Evidence of nearby supernovae affecting life on Earth

by Judith Curry

A very provocative paper by Henrik Svensmark has been published today by the Royal Astronomical Society.

Evidence of nearby supernovae affecting life on Earth

Henrik Svensmark

Abstract. Observations of open star clusters in the solar neighborhood are used to calculate local super- nova (SN) rates for the past 510 million years (Myr). Peaks in the SN rates match passages of the Sun through periods of locally increased cluster formation which could be caused by spiral arms of the Galaxy. A statistical analysis indicates that the Solar System has experi- enced many large short-term increases in the flux of Galactic cosmic rays (GCR) from nearby supernovae. The hypothesis that a high GCR flux should coincide with cold conditions on the Earth is borne out by comparing the general geological record of climate over the past 510 million years with the fluctuating local SN rates. Surprisingly a simple combination of tectonics (long-term changes in sea level) and astrophysical activity (SN rates) largely ac- counts for the observed variations in marine biodiversity over the past 510 Myr. An inverse correspondence between SN rates and carbon dioxide (CO2) levels is discussed in terms of a possible drawdown of CO2 by enhanced bioproductivity in oceans that are better fertilized in cold conditions – a hypothesis that is not contradicted by data on the relative abundance of the heavy isotope of carbon, 13C.

Full text available online [here].

The paper is long and dense (i.e. not an easy read).  The press release by the Royal Astronomical Society summarizes the article, some excerpts:

When the most massive stars exhaust their available fuel and reach the end of their lives, they explode as supernovae, tremendously powerful explosions that are briefly brighter than an entire galaxy of normal stars. The remnants of these dramatic events also release vast numbers of high-energy charged particles known as galactic cosmic rays (GCR). If a supernova is close enough to the Solar System, the enhanced GCR levels can have a direct impact on the atmosphere of the Earth.

Prof. Svensmark looked back through 500 million years of geological and astronomical data and considered the proximity of the Sun to supernovae as it moves around our Galaxy, the Milky Way. In particular, when the Sun is passing through the spiral arms of the Milky Way, it encounters newly forming clusters of stars. These so-called open clusters, which disperse over time, have a range of ages and sizes and will have started with a small proportion of stars massive enough to explode as supernovae. From the data on open clusters, Prof. Svensmark was able to deduce how the rate at which supernovae exploded near the Solar System varied over time.

Comparing this with the geological record, he found that the changing frequency of nearby supernovae seems to have strongly shaped the conditions for life on Earth. Whenever the Sun and its planets have visited regions of enhanced star formation in the Milky Way Galaxy, where exploding stars are most common, life has prospered. 

In the new work, the diversity of life over the last 500 million years seems remarkably well explained by tectonics affecting the sea-level together with variations in the supernova rate, and virtually nothing else. To obtain this result on the variety of life, or biodiversity, he followed the changing fortunes of the best-recorded fossils. These are from invertebrate animals in the sea, such as shrimps and octopuses, or the extinct trilobites and ammonites.

They tended to be richest in their variety when continents were drifting apart and sea levels were high and less varied when the land masses gathered 250 million years ago into the supercontinent called Pangaea and the sea-level was lower. But this geophysical effect was not the whole story. When it is removed from the record of biodiversity, what remains corresponds closely to the changing rate of nearby stellar explosions, with the variety of life being greatest when supernovae are plentiful. A likely reason, according to Prof. Svensmark, is that the cold climate associated with high supernova rates brings a greater variety of habitats between polar and equatorial regions, while the associated stresses of life prevent the ecosystems becoming too set in their ways.

He also notices that most geological periods seem to begin and end with either an upturn or a downturn in the supernova rate. The changes in typical species that define a period, in the transition from one to the next, could then be the result of a major change in the astrophysical environment.

Life’s prosperity, or global bioproductivity, can be tracked by the amount of carbon dioxide in the air at various times in the past as set out in the geological record. When supernova rates were high, carbon dioxide was scarce, suggesting that flourishing microbial and plant life in the oceans consumed it greedily to grow. Support for this idea comes from the fact that microbes and plants dislike carbon dioxide molecules that contain a heavy form of carbon atom, carbon-13. As a result, the ocean water is left enriched by carbon-13. The geological evidence shows high carbon-13 when supernovae were commonest – again pointing to high productivity. As to why this should be, Prof. Svensmark notes that growth is limited by available nutrients, especially phosphorus and nitrogen, and that cold conditions favour the recycling of the nutrients by vigorously mixing the oceans.

Although the new analysis suggests, perhaps surprisingly, that supernovae are on the whole good for life, high supernova rates can bring the cold and changeable climate of prolonged glacial episodes. And they can have nasty shocks in store. Geoscientists have long been puzzled by many relatively brief falls in sea-level by 25 metres or more that show up in seismic soundings as eroded beaches. Prof. Svensmark finds that they are what can be expected when chilling due to very close supernovae causes short-lived glacial episodes. With frozen water temporarily bottled up on land, the sea-level drops.

The data also support the idea of a long-term link between cosmic rays and climate, with these climatic changes underlying the biological effects. And compared with the temperature variations seen on short timescales as a consequence of the Sun’s influence on the influx of cosmic rays, the heating and cooling of the Earth due to cosmic rays varying with the prevailing supernova rate have been far larger.

WUWT has a post on this with some explanations of the basic underlying science by  Liz Calder.

JC comment:  I haven’t had time to go through this in detail, but this is definitely a mind bending paper.  The implications of this research, if correct, are extremely far reaching.  The paper is getting a lot of press, but I haven’t seen much in the way of detailed critique (although Leif Svalgaard makes some comments on the WUWT thread).  It will be very interesting to see how the science establishment reacts to this paper and how this line of research plays out.

148 responses to “Evidence of nearby supernovae affecting life on Earth

  1. Oh yeah. I think I saw that episode of Star Trek.

  2. Last week there was a paper in Nature that indicated cosmic rays were more likely derived from black holes than super novas. Unfortunate timing for Svensmark.

    • The new paper in nature is about very high energy cosmic rays

      which is not what Svensmark’s paper is about

    • Albert Stienstra

      The cosmic rays from black holes consist of particles with energies of 10E18 – 10E20 eV. The flux density on earth is no more than 1-2 particles per square km per year. This is totally different from the cosmic rays originating from Super Novae with energies around 10E9 eV and flux densities of thousands of particles per square km per year. The Nature article from your link is behind a paywall and I do not believe articles from Nature are worth paying for. SInce you say the article claims or indicates that cosmic rays originate from black holes I feel quite strengthened in my opinion of Nature. Svensmark has nothing to fear from that publication.

