Cosmic Radiation Makes Trees Grow Faster

Diamonddavej writes "The BBC reports that researchers at the University of Edinburgh have found that Galactic Cosmic Rays (GCRs) somehow makes trees grow faster. GCRs vary according to the 11-year solar cycle, with more GCRs hitting the Earth during solar minimum when there is a lull in the solar wind, which normally acts to protect the inner solar system from external galactic radiation. The mechanism might have something to do with GCRs increasing cloud cover, which diffuses sunlight and increases the efficiency of photosynthesis. Nevertheless, the researchers remain mystified and are requesting further ideas and research collaboration to test hypotheses. (How about Radiation Hormesis, AKA 'Vitamin-R?')" Here is the paper's abstract at the journal New Phytologist. The researchers say: "The relation of the rings to the solar cycle was much stronger than to any climatological factors. ... As for the mechanism, we are puzzled."

Comments

Big Surprise

[JumperCable]

researchers at the University of Edinburgh have found that Galactic Cosmic Rays (GCRs) somehow makes trees grow faster

I don't think they need to look any further for answers than the Fantastic Four.

It's called research

[EdIII]

As for the mechanism, we are puzzled

Geez and they're scientists? Just do a little research. I suggest Marvel Comics. Plenty of good info there. At the risk of starting war, I would caution them against research using DC Comics as they are for simple idiots that live in their mother's basements.

causality is possibly wrong

[wizardforce]

If the solar cycle is what determines the level of GCR that gets to Earth then it may very well have absolutely nothing to do with the tree growth its self but an indicator of solar conditions which influence tree growth rates.

Re:causality is possibly wrong

[cjfs]

But correlation is causation.

No, the two are merely correlated.

Ow...

Re:causality is possibly wrong

[khayman80]

That's what I'm thinking too. GCR intensity is highest when sunspot activity is lowest, generally modulating on an 11 year cycle. But solar irradiance also varies at the same frequency; the Sun is actually (~0.1%) brighter when more sunspots are present, contrary to intuition.

If tree growth between 1953-2006 really is highest when sunspot activity is lowest, that implies trees grow faster when the Sun is very slightly dimmer. Weird. Their diffusion explanation makes sense, but as they note this cloud condensation effect is supposed to be a very small effect. Perhaps it's just large enough to be noticed in these proxy data, though. I agree, however, that a link to solar irradiance is more intuitively appealing, and it's not immediately obvious how it could be ruled out.

I'd bet they've already considered this issue and ruled it out, possibly by using satellite measurements of solar irradiance and solar wind over the last few decades. They're supposed to be tightly correlated, but if the solar wind varies even slightly differently than solar irradiance it should be possible to see which is causing this variation in growth rates.

cue the bad superhero jokes ...

[Korbeau]

in one, two, tree ...

Cloud cover

[MichaelSmith]

The mechanism might have something to do with GCRs increasing cloud cover, which diffuses sunlight and increases the efficiency of photosynthesis.

How about cloud cover leads to more precipitation?

Re:Cloud cover

[MichaelSmith]

How about cloud cover leads to more precipitation?

No. Precipitation cannot be larger than evaporation. Evaporation is heat driven, and cosmic rays do not input enough heat energy to significantly contribute to evaporation.

Radiation nucleates droplets in clouds so that water vapor precipitates where it otherwise would have stayed in the atmosphere. Its a bit like how dust from outer space contributes to rainfall by encouraging the formation of drops big enough to fall as rain.

Repeat after me: Correlation Is Not Causation

[Shaterri]

Especially in a case like this, where there are other tightly-correlated variables. Why is the authors' presumption that it's the cosmic rays (or lack thereof) that are regulating tree growth, rather than solar and sunspot activity itself? It seems at least as plausible to me that sunspot activity correlates to some other solar features (e.g., solar irradiance) that would have a more natural and direct effect on tree growth than cosmic rays.

Re:Repeat after me: Correlation Is Not Causation

[MichaelSmith]

Are you saying that tree growth may be causing cosmic radiation?

Re:Repeat after me: Correlation Is Not Causation

[Anonymous Coward]

it's the butterfly effect or something

It's Simple Really

[eldavojohn]

What else grows from radiation? Cancer. Quod erat demonstratum, trees are cancer. Therefore we must cut them down and burn them. Perhaps form some sort of industry devoted to this.

What? The "logging" industry? Oh, well, very good then. Continue.

Re:It's Simple Really

[MichaelSmith]

I am the lorax. I speak for the trees, which you seem to be cutting as much as you please.

Re:Breaking News

[olsmeister]

Chernobyl is not cosmic radiation.

Re:Once upon a time

[wizardforce]

objects do not become radioactive unless they are bombarded with neutron radiation, high energy protons or extremely high energy gamma radiation capable of ejecting a proton or neutron to form a radioactive isotope. Simply irradiating an object does not necessarily make the object radioactive. Now in so far as plants having a higher growth rate due to radiation, I haven't heard much on the subject other than radiotropic melanized fungi living near Chernobyl having a substantially increased growth rate.

Nitrogen Fixation

[physburn]

This is an easy mystery to solve. When a cosmic ray hits the atmosphere, it creates a shower of ionizing radiation, each of the secondary particles are enough to ionizing oxygen and nitrogen molecules in the atmosphere, forming nitrogen oxides, these react ready with water forming nitric acid, which will precipitate in dilute form in the rain. Only lightning and cosmic rays can form nitrogen oxide, and lightning is relatively rare, so the amount of available free nitrates in the soil, depends very much on the amount cosmic rays hitting the earth.

Plants of course need nitrogen to grow, the trouble is they can't absorb nitrogen from the atmosphere (except for Legumes (pea, and beans and similar plants)). So for the majority of plants and trees, not feed by human fertilizers, the amount of fertilizing nitrate available to them, is directly proportional the cosmic ray flux.

Mystery Solved.

---

Dark Matter Feed @ Feed Distiller

Re:Nitrogen Fixation

[AJWM]

Only lightning and cosmic rays can form nitrogen oxide, and lightning is relatively rare,

Well no, lighting is fairly common, actually -- there's always a lighting storm going on somewhere. However, if one assumes that the global rate of lightning is fairly constant then given that the amount nitrogen oxides contributed by cosmic rays fluctuates, you'd still see a correlation. So you may be right.

Further ideas?

[kauttapiste]

Nevertheless, the researchers remain mystified and are requesting further ideas ...

Have they considered Ask Slashdot?

Re:I remember this finding...

[tabrnaker]

Obviously you've never grown plants!
Get back to us when you have real knowledge and not 'book smarts'.

Sun spots

[Anonymous Coward]

At the university I studied physics at, they had a nice (old) telescope with which they projected solar images to count sun spots. They had a graph on the wall of the number of sun spots, going decades back. There was a nice periodicity in that graphc, and interesting thing is that they could point out two types of events: good wine years, and the occurrence of the "Elfstedentocht" (a major Dutch ice skating event which only happens when the outdoor ice conditions are exactly right).

I forgot which one happened at sunspot maxima and which at the minima, but there was a striking correlation.