Does the Sun Cause Climate Change?

In recent years, the idea that the climate is driven by clouds and cosmic rays has received plenty of attention. Despite quasi-religious insistence in some quarters, the theory is significant because it suggests the fundamental driver of "climate change" is the sun.

The notion sometimes is ridiculed, but recently we have seen potential evidence that even settled theories of major consequence are subject to new experimental evidence.
Einstein's famous equation E=MC2  is among the fundamental aspects of modern physics that would have to be revised if it turns out other scientists can replicate the recent finding of a sub-atomic particle that travels faster than the speed of light, as physicists at CERN recently have reported.

If "C" is off, it means that all nuclear physics has to be recalibrated, says scientist Michio Kaku, theoretical physics professor at City College of New York.


Modern physics is based on two theories, relativity and the quantum theory, so half of modern physics would have to be replaced by a new theory.


The point is that all scientific theories are just that: theories. When the evidence changes, theories have to change.

Interest in the idea that it is sun activity that explains Earth's dramatic changes of climate in the past is credited to Danish physicist named Henrik Svensmark, who first suggested it in the late 1990s.

Using satellite data on cloud coverage, which became available with the establishment of the International Satellite Cloud Climatology Project in 1983, Svensmark found a correlation between lower troposphere cloud cover and the 11-year solar cycle.


He proposed that cosmic rays initiate the formation of aerosols in the lower atmosphere that then form condensation nuclei for cloud droplets, increasing cloud formation from water vapor. Since low-level clouds increase Earth’s albedo (the amount of incoming solar radiation that is reflected back into space), more clouds mean cooler temperatures.

Svensmark claimed that this mechanism was responsible for virtually every climatic event in Earth history, from ice ages to the Faint Young Sun paradox to Snowball Earth to our current warming trend. Needless to say, this would overturn decades of climate research, and challenge the notion that human-caused activity is primarily responsible for climatic change.

The assertion will be met in some instances by quasi-religious opposition. But that opposition is just that: quasi-religious, not scientific.

Do cosmic rays set the earth's thermostat?