Earth's position in the Milky Way-major effect on Climate Change

In responding to another thread, I came across this article:
www.guardian.co.uk...
Of major interest to me was this excerpt:

Nir Shaviv is a senior lecturer in physics at the Hebrew University in Jerusalem, Israel:

"Once every few decades a massive star from our galaxy, the Milky Way, runs out of fuel and explodes, in what is known as a supernova. Cosmic rays (high-energy particles like gamma rays) spew out in all directions and if the Earth happens to be in the way, they can trigger an ice age. If the Earth already has a cold climate then an extra burst of cosmic rays could make things really icy and perhaps cause a number of species to become extinct. The Earth is at greatest risk when it passes through a spiral arm of the Milky Way, where most of the supernova occur. This happens approximately every 150m years. Paleoclimate indicators show that there has been a corresponding cold period on Earth, with more ice at the poles and many ice ages during these times.

"We are nearly out of the Sagittarius-Carina arm of the Milky Way now and Earth should have a warmer climate in a few million years. But, in around 60m years we will enter the Perseus arm and ice-house conditions are likely to dominate again."

So, according to Shaviv, our position in the Milky Way has a major effect on Climate. Perhaps Al Gore and his cohorts ought to stop worrying about manmade GW, he should accept the fact the Earth is just entering another area of our Galaxy, and nothing that he or the Nobel Committee can do, will alter that.