    • Wasn’t that on ultra high energy cosmic ray particles? The bulk of cosmic rays are not that energized.

    • That was about the very highest energy range of cosmic rays, which were theorized to be generated by the largest gamma ray burst explosions (which most super novae do NOT produce!). That new paper is remarkable as now it seems those enigmatic super gamma ray explosions do not create high energy cosmic rays as one would think explosions of that magnitude would. That means, the nature of those explosions are still not well understood.

  3. Willis Eschenbach

    Svensmark’s paper depends on a complex model of supernova formation over the last half billion years.

    Unfortunately, the best available models say there should be a supernova about every thirty years in the Milky Way … but we have seen neither the supernovas (which might have been obscured by dust) nor their remnants (which should be very visible in x-ray frequencies). No one knows why the models have failed so badly.

    And since we can’t hindcast the recent supernova production in the Milky Way for a couple thousand years, thinking we can hindcast it for half a billion years seems … well, let me call it “unlikely” in lieu of a more earthy word.


    • I’m no scientist and I respect your opinions WIllis, but I can’t help thinking that with all the work professor Svensmark put into what seems a major paper that will undoubtedly have important implications for his reputation down the line, it’s quite likely that he’s got this covered.

      • Yet thousands of people believe that Drs Mann, Hansen, Jones, Briffa, etc are soooo wrong

      • Bruce Cunningham

        The dubious and unethical workings of Mann, Jones, and Hansen have been openly and expertly exposed for several years now, and should be obvious to even the densest of dolts. That you are defending them is outright laughable.

      • Svensmark could be smeared just as easily

      • lolwot – You only wish Svensmark could be smeared. He would have to exhibit bad behavior first, like some of the notorious climate scientists have.

      • lolwot cracks the whip, and thrills inside.

      • lolwot, you have some Svensmark e-mails you want to share?

      • There are potentially some similarities between Mann’s work and Svensmark’s, yes? Each putting out ground-shacking papers putting forth new ideas, but that may hinge on some questionable data and/or modeling– though because of the nature of the conclusions they are published anyway. In Mann’s case, future studies conducted more robustly and more ‘correctly’ appear to confirm some of his broad-brush initial theories… but he takes it as a license to say his original work was perfect, glorious, and unassailable. Does making such a leap manifest high scientific research standards?

        Perhaps Svensmark can be given the same license with his forays down these particular research roads?

      • When and if Svensmark is demonstrated to behave as Mann, Hansen, Jones, Briffa, etc. I will change my opinion of him to match that of Mann, Hansen, Jones, Briffa, etc.

      • Precisely, Hunter.

      • Svensmark’s paper is about separating infants from the toddlers. He knows how to insult human intelligence. Anybody ”genuinely” believing in that doo-doo, wouldn’t pass the psychiatric test, Supernova explosion influences the climate on earth; as much as when Al Gore farts. Fortunately, supernova explosion affects less nutter’s brains than Al’s farts, because of the proximity; their noses are into Al’s… Nutters from both camps; being too close behind Al – they can’t see the reality. Thanks Mr. Svensmark, for helping the nutters to sort themselves out. Next week make a paper how the other parallel universe is affecting climate. Mushrooms need regular food supply.

    • John Robertson

      Not that I know much at all about astronomy, but a casual read of the first couple of pages suggests that the author is using the approximate creation date of open star clusters to fix the time of the originating supernovas (those that were creating the aforementioned clusters). Is that what you are referring to when you speak of ‘the best available models’? It doesn’t appear to match what I am reading. Can you clear that up a bit for me?

      • See Bruce, already here we have an opening to claim svensmark is BSing. This is all it takes. it starts off by finding “problems” we can’t understand and using those to ridicule the scientists.

        Hey maybe its fraud?

      • lolwot,
        That is a very mediocre try on your part to avoid the issue. But it is the best you got. You are sort of like a wannabe corner preacher who does not know preaching, the Bible, or theology, but you do know how to shout.

      • The issue here is how deniers smear any scientist who says something they don’t like. If svensmark wasn’t favored by them they’d be crawling all over the paper looking for any old trite reason to dismiss it. Then they would point the fraud finger aT him.

    • And yet, after a quick read, I note that Cassiopeia A (Cas A) is the “brightest extrasolar radio source in the sky” yet no one saw it …

      “It is believed that first light from the stellar explosion reached Earth approximately 300 years ago but there are no historical records of any sightings of the progenitor supernova, probably due to interstellar dust absorbing optical wavelength radiation before it reached Earth (although it is possible that it was recorded as a sixth magnitude star 3 Cassiopeiae by John Flamsteed on August 16, 1680[5]). Possible explanations lean toward the idea that the source star was unusually massive and had previously ejected much of its outer layers. These outer layers would have cloaked the star and reabsorbed much of the light released as the inner star collapsed.”


    • David Springer

      So now the carpenter is moonlighting as a cosmologist.


      You’re a moron, Eschenbach.

  4. So, are global warming alarmist positively giddy about the possible mass extinction of all humanity — even if due to natural causes — if it gives the Earth a chance to recover from our polluting influence?

    • Oddly, I haven’t noticed a great deal of overlap between climatology and ‘redemptive eschatology’ (http://en.wikipedia.org/wiki/Eschatology).

      By and large, the ones who forecast a hard time for humanity appear to genuinely think it’ll be a bad thing, if they show the least competency in climate science at all.

      That’s not to say a great number of ‘ecstatic apocalyptics’ don’t embrace whatever ‘sign from the Beyond’ du jour they come across. My personal favorite is the Douglas Adams’ version involving a goat and a handkerchief. But whether it’s because climate change is too slow or too complicated or has too much hard math for their liking, they don’t seem to be piling on the climate change theme nearly as much as, say, alien invasions, exploding stars, or earthquakes.

      Do you have any insight into why this is?

  5. Dr. C, I’d be interested in your comment if you care to give one, concerning this quote by Calder I believe:

    “… Svensmark stands the currently popular carbon dioxide story on its head. Some geoscientists want to blame the drastic alternations of hot and icy conditions during the past 500 million years on increases and decreases in carbon dioxide, which they explain in intricate ways. For Svensmark, the changes driven by the stars govern the amount of carbon dioxide in the air. Climate and life control CO2, not the other way around.”

