Citola Blog
Cosmic Rays and Climate Science - Part III
In two previous blogs we described a recent study by Dengel, Aeby and Grace which reported correlation between cosmic-ray intensity and tree-growth rate. Now to consider how these findings sit within climate change science…
We noted the absence of an agreed explanation for the study’s findings. Dengel proffered, as you may recall, two possible explanations; the first being a direct effect of cosmic rays on trees, the second a causal chain of events involving cloud cover. The first of these explanations is more opaque, with very little scientific understanding of how this mysterious direct effect would function. For the sake of further discussion, therefore, let's assume for the moment that Dengel’s ‘cloud cover’ explanation is accurate. (That cosmic rays cause ionised particles in the atmosphere, in turn causing greater cloud cover, greater light diffusion, increased light penetration in forests, higher photosynthesis and increased tree growth).
What could this mean for climate change? Some may cite this as an example of a non-man-made force effecting the Earth’s climate and ecology. Scientist Professor Svensmark, Director of the Center for Sun-Climate research of the Danish National Space, has for some time been a vocal proponent of the hypothesis that cosmic rays (and solar activity) regulate the Earth’s temperature.
Dengel’s findings could be seen as further evidence of the impact of cosmic rays and solar activity.
More recently, however, reports have been published which discount Svensmark’s theories. Studies such as that of Pierce & Adams (2009) employed climate models to measure the impact of the ionising effect of cosmic rays on the atmosphere, and hence on the climate. They concluded that the impact of cosmic rays was 100 times too small to impact the Earth’s climate.
What of the IPCC? In their 2001 report the IPCC discounted cosmic rays and solar activity as causes of climate change. The report concludes that “mechanisms for the amplification of solar forcing are not well established” ) owing to problems in Svensmark’s theory, and a lack of sufficient evidence in the work of other scientists in the field.
Interesting fodder for further debate…
In our next blog we’ll put climate change arguments aside and consider what Dengel’s study can add to forestry…
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