumed, since it takes 10C of cooling from the 10% area of effect to get 1C cooling in the global averages.
  • Claim D: The key issue is the effect of CO2 vs. other effects in the complex climate system. We know CO2 causes some warming in a lab, but how much on the real earth? The main evidence climate scientists have is that their climate models are unable to replicate the warming from 1975-1998 without the use of man-made CO2 — in other words, they claim their models are unable to replicate the warming with natural factors alone. But these models are not anywhere near good enough to be relied on for this conclusion, particularly since they admittedly leave out any number of natural factors, such as ocean cycles and longer term cycles like the one that drove the little ice age, and admit to not understanding many others, such as cloud formation.
  • Claim E: There are multiple alternate explanations for the 1975-1998 warming other than manmade CO2. All likely contributed (along with CO2) but it there is no evidence to give most of the blame to Co2. Other factors include ocean cycles (this corresponded to a PDO warm phase), the sun (this corresponded to the most intense period of the sun in the last 100 years), mankind’s land use changes (driving both urban heating effects as well as rural changes with alterations in land use), and a continuing recovery from the Little Ice Age, perhaps the coldest period in the last 5000 years.
  • Claim F: Climate scientists claim that the .4-.5C warming from 1975-1998 cannot have been caused natural variations. This has never been reconciled with the fact that the 0.6C warming from 1910 to 1940 was almost certainly due mostly to natural forces. Also, the claim that natural forcings could not have caused a 0.2C per decade warming in the 80’s and 90’s cannot be reconciled with the the current claimed natural “masking” of anthropogenic warming that must be on the order of 0.2C per decade.
  • Claim G: Climate scientists are embarrassing themselves in the use of the word “climate change.” First, the only mechanism ever expressed for CO2 to change climate is via warming. If there is no warming, then CO2 can’t be causing climate change by any mechanism anyone has ever suggested. So saying that “climate change is accelerating” (just Google it) when warming has stopped is disingenuous, and a false marketing effort to try to keep the alarm ringing. Second, the attempts by scientists who should know better to identify weather events at the tails of the normal distribution and claim that these are evidence of a shift in the mean of the distribution is ridiculous. There are no long term US trends in droughts or wet weather, nor in global cyclonic activity, nor in US tornadoes. But every drought, hurricane, flood, or tornado is cited as evidence of accelerating climate change (see my ppt slide deck for the data). This is absurd.
4) The peer-reviewed literature totally supports the theories of CO2 driven dangerous global warming
I haven't read enough of the peer-reviewed literature to give an exhaustive summary, but suffice to say despite efforts of certain scientists to exclude sceptical papers from publication, some have still slipped through the cracks. A brief list of more recent articles follows:

Nov 27, 2009

Worse than the emails: the code

Some telling excerpts:
What the hell is supposed to happen here? Oh yeah - there is no )'supposed', I can make it up. So I have :-)...
So with a somewhat cynical shrug, I added the nuclear option - to match every WMO possible, and turn the rest into new stations (er, CLIMAT excepted). In other words, what CRU usually do. It will allow bad databases to pass unnoticed, and good databases to become bad, but I really don't think people care enough to fix 'em, and it's the main reason the project is nearly a year late. 
(See file HARRY_READ_ME.txt)

Apply a VERY ARTIFICAL correction for decline!!
(See file

IMPORTANT NOTE: The data after 1960 should not be used. The tree-ring density' records tend to show a decline after 1960 relative to the summer temperature in many high-latitude locations. In this data set this "decline" has been artificially removed in an ad-hoc way, and this means that data after 1960 no longer represent tree-ring density variations, but have been modified to look more like the observed temperatures.
(See file

Nov 24, 2009

The CRU emails

Since the release of the "hacked" (or leaked) emails from the server of the CRU at the University of East Anglia (UK), there has been a lot of commentary, argument and opinions expressed regarding the content and implications of the emails, appearing on blogs and in the news media. 

The opinions can roughly be divided as follows:
1) The emails don't really mean anything, they are simply private correspondence containing "robust" discussions, taken "out of context" (for some reason, "robust" seems to be a favourite word)
see e.g.,0,913036.story

2) The emails are concerning and reflect badly on the main parties involved, but may not really affect general climate science very much.
see e.g.,1,26386792-401,00.html

3) The emails expose deeply disturbing practices at the very top of climate science which seriously undermine the integrity of those involved.  The emails also taint the related scientific conclusions, though the emails do not themselves prove that global warming is false.
see e.g.

4) The emails prove a giant global conspiracy to lie to the public about global warming.  The perpetrators know that warming is a lie and are simply perpetuating this lie for profits.
(see comments on various blogs - I can't actually find a blogger or columnist/reporter who seems to actually believes this)

I would say I fall into category three above.  Before going further, I want to share an excerpt from an excellent speech made by Richard Feynman, winner of the Nobel Prize for Physics, regarding the scientific method:

Now it behooves me, of course, to tell you what [is] missing [in bad science].
That is the idea that we all hope you have learned in studying science in school--we never explicitly say what this is, but just hope that you catch on by all the examples of scientific investigation. It is interesting, therefore, to bring it out now and speak of it explicitly. It's a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty--a kind of leaning over backwards. For example, if you're doing an experiment, you should report everything that you think might make it invalid--not only what you think is right about it: other causes that could possibly explain your results; and things you thought of that you've eliminated by some other experiment, and how they worked--to make sure the other fellow can tell they have been eliminated.

Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can--if you know anything at all wrong, or possibly wrong--to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition.

In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.

