All this data and the databases he complains about is what the IPCC relies so heavily upon.

But by all means keep ‘hiding the decline’

The only real attempt at criticism of the paper I’ve found is in a blog post at RealClimate by Rasmus Benestad. Personally I found the criticisms scattered and lacking substance, although I still have some reading to do before I’ve verified that to at least my own satisfaction. Benestad also seems to make an accusation of cherry-picking data (“If one looks long enough at a large set of data, it is often possible to discern patterns just by chance. “).

The paper stands unchallenged in the peer-reviewed literature. Presumably the proper scientific criticism is still being formulated or finding its way through the peer-review process.

On this note, you may be interested to read Nicola Scafetta’s reply to Benestad and Schmidt 2009. It’ll be a few months before it’s published in a journal, but it’s been posted at http://climatesci.org/2009/08/03/nicola-scafetta-comments-on-solar-trends-and-global-warming-by-benestad-and-schmidt/

I don’t think that is quite what the proxies did. Because we don’t have a good instrument record for the first part of the 20th century, especially for much of the non-First-World. We do have better and better records for the post-1960s world.

The proxies do not show warming. They show tree ring growth or the like. That has to be calibrated against a known, reliable, instrument record. The modern period is the obvious period to use as a base line. If the proxies disagree with the modern satellite data, there is something wrong with the assumptions about the proxies. There can be no other conclusion.

“It’s not just about assuming n degrees of warming for a certain width of tree ring, it’s about the trend – if the trend is wrong you can’t get round it by assuming a diffent value for n and you can’t get away from the fact that in this case there was an anomaly in the data.”

Then the proxies are rubbish and need to be thrown out. Do you have a reference for the problem with the trend anyway?

“Therefore there are only two possible conclusions – either the whole science of dendrochronology is invalid, unlikely given it has a sound scientific basis and temperature reconstructions for past centuries broadly match those using different proxies”

Actually it is perfectly likely. Tree growth is influenced by a lot of different factors. Temperature is just one. Soil quality for instance. Water availability. Even CO2 levels in some parts of the world. So it needs to be used with caution.

“or there was something odd about the behaviour of those particular trees over the previous 40 years, possibly due to some external factor.”

Or, even if everything you say is true – and it does not apply to trees in Siberia or outside of Europe – there is something wrong with the first forty years.

“When it came to compiling the graph for the WMO, they used the data which was known to be most accurate – the proxy records for past centuries and the instrumental records for recent years.”

Except if the proxies are not accurate for the period with modern instruments and especially satellites you cannot know they are accurate for the past either. Especially as proxies are, obviously, proxies. They do not give temperatures. They may be the only data they have, but that does not make them accurate. Why calibrate them against the 40 years before 1960 rather than the 40 years after?

“The point of the graph was to give as accurate a representation as possible of gloal temperatures over the last 1,000 years and that’s what it did – there was no deception, no “fudging”, no dishonesty.”

Except it is clear from their computer code that there was fudging from the start and it was dishonest of them to pretend otherwise. Mike Mann did not, by the way, use instrument data from the post-1960s period. He used adjusted and selected data. I wonder how long that will stand up to scrutiny once it is openly released.

“Francis, it sounds like you haven’t kept up with the science.”

I would say that I’ve kept up pretty well with the science, considering that I no longer work as a research geophysicist, and have to concentrate on industrially relevant research in my work as a science journalist. I keep an eye on the literature, and also online chatter among climate scientists.

The GCR-climate link has failed to convince more than a very small number of people. The work passes muster when it comes to the peer-review process, but the science is weak, and the statistics of marginal significance.

Regarding Henrik and his latest paper on Forbush decreases, this work has been thoroughly deconstructed by specialists who understand atmospheric chemistry. Henrik clearly doesn’t. The timing is all wrong, for one thing.

Also, many researchers have expressed unease with Henrik’s failure to cite in his 2009 paper a number of highly relevant studies that impact directly on his hypothesis. Another criticism concerns Henrik’s choice of aerosols used in his study.

