A relationship between galactic cosmic radiation and tree rings

Abstract

Summary• 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 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.

Solar change and climate: an update in the light of the current exceptional solar minimum

“…For example, Dengel et al (2009) have recently published a small but significant correlation between cosmic ray fluxes and tree growth rates in the UK. On its own, one such correlation means little for climate studies, but in the context that most paleoclimate evidence for solar influences of climate involves reported correlations between cosmogenic isotopes and proxies for local and regional rainfall rates (see review by Lockwood & Fröhlich 2007), they may take on additional significance.…”

Araucaria growth response to solar and climate variability in South Brazil

“…This modulation can be caused by the cosmic ray ionization, which increases the diffuse radiation, and consequently, makes the photosynthetic production more efficient (see Urban et al, 2007;Dengel et al, 2009, and references therein). Inoue et al (1979) showed that the tree growth is greater when it is not under extremely shady conditions compared to full daylight conditions.…”

“…It is also possible that the correlation and the phase shift between tree-ring width and the sunspot number series can be due to the modulation of the cloudiness (Dengel et al, 2009). This modulation can be caused by the cosmic ray ionization, which increases the diffuse radiation, and consequently, makes the photosynthetic production more efficient (see Urban et al, 2007;Dengel et al, 2009, and references therein).…”

Biosphere-atmosphere exchange of CO<sub>2</sub> in relation to climate: a cross-biome analysis across multiple time scales

“…Until eddy covariance time series are extended, it remains unclear how vegetation and climate interact to create low-frequency flux oscillations, and the relative importance of low frequency oscillations to the carbon balance of global ecosystems (Rigozo et al, 2007;Qian et al, 2008). Uncovering the mechanisms for these multi-annual energetic events require longer time series coupled with careful process-level studies (Dengel et al, 2009). …”