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Curious Cosmic Link to Tree Growth
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.
BBC News website: ‘Cosmic pattern to UK tree growth’
A relationship between galactic cosmic radiation and tree rings
Sigrid Dengel, Dominik Aeby and John Grace
Institute of Atmospheric and Environmental Science, School of GeoSciences, Crew Building, University of Edinburgh, EH9 3JN, UK
KEYWORDS
diffuse radiation • galactic cosmic rays • Sitka spruce (Picea sitchensis) • tree rings • volcanic eruptions
New Phytologist (2009)
ABSTRACT
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.
There’s also a commentary in the same issue of New Phytologist (free pdf):
Environment: On the possible links between tree growth and galactic cosmic rays (p 511-513)
Markku Kulmala, Pertti Hari, Ilona Riipinen, Veli-Matti Kerminen
October 20th, 2009 at 7:53 am
So let me get this straight-we can show that paleoclimate correlates with solar activity as estimated from cosmogenic nuclides. So the conclusion is “Oh, well, tree rings aren’t climate after all, they are cosmic rays, which clearly can’t impact climate, which only people can do”. I’m sorry but would Occam’s Razor step in here and say “this is silly, clearly the solar activity modulates climate, and therefore effects tree growth.”
At least the authors of this paper seem to be considering that much simpler explanation.