"The growth of British trees appears to follow a cosmic pattern, with trees growing faster when high levels of cosmic radiation arrive from space.

As yet, they cannot explain the pattern, but variation in cosmic rays impacted tree growth more than changes in temperature or precipitation.

The relation of the rings to the solar cycle was much stronger than to any climatological factors

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.

The intensity of cosmic rays also correlates better with the changes in tree growth than any other climatological factor, such as varying levels of temperature or precipitation over the years.

The correlation between growth and cosmic rays was moderately high, but the correlation with the climatological variables was barely visible.

When the researchers looked at their data, they found that tree growth was highest during periods of low sunspot activity, when most cosmic rays reached Earth.

We also thought it would be interesting to look for patterns related to solar activity, as a few people previously have suggested such a link. We found them and the relation of the rings to the solar cycle was much stronger than it was to any of the climatological factors we had looked at.

Ms Dengel's team proposes two main hypotheses as to how cosmic ray particles could influence the growth of trees.
The first idea is that cosmic rays ionise gases in the atmosphere, creating molecules around which clouds condense, therefore increasing cloud cover that would diffuse the amount of solar radiation reaching the trees.
As diffuse radiation penetrates forest canopies better than direct light, it would increase the amount of radiation that plants capture, and increase photosynthesis by trees, boosting growth.

Or there is some direct effect. What that might be is unknown, but experiments in space have shown that cosmic rays can have some positive impacts on biological materials.

The influence of cosmic rays could resolve other as yet unexplained cycles in tree growth found in studies in North America."