Here’s a surprise. The growth of trees in Britain appears to correlate to cosmic ray intensity. University of Edinburgh researchers have found that trees are growing faster when high levels of cosmic radiation arrive from space. This may also correlate to the Interplanetary Magnetic Field which tends to modulate Galactic Cosmic Rays. The discover lends credence to Svensmark’s work on GCR to cloud cover correlation by demonstrating yet another tangible effect.
The researchers made the discovery studying how growth rings of spruce trees changed over the past half a century.
Here’s the kicker: the variation in cosmic rays affected the tree growth more than changes in temperature or precipitation.
ABSTRACT (link)
- Here, we investigated the interannual variation in the growth rings formed by Sitka spruce (Picea sitchensis) trees in northern Britain (55°N, 3°W) over the period 1961–2005 in an attempt to disentangle the influence of atmospheric variables acting at different times of year.
- Annual growth rings, measured along the north radius of freshly cut (frozen) tree discs and climatological data recorded at an adjacent site were used in the study. Correlations were based on Pearson product–moment correlation coefficients between the annual growth anomaly and these climatic and atmospheric factors.
- Rather weak correlations between these variables and growth were found. However, there was a consistent and statistically significant relationship between growth of the trees and the flux density of galactic cosmic radiation. Moreover, there was an underlying periodicity in growth, with four minima since 1961, resembling the period cycle of galactic cosmic radiation.
- We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.
The BBC also covers this in an article, here is an excerpt:
By Matt Walker
Editor, Earth News
The growth of British trees appears to follow a cosmic pattern, with trees growing faster when high levels of cosmic radiation arrive from space.
Researchers made the discovery studying how growth rings of spruce trees have varied over the past half a century.
As yet, they cannot explain the pattern, but variation in cosmic rays impacted tree growth more than changes in temperature or precipitation.
The study is published in the scientific journal New Phytologist.
“We were originally interested in a different topic, the climatological factors influencing forest growth,” says Ms Sigrid Dengel a postgraduate researcher at the Institute of Atmospheric and Environmental Science at the University of Edinburgh.
“The relation of the rings to the solar cycle was much stronger than to any climatological factors “Sigrid Dengel University of Edinburgh
To do this, Ms Dengel and University of Edinburgh colleagues Mr Dominik Aeby and Professor John Grace obtained slices of spruce tree trunks.
These had been freshly-felled from the Forest of Ae in Dumfriesshire, Scotland, by Forest Research, the research branch of the UK’s Forestry Commission.
The trees had been planted in 1953 and felled in 2006.
The researchers froze the trunk slices, to prevent the wood shrinking, then scanned them on to a computer and used software to count the number and width of the growth rings.
As the trees aged, they showed a usual decline in growth.
However, during a number of years, the trees’ growth also particularly slowed. These years correlated with periods when a relatively low level of cosmic rays reached the Earth’s surface.
When the intensity of cosmic rays reaching the Earth’s surface was higher, the rate of tree growth was faster.
Read the entire BBC report here
To Gene Nemetz (22:52:58) :
the difference between honest skeptics and snarky close minded warmists like you is so stark and profound. Mann’s bogus tree ring studies are a sham because tree rings are a lousy proxy for temperature (that plus data manipulation). that’s what the good faith skeptics have shown in this and other blogs. tree rings are however true analogs of tree growth; what is causing the growth rate differences? it’s not temperature, so that’s the question. go on, be a close minded snark, it’s probably the peak of your intellectual capacity.
Re Agust Bjarnason (23:38:34) comment, including the quote from Loehle on how tree rings might vary with long run temperature changes:
“…typical reconstructions assume that tree ring width responds linearly to temperature, but trees can respond in an inverse parabolic manner to temperature, with ring width rising with temperature to some optimal level, and then decreasing with further temperature increases (D’Arrigo et al., 2004; Kelly et al., 1994)”
This is what I meant with my comment at 18:12:16, when I hypothesized that within a narrow temp band, you could have big tree ring growth benefits on cloudier, slightly cooler days, but in the long run, cloudy cold years and decades could have tree ring growth disbenefits.
Re Yarmy (02:05:49) comment on possible nitrogen benefits from more GCRs, and subsequent comments suggesting that any such effect would be minor or non-existent. First, one effect that we are seeing the in US from the increased nitrogen oxides from more cars and power plants and such in the last half century is a nitrogen fertilization effect. Increased growth due to more nitrogen oxide emissions, some of which is converted to nitric acid and neutralized to nitrate, has been documented in forests and crops. But, the nitrogen oxide emissions also contribute to more ozone, the major reason EPA is taking steps to reduce nitrogen oxide emissions.
