Solar System's Path May Have Spurred Ice Ages

ImproperShutdown writes "Space.com reports that a physicist has found a correlation between the amount of cosmic rays reaching the Earth, as it passes through the spiral arms of the Milky Way, and the planet's ice ages over the last billion years. Apparently, as the Solar System passes through the higher density spiral arm regions, it receives more cosmic rays from the higher density of supernovae that have occurred in the region. This larger flux of cosmic rays ionizes the Earth's atmosphere more, which makes it more cloudy and cools down the Earth."

Comments

Supernova

[slug359]

I remember seeing this interesting program on a Discovery program ~ 2 years ago, covering exactly the same topic.
It also explained the effects of cosmic rays on space missions, from supernovas, and how more older stars are present in the 'arms' of the galaxy.

It also went into great detail about the effects cosmic rays had on the early space missions, leaving very very very tiny dents (albeit all over) the spacecraft.

Re:Supernova

[no reason to be here]

I saw something recently (i.e. sometime in the last three months) on discovery (or possibly the learning channel) that explored the connection between average global temperature and deep sea currents. apparently, so long as the deep sea currents continue on un abated, avg. temperatures stay stable from year to year, and temperatures don't get too extreme in different areas of the globe.
the last major disruption began around the end of the last ice age, and we humans have had an usually steady climate during our reign as king species.

See, there they go again.

[Snafoo]

Once again our 'scientists' have managed to
misintepret perfectly clear statistical
data by imposing a faulty chain of causality.

Obviously, things are back-to-front. Ice ages
cause changes in the path of the solar system.

Duh.

Global warming?

[EvlG]

Is the inverse true? Does the current path through the universe mean fewer cosmic rays are hitting us, and leading to global warming?

Could this be a factor?

Re:Global warming?

[dankelley]

Probably not. The timescale is wrong. Besides, the warming trend [difficult as it is to measure] seems to be consistent with CO2 emissions, linked through climate models in which we have [some, of not great] confidence.

Re:Global warming?

[anthony_dipierro]

Besides, the warming trend [difficult as it is to measure] seems to be consistent with CO2 emissions, linked through climate models in which we have [some, of not great] confidence.

It is also consistent with changes in the magnetic flux of the sun.

The question of global warming is still out.

Re:Global warming?

[Planesdragon]

The question of global warming is still out.

Really? We know two things.

1: The world is getting hotter.

2: We're spitting out pollutants that, among other things, can theoretically raise the tempature of the world.

Let's do the prudent thing and reduce them first; even if the world still gets hotter, at least it'll be a mite bit cleaner.

Re:Global warming?

[g4dget]

There are many factors that influence climate. But we know for certain that CO2 levels have increased dramatically already, due to human activity, and that increase continue. If we don't stop that, that will lead to massive, unpredictable changes in our climate and that just can't be good. Looking at temperature records is secondary.

Re:Global warming?

[anthony_dipierro]

The world is getting hotter.

So?

Let's do the prudent thing and reduce them first; even if the world still gets hotter, at least it'll be a mite bit cleaner.

It's a question of cost and benefit. Time spent figuring out ways to limit CO2 emissions is time not spent on other things, like figuring out the cure for cancer. Nothing is free, everything has positive and negative effects.

Personally, I think yes, we should tax products which generate CO2 emissions and tax cutting down trees which also increases the CO2 in the atmosphere. Spend the money researching the problem, fixing it, and planting trees. But the jury is still out on whether or not there even is a problem in the first place.

Re:Global warming?

[yzquxnet]

There are many factors that influence climate.

You've got that right, Solar cycles, water vapor, dust, ?cosmic rays?, CO2. Lots of stuff.

But we know for certain that CO2 levels have increased dramatically already

Yeah, we can see that. This is pretty much a given.

due to human activity

Now, this is where things get ugly. As of to date, no one has conclusively shown that the dramatic increase in CO2 is soley caused by us. As natural fluctuations are easily shown in proxy records. The question is how much have we added to the change. Lets say that C02 levels have risen 100% in the last 10 years (just as an example). So, maybe we have contributed 99% of that, or maybe we are responsible for only 1%. Who knows?

If we don't stop that, that will lead to massive, unpredictable changes in our climate and that just can't be good.

The reverse may just as well be true as well. As the biosphere becomes more in tune with higher CO2 levels (a greening perhaps) a sharp reduction may cause just as much unpredictable change.

