Cosmic Ray Levels and Cloud-forming effects on temperature
March 12, 2010 by jason
I have previously written an article on why Cosmic ray levels do not directly affect climate change (ie. why the changes in radiative energy reaching earth do not directly affect the earth's temperature). I thought it might now be relevant to address a slightly more complex issue - the indirect effects of Cosmic ray levels on global temperature.
The reason I divided this topic into two separate articles, was because the first (the direct effect of cosmic ray levels on the earth's climate is basically an open and shut case - cosmic ray levels do not directly affect the climate). To illustrate why the story of cosmic ray levels is a little more complex, I will quote a danish paper titled Influence of Cosmic Rays on Earth's Climate, where the author states that
Quote:
"During the last solar cycle Earth's cloud cover underwent a modulation more closely in phase with the galactic cosmic ray flux than with other solar activity parameters.
Source: Influence of Cosmic Rays on Earth's Climate
This paper goes on to discuss the relevance of solar cycle length on temperature, which I will cover in a later article. In this article I will only discuss the indirect effects of cosmic ray levels on global temperature.
Effects of Cloud Cover
The first question in need of answering, is whether cloud cover can affect global temperature at all. There is no question that clouds affect the weather, but to answer whether cloud cover can have a significant long-term effect on the earth's global climate, or whether it is just a bystander, we can look at this graphic:
Scatter plot showing total monthly cloud cover against monthly global surface air temperature from July 1983 until June 2009 (Source: The International Satellite Cloud Climatology Project)
From this we can see a clear correlation between cloud cover and global temperature. Based on the linear fit coefficient of determination, cloud cover explains 26% of temperature variation. Whether cloud cover actually drives these changes is not evident from the graph, but we can at least conclude there is some relationship between the two.
How Cosmic Ray Levels affect climate
To answer the question of whether cosmic ray levels can affect the world temperature by affecting cloud cover, we don't really need to look farther than a plot of global temperatures against cosmic ray levels over the past 40,000 years (for more on how this is done, see my description of how historic information about cosmic ray levels is obtained). By taking data from the EPICA Ice Core records we can obtain the following plot of global temperature levels against cosmic ray levels for the past 40,000 years:
Plot of D18O concentrations (temperature levels) against the inverse of Be10 concentrations (indicator for the cloud forming tendency of cosmic ray levels) over the past 40,000 years (Data Source: EPICA Ice Core Data)
What is initially striking about this graph is that the fitted lines seem to correlate for most of the period. However, if you look at the left extreme of the graph, where large and rapid changes in cosmic ray levels occur, we should expect to see a noticeable change in temperature. It seems like only small and drawn out changes in cosmic ray levels would affect temperature, which doesn't make a lot of sense. There is one particular point of interest though, indicated in the graph with an arrow, where a strong correlation does seem to occur. Based on the above graph alone however, it does seem to be difficult to ascertain whether there is a correlation. To graphically illustrate whether or not there is a correlation, we can plot each temperature/cosmic ray level point for a given period of time, as points on a scatter plot:
Scatter plot of D18O concentrations (temperature levels) against Be10 concentrations (indicator for cosmic ray levels) over the past 40,000 years (Data Source: EPICA Ice Core Data)
From this we can see a general trend, that extremely low cosmic ray levels tend to produce higher temperatures (this is indicated by the dense cluster of points at high D18O levels and low Be19 concentrations), but higher cosmic ray concentrations do not really affect climate at all. This is presumably because particularly low cosmic ray concentrations significantly reduce cloud cover and thus force an increase in temperature. Why particularly high concentrations of cosmic ray levels would not significantly decrease temperature (by increasing cloud cover) is unknown. This also raises the question of the effect of H2O concentrations in the air: higher temperatures = higher H2O concentrations, so could there be a 3-point feedback between H2O, cloud formations and cosmic ray levels? That's a topic for another day...
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Comments
cosmic radiation and climate
September 26, 2010 by Willem Schot (not verified)
Jason, By the 10Be quantities you measure the cosmic radiation. The particles of that radiation are very fast and do have so much energy that they can split the atoms of the gasses in the Earths' atmosphere. So they produce a cascade of physical and chemical reactions and by this arise some condensation cores for water. Also new isotopes as the 10Be tracer are produced by that bombardment from space. The problem however is that this radiation, so these very fast protons from space, are so seldom. Only a 2 billionth part (5.10^-10) of the energy the atmosphere receives comes from the cosmic radiation and the rest is from the sun. By some cosmic events may exist primary variation in the cosmic radiation, but also if there is some increase the number of the fast particles from space their number remains small and variations in dust particles as condensation core high in the air by variation in the cosmic radiation is small in relation to earthborn causes of variation in dust as volcanic explosions, dust storms in deserts, etc. Moreover, as pointed out before the star sky in Greenland differs from that of Antarctica. So primary variation in the cosmic radiation probably is not the cause of the temperature change in your plots. It is well-known that the cosmic radiation is stopped by magnetic fields. The magnetic fields of both the Earth and the Sun are as a shield in space protecting the Earth against cosmic radiation. This protection, however is not complete and there are variations in the magnetic fields of both the Earth and the Sun. The changing in the Earths’ magnetic field is relative slow, but the fluctuations in the fields of the sun are very fast and intense. So the differences in the 10Be concentrations trace indeed cosmic radiation, but mostly as it has been modulated by the magnetic activity of the sun. This is very important for the analysis of the relation between the 10Be and the temperature in your plot. So in this statistic relation do exist some different cause → consequence chains as are: Cosmic event → cosmic ray and 10Be increase → more condensation cores and more clouds → cooler climate. Also for instance: Less magnetic activity of the sun → cosmic ray and 10Be increase → more condensation cores and more clouds → cooler climate. Also because the magnetic and the irradiative activity of the sun are physical united: Less magnetic activity of the sun → less radiation of the sun → cooler climate together with : Less magnetic activity of the sun → cosmic ray and 10Be increase. So in these later combination of chains the activity of the sun is the common cause of the changes in the temperature and the 10Be tracer giving here a negative statistic relation.
