Reviews of the IPCC review

The first IPCC report (Working Group One), "Climate Change 2013, the physical science basis", has just been released.

One way to judge the reliability of a source, is to see what it states about a topic you are knowledgeable about. I work on homogenization of station climate data and was thus interested in the question how well the IPCC report presents the scientific state-of-the-art on the uncertainties in trend estimates due to historical changes in climate monitoring practices.

Furthermore, I have asked some colleague climate science bloggers to review the IPCC report on their areas of expertise. You find these reviews of the IPCC review report at the end of the post as they come in. I have found most of these colleagues via the beautiful list with climate science bloggers of Doug McNeall.

Large-Scale Records and their Uncertainties

The IPCC report is nicely structured. The part that deals with the quality of the land surface temperature observations is in Chapter 2 Observations: Atmosphere and Surface, Section 2.4 Changes in Temperature, Subsection 2.4.1 Land-Surface Air Temperature, Subsubsection 2.4.1.1 Large-Scale Records and their Uncertainties.

The relevant paragraph reads (my paragraph breaks for easier reading):

Particular controversy since AR4 [the last fourth IPCC report, vv] has surrounded the LSAT [land surface air temperature, vv] record over the United States, focussed upon siting quality of stations in the US Historical Climatology Network (USHCN) and implications for long-term trends. Most sites exhibit poor current siting as assessed against official WMO [World Meteorological Organisation, vv] siting guidance, and may be expected to suffer potentially large siting-induced absolute biases (Fall et al., 2011).

However, overall biases for the network since the 1980s are likely dominated by instrument type (since replacement of Stevenson screens with maximum minimum temperature systems (MMTS) in the 1980s at the majority of sites), rather than siting biases (Menne et al., 2010; Williams et al., 2012).

A new automated homogeneity assessment approach (also used in GHCNv3, Menne and Williams, 2009) was developed that has been shown to perform as well or better than other contemporary approaches (Venema et al., 2012). This homogenization procedure likely removes much of the bias related to the network-wide changes in the 1980s (Menne et al., 2010; Fall et al., 2011; Williams et al., 2012).

Williams et al. (2012) produced an ensemble of dataset realisations using perturbed settings of this procedure and concluded through assessment against plausible test cases that there existed a propensity to under-estimate adjustments. This propensity is critically dependent upon the (unknown) nature of the inhomogeneities in the raw data records.

Their homogenization increases both minimum temperature and maximum temperature centennial-timescale United States average LSAT trends. Since 1979 these adjusted data agree with a range of reanalysis products whereas the raw records do not (Fall et al., 2010; Vose et al., 2012a).

I would argue that this is a fair summary of the state of the scientific literature. That naturally does not mean that all statements are true, just that it fits to the current scientific understanding of the quality of the temperature observations over land. People claiming that there are large trend biases in the temperature observations, will need to explain what is wrong with Venema et al. (an article of mine from 2012) and especially Williams et al. (2012). Williams et al. (2012) provides strong evidence that if there is a bias in the raw observational data, homogenization can improve the trend estimate, but it will normally not remove the bias fully.

Personally, I would be very surprised if someone would find substantial trend biases in the homogenized US American temperature observations. Due to the high station density, this dataset can be investigated and homogenized very well.

AVAAZ petition to Murdoch to report the truth about climate change

AVAAZ is a digital civil rights organisation, whose petitions and actions have influenced many important political decisions in the last few years.

Because, the summary for policy makers of the new IPCC report is published today, they are now organising a petition asking Rupert Murdoch to report the truth about climate change. The petition just started; they already have half a million signatures after one day.

To Rupert Murdoch:

The scientific consensus that human activities are causing dangerous climate is overwhelming, yet your media outlets around the world continue to seed doubt and spread inaccuracy. Any journalism that does not first acknowledge the evidence that humans are causing this problem is dangerous and irresponsible. As concerned citizens we call on you to tell the truth about man made climate change and report on what we must do to solve this problem.

You can sign this petition here. Please spread the word.

NoFollow: Do not give WUWT & Co. unintentional link love

The hubris at WUWT.

