'Cosmoclimatology' may explain the real drivers of climate change

To reach us here on Earth, GCRs must pass through, and is diverted by, the Sun's magnetic field, whichvaries in strength as solar activity changes as indicated by the changing sunspot numbers. When the field is strong during solar maximum, less GCRs penetrate into the solar system than when the field is weak (note: Cosmic Ray Flux (CRF) is also be affected by the Earth's magnetic field and that too may be influenced by the strength of the magnetic field of the Sun, but that is beyond the scope of this article).

As GCRs enter the Earth's atmosphere, they help form particles called aerosols in the lower atmosphere which may grow to cloud condensation nuclei. These are particles around which water can form to create droplets of water, a million of which are needed to make a moderate-sized raindrop. While the original droplets are microscopic in size, they are visible as clouds which act like a screen in a greenhouse controlling the amount of sunlight that can penetrate the atmosphere to heat the Earth's surface.

So, when the Sun is in a strong phase, with a stronger magnetic field, less GCRs enter the Earth's atmosphere and we have less clouds. This then amplifies the warming that is directly caused by a more active Sun.

Once again, the sequence of events is:

• a strong Sun causes slight warming on the Earth due to increased solar energy input to our planet.
• a strong Sun also causes a stronger solar magnetic field
• this field reduces the amount of GCRs that can enter the solar system and so Earth's atmosphere
• so less clouds form, amplifying the initial warming by the Sun.

The reverse is also believed to be true:

• a weaker Sun produces less warming on Earth due to decreased solar energy input to our planet.
• a weaker Sun also causes a weaker solar magnetic field
• this weakened field allows more GCRs to enter the solar system and so Earth's atmosphere
• so more clouds form, further reducing the initial reduced warming of the Sun.

Now here is where the work of Professor Nir Shaviv of the Hebrew University of Jerusalemand Professor Jan Veizer, the Distinguished University Professor (emeritus) of Earth Sciences at the University of Ottawa, that I discussed in the two previous parts of this series, comes in.

There was initially, and to some extent still is, disagreement in the climate science community (see The Cloud Mystery documentary) as to whether cosmic ray flux (CRF) really did cause significant changes in climate as Svensmark hypothesized.

But when the work of Shaviv and Veizer came out, it gave independent support to the idea that CRF was indeed a significant driver of climate, at least on geologic timescales. It was independent since it is not solar activity changing the cosmic rays affecting the climate over decadal time scales, as Svensmark proposed. Instead, Shaviv and Veizer's work was over hundred million-year timescales in which cosmic rays clearly drove climate due to the frequency and proximity of supernovae. This then lent significant support to Svensmark's theory, important parts of which were bolstered in experiments that Svensmark carried out, and also in the CLOUD experiment at the European Organization for Nuclear Research (CERN), an intergovernmental organization that operates the largest particle physics laboratory in the world in Switzerland.

Science writer Nigel Calder reported that the experiments that could prove Svensmark's theory were delayed for a strange reason:

"The Director General of CERN stirred controversy last month, by saying that the CLOUD team's report should be politically correct about climate change. The implication was that they should on no account endorse the Danish heresy – Henrik Svensmark's hypothesis that most of the global warming of the 20th Century can be explained by the reduction in cosmic rays due to livelier solar activity, resulting in less low cloud cover and warmer surface temperatures."