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.

Read the rest of this entry »

Do clouds disappear? 2


Added 12 June 2010: There is now a thoughtful reply from Eimear Dunne.

Climate Change – News and Comments, and an echo of a Falsification Test

Wake up! Models don’t trump observations

The most important article since I launched this blog on 1 May may be Do clouds disappear when cosmic rays get weaker? — see here

It tells of unremitting attempts to falsify the Svensmark hypothesis by claiming that there’s no important effect on global cloud cover when eruptions from the Sun briefly cut the influx of cosmic rays, in “Forbush decreases”. The centrepiece is a summary of results published last year by Svensmark, Bondo and Svensmark. They show very plainly, in observations of the real world, that Forbush decreases have big impacts both on aerosols (chemical specks that grow into cloud condensation nuclei) and on low-level clouds.

That earlier post continues with the efforts in 2009-10 by Wolfendale and Arnold and their collaborators, who try to deny the Svensmark group’s result, by using relatively weak Forbush decreases. Svensmark can explain exactly how the impacts in those cases are masked by quasi-random meteorological noise, like tigers hidden in a jungle’s undergrowth.

Real-world results by Svensmark, Bondo & Svensmark (2009) for the remarkable loss of fine aerosols from the atmosphere (black curve) following five strong Forbush decreases in cosmic rays (red curve). Each aerosol datum point is the daily mean from about 40 AERONET stations world-wide, using stations with more than 20 measurements a day.

New nonsense comes in an abstract posted on the CERN website. It’s for a paper by researchers at Leeds, to be presented at a meeting about aerosols in Helsinki in three months’ time.

At issue are the Svensmark team’s results on aerosols (see right).  These show fine aerosols disappearing from the sky, because the shortage of cosmic rays lessens the chemical production of the  clusters of sulphuric acid and water molecules that seed the aerosols.

According to the people in Leeds, that can’t be right because they have a computer model that contradicts it.

The GLOMAP model was developed by Ken Carslaw, and the unlucky person named as lead author is a graduate student, Eimear Dunne.

An open letter to the lead author

Read the rest of this entry »

2.75 million years ago


Climate Change – News and Comments and Updating The Chilling Stars

Why the big freeze 2.75 million years ago?

The CO2 folk are flummoxed. In the current issue of Science (14 May) William F. Ruddiman of the University of Virginia wrings his hands over the mismatch between unchanging carbon dioxide levels and the drastically cooling climate over the past 20 million years. “Major glaciations began in the Northern Hemisphere around 2.75 million years ago, after a long prior interval of climatic cooling,” Ruddiman says, “… but our understanding of the driving forces behind the cooling remains incomplete.”

For Henrik Svensmark and me, an explanation for that big freeze of 2.75 million years ago is the “jewel in the crown” of climate history, because of its importance for the subsequent origin of the first human beings.Here’s a picture from The Chilling Stars of one of the earliest known stone tools, which were made less than 200,000 years after the big freeze began.

But if you want CO2 to be the big driver of climate change, as Ruddiman evidently does, the commonly used data are disobedient. Here are his graphs.

(A) Oxygen-18 index of deep-ocean temperature and ice volume (after Miller & Fairbanks1987 and Zachos et al. 2001). (B) Estimates of past CO2 concentrations from alkenones (after Pagani et al. 2005). Source: W.F. Ruddiman, Science, 14 May 2010, p.839.

Ruddiman thinks that the data must be wrong. He suggests pushing the CO2 up a little, 20 to 10 million years ago (using boron/calcium ratios) and finding a decline between 5 and 2 million years ago in new alkenone data. He concludes, “Geochemists still have work to do in refining the CO2 proxies.”

But that would be wasted effort if CO2 were not the driver. In The Chilling Stars Henrik Svensmark and I tell a completely different story about what was happening 2.75 million years ago. In Postscript 2008 we relate how the Sun and Earth, wandering through the Galaxy, blundered into a region of space packed with extra cosmic rays – just what was required to chill the world by making more low clouds, in accordance with the Svensmark hypothesis.

Read the rest of this entry »

Do clouds disappear?


Falsification tests of climate theories

Do clouds disappear when cosmic rays get weaker?

or “Don’t you worry, my dear, we’ve seen no tigers”

The Sun makes fantastic natural experiments” Henrik Svensmark says, “that allow us to test our ideas about its effects on the Earth’s climate.” Most dramatic are the events called Forbush decreases. Ejections of gas from the Sun, carrying magnetic fields, can suddenly cut the influx of cosmic rays coming to the Earth from exploded stars.

