'Cosmoclimatology' may explain the real drivers of climate change

Changes in solar output, not humanity's carbon dioxide emissions, are likely the primary driver of climate change over at least the past few centuries.

Scientists have long observed a noticeable relationship between solar activity, as indicated by sunspot numbers, and so-called "global temperatures" for centuries. It was in 1613 when GalileoGalilei, the father of modern astronomy, used the newly invented telescope to begin recording darker areas, some far larger than the Earth, on the surface of the Sun. It caused a social and religious uproar because everything beyond the Moon was supposed to be pristine and unblemished despite the fact that there are records from Ancient Greece and China from centuries before Christ of observations of these dark areas.

Some people argued that the dark areas were moons or planets in front of our home star. But Galileo was right - they are actually a characteristic of the Sun itself, a phenomenon we now call sunspots.

Today, we know that sunspots are areas of the sun's atmosphere which are up to 3,000 degrees Kelvin cooler than the surrounding photosphere, making them appear much darker. They are caused when the Sun's magnetic field breaks through the surface.

The number of sunspots rises and falls in a regular 11-year cycle. This coincides with a change in the amount of radiation emitted by the Sun. Even though sunspots are much cooler than the rest of the photosphere, the Sun is more active when the number of sunspots is also at a maximum.

What scientists observed was that, when there were many sunspots, the Earth was warmer. When there were fewer spots, it was colder. Why this was the case, no one knew. After all, as I pointed out in my article from two weeks ago:

The Total Solar Irradiance, the amount of solar energy reaching the top of Earth's atmosphere, only varies by about 0.1% over the course of the familiar 11-year sunspot cycle. While the variations can be greater for longer cycles, for example, the 200-year solar cycle, they are still insufficient to account for the observed warming, at least via direct solar insolation changes.

So, for changes in the Sun's output to be a significant driver of the climate change we have seen over the past century and before, there would have to be a natural factor amplifying these changes.

Until the 1990s, no plausible explanation for this problem existed, so one could argue that the United Nations Intergovernmental Panel on Climate Change (IPCC) was probably justified to ignore sunspots in predicting future climate. But, in 1991, two researchers from the Danish Meteorological Institute, E. Friis-Christensen and K. Lassen, published a new theory in "Length of the Solar Cycle: An Indicator of Solar Activity Closely Associated with Climate."It was not the answer to the amplification issue, but it was a step forward in recognizing that the Sun plays a more significant role than previously thought. By 1997 scientists started to home in on the answer when Friis-Christensen and Henrik Svensmark, also of the Danish Meteorological Institute,published the paper, "Variation of Cosmic Ray Flux and Global Cloud coverage – A Missing Link in Solar-Climate Relationships."

As I described in last week's article, galactic cosmic rays (GCRs) are high-energy (and high speed, nearly the speed of light) atomic nuclei or other particles traveling through space that originate in supernovas in deep space, eventually flooding into our solar system. When they enter the Earth's atmosphere, they appear to affect climate (note: lower energy cosmic rays originate in the Sun and the variability of solar cosmic rays probably affects climate as well).

The IPCC was still perhaps right to not accept these untested new ideas. However, by 2000 the theory was evaluated through experiments and what is now known as the Svensmark or Cosmic Theory appears to provide the missing amplifier that accounts for the observed correlation between solar activity and Earth's climate.

Here is how it works.