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Cosmic Rays–Climate Link Found

December 19, 2017

By Paul Homewood


News of a new paper from Henrik Svensmark, which is a game changer in our understanding of how cosmic rays can influence cloud cover:


From GWPF:


The idea of a significant solar influence on climate change via cloud cover produced by cosmic rays has been proposed many times but it lacked conclusive experimental evidence as well as a detailed theoretical framework. Some have labelled the idea controversial with, at best, a weak effect. The principle is that cosmic rays – high-energy particles that traverse the galaxy from supernovae – knock electrons out of air molecules. This produces ions – electrically positive and negative molecules in the atmosphere. The ions help aerosols – clusters of mainly sulphuric acid and water molecules – to form and become stable against evaporation – a process is called nucleation. The problem was that small aerosols need to grow nearly a million times in mass in order to have an effect on cloud formation. Until now, it was not known how this could happen.

The theory is that variations in the Sun’s magnetic activity alters the influx of cosmic rays reaching the Earth. When solar activity is low more cosmic rays reach the earth forming 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.

Lead author Henrik Svensmark told the GWPF, “We have finally found the last piece of the puzzle of why cosmic rays make clouds. It was to prove that ions do in fact produce cloud condensation nuclei that are needed for making clouds. After four years of intense work we have cracked the problem and found the underlying mechanism.”

The new results reveal, both theoretically and experimentally, how interactions between ions and aerosols can accelerate the growth by adding material to the small aerosols and thereby help them survive to become cloud condensation nuclei.

Physical basis

According to Professor Svensmark it means that we now know why and how solar activity could be 5-7 times stronger than that estimated due to changes in the radiant output of the sun alone. It also explains why over geological times there has been much larger climate variations correlated with changes in cosmic rays. He adds that it also negates the idea that carbon dioxide has been controlling climate on these timescales. “It provides a physical basis to the large body of empirical evidence showing that Solar activity plays a role in variations in Earth’s climate,” he says.

For example, the Medieval Warm Period around year 1000 AD and the cold period in the Little Ice Age between 1300-1900 AD fits with changes in solar activity. As does the recent so-called pause in global surface temperature this century which occurs at a time of remarkably low solar activity. Professor Svensmark believes it also explains climate changes observed during the 20th century, as well as coolings and warmings of around 2 degrees C that have occurred repeatedly over the past 10,000 years, as the Sun’s activity and the cosmic ray influx have varied. The are also much larger variations of up to 10 degrees C that occur as the Sun and Earth travel through the Galaxy visiting regions with varying numbers of exploding stars.

To achieve the results a theoretical description of the interactions between ions and aerosols was formulated along with an expression for the growth rate of the aerosols. This was subsequently confirmed experimentally in a large cloud chamber.

“Finally we have the last piece of the puzzle explaining how particles from space affect climate on Earth. It gives an understanding of how changes caused by Solar activity or by supernova activity can change climate,” says Henrik Svensmark,

Co-authors are senior researcher Martin Bødker Enghoff (DTU Space), Professor Nir Shaviv (Hebrew University of Jerusalem), and Jacob Svensmark, (University of Copenhagen).

  1. December 19, 2017 11:52 am

    Just sent this to my brother, the nuclear physicist He also knows that man-caused global warming is bunk. Although a botanist, who gives physics and chemistry and math wide berth, I found the posting easy to follow.

  2. Jack Broughton permalink
    December 19, 2017 12:57 pm

    Was always a likely cause of cloud nucleation, but maybe this will cement the link between clouds and solar activity. The cloud cover has been historically low so far as I can tell over recent years (sunshine hours up etc), which tie in with the theory well.

    However, how do they know what the solar activity was hundreds of years ago???

    • dave permalink
      December 19, 2017 2:56 pm

      Sunspot data (which stands in for magnetic activity) goes back four hundred years. Naturally, it is always being retroactively ‘adjusted’ and generally ‘nobbled’ but one can ignore such silliness. Some of the postulated causes of variation (planetary orbits, gravitational shocks to the sun etc.) can be calculated, and compared with old weather records. There is also much proxy data for ‘cosmic weather’ in earth’s sediments. The whole subject is a work in progress, of course.

      This is a fairly recent review:

      Solar Cycle 25 should prove interesting – if I live to the end of it !

  3. Dung permalink
    December 19, 2017 1:30 pm

    I have long believed that Svensmark’s theories offered the best explanation of the (long held and now proven) theories about cosmic rays and cloud cover/climate. If you read his theories he predicts some interesting stuff ^.^
    Svensmark says that the earth is transitioning from a cosmic ray rich part of space into an area well clear of them (obviously this is over a long time period). According to Svensmark then, we are headed into a long period in which the sun’s activity will be diminished. What price global warming? hehe

    • Ben Vorlich permalink
      December 19, 2017 2:47 pm

      Is that due to the rotation of the Milky Way?

      • Dung permalink
        December 19, 2017 3:11 pm

        Svensmark’s explanations ‘seem’ to involve our sun traveling independently through the universe in and out of galaxies over its long life. I do not think that if we stay in the Milky Way we would ever be well away from cosmic rays.

  4. December 19, 2017 1:42 pm

    It also explains why over geological times there has been much larger climate variations correlated with changes in cosmic rays

    That seems to imply any variations would have to be measured over decades or longer.

