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

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.

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.

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