to Dan
September 22, 2010 by jason
I read your article (presumably you meant this: http://www.middlebury.net/op-ed/pangburn.html), and found it very interesting, although I think it requires some updating in light of recent events. For example, you state:
While this was true at the time of writing, it is now a little misleading given the drastic rises in temperature we have experienced in the past 2 years. I wrote a short article on March 2010 being one of the hottest "Marches" ever recorded, and now 2010 as a whole is shaping up to be the hottest year ever (http://data.giss.nasa.gov/gistemp/graphs/).
You go on to make several entirely valid points about the fact that historic CO2 concentrations have not correlated temporally with temperature rises. I think this should be complemented with the fact that logically, the ability of temperature to drive up CO2 does not exclude the ability of CO2 to drive up temperatures. They are not logically exclusive, and plenty of evidence exists to suggests that CO2 did in fact drive up temperatures in the past, it just wasn't the primary driver. More on this here: http://www.warmdebate.com/jason/epica-ice-core-data-and-temperature-co2-...
One final comment; you stated that
This is not true. Let me show you a simple statistical plot I created a couple of months ago:
This graph (taken from http://www.warmdebate.com/jason/correlation-between-temperature-and-co2-...) shows a 76% correlation between temperature and CO2 over the past 50 years. The same graph over the past half a million years is also shown on the article, where the correlation is, as expected, higher, at 89%. However, this is no evidence of CO2 to drive up temperature, as - as you stated - CO2 is historically not primarily responsible for temperature changes, despite there being a correlation between temp and CO2. Historically, we know that the lag from temperature to CO2 is a few hundred years, so it cannot be argued that the correlation over the past 50 years is a result of CO2 reacting to increased temperatures.
correlation of average global temperature
May 29, 2010 by Dan Pangburn (not verified)
Average global temperatures from 1895 to the present are accurately calculated by an equation that can be seen by Googling Dan Pangburn average global temperature . The coefficient of correlation is 0.87. The equation projects a cooling trend until about 2037. The future cooling trend is a bit slower but still cooling when the influence of added atmospheric carbon dioxide is included. The equation was discovered by a rather straightforward application of the first law of thermodynamics.
Cosmic ray and temperature
May 23, 2010 by Willem Schot (not verified)
Jason, Thank for your interesting graphics about the correlation of the 10Be data and the temperature. In my experience, however is the 10Be plot here from the data of the GISP ice core, so from Greenland, while the temperature plot indeed is from EPICA in Antarctica. This makes the correlation here much more important, because this excludes disturbance. If they were both from Antarctica the variation in the 10Be data and in the temperature could be determined by the same atmospheric variations. Furthermore that North – South comparison also makes probable that no primary or direct variation of the cosmic radiation was the determining factor in the temperature variation. That is because the star sky of Greenland is totally different from that of Antarctica and so Greenland ever receives cosmic radiation different from Antarctica. Cosmic radiation from the area of the great Bear constellation for instance can be traced by the 10Be in Greenland, but not in Antarctica and cannot have influence on the climate there. It seems very likely so that the relation between the temperature variation and the 10Be is indirect via the sun. If the sun is more active it produces stronger magnetic fields and more radiation. That stronger magnetic fields will stop the cosmic radiation, which may have some influence on the climate by cloud formation. Differences in the radiation energy from the sun however is a more probable cause for temperature variation. In the very short time of 30 year, people can measure differences in the solar radiation by satellites differences of 0,1% are found. Of many thousands of years that variation some 2% or 3%.
Willem Schot
Hi Chic, Ideally, I would
April 11, 2010 by jason
Hi Chic,
Ideally, I would have loved to have been able to work with more comprehensive data, but it simply wasn't available. The image of cloud cover and temperature was cited from the International Satellite Cloud Climatology Project, and on their website I simply couldn't find the sources of the data. Based on what I have seen, it seems apparent that cosmic rays are at the very least an indicator for global temperature. There seems little evidence to suggest it is a driver, and even less to suggest that its effect could be highly significant. However, that's just my opinion and if you do happen to come across a more complete set of information or data sources on cosmic ray concentrations - possibly along with latitudinal data - please do let me know.
cloud cover
April 9, 2010 by Chic Bowdrie (not verified)
Jason, I like that graph of surface temp vs. % cloud cover. It has been awhile since I've done any statistics, but I seem to remember you can block the data and better evaluate the contributions to the variance. For example, if you took month and distance from the equator into account, the cloud temperature relationship may be much stronger.
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