According to the Svensmark hypothesis, cosmic rays seed the formation of low clouds, so there should be a reduction in the Earth’s low cloud cover in the aftermath of a Forbush decrease. During the past few years there have been repeated attempts to declare the hypothesis falsified, when various teams failed to find the expected decrease in the low cloud cover.

One morning in April 2008, I woke up to find that since midnight the BBC had spread all around the world the news that British physicists had more or less destroyed the Svensmark hypothesis. Violating a basic principle of objective reporting, the broadcasts went out before Svensmark himself had a chance to comment.

By lunchtime he and I had done our best to limit the damage – and the deception of the public – in brief radio and TV interviews. A remark from Svensmark went belatedly onto the BBC website, that the critic it quoted had “simply failed to understand how cosmic rays work on clouds”.

Two years later, critics still don’t understand it. But they go on telling the tale that Forbush decreases have no important effect on clouds, and the media go on echoing them. When Svensmark and his colleagues published in August 2009 a report that showed very clear effects, and explained why others had failed to see them, the BBC and almost everyone else ignored it. But not the scientific critics, who returned to the fray in December 2009 and February 2010. Read the rest of this entry »

Monsoons and the Sun


Climate Change: Updating The Chilling Stars

Monsoons and the Sun

Late rains saved most of the 2009 harvest of India, despite a shortfall of 21% in the summer’s rainfall that led to a ban on rice exports, after a 17% loss of production in West Bengal. But 2009 saw the worst deficit in India’s summer monsoon since 1972, while Burma (Myanmar) had its the shortest monsoon season since 1979.

It is chastening to recall that, in April 2009, Reuters reported the Indian Meteorological Department as saying, “IMD’s long range forecast for the 2009 south-west monsoon season (June to September) is that the rainfall for the country as a whole is likely to be near normal.” Even an updated forecast in June expected only a small rainfall deficit. Clearly, the unpredictable monsoons remain a problem for meteorology and climate physics.

Is there a link between reduced monsoon rains and the Sun’s recent sluggish behaviour, shown by the scarcity of sunspots? Probably. But to clarify the solar link well enough to make better regional forecasts, for even a few months ahead, remains an urgent task. Read the rest of this entry »

Climate Change intro


CLIMATE CHANGE – Introduction

This section of Calder’s Updates is unavoidably a battleground, but within reason it will stick to the physics and dodge the propaganda that surrounds climate research.

Headings in this section

  • News and Comments watching developments
  • The Svensmark Hypothesis outlining the science
  • Falsification Tests digging deeper into the physics
  • Updating The Chilling Stars with evolving stories

In 1997 The Manic Sun by Nigel Calder was the first book to describe a new wonder of Nature – namely Henrik Svensmark’s discovery that the effect of cosmic rays on clouds amplifies the influence of the Sun on the Earth’s climate. Ten years of progress with the physics led to a second book The Chilling Stars in 2007, co-authored with Svensmark.I was also a script consultant to Mortensen Film for the TV programme about Svensmark’s work, “The Cloud Mystery”.

Despite plenty of time to re-consider the story, if it had turned out to be foolish, the evidence looks better and better as the years pass. Yet most climate scientists still ignore or reject Svensmark’s findings from observations of the real world, physics experiments, and theoretical analyses. Scoffing or vehement objections come from supporters of the man-made global warming hypothesis, who realise that the Svensmark hypothesis offers the strongest challenge to the assumptions in their climate models that predict climatic catastrophe.

The customary give-and-take arguments among experts, about which scientific theory fits the facts better, would be fair enough. But since climate physics became a political issue, the involvement of governments, funding agencies, scientific journals and the media in propagating a particular view of climate change has made rational debate difficult. Here’s a comment from Svensmark in an interview by Discover magazine, July 2007.

Question: In 1996, when you reported that changes in the Sun’s activity could explain most or all of the recent rise in Earth’s temperature, the chairman of the United Nations Intergovernmental Panel [on Climate Change] called your announcement “extremely naive and irresponsible”. How did you react?