While the cloudiness effect is likely the major reason for the growth spurts in tree rings in the last several decades, I would like to see some analysis which could quantify the amount of increased nitrate in the atmosphere when GCRs are more abundant. Right about now would be a good time to look.
From the abstract: We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.
What is such a diffuse component. If there are more clouds=more shade=less photosynthesis. It proves the contrary!.
The key element in chlorophyll is magnesium, then if there is a magnesium increase there is an increase in photosynthesis and a deepening of the green color on plants´leaves. It could be many things.
Great stuff – this is what I read WUWT for!
Just a few points on British geography/forestry/climate, which I’m sure others have mentioned, but to bring them all together…
– 55N 3W and the team’s location in Edinburgh probably puts us in the Southern Uplands of Scotland – has anyone actually seen the paper, is it more specific?
– Rainfall is definitely *not* the limiting factor in that environment!
– The tree is Sitka Spruce, so this is almost certainly commercial plantation forestry
– The environment is relatively warm for the latitude and we are nowhere near the Sitka’s northern limit, so I don’t think temperature would be limiting either.
http://en.wikipedia.org/wiki/Picea_sitchensis
– Plantation spruce creates an incredibly dense canopy with almost no light getting through to the understory, and any direct sunlight is probably absorbed in the top few feet
http://linkinghub.elsevier.com/retrieve/pii/S0378112700006964
– The planting density is such that the trees are probably mostly stressed by competition for space (= light)
– Sun angles at that Lat are always pretty low which makes diffuse insolation even more important
So the explanation that it is the effect of clouds on scattering rings true to me… Is this testable directly? Are there measurements of the ratio of direct and diffuse sunlight?
Adolfo: The “diffuse component” is the blue-grey light you get from open sky/clouds as opposed to the direct (white/yellow) sunlight you get from the sun itself. As it gets cloudier the total amount received does indeed fall, but the amount received from the diffuse part *increases* because the clouds scatter the light that would have been direct for someone else (if that makes any sense!).
As I wrote above, the geography and nature of the forest here lends good support to that explanation.
Suddenly this seems very relevant again:
“Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds”, Harrison and Stephenson, Proc. R. Soc. A 8 April 2006 vol. 462 no. 2068 1221-1233
http://rspa.royalsocietypublishing.org/content/462/2068/1221.full
Sorry, I missed the note on the BBC site about it being in Dumfriesshire. It is indeed in the Southern Uplands:
http://stable.toolserver.org/geohack/geohack.php?pagename=Ae,_Dumfries_and_Galloway¶ms=55.1881_N_3.6_W_region:GB_type:city
Also, if you look at the the picture of the forest (taken by the paper’s author) on the BBC site:
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8311000/8311373.stm
you can see what I mean about density – and imagine where those trees get their light from when the sun angle is as low as 12 degrees. I wonder whether the rings can show whether the trees are more sensitive in the winter (or early and late in their growing season, if they go dormant), when diffuse light is more important?
maksimovich
Great post!
On chirality and polarisation, I make the obvious speculation that direct sunlight in high latitudes is heavily polarised, but cloud cover will diffuse the light and so depolarise it, and that may be why photosynthesis seems to be faster in cloudy conditions.
Maybe plants like depolarised light, so high latitude tree-rings could be a proxy for variation in polarisation of sunlight … such as cloud cover, local magnetic field, auroral effects, & co. etc. ,
evanmjones (17:33:50) :
That’s what I thought.
Very funny.
supercritical (07:12:27) :
Please don´t forget the rain. If clouds increase, rain increases.
Adolfo: This is the Southern Uplands we’re talking about! It’s hard to imagine how it could possibly rain any more than it already does 🙂
Scotland climate details: http://www.metoffice.gov.uk/climate/uk/ws/print.html
The Ae Forest is roughly near the ‘n’ of Drumlanrig, just north of Dumfries.
Wrong again. GCR just happened to correlate with volcanic activity during this period.
The idea that trees respond to solar cycles need not be derided here. It was the original intent of the science of tree rings.
http://www.treeringsociety.org/TRBTRR/TRRvol59_1_21-27.pdf
That these researchers are retracing ground alteady covered is a tribute to the pioneer who first went there, the objectives of this “new” research notwithstanding. (These researchers have not shown how they eliminated decreased moisture from the list of potential climatic growth factors.)
To be more exact, the scientists here need to show that these trees were not sensitive to moisture deprivation as a limiting factor to growth. WRT the high rainfall of the southern uplands. Consider that trees in a high rainfall area accustom themselves to such conditions – their root systems remaining moderate to small in size – whereupon a warmer, dryer year comes along. They “suffer” less growth in those years.
