(1:20m) … there has not been a clear indication of changes in exceptional low rainfall years.
(1:40m) … but in terms of a long term trend its not very clear in terms of exceptional low rainfall years.
This totally contradicts the the confident expectations of more years of exceptionally low rainfall as stated clearly in the summary (emphasis added):
There must have been some way that the models of exceptionally low rainfall (drought) were validated in the CSIRO/BoM Drought Exceptional Circumstances Report. Usually, models are checked against observations to make sure they have ’skill’ at the purpose for which they are intended. In this case, the global climate models used in the Drought Exceptional Circumstances Report must have been compared with observations, before they were used to show increasing frequency and severity of droughts in the next 30 years.
This post is the first cut at R statistics for the Rybski approach to detecting change in global temperature. It follows Global Warming Statics giving the literature context to the analysis, and the introductory post July 2008 Global Temperatures that caused all the fuss at ClimateAudit.
It is often stated that global temperature has increased over some specific time frame. Few realize there are different ways to answer this question, and the increase may not actually be significant, particularly in view of persistent correlation between temperature over long time scales (LTP).
In Statistical analysis of hydroclimatic time series: Uncertainty and insights Koutsoyiannis evaluates two publications using two different approaches to this issue: the evaluation of trends as done in Cohn, T. A., and H. F. Lins (2005), or as the simple change in temperature between two points as in Rybski et al. (2006).
Much ado has been made about global warming stopping since 2001, since 1998 or not increasing in the last decade. Here’s more grist to the skeptic mill. The analysis below shows the global temperature has not increased significantly since July 1979!
Data are from the TLT Satellite measurements of the Earth’s lower troposphere at RSS MSU. When you calculate the global surface temperatures from July to July 1979-2008, the earth has warmed the grand amount of 0.295 degrees C. The standard deviation of the temperature changes for each July to July is 0.2522C, putting the change over 30 years at just over a non-significant one standard deviation (actually p=0.13, significant if p<0.05) of the expected change in just one year. Stated another way, every one out of eight years, global temperature changes by a similar amount to the total increase in the last 30 years.
William M. Briggs, Statistician, is one of the outstanding technical blogs on the internet today. As indicated by the sub-title, “All manner of statistical analyses cheerfully undertaken”, it occupies a similar niche to Niche Modeling, recognizing and filling a felt need for basic statistical analysis of everyday events. The posts are often illustrated by programming in R code, providing a wonderful introduction to programming in R for statistics. The subjects range from global warming to clinical trials. As writing, the posts are literary, fluid and print-ready. In particular, W.M. Briggs is master of the arresting opening sentence, essential in a surfing medium. Here are some notable examples.
The Prime Minister of Australia, Kevin Rudd, made more indecorous remarks about scientists on 60 minutes last night. He obviously felt the need to retell his joke about scientists, first made on the 18th July, as nobody laughed the first time.
There’s a group of scientists called the International (sic) Panel on Climate Change – 4000 of them. Guys in white coats who run around and don’t have a sense of humour. They just measure things. 17 August 2008 — 60 minutes
Climate change is real, an international panel of climate change scientists, 4,000 essentially humourless guys in white shirts and white coats with their heads stuck down test tubes … 18 July 2008 — Interview with Rhys Muldoon, 666 AM Radio, Canberra
He might not realize that it is National Science Week this week. It must be like a blow to the midsection for teachers struggling to interest schoolchildren in science when the PM ad homs scientists at the start of their National Science Week events. Well I thought this joke was funny.
Author and scientist Dr Henry Bauer invites reviews of his book “The Origin, Persistence and Failings of HIV/AIDS Theory” (McFarland 2007) at WikiChecks.
I was led through a by-the-way remark in a “dissident” HIV/AIDS book, and subsequent astonishment as I looked at the original source, to collect essentially all the published data on HIV tests in the USA. The demographics are stunningly regular, during more than two decades. The rates of positive tests, in any given group, vary uniformly with age, sex, and race, and the geographic distribution has remained unchanged; moreover it’s the same for different “risk” groups: blood donors, gay men, injecting drug abusers, military personnel. As to race, the differences are close to quantitative, roughly Asian 0.3–0.6 with White arbitrarily 1; Native American ~1.5, black more than 5. As to age, “HIV+” rates increase from adolescence into middle age and then decrease again; males test HIV+ more often than females except in the early teens.
The author Paul Spite invites reviews at WikiChecks of his book “A Climate Crisis a la Gore.” It is organized as follows:
• Introduction – What motivated the assembly of this research for
public use.
• Part 1 – excerpted ideas from Mr. Gore’s book, The Assault on
Reason, regarding what he claims to be the proper and reasonable way to
enter an argument or evidence in the marketplace of ideas, the forum of
reason, the real power behind democracy.
Following up on the post from yesterday, I test the assumption underpinning the regional climate change work in Australia.
The most common approach has been to assess how well each of the available models simulates the present climate of the region (e.g. Dessai et al. 2005), on the assumption that the more accurately a model is able to reproduce key aspects of the regional climate, the more likely it is to provide reliable guidance for future changes in the region.
As far as I can see this is an untested assumption, and may be a case of ‘accident chasing’.
I have started looking into the way GCMs are used to produce regional climate predictions. The method seems to consist of weighting GCMs according to their regional concordance. I wonder if they are aware of the pitfalls of ‘chasing higher correlations’.