The easiest way to explain this idea is to contrast it, for example, with advertising. Last night I heard that Wesson oil doesn't soak through food. Well, that's true. It's not dishonest; but the thing I'm talking about is not just a matter of not being dishonest, it's a matter of scientific integrity, which is another level. The fact that should be added to that advertising statement is that no oils soak through food, if operated at a certain temperature. If operated at another temperature, they all will-- including Wesson oil. So it's the implication which has been conveyed, not the fact, which is true, and the difference is what we have to deal with.

We have learned a lot from experience about how to handle some of the ways we fool ourselves. One example: Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off, because he had the incorrect value for the viscosity of air. It's interesting to look at the history of measurements of the charge of the electron, after Millikan. If you plot them as a function of time, you find that one is a little bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher.

Why didn't they discover that the new number was higher right away? It's a thing that scientists are ashamed of--this history--because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong--and they would look for and find a reason why something might be wrong. When they got a number closer to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that.
After reading those excellent words from Feynman, I then turn to some less excellent words found in these emails:

Can you delete any emails you may have had with Keith re AR4?
Keith will do likewise. He's not in at the moment - minor family crisis.
Can you also email Gene and get him to do the same? I don't have his new email address.
We will be getting Caspar to do likewise.
I see that CA claim they discovered the 1945 problem in the Nature paper!!
Note: "AR4" means the latest IPCC report, the 4th Assessment Report
The "Mike", "Keith" and "Phil" were all major contributors
to the 4th IPCC report (2007).
I presume congratulations are in order - so congrats etc !
Just sent loads of station data to Scott. Make sure he documents everything better this time! And don't leave stuff lying around on ftp sites - you never know who is trawling them. The two MMs have been after the CRU station data for years. If they ever hear there is a Freedom of Information Act now in the UK, I think I'll delete the file rather than send to anyone. Does your similar act in the US force you to respond to enquiries within 20 days? - our does ! The UK works on precedents, so the first request will test it. We also have a data protection act, which I will hide behind. Tom Wigley has sent me a worried email when he heard about it - thought people could ask him for his model code. He has retired officially from UEA so he can hide behind that. IPR should be relevant here, but I can see me getting into an argument with someone at UEA who'll say we must adhere to it !
Note: "CRU station data" refers to the raw temperature
data collected by the Climate Research Institute and used
to calculate global average temperatures.
"MM" refers to Steve McIntyre and Ross McKitrick.

Phil and I have recently submitted a paper using about a dozen NH records that fit this category, and many of which are available nearly 2K back--I think that trying to adopt a timeframe of 2K, rather than the usual 1K, addresses a good earlier point that Peck made w/ regard to the memo, that it would be nice to try to "contain" the putative "MWP", even if we don't yet have a hemispheric mean reconstruction available that far back [Phil and I have one in review--not sure it is kosher to show that yet though--I've put in an inquiry to Judy Jacobs at AGU about this].

Note: MWP means "Medieval Warm Period".
Thanks, Phil.

The stuff on the website is awful. I'm really sorry you have to deal with that kind of crap. If the RMS is going to require authors to make ALL data available - raw data PLUS results from all intermediate calculations - I will not submit any further papers to RMS journals.

Note: RMS = Royal Meterological Society, which publishes the
"International Journal of Climatology", "Atmospheric Science
Letters", and "Weather", and other journals.
Attached are the calibration residual series for experiments based on available networks back to:
AD 1000
AD 1400
AD 1600
I can't find the one for the network back to 1820! But basically, you'll see that the residuals are pretty red for the first 2 cases, and then not significantly red for the 3rd case--its even a bit better for the AD 1700 and 1820 cases, but I can't seem to dig them up. In any case, the incremental changes are modest after 1600--its pretty clear that key predictors drop out before AD 1600, hence the redness of the residuals, and the notably larger uncertainties farther back...
You only want to look at the first column (year) and second column (residual) of the files.
I can't even remember what the other columns are!
Let me know if that helps. Thanks,
p.s. I know I probably don't need to mention this, but just to insure absolutely clarify on this, I'm providing these for your own personal use, since you're a trusted colleague. So please don't pass this along to others without checking w/ me first. This is the sort of "dirty laundry" one doesn't want to fall into the hands of those who might potentially try to distort things...

There are many, many more troubling emails.  Regarding my preference for category three above I would say this.  First, these emails contain more than just robust discussion.  Discussing the deletion or withholding of scientific information is not robust, it is troubling.  As for the claim that statements have been taken out of context - the beauty of this situation is that anyone can work out the context if they read the emails in full and put some effort into doing some basic background research on the points they are unfamiliar with.  For me, these considerations rule out category one.  Category two is ruled out because if some of the key scientists are of questionable integrity, all their work is now suspect.  Not wrong, but suspect.  And all their public statements about consensus, about there being "no doubt" are suspect.  So I find myself agreeing with category three.  Global warming has not been disproved nor proved a hoax.  But the integrity of those at the top is now open to question - and thus, so is the quality of their work.

For more info, see: - good article - searchable full-text of all emails - blog detailing some of the problems. - run by Steve McIntyre, a key sceptic mentioned in many of the emails.

{Addendum - the emails are not the whole story regarding the released data.  Regarding some of the other files, see: for a good, regularly updated summary).

Nov 10, 2009

Climate reconstructions - interview with Steve McIntyre and Richard Lindzen on Finnish TV

English transcript can be found here.  Well worth a read.

Nov 9, 2009

Rudd's climate change speech

Kevin Rudd made a strong speech, attacking "climate change sceptics", at the Lowy Institute last week.

A good response is made by Prof. Davidson here.
Roger Pielke Jnr has some interesting comments on it on his blog here.

A "refutation" has been posted on Climate Depot, though I can't fully endorse it's content.  It still may be worth referring to though.

Nov 5, 2009

Richard Lindzen speaks on climate change issues

Richard Lindzen, Alfred P. Sloan Professor of Meterology at MIT speaks on global warming science and policy.  First youtube video here.