  6. Is the paper saying that the best conditions for bio-diversity are correlated with cold conditions and low carbon dioxide?

    I always thought that plants liked more carbon dioxide and warmer conditions. Presumably, animals thrive better when there is lots of plant life to eat. What am I missing here?

    • Thinking about moving from the iceball to the middle of the more nutrient-rich ocean during the next ice age where phosphorus and nitrogen are more plentiful?

    • Sheer biomass and diversity are different. A monolithic period of warmth and growth is opposed, it seems, to the trying and evolutionarily innovative chillin’s.

      • That which causes the chillin’ is that which leads to diversity: galactic cosmic rays, tra la. Variations in marine biodiversity is not synonymous with the long and happy life of a species. But where there is challenge there is opportunity–e.g.,

        “Between the Dalton Minimum and the Maunder Minimum December 1776 was a desperate time for George Washington and the American Revolution. During the night of December 25, Washington led his small Continental army of 2,400 troops from Pennsylvania across the Delaware River made dangerous and barely navigable by huge chunks of ice. Once across they launched a surprise attack on the Britain’s Hessian mercenaries at Trenton, New Jersey, capturing 1,000 prisoners and seizing muskets, powder, and artillery. [Sources: George Washington crossing the Delaware River by Leutze, Washington’s crossing of the Delaware River]” ~James A. Marusek, “There are two paths ahead; each marked with a ‘Danger’ signpost,” 2 April 2009

    • The photosynthizers in the ocean would have more CO2 because cold water can hold more CO2 than warm.

  7. A strange feeling came over me as I felt quite isolated; we are alone. In all the vastness, for just a moment, cosmic forces have come together. In shape we stand upon a rock, substances derived from collapsing stars, flickered to life by distant energy and our destiny we can see.

  8. All I have to say is, when all you have is a hammer, everything looks like a nail.

    • Steven Mosher

      More than that. I love the way people assume that just because GCR might cool the planet that C02 does not and cannot warm it

      Its as if upon discovering that a car has a brake they argue that pressing on the gas cannot make the car go faster.

      • Very few make that claim. Especially if framed as the brake metaphor. The interesting question is as always how much warming was the result of other factors – and where natural variability is heading in the near future. Oh wow – it’s like discovering that you have a hybrid drive and can run on both electricity and petrol to. If we are into simplistic metaphors.

      • Steven Mosher

        Look no further than this thread or wuwt to see how few people get that WHATEVER the truth about GCR is, it has nothing to do with the subject of how C02 warming the planet. Nothing.

      • Oh Steven,

        I am agnositic on GCR – especially the 500 million year supernova variety. It is all fun but how well can anything over that scale be known.

        The question with recent warming is how much was natural variability and whence is it heading. Most of recent warming was greenhouse gases? That isn’t what you would expect from ocean variability – and isn’t what the satellite data shows. Warming continue at 0.2 degrees C/decade? It wasn’t warming at that rate when ocean variability is removed – it isn’t now and won’t for a decade or three.

      • Rob

        When you say “a decade or three”, how about “two”?

      • Steven,
        But cosmic rays, if they do impact cloud formation, would impact an important feedback/control mechanism of the cliamte as a whole.

      • Steven Mosher

        hunter, wrong.

      • Moshe, see Kanute. Chanute, too, WTH.

      • Your radiative effect may be a sandcastle @ the seaside.

      • Lay back, and think of getting a tan.

      • John Costigane


        Cnut and Boudicca, British history without the Roman influence.

      • Paul Vaughan

        @Steven Mosher | April 25, 2012 at 4:30 am |

        Your “central question” (posed in the parallel wuwt thread) is YOUR central question. Maybe there’s a thread idea here – i.e. ask everyone “What’s your central question?”. Mine: What can we learn about nature by exploring? My suspicion about many others (although I doubt they will admit it, if they are even aware of it): How can I sway votes to my political party? If there was some way to vanish the political dimension of the discussion, it would be orders of magnitude more efficient & healthy.

      • A. C. Osborn

        Steven, calling CERN scientists liars as well I see.

      • David Springer

        You and Eschenbach should get a room.

        Padded, preferably.

        The carpenter cosmologist and the one trick pony. Make sure they allow pets.

      • “I am agnositic on GCR – especially the 500 million year supernova variety. It is all fun but how well can anything over that scale be known. ”

        Sol has a 225 to 250 million year galactic year:

        “The galactic year, also known as a cosmic year, is the duration of time required for the Solar System to orbit once around the center of the Milky Way Galaxy. Estimates of the length of one orbit range from 225 to 250 million “terrestrial” years”

        A guess could be that we line up with some massive galactic object in which it takes about 2 our galactic years to line up with it . That galactic object has a has something like a galactic year of 168 to 187 million years [we are 25% slower than it is]. Or whatever velocity so that in a galactic year after being nearest to it, it’s on opposite side of galaxy from us.
        Or it’s on highly elliptical galactic orbit which come near earth every second orbit

    • Hector Pascal

      If you have no imagination, and no talent, then armed with a hammer, everything may look like a nail.

      Michelangelo managed to make this with a hammer. I guess he is more imaginative and more talented than you.

      • Mango Chutney

        Michelangelo hit the nail on the head with his hammer

        (but I know what you mean)

  9. So here is more that we don’t know about important natural climate influences ….

    I am once again reminded of F. A. Hayek’s Nobel lecture, ‘The Fatal Conceit’ (another essay: ‘The Pretense of Knowledge’) that warns against social scientists who think they know so much that they can model and plan. Climate planners are like the economic central planners of old in this regard.

  10. Its an interesting hypothesis. It will need some careful researching and testing. I look forward to seeing every ones perspectives on this as it is way out of my field of expertise.

  11. Hey Jude
    What happens when the cosmic rays meet the solar wind and is there any effect on the output of the sun?
    Sorry if these are stupid questions but no doubt you won’t be surprised considering the source

  12. Svensmark may be correct in his conclusion that a two parameter model, tectonics and supernovae, can directly explain the fluctuation of life on earth and, indirectly, levels of CO2 and climate but I’m not convinced he has proved it. The word ‘assume’ (and derivatives) appears in his paper 20 times along with 6 ‘approximates’, 6 ‘likelies’ and 15 ‘hypotheses’. If you select two parameters out of, say, 20 possibilities (or, what amounts to the same thing, two data representations out of 20) you have greatly increased the degrees of freedom in your model. Svensmark’s key figure (number 20), which purports to show a link between supernova rates and marine genera, has about 5 pairs of peaks and troughs. To represent 5 events with a model which has 20 degrees of freedom is no big deal.