Do you remember the search engine AltaVista? One reason it was overrun by Google, was that Google presented the most popular homepages at the top. It did so by analysing who links to who. Homepages that receive many links are assumed to be more popular and get a better PageRank, especially when the links come from homepages with a high PageRank.

The idea behind this is that a link is a recommendation. However, this is not always the case. When I link to WUWT, it is just so that people can easily check that what I claim WUWT has written is really actually there. It is definitely not a recommendation to read that high-quality science blog. To the readers this will be clear, but Google's algorithm does not understand the text, it cannot distinguish popularity from notoriety.

This creates a moral dilemma. Do you link to a source of bad information or not? To resolve this dilemma, and make linking to notorious pages less problematic, Google has introduce a new HTML-tag:

<a href="" rel="nofollow">Some homepage</a>.

If you add NoFollow to a link, Google will not follow the link and not interpret the link as a recommendation in its PageRank computation.

Skeptical sunlight

We are not the only ones with this problem. Many scientifically minded people have this problem, especially people from skeptical societies. Note, that here the word skeptical is used in the original meaning. From them I have this beautiful quote:

As Louis Brandeis famously said, "sunlight is the best disinfectant". Linking directly to misinformation on the web and explaining why it is wrong is like skeptical sunlight. ...

I think the correct way to proceed is to continue providing skeptical sunlight through direct linking. For one thing this demonstrates that we are not afraid of those who we oppose. In general they don’t link back to us, and that demonstrates something to casual readers who take note of it. ...

But while we are doing this we must be constantly vigilant of the page rank issue. Page ranking in Google is vitally important to those who are pushing misinformation on the web. It is how they attract new customers to their vile schemes, whether they be psychics or astrologers or homeopaths or something else. Even if we as skeptics are providing only a miniscule fraction of a misinformation peddler’s page rank, that fraction is too much.

Our links are probably the smallest part, but they may be important nonetheless. These links connect the climate ostrich pages with the main stream. Without our links, their network may look a lot more isolated. This is also important, PageRank is not just about links, but about links from authoritative sources.

If you search in Google using:

link:www.wattsupwiththat.com

You will find many pages linking to WUWT that most likely do not want to promote the disinformation, on the contrary.

Proceedings of the Seventh Seminar for Homogenization and Quality Control in Climatological Databases published

The Proceedings of the Seventh Seminar for Homogenization and Quality Control in Climatological Databases jointly organized with the Meeting of Cost ES0601 (Home) Action MC Meeting (Budapest, Hungary, 24-27 October 2011) has now been published. These proceedings were edited by Mónika Lakatos, Tamás Szentimrey and Enikő Vincze.

It is published as a WMO report in the series on World Climate Data and Monitoring Programme. (Some figures may not be displayed right in your browser, I could see them well using Acrobat Reader as stand-alone application and they did print right.)

Anthony Watts calls inhomogeneity in his web traffic a success

[UPDATE. Dec. 2013. The summary of 2013 of WUWT has just been released and the number of pageviews of WUWT has dropped. In 2012 WUWT had 36 million page views, in 2013 only 35 million. Not a large drop, but a good beginning. And it should be noted that a constant readership leads to reductions in ranking as the internet is still growing fast. Thus these number are a clear contrast to the increases in ranking that Anthony Watts announced below.

This confirms that WUWT does not only gives bad information on climate science. Let's hope more people will realize how unreliable WUWT is and start reading real science blogs.]

Success

Anthony Watts pretends to be beside himself with joy. WUWT has an enormous increase in traffic!! In his post Announcement: WUWT success earns an invitation to “Enterprise” he writes: "You are probably aware of the ongoing improvements to WUWT I’ve made. They seem to be paying off. Lately, things have been looking up for WUWT:" and shows this graph.



With such an increase in the quantity of readers, why care about quality? Thus suddenly it is no longer a problem that Wotts Up With That Blog (now called: And Then There's Physics) clarifies the serious errors on WUWT daily.

@CollinMaessen @wottsupwiththat His every post "Watt about..." is an attack on my name. But I don't care. Success is best revenge.

