Milky-Way Galaxy/Earth Biodiversity Link? Experts Say "Yes"

[HowToBe]

Interesting article on how the cyclical movements of our sun through the Milky Way possibly affect the evolution of life on Earth. SOTT has already run a few articles mentioning this phenomenon (I should have searched first!: http://www.sott.net/article/220248-Earths-Exposure-to-Radiation-Stresses-Biodiversity-Study-Says http://www.sott.net/article/192194-Death-Rays-From-Space-How-Bad-Are-They http://www.sott.net/article/181905-Earth-seems-to-be-driven-by-the-wave-like-cycle-of-the-solar-system and I bet there are more...), but I did a little research about this which is below the quote.

http://www.dailygalaxy.com/my_weblog/2009/05/hubbles-secret.html
Here's the relevant excerpt:

[...]

Researchers at the University of California, Berkeley found that marine fossil records show that biodiversity increases and decreases based on a 62-million-year cycle. At least two of the Earth's great mass extinctions-the Permian extinction 250 million years ago and the Ordovician extinction about 450 million years ago-correspond with peaks of this cycle, which can't be explained by evolutionary theory.

Our own star moves toward and away from the Milky Way's center, and also up and down through the galactic plane. One complete up-and-down cycle takes 64 million years- suspiciously close to the Earth's biodiversity cycle.

Once the researchers independently confirmed the biodiversity cycle, they then proposed a novel mechanism whereby which the Sun's galactic travels is causing it.

It’s no secret that the Milky Way is being gravitationally pulled toward a massive cluster of galaxies, called the Virgo Cluster, which is located about 50 million light years away. Adrian Melott and his colleague Mikhail Medvedev, speculate that as the Milky Way rushes towards the Virgo Cluster, it generates a so-called bow shock in front of it that is similar to the shock wave created by a supersonic jet.

"Our solar system has a shock wave around it, and it produces a good quantity of the cosmic rays that hit the Earth. Why shouldn't the galaxy have a shock wave, too?" Melott asks.

The galactic bow shock is only present on the north side of the Milky Way's galactic plane, because that is the side facing the Virgo Cluster as it moves through space, and it would cause superheated gas and cosmic rays to stream behind it, the researchers say. Normally, our galaxy's magnetic field shields our solar system from this "galactic wind." But every 64 million years, the solar system's cyclical travels take it above the galactic plane.

"When we emerge out of the disk, we have less protection, so we become exposed to many more cosmic rays," Melott has said.

The boost in cosmic-ray exposure may have a direct effect on Earth's organisms, according to paleontologist Bruce Lieberman. The radiation would lead to higher rates of genetic mutations in organisms or interfere with their ability to repair DNA damage. In this way, the process could lead to new species while killing off others.

Cosmic rays are also associated with increased cloud cover, which could cool the planet by blocking out more of the Sun's rays. They also interact with molecules in the atmosphere to create nitrogen oxide, a gas that eats away at our planet's ozone layer, which protects us from the Sun's harmful ultraviolet rays.

[...]

So maybe aligning with the galactic plane is not so significant, except that it is a transition between a harsher environment and a more sheltered one.

After some searching I think I've figured out which side we are currently passing into, but someone would have to confirm it. The solar apex - the direction our solar system is traveling through the galaxy right now - is in the general direction of the star Vega (https://en.wikipedia.org/wiki/Solar_apex).
According to _http://www.idialstars.com/tspm.htm (warning - this website has an annoying bright yellow background)

Presently, the Sun resides some 88 light-years north of the galactic plane and is flying northward at 7 kilometers per second.

Quoting the article again:

The galactic bow shock is only present on the north side of the Milky Way's galactic plane, because that is the side facing the Virgo Cluster as it moves through space, and it would cause superheated gas and cosmic rays to stream behind it, the researchers say. Normally, our galaxy's magnetic field shields our solar system from this "galactic wind." But every 64 million years, the solar system's cyclical travels take it above the galactic plane.

So crossing the plane is at least a transition in this sense. Things are "heating up". ;) The time scales, however, are astronomical (pun intended).

According to one of those other SOTT articles I linked above ("Earth's Exposure to Radiation..."):

At the lower bound, Earth would receive 88 percent more radiation than normal, or about 1.88 times the average dose.

And I definitely should have searched first:

So what's in store for Earth in the near future? The solar system is on the upswing now, bobbing toward the northern edge of the galactic disk. But big increases in cosmic-ray exposure are probably still about 10 million years off, researchers have said.