    I’m also wondering what has happened to his previous theory, that there is a strong negative correlation between sunspots and cosmic radiation reaching earth (true) and that this effects the climate by varying the level of cloudiness (still unproven).

    • Could the two theories not work in conjunction, or are we only allowed to have a CO2 theory of warming and nothing else?
      Maybe some of the commentators here are afraid that someone else’s theory is going to be bigger and better than theirs and possibly threaten the big green funding machine?

  13. Students of history find much in Svensmark’s article to reflect upon. The American Institute of Physics (AIP) hosts a fine website on the history of climate change science, and we see find the methodology of Svensmark’s analysis belongs to a large class of dubiously successful statistics-driven analyses whose history the AIP describes in “Changing Sun, Changing Climate?” (a Google search for this phrase will find it).

    Willis Eschenbach has been doing a good job of demonstrating that Svensmark’s analysis repeats these earlier mistakes; for this public service Willis deserves our thanks.

    Striking too is the intense publicity that Svensmark’s article is receiving. Students of history recognize a repetition of previous patterns of behavior, of which well-documented examples can be found on PUBMED, including “Turning free speech into corporate speech: Philip Morris’ efforts to influence U.S. and European journalists regarding the U.S. EPA report on secondhand smoke..”

    Prediction: Svensmark’s article will be spotlighted next month at the Heartland Institute’s Seventh International Conference on Climate Change (ICCC-7), and this spotlighting will further the corporate objectives of Heartland Institute donors.

    • Students of history think your claims are superficial at best, Joy.

      • Here is the AIP link: http://www.aip.org/history/climate/solar.htm

        This analysis is obviously one sided. But it is at least scientific, unlike your little diatribe.

      • Thank you, David, for providing that link to the AIP’s outstanding “Changing Sun, Changing Climate?” web site — no doubt many Climate Etc. readers will find its historical perspective to be instructive.

        The American Journal of Public Health provides a similarly instructive historical survey in “Tobacco industry efforts to undermine policy-relevant research” … it is interesting that several participants in the climate-change debate — including recent fervent advocates of Svensmark’s research — have direct or indirect ties to these earlier tobacco industry efforts … and so the history of these corporate efforts repays close study.

      • Joy, not that it matters but the ties you refer to are primarily related to the second hand smoke debate, where skepticism is proper. But if you are making the argument that climate skepticism is some sort of evil industry funded disinformation campaign then you are wasting our time. Most skebptics get no funding. Those who are lucky enough to get some, including me, strongly support industry’s attempts to defeat the green menace that threatens us all.

        As for the AIP site, as I said it is completely one sided, hence historically useless. The sun-climate debate is far from over. It is sad to see AIP take this anti-science line.

      • David, a fans of history will recall a previous Svensmark cosmic-ray kerfuffle that Anthony Watt’s WUWT page of September 10, 2009 documents, in an article (by Anthony) titled “Svensmark: “global warming stopped and a cooling is beginning – enjoy global warming while it lasts

        There followed a dip in sea-level rise rates &mash; much to the excitement of Svensmark’s supporters! &mash; and yet the sea-level rise observed in 2012 has quietly reverted to the accelerating trend-line … which is contrary to the predictions of any of Svensmark’s cosmic-ray theories.

        That is why it appears (to me) that with this latest cosmic-ray theory of Svensmark’s, history is simply repeating itself.

      • Joy

        I have no feelings either way at present on the cosmic ray theory, other than observing that our current state of knowledge of the climate is very limited and cosmic rays may or may not be an important component factor.

        However you are wrong on the sea level rise. It has stumbled several times in recent years including from 2010.


        If you go to Proudman or one of the other sea level organisations you will see that sea level is falling in some places. All this has to be untangled from changes in the adjoining land level of course, which is often of a greater order than is the sea level rise itself, as I described in my article that contained the Doggerland reference. That article also looked at sea level rise vis a vis today compared to Roman times along the south coast of England.

        Contrary to your earlier comments calculating sea levels are highly complex if satellites rather than tide gauges are used (which they are in ‘official’ circles)


      • David Wojick

        What history is repeating itself, Joy? Tobacco history or scientific history? You started off making some nasty claims so it is not clear what point you are now making. Science is a matter of trial and error, conjecture and refutation, and research on the sun-climate link has a long history indeed. Are you now claiming that such research is pointless, that there is only a minor direct energy link, as the IPCC and AIP seem to claim? Or are you saying Svensmark is dishonest, or what?

        I think the sun-climate question is very much alive, and so do many others, including scientists. If you are claiming the science is settled you are making a very strong claim indeed.

      • Climatereason, readers of Climate Etc. are invited to visit the CU Sea Level site that you link, and download the 2012 sea-level rise data — which the website provides, but does not yet plot — and verify for themselves that 2012 sea-levels have reverted to the rising trend-line … which is precisely opposite to Svensmark’s 2009 prediction “cooling is beginning.”

        These observations indicate that — directly contrary to Svensmark’s cosmic-ray prediction — the Earth’s energy budget is presently in a state of persistent warming imbalance.

      • Joy

        Here is the same data with the seasonal figure retained. (the previous ones were with them removed) You’re surely not just computing 2012 figures to date i.e Jan to April?


        By the way you might find it interesting to research the accuracy of the satellites.


      • Yes David, history *is* repeating itself (let’s face it!).

        Namely, patterns of tobacco industry opposition to scientific research showing that smoking causes cancer, are being repeated by patterns of carbon-energy industry opposition to scientific research showing that CO2 causes climate change.

        So it’s not complicated. And it’s not even surprising.

      • Joy

        I will assume you are not conversant with sea level measurements and their history?

        The reconstruction by IPCC using 23 tide gauges from 1900 -only 2 from the SH- and which include only seven that haven’t permanently moved -but ALL of those subject to considerable development around them necessitating temporary removal or cessation-is a poor piece of work. The latest existed only from 1933. A couple predate 1900. Missing information is interpolated. To then stick inaccurate satellite altimetry on top and try to pass it off as a highly accurate measure of the recent past is nonsensical.

        The criteria and location of these gauges is shown here
        As an aside, Tide gauges (like thermometers) were never intended to be highly accurate and varied enormously until very recent years with no standardisation.
        Here is one example;

        Accurate to a fraction of an inch? I don’t think so, yet our entire sea level record is built on such as these.

        I would refer you to Chapter 5 of AR4 which mentions this controversy over satellites as a brief note


        Figure 5.13 on page 410 is the basis of many graphs used by Government and their agencies to promote scary sea level rises which are then eagerly picked up by the more sensationalist media and Al Gore.

        There is a ‘missing’ section-reproduced below- of this report which is not generally seen as it is tucked away after many pages of references; It is 5A


        It’s all worth reading-satellite inaccuracy is briefly mentioned but to keep on topic the tiny number of tidal gauges is shown as the very last graphs after 5A2 page 429

        There is nothing at all untoward with the rates of sea level rise.

      • David Wojick

        Joy, here is no comparison between the climate debate and tobacco industry resistance. The differences in scale are enormous. There are literally many millions of people debating the climate science, many of whom are skeptics and few of which have anything to do with the energy industry Moreover, the skeptics are right. These are fundamental differences..

      • David, please let me summarize your post’s three main points:

        • The carbon-energy industry is huge.
        • It’s hard to imagine an alternative energy economy.
        • Therefore AGW cannot be real.

        Hmmm … these arguments aren’t all that strong.

      • A. C. Osborn

        Is this person real, or a clone of the trolls that were on this forum last year.
        Just repeating the same thing over and over.

      • >>Joy Black | April 25, 2012 at 12:01 pm |

        David, please let me summarize your post’s three main points:

        • The carbon-energy industry is huge.
        • It’s hard to imagine an alternative energy economy.
        • Therefore AGW cannot be real.

        Hmmm … these arguments aren’t all that strong.<<

        Sniff, sniff, sniff. Do I smell straw? Do you smell straw? I'm pretty sure I smell straw.

      • David Wojick

        Joy, my points bear no resemblance to your summary of them. I judge therefore that you are not here for a serious discussion, which requires trying to understand the person you are talking to. It is not the industry that is huge, but the debate, which dwarfs the industry.

    • ceteris non paribus


      Could you be less historical about Svensmark?

      Don’t you recognize a Galileo-of-the-month when Anthony and Judy show you one?

      Please – take the high moral ground, be more science-y, and strongly support industry’s attempts to defeat the green menace that threatens us all.

    • David Springer

      Willis Eschenbach hasn’t done a good job at anything in his life. He hasn’t stuck with any job very long and just wanders around through life from one bungle to another with hardly a pot to piss in. Spare me.

  14. Alfred Wegener had the same reaction with his ‘continental drift’ theory.

  15. To me, the importance of papers like this one from Henrik Svensmark, is that they show that there are reasons to believe that the earth’s climate might be dominated by extraterrestrial effects. The IPCC’s ideas on CAGW are based, in part, on the assumption that extraterrestrial effects have a negligible effect on climate. That the only extraterrestrial effect is a slight change in the solar constant. It is that assumption that has always convinced me that the IPCC’s ideas are almost certainly wrong.

    Will this paper from Svensmark be considered in the AR5?

    • David Wojick

      It will probably be considered, but dismissed, as usual with the indirect sun-climate research literature.

    • “The IPCC’s ideas on CAGW are based, in part, on the assumption that extraterrestrial effects have a negligible effect on climate.”

      That’s not assumption, that’s what is currently known. The IPCC reports lay out what is currently known, they can’t do anything but.

      Besides the estimation of warming from a doubling CO2 is independent from whatever extraterrestrial effects there are.

      “That the only extraterrestrial effect is a slight change in the solar constant. It is that assumption that has always convinced me that the IPCC’s ideas are almost certainly wrong.”

      Aren’t you the one assuming here? You are assuming there must be some bigger extraterrestrial effect than TSI changes.

  16. An interesting paper. Certainly, something that attempts to explain climate variation and those as yet unexplained bursts of biodiversity, based on a plausible theory and data rather than computer models, makes a refreshing change. If it checks out, and only time and further research will tell, it’ll have an explosive effect on a range of disciplines.


    • Paul Vaughan

      Corbyn has weighed in (in the parallel wuwt thread):

      “Citizens, Svensmark is a good guy but his theory does not work and he will become a fall guy for the CO2 warmists: “AAh you are wrong so it must be CO2″.”

      “It elevates proxies to a causal role. GCR is a proxy for solar scalar magnetic activity. Increases in GCR sources (supernovae) are a proxy for dust which also causes solar dimming.”

      Corbyn cautions us further in a detailed comment (“Posted by Piers Corbyn (Twitter) on Apr 24th 2012, 7:54 PM EDT”) volunteered under this article: http://climaterealists.com/?id=9491


      • Since when has corbyn been an expert. Sorry but if Corbyn is saying Svensmark is wrong I am almost considering maybe Svensmark is right.

      • Paul Vaughan

        Statistical paradox. Dead simple but impossible or almost impossible for many people to understand. My experience teaching Stat 101 for years was that even bright students achieve only fleeting awareness of paradox. It’s a VERY rare individual who is PREEMPTIVELY, watchfully on alert for it.

        Spatiotemporal pattern is a function of aggregation criteria. It’s a rare individual in the climate discussion who realizes this. I can name only 2 people: Piers Corbyn & Tomas Milanovic. There may be others. If they exist, I’ve not seen them commenting or publishing.

        Too much is riding on the abilities of too few.

      • Paul, we are in a (long) warm period. That mean GCRs are weak. So Peirs could be right and wrong. Right because other charged particles dominate now. But in a cool period, couldn’t SN GCRs dominate? Honest question. No trap.

      • Let’s consider a Galactic Triode. The incoming (GCRs/solar) charged particles are analogous to the electrons streaming from the filament to the plate in the tube. The grid is analogous to the Solar magnetic field. A low SN region is analogous to a low plate voltage. The high SN region is analogous to a high plate voltage. The magnetic field effect will be relatively constant over the longer periods under consideration, say 1,000 years. For adjacent periods of 1,000 years, the Solar magnetic field effect will be about the same. So, if the plate voltage is increased, higher SN events, the charged particle current will increase also. So while the grid voltage modulates the current, a varying plate voltage will do so as well. For long periods, the Galactic grid will exert a constant effect, so any long term variations would have to be due to varying quantities of extraterrestrial radiation.

      • NeedleFactory

        Spatiotemporal pattern is a function of aggregation criteria.
        I’m curious; a reference or two would be appreciated.

    • Hi Paul. It seems to me we now have a three-cornered dispute as to what exactly drives climate; GCR, the sun or CO2. Certainly, I was never convinced that it was CO2, which leaves the other two putative candidates, either of which or both of which might eventually prove to be wrong as well.

      I look forward to following the debate between Swensmark and Corbyn, especially since I know it will be spirited but civilized. It’s not an area I have a particular expertise in but on an intuitive basis, if I had to pick between the two, I’d lean more towards Swensmark, if only because he casts the earth and the solar system into the larger context of the Milky Way, where the titanic energies, dwarf anything our sun can put out, close though it is.

      Both of their theories are potentially paridigm changes, so a big debate is inevitable. Enjoy.

      As for a failure of the Swensmark theory, somehow being used to validate the CO2 explanation, I think that’s a reach.


      • The CO2/Temp chart presented by Al Gore shows that temperatures rise first, followed by a rise in CO2. That fits Svensmark’s theory. Warmists have recently been trying to revise that inconvenient truth, but no one’s buying it. (Just like they tried to revise away the MWP.)

      • Hi Jim2, I think “Honest” Al’s chart had the CO2 leading rather than following temperature rises, but I know what you mean.


      • I think you have it backwards, PM. Temperature rises, then later CO2 rises.

      • The sequence of events during Termination III suggests that the CO2 increase lagged Antarctic deglacial warming by 800 – 200 years and preceded the Northern Hemisphere deglaciation.


      • And here:

        The direction of the causal relationship can be shown in many ways: for example, it is not just CO₂ but other gases such as methane that follow temperature. The hypothesis of CO₂ as the primary reason wouldn’t explain why these other gases are correlated, too. Also, we understand how oceans react to temperature changes by releasing gases. Finally, the gas concentrations lag behind the temperature by 800 years, see e.g. this 2003 paper in Science by Caillon et al.


      • And Lubos also has this:
        19,000-17,000 years ago: deep sea temperatures increased by 2 Celsius degrees or so
        1,000 years later: CO₂ increases


      • “That fits Svensmark’s theory.”

        Uh no it doesn’t. It does fit what climate scientists expect though.

      • And it does fit Svensmark’s theory.

      • Sometimes, you just gotta walk away. Van da Man.



      • You got nothin’ PM.

      • Paul Vaughan

        Quite the contrary. Pointman understands human nature. It’s natural for people to fear what they don’t understand:


        “I’m criticized but all your bullets ricochet
        Shoot me down, but I get up

        Cut me down
        But it’s you who have further to fall

        I’m bulletproof, nothing to lose – fire away, fire away
        Ricochet, you take your aim – fire away, fire away
        You shoot me down but I won’t fall”

        — David Guetta featuring Sia – Titanium


        Le Mouël, J.-L.; Blanter, E.; Shnirman, M.; & Courtillot, V. (2010). Solar forcing of the semi-annual variation of length-of-day. Geophysical Research Letters 37, L15307. doi:10.1029/2010GL043185.

        Short of data vandalism of an unconscionable nature, their seminal finding – which demands paradigm shift – is indestructible.

      • “Hi Paul. It seems to me we now have a three-cornered dispute as to what exactly drives climate; GCR, the sun or CO2. Certainly, I was never convinced that it was CO2, which leaves the other two putative candidates, either of which or both of which might eventually prove to be wrong as well.”

        Of course driving climate, doesn’t have to mean getting warmer,
        it seems to me one should need to answer why the Little Ice Age was cooler.
        Obviously cooling of the climate is something that drives climate.
        And of course there no need for warming or cooling to drive climate- changes in wind patterns, changes in vegetation, volcanos, and simply the duration at certain temperature can change climate.
        Climate is and always has been changing, if climate were to stop changing that could more frightening [or simply weird] then compared our “normal world” with it’s constantly changing climate.

      • Hello gbaikie, I think it’s the ignorant idea that nothing should change which drives so much of the environmental movement.

        “We look at our world and the universe with human eyes and more importantly, with a human lifespan. In terms of the latter, we see an apparently ageless and unchanging view but it’s a false impression. When looked at through the eyes of “deep” time, it is dynamic, violent and forever changing. There is no ideal static harmonious state which must be maintained. There never was and there never will be either.”



      • Paul Vaughan

        In order to advance, the discussion needs less narrow obsession with ‘global temperature’ – as if it were a metric that spans the variable space of climate – and more focus on (1) temperature gradients and (2) hydrology.

        Precise Earth orientation data and good atmospheric angular momentum data exist. The data inform simply & clearly about global constraints on flow.

        Sensible discussion participants will need to (a) learn about the concept climatologists call “thermal wind” and (b) realize that temperature anomalies are at times paradoxical indicators of hydrology (which is a function of absolutes, not anomalies).

        Unfortunately, what one observes in these discussions is ignorance & intransigence.

        New arguments based on logical premises can be constructed, but we see contributors clinging to yesterday’s logically false arguments, which are based on cultural premises. One plus one does not equal three; for those who invest the time & effort needed to DEEPLY understand Le Mouël, Blanter, Shnirman, & Courtillot (2010), that’s a direct analogy.

        Alert, capable science historians might now find it informative to review with hindsight (20/20 hindsight IF they’ve carefully & thoroughly done their homework) what was considered the best available analysis & interpretation in 1994:

        Gross, R.S.; Marcus, S.L; Eubanks, T.M.; Dickey, J.O.; & Keppenne, C.L. (1994). Effect of climate change on seasonal length-of-day variations.

        “ACKNOWLEDGMENTS. The work of some of the authors (RSG, SLM, JOD, CLK) described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.”

        An amateur can see that they did NOT assess the sensitivity of parameter estimates to extent adjustments (which should NOT be confused with grain adjustments).

        [ For those unfamiliar with grain & extent, here’s an animation illustrating varying extent with grain held constant (at 11 years):
        http://i41.tinypic.com/bgwmmf.gif ]

        It’s natural. People overlook simple things. Sometimes those simple things are tremendously important and are pointed out by careful auditors. This isn’t about issuing blame. It’s about correcting errors and moving forward with EYES OPEN.

  17. Judith,

    It would depend on the intensity of the particles to do any effect on our ROTATING ATMOSPHERE. Many solar flare have hit our atmosphere with only minor effects on our electronics.

  18. I think they are either desperate or clutching at straws.

  19. Judith,

    Many a time I feel like I am talking to my hand…
    ‘Hello hand’
    ‘Hello Joe, what you know?’

    Anyway, our sun is very quiet right now and the mass of material it was spewing has demised greatly. Our rotating atmosphere(outer) has also diminished greatly which is our insulation to the vast coldness of space.

  20. I think it is fair to observe that, considering the scale- stellar activity across a significant piece of a galaxy, the time frame involved- hundreds of millions of years, and the results- life on Earth- that there is very little in this paper that will make any sort of difference in what we should do regarding any policy decisions we can conceivably make. This is not to take away from the elegance or science of the paper at all.

    • I dunno. Showing that albedo is the Ace of Trumps, and radiative effect the Three of Clubs is a useful and practical lesson.

  21. thisisnotgoodtogo

    I’d like to get a better understanding of differences between fast evolutionary rate and diversity, as they apply to this sdudy.

    I understnd that rate of evolution increases in a stable environment. If that is true, does it imply a corresponding greater biodiversity ?

    • The maths are tumbling through my head, but I agree, there are curious questions about biodiversity in here. Probably enough chaos to justify any position. Heh.

    • The rate of evolution tends to be a function of niche formation, the greater the heterogeneity of ecologies the more biodiversity. Recycling, in geological time is the key to the total biosphere mass. The majority of the oceans are dead deserts as there is a lack of nutrients.
      Plate movements and vulcanoes are good for biodiversity.

  22. These ideas are going nowhere, there just aren’t enough cosmic rays reaching the earth from any source to affect the number of available cloud condensing nuclei in the atmosphere to any degree.

    • David Wojick

      I think these folks know quite a bit about cosmic rays, since they have been studying them for decades. These ideas were first presented to me by the ESA people that run the SOHO satellite, at least 15 years ago. Thus your claim seems rather strong. Is this your field by any chance, or just something you read somewhere? In either case can you elaborate?

      • Cosmic rays are not my field but radiation is. I manufacture cosmic rays and turn them in to antimatter. Radioactive pharmaceuticals are my field of endeavor. So I am familiar with the science with respect to the concentration of particles possibly created by cosmic rays and the amount of particles encountered in HEPA filtered air. If there are not enough particles created by cosmic rays to affect the amount of particles in HEPA filtered air, then surely there are not enough to change the concentration in the air. Where there are dust clouds visible from space from time to time.

        It come from the difference between the numbers ascribed to Mr. Avogadro and Ms. Curie.

      • “I think these folks know quite a bit about cosmic rays, since they have been studying them for decades.”

        Don’t you mean, they’re on the cosmic ray gravy train so we have to take their “results” with a grain of salt?

      • Seriously, what gravy train are you talking about? You mean the cosmic ray guys ALSO get $1.4 billion a year from Obama for “battling cosm

      • “battling cosmic rays”?

        (sorry iphone screen messed me up)

    • bob, I would be interested in your thoughts on the effects that have been observed on weather during Forbush Decreases. I have read as much as I can, but I cannot understand whether the data is convincing or not. Could you help me, please?

      • Not convincing,

        Have you read this?


      • bob, Your reference does not seem to relate to Forbus Decreases. I agree that the evidence presented in the paper from Serbia on Forbush Decreases and diurnal temperature range (DTR) is not very convincing, but I was looking for your take on that specific paper. I dont have the reference. Is there observed evidence that Forbush Decreases affect clouds?

      • I found the reference, I think,

        A. Dragić, I. Aničin, R. Banjanac, V. Udovičić, D. Joković´, D. Maletićand J. Puzović, “Forbush decreases – clouds relation in the neutron monitor era”,Astrophysics and Space Sciences Transactions, 7, 315–318, 2011

  23. There is definitely a lot to digest in this paper. I did make an initial scan of it last night, and will go through it again in the next few days. My initial reaction is there may be some over-reaching in this. with a tendency to attempt to explain some things that have other more likely explanations…but overall, this seems to be an impressive paper.

    • R Gates

      I look forward to your comments in due course. I was given the book on cosmic rays as a Christmas present some years ago and it only serves to reinforce my view that climate science is at a very primitive state at present and we still dont know all the component parts of it. Cosmic rays may or may not be one of these, but at present I dont know.

  24. –e.g., see:

    Nir J. Shaviv, ‘The Milky Way Galaxy’s Spiral Arms and Ice-Age Epochs and the Cosmic Ray Connection,’ Submitted by Shaviv on Thu, 2006-03-30


  25. Paul Vaughan

    Piers Corbyn has concisely cautioned us here:


    I encourage everyone to patiently & thoroughly read much more detailed cautionary notes volunteered by Piers here:

    (stamped “Posted by Piers Corbyn (Twitter) on Apr 24th 2012, 7:54 PM EDT”)


  26. –e.g., from, Climate Change Reconsidered p. 208

    5.1. Cosmic Rays
    The study of extraterrestrial climatic forcing factors is
    primarily a study of phenomena related to the sun.
    Historically, this field of inquiry began with the work
    of Milankovitch (1920, 1941), who linked the cyclical
    glaciations of the past million years to the receipt of
    solar radiation at the surface of the earth as modulated
    by variations in earth’s orbit and rotational
    characteristics. Subsequent investigations implicated
    a number of other solar phenomena that operate on
    both shorter and longer timescales; in this summary
    we review the findings of the subset of those studies
    that involve galactic cosmic rays…

  27. Compelling as it may be, nominally, of course, it’s the sun, stupid.

    “That same year, Shaviv and Veizer (2003)
    suggested that from two-thirds to three-fourths of the
    variance in earth’s temperature (T) over the past 500
    million years may be attributable to cosmic ray flux
    (CRF) variations due to solar system passages
    through the spiral arms of the Milky Way galaxy.
    This they did after presenting several half-billion-year
    histories of T, CRF, and atmospheric CO2
    concentrations derived from various types of proxy
    data, and after finding that none of the CO2 curves
    showed any clear correlation with the T curves,
    suggesting to them that ‘CO2 is not likely to be the
    principal climate driver.’ On the other hand, they
    discovered that the T trends displayed a dominant
    cyclic component on the order of 135 ± 9 million
    years, and that ‘this regular pattern implies that we
    may be looking at a reflection of celestial phenomena
    in the climate history of earth.’” (Ibid.)

  28. CO2 is the Medium and Liberal Utopianism is the Message:

    We can predict a monotonic increase in CO2 and that is all the Left needs to know about global warming. Since the Left’s real objective is to use the fear, superstition and ignorance of a dysfunctional society to take over the economy, we do not need to know about undersea volcanoes, recurring solar activity and ENSO events on decadal, centennial and millennial climate cycles, cosmic radiation as our solar system skitters through the spiraling arms of the Milky Way at the edge of the galaxy, the interaction between the Earth the big planets of Jupiter and Saturn on the Earth’s rotation, axis, magnetosphere, etc.

    By ignoring reality, the global warming alarmists feel free to ignore history: “over the past 12,000 years, there were many icy intervals like the Little Ice Age [that] alternated with warm phases, of which the most recent were the Medieval Warm Period (roughly AD 900-1300) and the Modern Warm Period (since 1900).” ~Henrik Svensmark: “over the last 12,000 years virtually every centennial time-scale increase in drift ice documented in our North Atlantic records was tied to a solar minimum.”

  29. Paul Vaughan

    “JC comment: […] The paper is getting a lot of press, but I haven’t seen much in the way of detailed critique (although Leif Svalgaard makes some comments on the WUWT thread).”

    He’s on better behavior than usual in the parallel wuwt thread. So far I’ve spotted one major slip that is strictly at odds with empirical evidence:

    “There is a third option: that cosmic rays have nothing to do with climate. [not on a time scale that matters for society].”

    Svalgaard has valuable knowledge, but I caution readers that his conceptual understanding of cross-scale aggregation summaries is grossly deficient. Such innocence isn’t a sin, but due to his rank & status in the community – and the responsibility thus carried – he cannot be forgiven for seriously misleading public opinion (in this very particular but tremendously important case) by projecting his expertise well beyond its boundaries. Svalgaard’s had well over a year to learn how to test the sensitivity of parameter estimates to temporal extent (NOT to be confused with temporal grain), but he remains intransigent.


  30. I am struck by the fact that despite the paper being release only yesterday, many of the people here dismiss it out of hand or criticize if as if they had read and understood it.

    I may not be a scientist or understand the science in all of this, but like any football fan, I can tell trash talking when I see it.

    I would ask that those who have a problem with his paper do exactly what I’ve seen them tell others to do. Write a paper rebutting his arguments and get it published.

    Until then, you are nothing but trash talking.

    Crap, and I though this place would be better than Slashdot.

    • I don’t see anyone trashing it.

      • To be fair, the first comment was pretty trashy. Comparing Dr. Svensmark to Gene Roddenberry could hardly be called praising him, however fitting the analogy.

        Clearly, something from beyond the atmosphere appears to be affecting the Earth’s climate profoundly on the scale of periods greater than 20,000 years. Dr. Svensmark may have contributed somewhat (albeit ambitiously and with little of the humility normally associated with claims on so vast a span involving so many unknowables) to our understanding of things where 20,000 years pass by like the flutter of an eyelid.

        Which brings into sharp relief just how profound human activity is, to in a mere quarter of a millennium to have raised the CO2 level by more than it has raised in any span of 20,000 years in the past 15 million years, and to higher than the peak of the past 15 million years by that amount in so short a span of time.

        I thank Dr. Svensmark for the lesson in perspective, that all the forces of the galaxy, up to supernovae and plate tectonics, are now contested by accidental human blundering for influence on the direction of all life on our planet.

      • I take it that you base your claim of anthropogenic cause of co2 on the c12/13 RATIO. Most who make this link appear to be unaware that seasonal variations in c13 mirror co2 seasonal variations, strongly suggesting natural causes as the driver of that ratio change.

      • Neil Fisher | April 26, 2012 at 4:15 am |

        Sorry, no. You’ve mis-guessed the sources of my conclusions; I’ve taken approaches less susceptible to the Salbyist Fallacy, for the simple reason that C12/C13 ratio, while entertaining, is unduly complicated, akin to asking which pennies in a gumball machine were part of which loan interest payments and which were part of which loan capital payment. Clever if you can pull off the math, but pointless to do while there’s so many better options.

        I think the anthropogenic causes of CO2 rise can be adequately proven without resort to the consilient C12/C13 ratios, thus cutting the Gordion Knot.

        However, I needed to use Propositional Logic in addition to Judgement Logic to get there.

    • Different than slashdot. Less techie snark, but lots of ignorance to make up for it. I am still looking for good science forums to discuss energy topics and environ mental modeling. Azimuth project.org is top of the line no question, but slow traffic.

    • Albert Stienstra

      Sycodon, I agree with your observations and you do not need to be a scientist to see this. I hope some of these AGW court fools will do what you ask them to do, but it will be work…and probably that is too much.

  31. This is interesting stuff. I recall reading that a peculiar regularity was thought to be seen in extinction events. Both an orbiting brown dwarf that regularly crosses the oort-cloud every so much million years as oscillation of the sun trajectory around the galactic core, which would bring it out of the relative shielding of galactic clouds every so much million years were suggested.


  32. Michael Larkin

    Well, I’m grateful for the press release by the RAS, which at least allows me to get the flavour of the paper in layman’s terms. Of course, I have no idea as to whether Svensmark is right or wrong, but regardless, it looks interesting. I guess we’ll have to wait for reactions and outcomes. But one thing: Svensmark is, I am convinced, an honest scientist, and if he is wrong, it will be honestly so.

    As for the joyless Joy, WTF has anything about this to do with the tobacco industry? Why not really go for it and try to link Svensmark with paedophilia or terrorism? You make me want to vomit.

  33. H/T to Wagathon @ 25/4. 11.38 am:
    Co2 is the Medium amd Liberal Utopianism is the Massage.

    Volcanoes, recurring solar activity, maybe cosmic rays and solar minimums, albido, Enso events? Merely data on a ‘do not need to know’ basis.

  34. More news from the neighborhood of outer space on the scale of tens of millions to billions of years ago affecting life: http://www.upi.com/Science_News/2012/04/25/Spherules-tell-of-asteroid-impacts/UPI-84941335400148/

  35. David Springer

    I don’t think this is either provocative or mind bending. It’s interesting but not surprising. Didn’t everyone already know that Sol orbits the galactic center at rate different than the spiral arm rotation rate? It wanders above, below, and through the galactic plane and cuts a path through and between spiral arms. Stellar density in its local neighborhood varies dramatically along its path and by consequence the average and peak intensities of high energy particles. A close supernova (within 100 light years IIRC) would cause a mass extinction leaving only extremophiles alive to start over again. Supernovae further away have commensurately less dramatic effects than wiping out all life. A less dramatic effect than a mass extinction event would be mild/moderate climate change.

  36. The paper rests on poor statistics, cf. Figure 2, where just a few changes would lead to completely different correlations. Thus the conclusions are not well founded and the whole paper is more speculation than based on any kind of facts.