Svensmark: I was just stunned. I remember being shocked by how many thought what I was doing was terrible. I couldn’t understand it because when you are a physicist, you are trained that when you find something that cannot be explained, something that doesn’t fit, that is what you are excited about. If there is a possibility that you might have an explanation, that is something that everybody thinks is what you should pursue. Here was exactly the opposite reaction. It was as though people were saying to me, “This is something that you should not have done.” That was very strange for me, and it has been more or less like that ever since.

To me (Calder) as a reporter of major discoveries that went on to win Nobel prizes in several different fields, the contrast between flimsy conjecture and creative brainpower backed by real evidence is fairly obvious. Being a generalist, rather than a specialist reporter of climate science, also helps to keep me objective, but I’m not inexperienced or ignorant in this field. It can be irritating when “warmist” journalists and campaigners with no relevant training of their own try to question my competence. Hey, I’ve even published a couple of formal scientific papers of my own.

Calder’s writing and editing on climate-related subjects

2007 (updated 2008) book: The Chilling Stars: A New Theory of Climate Change. Joint author with Henrik Svensmark

2003 book: Magic Universe: The Oxford Guide to Modern Science. Topics Include Biosphere from space, Carbon cycle, Climate change, Cosmic rays, Cryosphere, Earthshine, Earth system, El Niño, Ocean currents, Solar wind, and Volcanic explosions

1999 scientific paper: ‘The Carbon Dioxide Thermometer’, Energy & Environment, 1999, Vol. 10, pp. 1-18, on how CO2 seems to respond to climate change rather than the other way around.

1997 book: The Manic Sun: Weather Theories Confounded about the Sun & climate, including Svensmark’s initial discovery about cosmic rays and clouds

1991 book and related TV series: Spaceship Earth about Earth observation, Including space observations of clouds, storms, temperatures, ice, oceans, bioproductivity, land use, and deforestation.

1990 book: Scientific Europe (editor, for Foundation Scientific Europe). It includes climate articles by Hermann Flohn, Bert Bolin, Paul Crutzen, and Lennart Bengtsson.

1983 book: Timescale: An Atlas of the Fourth Dimension. Among many other topics it traces climate change from the first ice ages 2300 million years ago to the Little Ice Age ending in 1850.

1974 book and related 2-hour TV programme: The Weather Machine. These included the first public reports of the confirmation of the Milankovitch ice-age hypothesis. Participants on TV include Hubert Lamb, Nicholas Shackleton, John Imbrie, Willi Dansgaard, George Kukla, Syukuro Manabe and Bert Bolin.

1974 scientific paper: ‘The Arithmetic of Ice Ages’, Nature, Vol. 252, pp. 216-18, with the first formal confirmation of the Milankovitch Effect. (Done with a pocket calculator, to legitimize what we were saying in The Weather Machine.)

1973 book: Nature in the Round: A Guide to Environmental Science (editor). Includes articles on climate change by L.P. Smith and Grahame Clark.

1968 book: Unless Peace Comes (editor). Includes Gordon MacDonald on weather and climate modification as weapons of war

1965 book: The World in 1984 (editor, for New Scientist). Among about 100 commissioned 20-yr forecasts, contributions on weather & climate came from Graham Sutton, Fred Singer, D.A. Davies & Roger Revelle

Calder has often spoken about climate change in lectures and on TV and radio, including an interview (2007) for The Great Global Warming Swindle, WagTV’s production for Channel 4. He has published articles on the subject since 1961.

About The Chilling Stars


About The Chilling Stars by Henrik Svensmark & Nigel Calder

As Svensmark’s theory of cosmic rays, clouds, and climate penetrates a wide range of sciences, I suspect that specialists in various fields will profit from this plain-language introduction as much as general readers.” So ends the foreword to The Chilling Stars, written by Prof. Eugene Parker of Chicago, who also recalls how “eminent referees” opposed the publication of his own discovery of the solar wind, half a century earlier.

The Good Book Guide commented on The Chilling Stars: “If you are concerned by the doomsday scenarios regarding runaway climate change, then this alternative view of why the climate is warming will be of great interest.”

The Times of London described the book as “The new totem of the climate-change sceptics.”

Editions and translations

In English: UK etc. (Icon), Canada (Icon) and USA (Totem)

The Chilling Stars – A New Theory of Climate Change 2007

The Chilling Stars – A Cosmic View of Climate Change 2008 (with updating Postscript) illustrated above.