The point is that Henrik has done his work, and the science has been subject to intense, detailed, open and civilised discussion. It’s way beyond the scope of a knockabout political blog to repeat that detail here, but if readers are interested, they can easily find the online discussion with the aid of a suitable search engine.

Henrik is not the only researcher working in this area, yet owing to the political sensitivity of the subject, it would seem that just one paper with Henrik’s name on it has more public impact than a dozen by researchers who have spent their entire professional lives attempting to solve complex problems in lower atmosphere chemistry and physics. I can understand their frustration with this lamentable state of affairs.

Francis, it sounds like you haven’t kept up with the science. It’s not just a hypothesis anymore, it’s been repeatedly confirmed by real-world measurements. The GCR-climate link is also visible in the paleo-record. The criticisms of the theory have been, as Shaviv described it, “toothless”.

Andrew, one of your two links was to a model study, which isn’t that helpful – real-world observations are more interesting and relevant, because they trump model results, they’re needed to confirm the usefulness of models, and they’re the only thing that can prove or disprove the GCR-climate hypothesis.

The other paper, by Sloan and Wolfendale, is flawed because they studied the wrong type of cosmic rays (low energy ones) – Svensmark theory is about higher energy cosmic rays. They also failed to consider the lag-time.

They failed to find the Forbush decreases because they made the wrong assumptions, and so looked in the wrong place for the wrong predictions.

Svensmark et al. 2009 interpreted the hypothesis correctly, knew what to look for, and found results confirming the hypothesis : observations from 4 independent satellites show the effects of Forbush decreases on clouds and aerosols, after ~5 day lag.
“Cosmic ray decreases affect atmospheric aerosols and
clouds” (Svensmark et al 2009)
Please see the graph of results on page 15
http://wattsupwiththat.files.wordpress.com/2009/08/svensmark-forebush.pdf

There’s far more evidence for the GCR-climate link in the peer-reviewed literature than there is against it. The criticisms have generally been well-answered, by gathering of more observational evidence confirming the GCR-climate hypothesis, and by pointing out the flaws in the criticising papers.

How can the tree-ring proxy records be known to be accurate for the past centuries, when they weren’t accurate for the modern instrumental period, including 1870-1910 before human activity was at significant levels. There’s no reason to think that they become more accurate in the past.

Why would they want to hide the decline, Andrew?

But the tree rings showed no warming at all for the previous 40 years when the instrumental records showed pronounced warming, but they did show warming for the first part of the 20th century in line with the instrumental records. It’s not just about assuming n degrees of warming for a certain width of tree ring, it’s about the trend – if the trend is wrong you can’t get round it by assuming a diffent value for n and you can’t get away from the fact that in this case there was an anomaly in the data. Therefore there are only two possible conclusions – either the whole science of dendrochronology is invalid, unlikely given it has a sound scientific basis and temperature reconstructions for past centuries broadly match those using different proxies, or there was something odd about the behaviour of those particular trees over the previous 40 years, possibly due to some external factor.

Sorry? You mean the late 20th century was not warming? You have become a Denier?

Er, no, I’m not sure how you came to that conclusion.

Have you misplaced a “not”? If they had adjusted their assumptions about the proxies, they would not have cooled the present – the proxies *must* agree with the instruments – they would have warmed the past. That is precisely what they did not want to do. So they ignored the fact that their assumptions were wrong and fudged the data. Like any cheating first year student.

Not at all. For a start, when they published their initial findings they did not “fudge” anything – they were perfectly open about the fact that the data showed an anomalous lack of warming in recent years. When it came to compiling the graph for the WMO, they used the data which was known to be most accurate – the proxy records for past centuries and the instrumental records for recent years. The point of the graph was to give as accurate a representation as possible of gloal temperatures over the last 1,000 years and that’s what it did – there was no deception, no “fudging”, no dishonesty.

The fact that pro AGW people on here are referring to those who question the AGW hypothesis as ‘fucking denierscum’ just shows to me just how far some environmentalists have moved from a responsible scientific and rational point of view to a quasi religious one.

Saying ‘fucking denierscum’ is like shouting ‘fucking heretic’ was a few hundred years ago.