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.
- 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