The most common approach has been to assess how well each of the available models simulates the present climate of the region (e.g. Dessai et al. 2005), on the assumption that the more accurately a model is able to reproduce key aspects of the regional climate, the more likely it is to provide reliable guidance for future changes in the region. The method of weighting models is presented shortly. From Climate Change in Australia 2007, Technical Report – Chapter 5: Regional climate change projections (temperature and precipitation)
Its time to address comments on my review of the CSIRO Drought Exceptional Circumstances Report. Thanks to Lazar for taking the time to provide the following feedback at Open Mind, placed at WikiChecks here. I have not yet received any comments from the authors, or Kevin Hennessy of CSIRO.
I think its clear that the core issue of the lack of skill of climate models at simulating frequency of extremely low rainfall is unaffected by Lazar’s points.
Why the Climate Audit / David Stockwell attack on CSIRO “Drought Exceptional Circumstances Report” is wrong.
Here is an example of doing statistics in R, illustrating a pitfall of simple linear regression, using the global temperatures by satellite from 1979 to 2008. I have never seen the problem of ’spurious compensation’ mentioned, but it is a common problem when trying to develop a model from a set of additive factors.
The linear regression below ‘invents’ large positive and negative factors that when added together, create a small difference that is a very good fit. The factors themselves are pronounced ‘highly significant’. Could ’spurious compensation’ explain high positive forcing from CO2 and high negative forcing from aerosols found in some attribution studies?
* be full 3D coupled ocean-atmospheric GCMs,
* be documented in the peer reviewed literature,
* have performed a multi-century control run (for stability reasons)and
* have participated in CMIP2 (Second Coupled Model Intercomparison Project).
He observes that there are no actual criteria that show predictive skill. I am glad the IPCC are not designing mobile phone networks or market research software. One of the IPCC models called FOALS (aka Planet Alternating Current) is plotted over at The Blackboard.
One of the very first questions that a person who is promoting a model encounters from scientists and engineers is “has your model been validated?”. By validation we mean, has it been shown to adequately perform its intended use.
According to Charles M. Macal, Argonne National Laboratory, if the answer to this critical question is No, then
1. Experience has shown that the model is unlikely to be adopted or even tried out in a real-world setting
2. Often the model is “sent back to the drawing board”
3. The challenge then becomes one of being able to say “yes” to this critical question
These are the generally accepted steps to prediction using statistics. When you obey these rules, you have taken out insurance by demonstrating good practice. The chances of reliable prediction are maximized. When steps are missed out or done badly, poor predictions result. Either people don’t know them, or they just forget a step, like validation in the Drought Exceptional Circumstances report. If you apply them to the latest climate change analysis and research, it is easier to see where the problems are. They are as follows:
For those interested in how to make money from carbon credits, here is an interesting example of a successful scheme from the Northern Territory of Australia. The WALFA project (West Arhnem Land Fire Abatement) certifies it will create a minimum annual carbon offsetting of 100,000 tonnes of cabon dioxide equivalent by controlling late-season wildfires. In return, Darwin LNG (Liquid Natural Gas) pays approximately $1 million per year to create a carbon abatement of 100,000 tonnes. Cheap at $10 per tonne. In 2007 the Northern Territory Government paid $130,000 to the Tropical Savannas Cooperative Research Center, $380,000 for indigenous employment, and $500,000 on vehicles and operations. The project is proudly proclaimed as producing ‘quadruple bottom line outcomes’: economic, environmental, social and cultural.
I don’t recommend blogs or blog posts often; that’s for lazy bloggers. But here is an exception. William M. Briggs, Statistician is a man who beats his own path through the underbrush of uncertainty. His article, “Don’t be too sure” is worth reading. His polygenous blog is worth adding to your feed.
“I think the lesson for conservationists today is that, yes, the world is full of surprises. There’s a lot of uncharted territory.” I wonder if she’ll still feel the same way during the next round of fund raising.
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This week’s Science magazine has an article (subscription required) on how Purdue is castigating Taleyarkhan. They suspected he fudged his data, but couldn’t prove it, so like the feds with Al Capone, they got him on a technicality
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Doubt, therefore, is the proper emotion.
Now check out this letter from an APS member, Roger W. Cohen, in support of Lord Monckton’s paper published in the July APS newsletter: Read the rest of this entry…
In a statistical re-analysis of the data from the Drought Exceptional Circumstances Report, all climate models failed standard internal validation tests for regional droughted area in Australia over the last century. The most worrying failure was that simulations showed increases in droughted area over the last century in all regions, while the observed trends in drought decreased in five of the seven regions identified in the CSIRO/Bureau of Meteorology report. Therefore there is no credible basis for the claims of increasing frequency of Exceptional Circumstances declarations made in the report. These results are consistent with other studies finding lack of adequate validation in global warming effects modeling, and lack of skill of climate models at the regional scale.
WikiChecks started out so I didn’t have to search for my reviews, then grew when I realized it might be of use to the whole community. I am still writing the software, but it is usable. I need help populating it with reviews, documents and web design. If you are slick with a digital camera, email any images. I thought of calling it McIntyre’s Jack Russell Terrier but few would have got the reference. It will be hosted on the landshape server for the moment, but I have registered the domain names wikichecks.org and wikichecks.com also. Below is from the FAQ:
