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Could Cosmic Rays Influence Global Warming?

Global warming… could cosmic rays have a significant effect on cloud cover? (credit: Ian O'Neill)
The idea goes like this: Cosmic rays, originating from outside the Solar System, hit the Earth’s atmosphere. In doing so these highly energetic particles create microscopic aerosols. Aerosols collect in the atmosphere and act as nuclei for water droplet formation. Large-scale cloud cover can result from this microscopic interaction. Cloud cover reflects light from the Sun, therefore cooling the Earth. This “global dimming” effect could hold some answers to the global warming debate as it influences the amount of radiation entering the atmosphere. Therefore the flux of cosmic rays is highly dependent on the Sun’s magnetic field that varies over the 11-year solar cycle.

If this theory is so, some questions come to mind: Is the Sun’s changing magnetic field responsible for the amount of global cloud cover? To what degree does this influence global temperatures? Where does that leave man-made global warming? Two research groups have published their work and, perhaps unsurprisingly, have two different opinions…


I always brace myself when I mention “global warming”. I have never come across such an emotive and controversial subject. I get comments from people that support the idea that the human race and our insatiable desire for energy is the root cause of the global increases in temperature. I get anger (big, scary anger!) from people who wholeheartedly believe that we are being conned into thinking the “global warming swindle” is a money-making scheme. You just have to look at the discussions that ensued in the following climate-related stories:

But what ever our opinion, huge quantities of research spending is going into understanding all the factors involved in this worrying upward trend in average temperature.

Cue cosmic rays.

Researchers from the National Polytechnic University in the Ukraine take the view that mankind has little or no effect on global warming and that it is purely down to the flux of cosmic radiation (creating clouds). Basically, Vitaliy Rusov and colleagues run the analysis of the situation and deduce that the carbon dioxide content of the atmosphere has very little effect on global warming. Their observations suggest that global temperature increases are periodic when looking into the history of global and solar magnetic field fluctuations and the main culprit could be cosmic ray interactions with the atmosphere. Looking back over 750,000 years of palaeotemperature data (historic records of climatic temperature stored in ice cores sampled in the Northern Atlantic ice sheets), Rusov’s theory and data analysis draw the same conclusion, that global warming is periodic and intrinsically linked with the solar cycle and Earth’s magnetic field.

But how does the Sun affect the cosmic ray flux? As the Sun approaches “solar maximum” its magnetic field is at its most stressed and active state. Flares and coronal mass ejections become commonplace, as do sunspots. Sunspots are a magnetic manifestation, showing areas on the solar surface where the powerful magnetic field is up welling and interacting. It is during this period of the 11-year solar cycle that the reach of the solar magnetic field is most powerful. So powerful that galactic cosmic rays (high energy particles from supernovae etc.) will be swept from their paths by the magnetic field lines en-route to the Earth in the solar wind.

It is on this premise that the Ukrainian research is based. Cosmic ray flux incident on the Earth’s atmosphere is anti-correlated with sunspot number – less sunspots equals an increase in cosmic ray flux. And what happens when there is an increase in cosmic ray flux? There is an increase in global cloud cover. This is the Earth’s global natural heat shield. At solar minimum (when sunspots are rare) we can expect the albedo (reflectivity) of the Earth to increase, thus reducing the effect of global warming.

This is a nice bit of research, with a very elegant mechanism that could physically control the amount of solar radiation heating the atmosphere. However, there is a lot of evidence out there that suggests carbon dioxide emissions are to blame for the current upward trend of average temperature.

Prof. Terry Sloan and Prof. Sir Arnold Wolfendale from the University of Lancaster and University of Durham, UK step into the debate with the publication “Testing the proposed causal link between cosmic rays and cloud cover“. Using data from the International Satellite Cloud Climatology Project (ISCCP), the UK-based researchers set out to investigate the idea that the solar cycle has any effect on the amount of global cloud cover. They find that cloud cover varies depending on latitude, demonstrating that in some locations cloud cover/cosmic ray flux correlates in others it does not. The big conclusion from this comprehensive study states that if cosmic rays in some way influence cloud cover, at maximum the mechanism can only account for 23 percent of cloud cover change. There is no evidence to suggest that changes in the cosmic ray flux have any effect on global temperature changes.

The cosmic-ray, cloud-forming mechanism itself is even in doubt. So far, there has been little observational evidence of this phenomenon. Even looking at historical data, there has never been an accelerated increase in global temperature rise than the one we are currently observing.

So could we be clutching at straws here? Are we trying to find answers to the global warming problem when the answer is already right in front of us? Even if global warming can be amplified by natural global processes, mankind sure ain’t helping. There is a known link between carbon dioxide emission and global temperature rise whether we like it or not.

Perhaps taking action on carbon emissions is a step in the right direction while further research is carried out on some of the natural processes that can influence climate change, as for now, cosmic rays do not seem to have a significant part to play.

Original source: arXiv blog

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Hello! My name is Ian O'Neill and I've been writing for the Universe Today since December 2007. I am a solar physics doctor, but my space interests are wide-ranging. Since becoming a science writer I have been drawn to the more extreme astrophysics concepts (like black hole dynamics), high energy physics (getting excited about the LHC!) and general space colonization efforts. I am also heavily involved with the Mars Homestead project (run by the Mars Foundation), an international organization to advance our settlement concepts on Mars. I also run my own space physics blog: Astroengine.com, be sure to check it out!

Comments on this entry are closed.

  • Chris March 22, 2008, 1:07 AM

    Good one UkMan,

    I’d also say that maybe what *really* burns the deniers is the realisation that when it comes to AGW, the left/liberals were right all along. The denialist idiots are so irredeemably stupid that rather than admit this, they’ll repudiate the scientific consensus that forms what the IPCC is reporting, what thousands of working climate scientists around the world are saying, and what every authoritiave national scientific body on the planet tells us.

    Remember how the deniers all cheered when some goose announced there had been no warming since 1998 … er … except that Nasa’s GISS temp data tells us the five hottest years are:

    1. 2005
    Tie 1998/2007
    4. 2002
    5. 2003

    The warming trend looks pretty clear to me.

    But clutching at any straw (no matter how thin) to support their dishonest rantings I’d now expect them to start droning on with the usual FUD about how and why GISS is wrong, Hansen’s work can’t be trusted etc, ad infinitum, ad nauseum.

    I find it pretty strange that the deniers could think like that when they’ve got no robust published science that backs them up. None. Zip. Zero. Nada. Kinda creepy really.

  • Dirk March 22, 2008, 9:07 AM

    We all comment because we all are right, right? So here’s the truth: we know virtually nothing about interstellar interaction and even gravity is really puzzling, so read “The electric sky’ (Scott) and “The final theory” (McCutheon) for understanding why humanity can’t be involved in our global warming. It is only plasma that rules the continuous universe.

  • sciencebabble March 22, 2008, 11:33 AM

    ‘…..we know virtually nothing about interstellar interaction and even gravity is really puzzling…..’

    I am puzzled now.
    Ian knows it and if he reports it to us it cannot be wrong.

    He is reporting everything the truth, the progress, the unknown and the undiscovered. A frontrunner at the edge of knowledge.

    All for our education and his monetary benefit.
    Lets pray to our high priest of technobabble.
    Thanks for the truth.
    Thanks for the insight.
    Thanks for the ingenuity

  • Rob March 22, 2008, 12:27 PM

    It always amuses me that when Global Warming Alarmists are confronted with intelligent, solid debate on that the matter that they resort to their mantra of “attack the man, not the science”, as the increasing number of scientific papers are rapidly eroding the base for their nonsensical arguments. Anyone who is a sceptic of the IPCC is immediately labelled a “denier’, drawing non-too-subtle” comparisons to Holocaust deniers. What a healthy way to engage in scientific debate.

    Chris: You say that NASA’s GISS temp data tells us that the five hottest years were 1998/2007, 2002, 2003, 2005. Really? You forgot about 1934. I checked the NASA GISS site at http://data.giss.nasa.gov/gistemp/2007/. They say that 1934 was technically the warmest year in their records, although 1934, 1998 and 2005 were essentially tied. Even the IPCC admits that supposed anthropogenic influences in GW only go back 30 years. How do you explain 1934?

    The reality is the Global Climate has always been and always will be in a state of change. Surely you do not deny the Medieval Warm Period (a time when temperatures were much warmer than they are today) or the Little Ice Age (1700s). Global temperature has never been static for any significant duration. These events prove that there are much larger forces in play in determining global climate. Man’s increases in CO2 emmisions are insignificant when compared those from oceans (by far the largest), volcanos, and the biosphere (plants, animals). The IPCC refuses to adequately account for natural causes of global warming. It is simply ludicrous to believe that anthropogenic causes are soley or largely to blame.

    As for your claim that there is no science backing up the belief that anthropogenic factors are insignificant to climate change in the grand scheme of things – you’re joking, right? The National Post has an excellent set of articles describing the works of various well-respected scientists around the world that are poking all kinds of holes in the AGW rantings. http://network.nationalpost.com/np/blogs/posted/pages/climate-change-the-deniers.aspx

    A must read in this collection is the article “IPCC too blinkered and corrupt to save”.
    You must also ready the report from the NIPCC – the Non Intergovernmental Panel on Climate Change. The NIPCC is a parallel panel to the IPCC formed by scientists frustratrated by the lack of proper scientific rigour exhibited by the IPCC. Their report is at http://heartland.temp.siteexecutive.com/pdf/22835.pdf
    The scientific reality is that the sun is the single greatest influencing factor on the earth’s temperature (both through direct radiation and its affect on cosmic radiation). It’s radiation levels vary in three well known cycles. Oceanographers know that the worlds oceans are by far the single greatest CO2 emitter/sink. When the oceans temp goes up, they emit more CO2 (this is not scientifically disputed). They also know that that oceans have an 800 year memory (ie. it takes about 800 years before global temperature changes are are reflected in deeper ocean temperatures). What that means is that our oceans are currently reacting to temperatures from about 1200 AD …right in the middle of the Medieval Warm Period. As a result, they are emitting a lot of CO2. Ice core studies – the same ones incorrectly interpreted by Al Gore in his film – show that throughout history global CO2 levels have lagged temperature by about 800 years.
    The IPCC is a politically corrupt organization that quite remarkably has hijacked the environmental agenda. We should be more worried about exhausting our fresh water supplies, and striving towards a clean, safe replacement for fossi fuels (as we have only about 100 years supply left of conventional oil).

  • Aqualung March 25, 2008, 6:22 AM

    Just because the earth is warming up a bit at the moment does not make it man made.

    We must all do our bit to look after the environment and recycling has the effect of reducing CO2 and reducing the amount of raw ore processed.

    Certainly recycling is a big issue in the UK with households soon to be fined for not recycling their rubbish. BUT we still have the situation where businesses DO NOT, and their are no plans to make them, have to recycle anything!

    We have lots of huge high street stores throwing out cardboard, cans, tins, bottles and plastics. They ALL go into landfill without being sorted because there is no legislation to make them.

    If saving the planet was that important, don’t you think business would have to do their bit as well.

    If you look at my previous posts you will see that I believe GW is a natural phenomena. I also believe it has been hijacked by government as a money making scam. Hence the pressure on ordinary citizens to do all the work while business continues on regardless.

  • alphonso richardson April 1, 2008, 5:16 AM

    Firstly, I agrer that GW is a natural procees. However, I disagree that mankind has not had an effect on the process.
    This is now an emotive subject, as opposed to a looney non-starter only a few decades ago. Consequently, of course, there will be individuals, politicians & businesses willing to make money out of people’s ingorance and fears.
    This however doesn’t mean that there is no problem.
    To stick with an ‘either – or’ stance so doggdley without real concern for facts & reasoned argument is simply not helpful. And I’m talking to BOTH sides on this – too much crap is talked on both sides of the debate.
    We all have a part to play & business don’t get involved unless legislation is levied AND enforced. there is another way – hit ‘em in the pocket. Once their bottom line is affected, they soon take notice.
    Not easy or perfect, but surley better than slagging each other off & getting nowhere.

  • Mr. R. L. Hails Sr. P. E. April 2, 2008, 8:45 PM

    I am an engineer, with forty years experience in power production: a score of nukes, two score fossil plants, and a decade + studying advanced energy technologies: fuel cells, solar electric, ultracapcitors, advanced ICE, and related material sciences, e.g. MMC, nanotechnologies, etc. I have read the pro and con GW debate, and find it vacuous. The central issue is this: > 90% of man’s energy is derived from the exothermic reaction of carbon, oxygen to carbon dioxide. Second place is held by nuclear power. The sum of all other sources is trivial, from a societal load viewpoint. All alternate prime energy sources have technical- cost limitations, e.g. material unit stress, energy conversion efficiencies, or rare materials; they can not, will not supplant fossil fuels, as bulk, cheap, universal, dependable technologies in this century. Therefore, if GW is lethal, and CO2 must be reduced by a large fraction, billions will be denied energy at today’s consumption levels. Most will die. Advanced nations can improve thermal efficiencies, as a secondary effect, but no earthly power can change the end condition. Mankind can not support 6+ billion people without combustion. It is the back bone of the industrial revolution, the prime demarcation between rich and marginally surviving societies. Extremely expensive energy is useless, and infuriating, to poor, starving people.
    The world wide ad hominum attacks among arrogant scientists, on GW must stop. We are not far from warfare on this issue, and you fuel the conflict. It is immoral to waste anything of value, and all societies waste. We must distribute the products of wealth, far more widely, so as to prevent strive. However, even this historically unattained condition will leave us with a Malthusian dilemma if fossil fuel combustion is dangerous to life.
    I am a denier. Call it abject fear, ratio a mort. I judge that the certitude of the GW arguments pales in relation to the inescapable consequences of the conclusion.
    I pray that I am wrong.

  • Ric Werme April 3, 2008, 4:53 AM

    I first heard about this paper through a friend who sent me the BBC story at http://news.bbc.co.uk/2/low/science/nature/7327393.stm

    The article quotes Terry Sloan with “The IPCC has got it right, so we had better carry on trying to cut carbon emissions.” While I haven’t had a chance to digest this paper, I get real concerned when IPCC and right are used in the same sentence because I’ve heard too many problems about how they do science.

    There is a chance that pressure to have a sensible scientific dialog will greatly increase, at the very least, we may be entering a the best period since the Dalton Minimum to see what impact solar activity has on climate.

    While this study says the Cosmic Ray theory is wrong, Svensmark’s SKY experiment is quite interesting, and CERN’s upcoming CLOUD experiment will be moreso. Even better, perhaps, are predictions and evidence that the Sun is entering decades of reduced activity.

    The only catch is that the Dalton Minimum was not a pleasant time even before volcanic eruptions made things worse. From reports around the world about this winter (I saw a Chinese report yesterday – they’re still having major problems) and the recent downturn in global temps climatology is becoming exciting.

    I recently wrote a web page that reviews how science should be working and takes a brief look at both CO2 and
    Solar forcings. I hope it will help Ian O’Neill avoid getting “big, scary anger” when he writes on the subject.
    See “Science, Method, Climatology, and Forgetting the Basics” at http://wermenh.com/climate/science.html

  • Professor Saumitra Mukherjee April 18, 2008, 11:46 AM

    With due regards to the “Pundits” of Global warming, it can be easy to understand that activities of human are not the sole cause of global warming. Sun as well as extragalactic cosmic rays has a role to play in the thermosphere,ionosphere, atmosphere,hydrosphere biosphere and geosphere of the earth. The research is going on and I have no hesitation to say that it has already been published what role the Sun and Extra galactic Cosmic rays are playing with the Environment of the earth.

    Prof.Saumitra Mukherjee
    School of Environmental sciences
    Jawaharlal Nehru University
    New Delhi-110067
    INDIA

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