Star positions matter


Updating The Chilling Stars

Why star positions matter for climate physics

The Making of History’s Greatest Star Map is an excellent account of the European Space Agency’s Hipparcos mission by the project scientist, Michael Perryman. It brings back vivid recollections:

  • of dismay after the launch in 1989, when the satellite failed to go into the right orbit and frantic steps were needed to improvise a survivable orbit and re-configure the observing programme.
  • of satisfaction when operations continued despite unplanned exposure to the Earth’s radiation belts, as well as some nasty solar flares, until the radiation damage became fatal in 1993.
  • of the appetizer in 1994, when early results of the Hipparcos star mapping helped in accurate prediction of the impacts of the fragmented Comet Shoemaker-Levy 9 on the planet Jupiter.
  • of joy on Isola di San Giorgo, Venice, in 1997 when the Hipparcos science team announced their first large-scale results, after a huge computational effort.

Hipparcos in an ESA impression

Astrometry took that great leap forward 30 years after Pierre Lacroute of the Strasbourg Observatory first proposed a space mission to measure the positions of stars, 20 years after Erik Høg of the Copenhagen Observatory refined the concept, and 17 years after ESA earmarked it as something to do. Ground-based astrometry had stalled, because of imprecisions due the turbulence of the atmosphere, and its remaining aficionados had little lobbying power. As a result, Hipparcos remained a distinctly European space project – the first in which there was no competition with the US or Soviet space science programmes.

Applications of the Hipparcos Catalogue of 100,000 plus stars and the Tycho 2 Catalogue with 2.5 million stars (to a lesser but still unprecedented accuracy) have ranged from detecting a bend in the Milky Way Galaxy to checking Einstein’s theory of gravity, General Relativity. But wanting to pursue here the relevance of Hipparcos to climate physics, I’m pleased to see that Michael Perryman points the way.

Michael Perryman. Photo by Richard Perryman

In The Making of History’s Greatest Star Map, pp. 236-243, Perryman notes the role of Hipparcos in refining observations the wobbles of the Earth’s axis, which are involved in the pacing of ice ages (the Milankovitch theory). Then he points to the link between solar activity and climate change, as evidenced by the Little Ice Age, the Medieval Warm Period and other variations. As to the mechanism for the solar connection, Perryman singles out the suggestion that cosmic rays, modulated by solar activity, influence cloud cover.

He continues the story with the Sun’s journey through the Galaxy and the icy intervals on Earth that correspond to exposure to intense cosmic rays when passing through spiral arms. That’s a major topic in The Chilling Stars and, as Perryman says, the Hipparcos data have improved our knowledge of motions in the Galaxy.

It’s reassuring when a professor of astronomy with no scientific or political axe to grind gives serious attention to the cosmic-ray/climate link (the Svensmark hypothesis). Let me reciprocate by reviewing what’s said about the climate-related significance of Hipparcos and its successor Gaia in The Chilling Stars and see if it needs updating or extending.

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Wiki Witch of the West


Predictions Revisited and Climate Change: News and Comments

The Wiki Witch of the West

A pingback comes from Lamont County Environment, which I guess must be Lamont County, Alberta, Canada, where birds throng in summer on the nature reserve of Beaverhill Lake.

That item quotes my recent Tradecraft of Propaganda post and also the entry about me in Wikipedia. Added comments defend me from a perceived bias in Wikipedia. But that entry really isn’t too bad, compared with three years ago, when it first picked up on a climate prediction of mine made in 1980.

Here’s the story told in a plain-text email sent in April 2007 to CCNet (Cambridge Conference Network) run by Benny Peiser of Liverpool John Moores University, who’s now director of the Global Warming Policy Foundation.


Dear Benny

It’s one thing to be held to account for daring predictions made nearly 30 years ago, another to have them perversely rated. Last year a blogger on the Vanity Fair website, Jim Windolf, reported that he had found in a junk shop “a worn-out copy of The Book of Predictions, a compendium of ‘4,000 exclusive predictions’ edited by the family team of David Wallechinsky, Amy Wallace, and Irving Wallace”. Among the gems from 1980 for his readers to chortle about, Windolf picked out the following:

British science journalist Nigel Calder wrote that, by 2000, ‘the much-advertised heating of the earth by the man-made carbon-dioxide ‘greenhouse’ fails to occur; instead, there is renewed concern about cooling and an impending ice age.”

A thought policeman who uses Wikipedia to promote the man-made global warming hypothesis has now added that quote to my biography, with the comment: “After his prediction was proven wrong, Calder participated in the polemic documentary film The Great Global Warming Swindle. He also co-authored The Chilling Stars.”

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CO2 thermometer


Climate Change: News and Comments

The Carbon Dioxide Thermometer

There’s an idea that keeps turning up like a bad penny, and I’ve had a part in it. But as I’ll explain, there’s a problem with it. The proposition is that the increase in the carbon dioxide concentration in the air has little to do with human emissions and a lot to do with prevailing temperatures, perhaps especially at the sea surface.

If CO2 follows temperature rather than the other way around, then changes in CO2 become a measure of temperature, as in a thermometer.

The latest manifestation is on the Watts Up website from Lon Hocker at

Let me mention three previous appearances of this idea:

Cynthia Kuo et al., “Coherence established between atmospheric carbon dioxide and global temperature”, Nature 343, pp. 709-14, 1990, which concluded: “Changes in carbon dioxide content lag those in temperature by five months.”