  5. Ben Vorlich permalink
    December 19, 2017 2:46 pm

    Am I wrong in thinking that the Wilson Cloud Chamber gave a hint about cosmic rays (charged particles) over a century ago. If my memory from High School isn’t failing me, then Robert WIlson created his chamber to study cloud formation and the discovery cosmic radiation trails accidental.
    I’m aware that the process in the atmosphere will be different.

    • dave permalink
      December 19, 2017 7:23 pm

      The exciting work at that time was the investigation of the “granular” nature of electricity and thus of matter and the discovery that electrical conduction in gases was essentially electrolytic rather than metallic. A scientist called Townsend investigated clouds in saturated vapours subsequent to ionization by various rays. WILSON’S first major discovery was actually that a smaller expansion is required to make a cloud about negative ions than positive ions. Really, a race was on to measure the charge of the electron. It involved a huge advance in the sensitivity of instruments. Cosmic radiation was indeed a side-interest.

  6. George Let permalink
    December 19, 2017 3:23 pm

    Can solar activity be predicted with confidence? If so what will be happening?

  7. Richard Bell permalink
    December 19, 2017 4:01 pm

    I wonder what Jasper Kirkby at CERN will make of this paper ??? ……. Comments in the CLOUD please !!!

  8. Old Englander permalink
    December 19, 2017 4:27 pm

    In Svensmark’s cosmic ray model, over geological time one could see the solar system moving through different bits of the Milky Way (not different galaxies). Co-author Shaviv is the astrophysicist who has published on this.

    The press release makes clear this paper fills in a missing part of the jigsaw, which the stage beyond formation of tiny aerosols (which ionisation by cosmic rays can induce) but also the *growth* of such aerosols to the point where they can become cloud condensation nuclei: ” The second role of ions is that they accelerate the growth of the small aerosols into cloud condensation nuclei “. This was the stage that lacked a mechanism, leaving room for anyone to say the theory was conjecture. Fair enough: Svensmark has now plugged that gap.

    As for the cloud chamber, quite right it’s a century old, and nuclear physicists have been using it to observe high energy charged particles for as long as the subject has existed. This is why this work started out as an experiment at CERN. One has to assume they have lots of background in cloud chambers.

    • dave permalink
      December 20, 2017 7:33 am

      They use ‘wire chambers’ now.

  9. Jeff LeMieux permalink
    December 19, 2017 6:46 pm

    I’ve often wondered about variations in the interstellar medium and the inyensity of cosmic ray radiation as the solar system moves at 40,000 mph toward Cygnus.

    • dave permalink
      December 20, 2017 7:55 am

      Since super novas are a major source of cosmic rays, the connection involves the sun occasionally moving through active star-forming clusters (where SNs occur), for these clusters are not evenly distributed through our galaxy. The statistical exposure to cosmic ray “major incidents” is therefore something which fluctuates on a scale of millions of years. Interesting for the long term history of the solar system but not the main point of the recent paper.

  10. December 19, 2017 7:14 pm

    Well, this has been proposed before. And again. And again. And thoroughly debunked every time.

    Nothing to see here.

    • George Let permalink
      December 20, 2017 8:25 pm

      tyy, do you say man-made climate change has been proven?

  11. Don B permalink
    December 19, 2017 7:25 pm

    The late Nigel Calder was the co-author with Henrik Svensmark of “The Chilling Stars, a cosmic view of climate change” which describes the theories in a readable manner.

    Calder’s blog had many posts on this subject.

  12. December 19, 2017 7:30 pm

    Color me unconvinced for two reasons: SN1054 aftermath disproved the climate connection even if Svensmarkmis right about the mechanism, and there are many other CCN sources independent of the mechanism. Posted a longish comment with details at WUWT.

  13. tom0mason permalink
    December 19, 2017 9:11 pm

    Svensmark, J.; Enghoff, Martin Andreas Bødker; Shaviv, N. J.; Svensmark, Henrik full paper is available at —

  14. Malcolm Bell permalink
    December 20, 2017 8:04 am

    At last – I have long looked forward to the Solar actuvity connection being demonstrated theoretically. Hooray.

    Thank you, thank you Professor Svensmark.

    I bet it takes decades before he gets his Nobel prize. I hope not.

  15. Bitter&twisted permalink
    December 20, 2017 3:01 pm

    Green religious dogma is looking more and more like a “god of the gaps” scenario.
    Each new scientific understanding diminishes the role of CO2 in climate change.

    • A C Osborn permalink
      December 20, 2017 5:25 pm

      You should take a look at the Graph post by Leif Svalgaard of Cloud vs Temps over at WUWT, CO2 should be so lucky to have such correlation (reverse actually but you will see what I mean).
      He and the usual suspect are doing their best to rubbish the paper.

  16. kaykiser permalink
    December 20, 2017 3:37 pm

    Reblogged this on Science is distorted by progressive philosophy.

  17. an Cunningham permalink
    December 21, 2017 11:11 am

    ……anyone heard this reported on the bbc??…….

  18. Rudolph Hucker permalink
    December 24, 2017 6:40 pm

    This will not appear on the BBC TV or Radio, as they think their climate ‘experts’ are infallible!!

  19. David permalink
    December 25, 2017 4:46 pm

    But I thought the science was settled.

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