The activity of the sun, after a long period of low activity, is getting higher. This means that the planet upon which we leave is subjected to more solar irradiance than normal. Solar irradiance is changing both as an overall amount and of ultraviolet irradiance. Our planet will receive more solar energetic particles and fewer cosmic rays. These cyclical changes are normal and some think that there is an eleven year cycle of a calm sun followed by eleven years of a more aggressive sun. We are now getting into the more aggressive phase of the sun.
These changes will inevitably affect our climate; more particularly they affect the climate in the lower part of the atmosphere where humans live. I shall explain how each part of the changing process affects our climate in later posts, but for now the simple thing to bear in mind is that the more solar irradiance there is, the greater the climate forcing of the sun is, warming the seas a little and affecting the water cycle. The greater solar ultraviolet radiation then there is more heating of the upper and middle atmosphere, which has a knock on effect. Solar energetic particles and galactic cosmic rays affect ionisations of the upper and middle atmosphere and the ionisation of the lower atmosphere respectively.
We understand more about climate change now than we did twenty years ago when the sun activity was higher. Scientists will be measuring and observing the changes in the sun now in more detail and with greater precision than ever. They may not establish exactly how much of our changing climate is due to solar activity changes but I expect within a few years we shall know much more about this than we do now.
The importance of this is that in a few years scientists should be able to explain with greater accuracy the causal link between human greenhouse gas emissions and climate change. A lack of a provable causal link is what is holding back universal acceptance of anthropogenic climate change and lack of universal acceptance of climate change is preventing the humans from changing their behaviour and carrying out measures to limit green house gas emissions with any significance.
It may be that we will never have an irrefutable causal link, or that when we do have one it will be too late.
Filed under: carbon emissions, climate change, global warming | Tagged: causal link in climate change, cosmic rays, galatic, soalr UV irradiance, solar energetic particles, solar irradiance, sun. solar activity | 4 Comments »