Nigel Calder, “The carbon dioxide thermometer”, Energy & Environment,10, pp. 1-18, 1999

Jarl Ahlbeck, “The carbon dioxide thermometer”, 2001, see

Since my own offering of 11 years ago, I’ve kept checking to my own satisfaction that what I suggested still works into the 21st Century. (The new story from Lon Hocker supports this.) The CO2-temperature link, with cause and effect swapped around, also looks arguable on geological timescales. Where the idea runs into difficulties is in the Holocene, since the end of the last ice age.

There have been repeated ups and downs of temperature, like those between the Medieval Warm Period, the Little Ice Age and the Modern Warm Period, without the strong variations in CO2 that you’d expect from this hypothesis. I’m not talking about the CO2 results from ice layers, which are suspect because CO2 is soluble in ice and variations are smoothed out. No, I mean results from leaf stomata, by Rike Wagner-Cremer and her colleagues at Utrecht, which are much more trustworthy. They’ve been a little disappointing for the hypothesis.

Here for example is the abstract of one that group’s papers:

T. B. van Hoof et al., “A role for atmospheric CO2 in preindustrial climate forcing,” PNAS, October 14, 2008; 105(41): pp. 15815 – 15818.

Complementary to measurements in Antarctic ice cores, stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of preindustrial atmospheric CO2 concentration. CO2 trends based on leaf remains of Quercus robur (English oak) from the Netherlands support the presence of significant CO2 variability during the first half of the last millennium. The amplitude of the reconstructed multidecadal fluctuations, up to 34 parts per million by volume, considerably exceeds maximum shifts measured in Antarctic ice. Inferred changes in CO2 radiative forcing are of a magnitude similar to variations ascribed to other mechanisms, particularly solar irradiance and volcanic activity, and may therefore call into question the concept of the Intergovernmental Panel on Climate Change, which assumes an insignificant role of CO2 as a preindustrial climate forcing factor. The stomata-based CO2 trends correlate with coeval sea-surface temperature trends in the North Atlantic Ocean, suggesting the possibility of an oceanic source/sink mechanism for the recorded CO2 changes.

At first sight, these researchers are singing much the same song as the CO2 thermometer-makers. So what’s the problem? Simply that the CO2 fluctuations reported in this and other papers are small compared with those of the past century. The period of which van Hoof et al. write includes the Medieval Warm Period when temperatures were at least as high as today. But their CO2 never got above 319 ppmv, compared with 392 at Mauna Loa for May 2010.

The implication is that the CO2 thermometer is not the whole story. Man-made emissions must have contributed to the increase of the past 100 years. How significant that has been as a driver of the temperature increase is another question entirely.

Tradecraft of propaganda



Climate Change: News and Comments

The tradecraft of propaganda

Ritchie Calder. Photo: National Library of Scotland.

Hearing about a story concerning my father  in The Independent, London (2 June), I’ve now seen that the professor of journalism at the University of Kent, Tim Luckhurst, describes him as a “war hero”. That’s for Ritchie Calder’s candid newspaper reports of the chaotic responses to the bombing blitz on London, 1940-41. The article is here:

As Luckhurst says, he faced accusations of “giving comfort to the enemy”. Yes, as a child I heard him telling my mother at the door that he’d be “home by eight if I’m not in Brixton Prison”. But although Luckhurst mentions a later involvement in propaganda, he doesn’t explain that the government silenced Calder’s troublesome reportage of the air raids by shanghai-ing him into the top-secret Political Warfare Executive, formed in August 1941.


A pass giving Ritchie Calder access to the plans for the D-Day landings. (P.I.D., Political Intelligence Department, was a cover-name for the Political Warfare Executive.) National Library of Scotland.

My aim in this blog is to stick to science and shun the politics. My Dad was more politically minded and finished up as a Labour peer. But I share his readiness to defy officialdom and, when the facts serve, to cock a snook at bigwigs of any kind.

What Ritchie Calder told me about wartime propaganda against the Nazis has helped me to understand how a few scientists and politicians have persuaded governments and the docile media about a danger from man-made global warming that goes far beyond the real facts.

While not exactly scientific, the tradecraft of propaganda can be considered technical, so I’ve decided to post here the text of a talk I gave on the subject in London 18 months ago. It’s lightly edited to remove one comment about an individual and to correct one historical over-simplification, but I’ve not bothered to update remarks corresponding to the time of delivery of the talk. [On 8 June, I’ve added some pictures, which I didn’t use in the talk, to break up the long-winded text.]


Global warming is just propaganda

Talk by Nigel Calder, Savile Club, London, 9 Dec. 2008

© Nigel Calder 2008

Let me start by mentioning two members of your club, my brother Allan here tonight, and our late father, Ritchie Calder. When Allan was six weeks old a damaged German bomber was about to crash in Surrey. It jettisoned its bombs and one hit our family home. There was a kerfuffle in London when it turned out that the German pilot had in his pocket a British propaganda leaflet produced by our Dad. Had there been a breach of security? Had his house been targeted? No, of course not. It was just a grisly coincidence.

Ritchie Calder was an ace science reporter, whose scoops included the splitting of the atom and the structure of DNA. But during the Second World War he was director of plans and campaigns in the Political Warfare Executive of the Foreign Office. In plain words, he was making propaganda. He later told me quite a lot about the wartime tradecraft. And now it dismays me to see the very same techniques being used to propagate the myth that we are in the grip of relentless global warming driven by manmade emissions of carbon dioxide.

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