Danish translation Klima og Kosmos(Gads Forlag)

German translation Sterne Steuern Unser Klima(Patmos Verlag)

Dutch translation Kosmisch Klimaat(Veen Magazines)

Swedish translation De Kylande Stjärnorna (Anarchos Forlag)

Hebrew translation כוכבים קרירים(Am Oved)

Japanese translation    (Kouseisha)

Russian translation    Леденящие звезды. Новая теория глоб. изм. климата / Chilling stars. A new theory of Globe. rev. Climate Леденящие звезды. Новая теория глоб. изм. климата (Lomonosov)

Main contents of The Chilling Stars 2008 edition

Foreword by Eugene Parker vii

Overview 1

1 A lazy Sun launches iceberg armadas 11

2 Adventures of the cosmic rays 35

3 A shiny Earth is cool 63

4 Getting piggy over the stile 99

5 The dinosaurs’ guide to the Galaxy 132

6 Starbursts, tropical ice and life’s changing fortunes 156

7 Children of the supernovae? 180

8 The agenda for cosmoclimatology 204

9 Postscript 2008 – Carbon dioxide is feeble 231

Sources for individuals quoted 251

Scientific papers 257

Link to Icon Books UK, primary publisher

Buy The Chilling Stars online

In English


USA Amazon






Norway Norli


In Danish

Denmark Saxo

In German

Germany Amazon

Austria Amazon


In Dutch

NetherlandsVeen Magazines

In Swedish


In Japanese

Japan Kouseisha (via Google Translate)

In Russian

Russia Lomonsov

USA Setbook

About The Manic Sun


Explaining where this book about the solar influence and the cosmic ray connection fits into the climate change story

About The Manic Sun: Weather Theories Confounded

Here, in plain language, is the story of the battle between the solar theory and the greenhouse theory.” So read part of the blurb for my book The Manic Sun, published by Pilkington Press in 1997. It continued: “Knud Lassen, Eigil Friis-Christensen and Henrik Svensmark, alone in Copenhagen, took on a global regiment of supercomputer operators. After years of disparagement the Danes have, for the time being, won the fight.”

“The solar-terrestrial Vikings” Friis-Christensen, Svensmark & Lassen. Photo: Kirsten Fich Pedersen for The Manic Sun

My first contact with Friis-Christensen had been five years earlier while working on a TV script about the Sun for the European Space Agency. Together with Lassen, Friis-Christensen had published in Science in 1991 a report that linked the changing temperature of the Northern Hemisphere to the length of the sunspot cycles – shorter cycles meaning warmer weather. It was powerful evidence for a solar influence on the climate but the puzzle remained, how did the Sun do it?

In 1996, in Denmark on completely different business, I telephoned Friis-Christensen to see how he was getting on with his climate story. There was someone he’d like me to meet, he said. This was Svensmark, who next day divulged to me, in confidence, the link between cosmic rays and cloud cover. As soon as I was back in England I contacted Alec Jolly for the Pilkington Press and the commissioning, writing and publication of The Manic Sun went very rapidly, though not so fast as to break any secret.

In the years that followed, thoughts about updating The Manic Sun kept nagging, but by 2006 the Svensmark hypothesis had progressed so much that that only a new book would do. Icon Press took it on and the outcome was The Chilling Stars jointly authored by Svensmark and me.

A questioner once asked me after a lecture if I’d change much in The Manic Sun, I said No, nothing. It remains a good record of thought processes in the 1990s, including my rather naïve optimism about the speed of impact of Svensmark’s discovery. But I did admit that maybe the title was wrong. While two manic phases of solar magnetic behaviour explained most of the global warming of the 20th Century, by time the book came out global warming was coming to an end, because the Sun had gone into a depressive mood. But that was with hindsight, and in any case The Lazy Sun might win no prizes as a title.