Perhaps a trick of the light is part of the reason for the extra growth. During solar minima sunlight contains less harmful ultraviolet ray (UVC) which can damage some plants, so better growth when this happens.
Just a quick question; anybody know what else correlates with cosmic ray activity? ( …. and therefore tree growth ….)
woodfortrees (Paul Clark) (07:11:18)
Paul, the pic you linked to in this post is interesting, all the foliage is in the top 1/3 of the trees. It’s almost a canopy in that pic.
supercritical, Paul (06:43:16) also posted the link to the study linking CRs to increased cloud formation, which might have some climate impact if it can be confirmed. The sunspot-climate correlation doesn’t have much in the way of mechanisms to describe how it’s supposed to work, so it’s been hard to defend the assertion that the two are really related. But that study might be a step in that direction.
Let’s not give too much credence to the authors’ basic finding. Note in particular that the correlation was weak, although significant. With this sort of data mining exercise, this admission should sound immediate warning bells. I don’t have access to the paper but it appears from the descriptions here and in their press release that several climate and non-climate variables were explored. The problem with this is that one of the variables has to come out to be top of the pops and the authors appear to admit there was no a priori reason for cosmic rays to be that one. In such circumstances the null hypothesis against which significance must be tested is not zero correlation but the population of maximum correlations among M uncorrelated trial variables with N years of record. This is a much higher bar to leap over than the basic one.
For example, assuming a reasonable figure of 0.25 for the standard deviation of the basic correlation coefficient given the length of record, then the expected largest correlation coefficient from a set of 10 trial variables would be about 0.4 even if all 10 were actually uncorrelated. This is the baseline from which one must judge significance, not the zero correlation that is customarily assumed. So a correlation coefficient of 0.5 or 0.6 which one might think very secure from its remoteness to zero would be far from safe if proper allowance were made for the circumstances of the analysis.
On a similar tache, without an a priori mechanism there is no reason to presuppose a postitive or a negative correlation, so did they use a two-tail test – most climatologists do not when they feel they are on the track of a real effect as it might spoil the story!
Another concern relates to the “y” variable, the tree ring widths. The assumption underpinning such testing is that this is an objective and error-free quantity. But the authors admit to a usual decline with age and normally the annual ring width is expressed not in raw form but as a departure from a computed trend line. How this is done is itself a source of uncertainty and gobbles up degrees of freedom which should be reflected in the significance test.
As I say, I have no access to the paper so the Edinburgh group may have got proper statistical advice that would warn them against reading too much into a marginal result. But from long and painful acquaintance with the statistical abuses of the research communities at the margins of climate and environment, I fear the worst.
Now! now! As alluring as the results of this study are, let’s all be good little science-peoples.
I am sure I heard some mention in recent years about correlation and causation?
paulhan (17:34:41) :
…
Either way, if confirmed, this has got to be yet another nail in the Hockey Stick’s coffin. Much more of this and we’ll need a second lid for it.
Actually I think we’ll need a stake for its heart, plenty of garlic and bright sunlight if we going to lay the hockey stick to rest.
Well, this is huge then. If CR is a bigger impact than temp, all the treemometers are broken.
Link to 1998 ice storm story and photos in Canada and US
http://windupradio.com/icestorm.htm
Just a subjective observation or two.
I’m an avid gardener, I love to grow veggies. When I grow tomatoes in the greenhouse I always paint the roof and the top line of the glass panes in the greenhouse walls with a whitewash type of stuff to stop direct sunlight on the growing tomato plants. This makes the plants grow straight up with a much lower tendency to put out axiliary shoots and it always results in a much heavier crop of fruit. I notice that commercial growers of tomatoes do the same thing.
Potatoes, also a member of the Solanacea family like tomatoes, do better when the summer is cloudy. Too much sun gives long, lank haulms with fewer and smaller tubers. In Ireland, where much of the summer is overcast, potatoes do very well indeed: shorter, sturdier haulms and better tuber yields.
It is a widely acknowledged fact here in the UK that, since the major decline in the use of coal to heat houses, there has now grown a necessity to spread sulphur on the ground in which certain crops are to be grown. This is to replace that sulphur which used to be had for free from the ‘polluting’ coal smoke. Another well-known gardener’s tip is to use Epsom Salts (magnesium sulphate) on green-leaf crops to increase yield.
A more practical and pragmatic view as to what affects the growth of any particular plant species must be part and parcel of any study of any vegetative matter, whether it be tree or algae before speculation of more esoteric factors are considered