— Watts Up With That (@wattsupwiththat) August 7, 2013

Comments

The WUWT regulars are cheering.

JimS: Congrats, Anthony Watts. I see that your blog stats have arisen to the level that the AGW alarmists wished the temperatures would also arise to confirming their folly.

John Whitman: The extraordinary ranking of your venue is the best kind of positive energy feedback loop to increase stimulation of critical independent thinkers in every country. You and everyone of them can draw rejuvenating intellectual energy from it. Wow.

George Lawson: The AGW crowd will see this as another nail in their coffin! Almost as painful as this year’s Arctic ice melt.

Stephen Brown: Congratulations! I bet that the rise and rise of WUWT is causing a certain amount of underwear wadding amongst the Warmistas!

Increase?

But is the number of WUWT readers really increasing?

A first indication that this is not the case, is that Anthony Watts did not really write it explicitly. His post and the plot certainly suggest it and he did not correct the people commenting that clearly thought so, but Watts did not explicitly write so. That should make one suspicious.

A second indication is that Watts is very touchy about it. When Collin Maessen, as someone working in IT, pointed out to Watts on Twitter that, Alexa is not very reliable, the response is that Watts blocks Maessen on Twitter.

Tamsin Edwards, what is advocacy?

Tamsin Edwards has started a discussion on advocacy by scientists. A nice topic where everyone can join in and almost everyone has joined in. While I agree with the letter of of her title: Climate scientists must not advocate particular policies, I do not agree with the spirit.

If you define a climate scientist as a natural scientist that studies the climate, it is clear that such a scientist is not a policy expert. Thus when such a scientist has his science hat on, he is well advised not to talk about policy.

However, as private citizen also a climatologist naturally has freedom of expression; I will keep on blogging on topics I am not an expert on, including (climate) policy.

Other scientists may be more suited to give policy advice (answer questions from the politicians or the public on consequences of certain policies) or even to advocate particular policies (develop and communicate a new political strategy to solve the climate problem). Are hydrologists, ecologists, geographers and economists studying climate change impacts climatologists? They surely would have more to say about the consequences of certain policies.

Some scientists focus their work on policy. If that is mainly about climate policy, does that make the following people climatologists? They are certainly qualified to publicly talk about climate policy.

For example, Roger Pielke Jr., with his Masters degree in public policy and a Ph.D. in political science. I guess he will keep on making policy recommendations.
Gilbert E. Metcalf and colleagues (2008) studied carbon taxes in their study, Analysis of U.S. Greenhouse Gas Tax Proposals and probably did not do this to have their study disappear in an archive.
Wolfgang Sterk of the Wuppertal Institut suggests to change the global cap-and-trade discussion to jointly stimulating innovation towards a sustainable economy (unfortunately in German). Sounds close to my suggestion to break the deadlock in the global climate negotiations.

Science and politics

One thing should be clear, science and politics are two different worlds. Politics is about comparing oranges and apples, building coalitions for your ideas and balancing conflicts of interest. Politicians are used to deal with ambiguity and an uncertain future.

Natural science is about comparing like with like. However, you cannot add up lives, health, money and quality of life. Science can say something about implications (including error bars) of a policy with respect to lives, health, money and maybe even quality of life if you define it clearly. The politician will have to weight these things against each other. Science is also about solving clear crisp problems or dividing a complex problem in multiple such simple solvable ones.

Statistically interesting problems: correction methods in homogenization

This is the last post in a series on five statistically interesting problems in the homogenization of climate network data. This post will discuss two problems around the correction methods used in homogenization. Especially the correction of daily data is becoming an increasingly important problem because more and more climatologist work with daily climate data. The main added value of daily data is that you can study climatic changes in the probability distribution, which necessitates studying the non-climatic factors (inhomogeneities) as well. This is thus a pressing, but also a difficult task.