Comment on The Manic Sun

While the `greenhouse theory’ is more strongly supported by science, the rival solar theory has many statistics in its favour. … Its subtitle is “Weather Theories Confounded”, and indeed a good deal of the book is devoted to arguing against the theories of greenhouse gases and global warming. But it is what Calder sees as the political manipulation of scientists that provokes his strongest reactions. William Hartston The Independent

You can buy The Manic Sun at:



In Danish Den Maniske Sol:

In Dutch De Grillige Zon:

In German Die Launische Sonne:

About The Cloud Mystery


About The Cloud Mystery

Since 1998 the Danish film producer/director Lars Oxfeldt Mortensen has filmed the work of Henrik Svensmark and his team repeatedly, even when no programme was in production, to build up a remarkable historical record of discovery in progress. Svensmark has appeared in two resulting Mortensen TV programmes:

  • The Climate Conflict, about the role of the Sun in climate change, 2001
  • The Cloud Mystery, about the effect of cosmic rays on clouds and climatic history, 2008. (Nigel Calder was script consultant.)

Mortensen Film’s description of The Cloud Mystery

Svensmark views low clouds from a mountain in Tenerife

‘Our clouds take their orders from the stars,’ says the Danish scientist Henrik Svensmark. That’s the amazing and provocative discovery reported here. Most experts thought the idea was crazy.

The film records ten years of effort by the small team in Copenhagen that, in the end, solved the mystery of how the Galaxy and the Sun interfere in our everyday weather.

It’s provocative because Dr Svensmark’s revelations challenge the belief of most climate theorists that carbon dioxide has been the main driver of global warming. As a result he has faced never-ending opposition.

But strong support for the cosmic view of climate change comes from astronomer Nir Shaviv and geologist Jan Veizer. In the film they tell how the Galaxy has governed the Earth’s ever-changing climate over 500 million years.

The Cloud Mystery is aimed at a wide audience. Astonishing pictures from our Galaxy, the Sun, and cloud formations are mixed with spectacular animations to simplify the science. Comments by astronomers, geologists and climate experts convey their sense of adventure, and give scientific weight to the discoveries presented. The audience is taken on a trip around the world, where scientists from Denmark, Israel, Canada, the USA, and Norway contribute to this exciting story.

Linking all the discoveries is the non-stop rain of cosmic rays – energetic particles from exploded stars that battle with the Sun’s magnetic field to reach the Earth. Central in the story is an experiment in a Copenhagen basement. It showed how cosmic rays help to make chemical specks in the air on which water drops condense to make clouds.

The story concludes that clouds are the main driver of climate change on Earth.

The documentary follows Henrik Svensmark in his struggle to find the physical evidence of a celestial climate driver. The film demonstrates that science can be a rough place to be if you are in opposition to the established “truth”.

The Cloud Mystery (52-minutes) was co-produced with Arte France and has been distributed for broadcasting to eleven countries: Denmark, Norway, Sweden, Finland, France, Germany, Italy, Belgium, Spain, Israel and Iran. Efforts to place it with a UK broadcaster have been unsuccessful so far.

Latest broadcasts: 2 April 2010 Germany ARTE 21:45 France ARTE 22:05

Buy The Cloud Mystery DVD

Preview clip

Some scenes in the film can be see on ClimateClips

The Cloud Mystery website http://thecloudmystery.coml

Mortensen Film website, with contact details

Mortensen’s ClimateClips



The Svensmark hypothesis in a nutshell

Illustration from Svensmark, “The Adventurous Journey of Spaceship Earth” DTU Yearbook 2009

  • Cosmic rays, high-energy particles raining down from exploded stars, knock electrons out of air molecules.
  • The electrons help clusters of sulphuric acid and water molecules to form, which can grow into cloud condensation nuclei – seeds on which water droplets form to make clouds.
  • Low clouds made with liquid water droplets cool the Earth’s surface.
  • Variations in the Sun’s magnetic activity alter the influx of cosmic rays to the Earth.
  • When the Sun is lazy, magnetically speaking, there are more cosmic rays and more low clouds, and the world is cooler.
  • When the Sun is active fewer cosmic rays reach the Earth and, with fewer low clouds, the world warms up.
  • The Sun became unusually active during the 20th Century and as a result “global warming” occurred.
  • Recently (2006-2010) the Sun has been unusually lazy and “global warming” seems to have gone into reverse, as expected by the Svensmark hypothesis.
  • Coolings and warmings of around 2 deg. C have occurred repeatedly over the past 10,000 years, as the Sun’s activity and the cosmic ray influx have varied.
  • Over many millions of year, much larger variations of up to 10 deg. C occur as the Sun and Earth, travelling through the Galaxy, visit regions with more or fewer exploding stars.

For objections to the Svensmark hypothesis and answers to them, see Falsification tests

Nigel Calder