For as long as I can remember, and read about, people have been living on the banks of the rivers around my area. Every spring the flood waters flow through and there are always a few houses that get washed away. In the last half decade or so, from what I have noticed, every spring now after the waters receed there is a cry. More like a plee. 'We must stop the greenhouse gasses', 'SUV's are flooding my land'. It has become so easy to place blame on CO2. It doesn't do anything when you pick on it. It just stays there and takes. The river banks have flooded in the past, they will flood again.

This is not his first bad theory.

[Peter T Ermit]

Here at the APS site, there's an abstract. It looks like a bad paper -- one of a zillion theories that make mountains out of correlations. It's not even this author's first proposal of this sort. Five years ago, he suggested that the cosmic rays caused extinction events.

Sounds like this guy has a favorite hammer, and he's now convinced that everything looks like a nail.

this could be good...

[skydude_20]

for geeks that is... see since we tend to like sci-fi, space exploration, etc... we just have to let the environuts know about this, then they lobby for us to build massive space structures to shield us from the cosmic rays or generate more... cuz comeon, really, save the environment! stop cosmic rays!

It does lend credence to another theory

[theolein]

There was this book by a scientist/philosopher called Fritjof Capra that I read many years ago that claimed that one cannot be objective as everything is part of some system. This sort of makes some kind of sense in that direction in that the solar system is not isolated from it's galaxy and is part of the "process" in our milky way.

Re:How can the solar system do this???

[CheshireCatCO]

First of all, the orbits of stars about the galaxy are Keplerian. They don't orbit as a solid body (like a record) but more like the planets.

What makes this more interesting still is that the spiral arms are not composed of specific stars all the time. The spiral pattern propogates through the stars and gas in the galaxy (triggering star birth along the way). A given star will enter and leave the arms as the star comes up from beind the arm, passes through, and leaves. (Or from the other direction, depending.)

I'm skeptical that we know the pattern speed of the sprial arms that well. When I was doing a paper on the "rare Earth" idea, I was looking up the co-rotation radius (the place where a star would always been inside or outside of a spiral arm because it orbits at the same speed as the pattern) for our galaxy. I found very conflicting numbers quoted in papers.

100's of millions of years, not thousands.

[apsmith]

Some of the other posts (not having read the actual article presumably) and the space.com report itself seem a bit confused about the way the term "ice age" is being used here. Based on estimates (somewhat shaky, as was pointed out in another comment) of the galactic rotational speed of the spiral arms relative to stars like our Sun, this paper shows a surprising correlation over the past billion years between times our solar system was within a spiral arm, and periods of significant glaciation lasting 10's or 100's of millions of years.

According to the calculations in the article, the solar system has passed through the four spiral arms ("Orion" or Sagittarius-Carina, Scutum-Crux, Norma, and Perseus) a total of seven times over the last billion years, or roughly once every 150 million years. We've actually only recently left the Orion arm (heading for Perseus) so the cosmic-ray flux is still quite high, and according to the author's diagram, we are STILL experiencing a major glaciation period. Since the last "ice age" as we know them ended just over 10,000 years ago, that time scale is WAY to short to show up on the scale of this article. In other words, we're still in the middle of an ice age, as far as this paper is concerned.

While the thickness of the spiral arms is such that we pass through them in about 30 million years, the cosmic ray effects last 50-60 million years or more, depending on the level of star-formation within the arms at any given time. The author also notes that it is believed our galaxy had a peak in star production about 300 million years ago, and had much lower star production prior to about 1 billion years ago (until you get back to the 2-3 billion year period and earlier, for which we don't have much in the way of geologic records). In addition to the ice age records, the author also looks at records from iron meteorites radio-isotope dating to get another measure of cosmic ray flux in those periods, which also seems to correlate.

Anyway, interesting stuff, but on a time scale much bigger than we normally think about when we think of ice ages. The ice age before the current one according to this model dates to before the rise of the dinosaurs; go back a couple more and it's before we have any evidence of complex life on Earth!

Re:Physics?

[Stoutlimb]

I give energy to my car's heating system when I flip the switch to the "off" position. (The act of flipping the switch requres energy). By your reasoning, this should also violate thermodynamics.

Re:How can the solar system do this???

[Tablizer]

What makes this more interesting still is that the spiral arms are not composed of specific stars all the time. The spiral pattern propogates through the stars and gas in the galaxy (triggering star birth along the way). A given star will enter and leave the arms as the star comes up from beind the arm, passes through, and leaves. (Or from the other direction, depending.)

The "arms" are often described as "waves" rather than a physical collection. It is a density compression and decompression pattern of some sort.

My understanding is that there are still many rough spots in the theories regarding knowing exactly what causes these spiral waves and how they move.

It might all be tied into the mystery of what the dark matter is that is helping to hold galaxies together.