The five main statistical problems are:

Problem 1. The inhomogeneous reference problem

Neighboring stations are typically used as reference. Homogenization methods should take into account that this reference is also inhomogeneous

Problem 2. The multiple breakpoint problem

A longer climate series will typically contain more than one break. Methods designed to take this into account are more accurate as ad-hoc solutions based single breakpoint methods

Problem 3. Computing uncertainties

We do know about the remaining uncertainties of homogenized data in general, but need methods to estimate the uncertainties for a specific dataset or station

Problem 4. Correction as model selection problem

We need objective selection methods for the best correction model to be used

Problem 5. Deterministic or stochastic corrections?

Current correction methods are deterministic. A stochastic approach would be more elegant

Problem 4. Correction as model selection problem

The number of degrees of freedom (DOF) of the various correction methods varies widely. From just one degree of freedom for annual corrections of the means, to 12 degrees of freedom for monthly correction of the means, to 120 for decile corrections (for the higher order moment method (HOM) for daily data, Della-Marta & Wanner, 2006) applied to every month, to a large number of DOF for quantile or percentile matching.

What is the best correction method depends on the characteristics of the inhomogeneity. For a calibration problem just the annual mean would be sufficient, for a serious exposure problem (e.g. insolation of the instrument) a seasonal cycle in the monthly corrections may be expected and the full distribution of the daily temperatures may need to be adjusted.

The best correction method also depends on the reference. Whether the variables of a certain correction model can be reliably estimated depends on how well-correlated the neighboring reference stations are.

Currently climatologists choose their correction method mainly subjectively. For precipitation annual correction are typically applied and for temperature monthly correction are typical. The HOME benchmarking study showed these are good choices. For example, an experimental contribution correcting precipitation on a monthly scale had a larger error as the same method applied on the annual scale because the data did not allow for an accurate estimation of 12 monthly correction constants.

One correction method is typically applied to the entire regional network, while the optimal correction method will depend on the characteristics of each individual break and on the quality of the reference. These will vary from station to station and from break to break. Especially in global studies, the number of stations in a region and thus the signal to noise ratio varies widely and one fixed choice is likely suboptimal. Studying which correction method is optimal for every break is much work for manual methods, instead we should work on automatic correction methods that objectively select the optimal correction method, e.g., using an information criterion. As far as I know, no one works on this yet.

Problem 5. Deterministic or stochastic corrections?

Annual and monthly data is normally used to study trends and variability in the mean state of the atmosphere. Consequently, typically only the mean is adjusted by homogenization. Daily data, on the other hand is used to study climatic changes in weather variability, severe weather and extremes. Consequently, not only the mean should be corrected, but the full probability distribution describing the variability of the weather.

WUWT not interested in my slanted opinion

Today Watts Up With That has a guest post by Dr. Matt Ridley. In this post he seems to refer to a story that was debunked more than a year ago:

And this is even before you take into account the exaggeration that seemed to contaminate the surface temperature records in the latter part of the 20th century – because of urbanisation, selective closure of weather stations and unexplained “adjustments”. Two Greek scientists recently calculated that for 67 per cent of 181 globally distributed weather stations they examined, adjustments had raised the temperature trend, so they almost halved their estimate of the actual warming that happened in the later 20th century.

I tried to direct those WUWT readers that are interested in both sides of the conversation to an old post of mine about why these Greek scientist were wrong and mainly how their study was abused and exaggerated by WUWT.

Naturally, I did not formulate it that way, but in a perfectly neutral way suggested that people could find more information about the above quote as my blog. I see no way my comment could have gone against the WUWT commenting policy. Still the response was:

[sorry, but we aren't interested in your slanted opinion - mod]

Strange, people calling themselves skeptics that are not interested in hearing all sides. I see that some people from WUWT still find their way here to see what the moderator does not allow. Here it is:

Investigation of methods for hydroclimatic data homogenization

(I may remove this redirect in some days, as this post does not really provide any new information.)


UPDATE: Sou at Hotwhopper wrote a post, WUWT comes right out and says "We Aren't Interested" in facts , about his post. Thank you, Sou. So I guess I will have to keep this post up. And that also makes it worthwhile to add another gem to be found in the WUWT guest post of Dr. Matt Ridley.