Solar System's Path May Have Spurred Ice Ages 34
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."
Supernova (Score:2, Interesting)
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 (Score:2, Interesting)
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. (Score:4, Funny)
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? (Score:2)
Could this be a factor?
Re:Global warming? (Score:2, Interesting)
Re:Global warming? (Score:3, Interesting)
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 [bbc.co.uk].
The question of global warming is still out.
Re:Global warming? (Score:3, Insightful)
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? (Score:3, Insightful)
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? (Score:1)
Some measurements actually indicate cooling. The latest "global warming" statistic also claimed temps were up a little...but would have been up a lot more if the planet hadn't actually been cooling
Well, I wouldn't expect actual temperature measurements to be conclusive for at least the next 20 years. On the other hand, once things take off, there's precious little we can do to stop it.
Look up the term "Little Ice Age". We've been warming up since medieval times...because European weather was unusually cold then.
Yes there is natural variation in the weather. Which shows that the climate does undergo changes in response to small forcing factors (i.e. minor changes in solar output). Which strongly indicates that the extra carbon dioxide will cause problems
Look at the planet's temperatures over millions of years. We're usually warmer than this -- and we had an Ice Age recently enough that parts of the planet are still rising now that the weight of the ice is gone (making ocean level measurements way too much work).
Yes, the planet IS usually warmer than this. That's a major part of the problem; the very large scope for temperatures to increase.
It's obvious that we are emitting gases which cause over 90% of the Earth's greenhouse effect. Actually, in recent decades our cars have been spewing out even more of this greenhouse gas, water vapor.
Water vapour cannot act as a forcing factor as it is always in close equlibrium - it can only ever respond. Which means it'll tend to magnify any trend that crops up - if it didn't, then it would be hard to imagine the earth's climate ever changing.
We've been collecting carbon that's been leaking upward through the crust and making use of it, instead of letting it eventually reach the surface and make tar pools or catch fire. Testing of these surface leaks is how engineers knew the types of materials which could be found in oil deposits.
You'd do well to think before you wrote things like this, esepcially if an ex-oil industry geologist happens to be looking. Surface seeps of oil do happen, but their volume is vastly less than the amounts pumped out (or we wouldn't need to pump...). Surface seeps have usually spend enough time near the surface to have undergone bacterial degredation and fractionation, and are hence a poor indicator of subsurface oil composition. In a steady state oil field, where all traps are filled, the volume of surface seeps should loosely approximate to the oil production rate - which is always much less than the extraction rate, since the refilling of reservoirs is rarely even a consideration in commercial oil extraction.
I find the large scale usage of fossil fuels by the west - and the poor rates of investment in long term alternatives like nuclear fusion - appallingly short sighted even *without* factoring in the cost of environmental change. It puts our economies in the hands of middle eastern zealots; the fuels will run out anyway; and our cities will be polluted.
Re:Global warming? (Score:3, Insightful)
Re:Global warming? (Score:2)
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. (Score:4, Informative)
Sounds like this guy has a favorite hammer, and he's now convinced that everything looks like a nail.
YAFWCCWC (Score:1)
this could be good... (Score:3, Funny)
Re:this could be good... (Score:1)
2-D vs. 3-D (Score:1)
To start off, let me say I am not a professor in celestial mechanics, just a backyard amatuer astronomer. However, you bring up an interesting point not addressed at all in the artice.
Although it sounds strange that the solar system 'passes through' arms of the galaxy, the motion that is being referrerd to is not contained within the same 2-D plane. The actual path that has been 'guessed' more resembles a sine wave oscillating in 3-D. In doing so the earth can 'pass through' the central plane of the galaxy several times, without being in danger of hitting anything
Re:2-D vs. 3-D (Score:1)
The Earth passes through the central plane of the galaxy without hitting anything because even in that plane, there ain't much stuff there. Space is big.
Re:How can the solar system do this??? (Score:2)
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.
Re:How can the solar system do this??? (Score:2)
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.
It does lend credence to another theory (Score:2)
Physics? (Score:1)
Re:Physics? (Score:2)
100's of millions of years, not thousands. (Score:5, Interesting)
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:100's of millions of years, not thousands. (Score:1)
Re:100's of millions of years, not thousands. (Score:1)
However, the 'white earth' problem shows the hole in this conjecture. If the insolation changes caused by clouds caused by cosmic rays were sufficient to start ice ages, then the presence of surface ice over the globe would also be sufficient to continue it - we should never have warmed up again!
No-one has ever come up with a good explanation for the *end* of significant ice ages - until and unless this chap's theory can do that, his observation is just 'interesting'.
J.
Re:100's of millions of years, not thousands. (Score:1)
This is correct. It's also easily apparent just by looking at climate evidence.
Considering the 'recent' Ice Age started 2 million years ago, the 10,000 year period of warmth we are experiencing could easily be an anomaly, or a brief thaw, and not a definitive end.
This does put the scope of the paper into better perspective. Of course, it also reminds us that we may not be as important as we think. On a greater scale, the worst Global Warming scenario we can think of might only appear as a slight blip in the Earth's climate history.
missing the point (Score:1)