Galactic Orbits and Mass Extinctions

Stories, Essays, Epic Poems, Rippin' Yarns

Moderator: Moderators

User avatar
Windwalker
Site Admin
Posts: 427
Joined: Fri Dec 08, 2006 12:47 pm
Location: The Shore of Waking Dreams
Contact:

Galactic Orbits and Mass Extinctions

Postby Windwalker » Sat Apr 28, 2007 7:46 pm

In the eighties, several scientists proposed that the movement of the solar system through the galaxy has an impact on terrestrial life. Since then, additional lines of evidence have converged to strengthen this hypothesis.

Recent research established that, as the solar system moves above and below the galactic plane, it gets exposed to heightened cosmic ray activity on one side on the plane. One full such orbit takes 65 million years, coinciding with the interval between mass extinctions observed in the fossil record.

Here are two relevant links:
http://www.itwire.com.au/content/view/11573/1066/
http://www.msnbc.msn.com/id/18277613/

This scenarior reminds me of Jack McDevitt's riveting novel The Engines of God, in which energy waves periodically sweep the galaxy, searching for regular structures and destroying the planets that contain them. In his universe, these were created by a civilization that wanted no competitors -- but apparently intelligence is not required for such an outcome.
For I come from an ardent race
That has subsisted on defiance and visions.

User avatar
bretonlass
Posts: 51
Joined: Tue Jan 23, 2007 11:09 pm

Postby bretonlass » Sat Apr 28, 2007 10:41 pm

Very interesting, that.

Considering that it has been a while yet since anything major has happened to the planet, do any of you reckon that the movements of the Solar system might have an impact on global warming? I'm not excusing the stupidity of (some) humans in that regard, far from it, but I thought simply that, like in many occasions, there might actually be a compound of many factors entering the equation. After all, natural phenomenon are seldom that simple to deconstruct.

Cheers,

Eloise :)
"First, you see the world in black and white. After a while, you begin to see the shades of gray. And if you but have the courage to try, you then get to see all the colours of the rainbow." My philosophy of life

User avatar
Windwalker
Site Admin
Posts: 427
Joined: Fri Dec 08, 2006 12:47 pm
Location: The Shore of Waking Dreams
Contact:

Postby Windwalker » Sat Apr 28, 2007 11:00 pm

bretonlass wrote: Considering that it has been a while yet since anything major has happened to the planet, do any of you reckon that the movements of the Solar system might have an impact on global warming?

Almost certainly. With the exception of the Little Ice Age of 1300-1800, all other Ice Ages happened either before humans were around or when they were too few and puny to affect earth.

Variations in solar output and small changes in earth's orbit contribute to the planet's climate fluctations, though the major determinant is the quantity of greenhouse gases in the atmosphere. Plate tectonics, patterns of ocean currents and volcanism also play a role in regulating greenhouse gases.
For I come from an ardent race
That has subsisted on defiance and visions.

User avatar
sanscardinality
Posts: 69
Joined: Wed Jan 24, 2007 7:10 pm
Location: West By God Virginny
Contact:

Postby sanscardinality » Mon Apr 30, 2007 2:59 pm

Cool thread!

Fist let me say that my opinion is that human impacted global warming is a reality, and that we should address our carbon output ASAP to hopefully stop any unnecessary climate change.

That said, Earth has obviously gone through numerous climate changes of a fairly drastic nature over time, none of which have produced Venus-like runaway greenhouse conditions or Mars-like runaway atmospheric loss. I worry when both kids and adults have "doomsday" misconceptions about the issue because in the end this will only harm environmental sensitivity. The debate isn't on whether we become Venus, but on how many species will become extinct and what will happen to wealth inequality and its attendant problems among humans. I suspect that the people who could really change things understand the issue pretty well, and think that a few thousand less species is a small price to pay for increased wealth inequality, especially when Dubai has shown one can make a decent indoor downhill skiing facility.

I think there is some solid evidence that changes in solar output have an effect, and we are entering a very high output phase for the Sun. Perhaps one of the highest in history. Another interesting contributor to global climate may be Earth's magnetic field. Every so often, the field goes through a period of instability and eventual reversal. When this happens, the amount of radiation making its way to the ground increases - for 200-300 years quite dramatically. There are signs that we are entering such a phase now, and it would both increase temperature and allow all sorts of harmful radiation and particles at Earth's surface that are now filtered out. While it would not be a catastrophe, it would certainly increase cancers, etc. should this prove to be true. This, combined with a relatively sudden need to relocate a large percentage of the human population would be an ugly time for human society.

- SC

PS> One reason for Earth's ability to moderate swings in greenhouse effect is the proliferation of life and the abundance of water. From my studies in planetary science (the worst and least enjoyable semester of my life) I was somewhat shocked to find out how large a role life has in determining the composition of Earth's atmosphere.

Related to global warming, when overall temperatures rise drastically, the very large land areas of the Northern Hemisphere become much more productive to plant life that consumes C02, and the oceans enlarge in volume and surface area as well (the ocean absorbs C02). In the oceans, this seems to cause a proliferation of algae, which is a terribly efficient converter of C02 to oxygen. Of course, lots of other ocean species die off. Conversely, when temperatures fall and ice volume increases, less plants live to consume C02 and the oceans have less surface area. This eventually helps reheat things (Volcanism and other non-life based effects are of course just as or more relevant, but we are talking about balances here of very large forces, so small leverage can have a big impact).

I'm not saying we shouldn't worry about greenhouse effect, but that Earth has unique moderating features that Venus and Mars are/were without.
Consistency is the last refuge of the unimaginative.

Oscar Wilde

User avatar
Windwalker
Site Admin
Posts: 427
Joined: Fri Dec 08, 2006 12:47 pm
Location: The Shore of Waking Dreams
Contact:

Postby Windwalker » Tue May 01, 2007 8:57 am

sanscardinality wrote:That said, Earth has obviously gone through numerous climate changes of a fairly drastic nature over time, none of which have produced Venus-like runaway greenhouse conditions or Mars-like runaway atmospheric loss. I worry when both kids and adults have "doomsday" misconceptions about the issue because in the end this will only harm environmental sensitivity. The debate isn't on whether we become Venus, but on how many species will become extinct and what will happen to wealth inequality and its attendant problems among humans.
//
One reason for Earth's ability to moderate swings in greenhouse effect is the proliferation of life and the abundance of water. From my studies in planetary science (the worst and least enjoyable semester of my life) I was somewhat shocked to find out how large a role life has in determining the composition of Earth's atmosphere.

Yes, indeed. Cyanobacteria were instrumental in turning the early Earth's atmosphere from mostly CO2 to 21% oxygen. However, that was also a huge ecocatastrophe until more lifeforms evolved that could handle oxygen (which is a corrosive poison at the cellular level, even though it allows a 10-fold more efficient metabolism once harnessed).

After that, life became an integral part of the equation. At the same time, a large shift in one of the astronomical or geological parameters (large change in solar output) will trump the life component -- although some type of bacteria will survive until/unless the earth becomes a molten rock.

I agree completely that loss of biodiversity and human misery (hunger, displacements, possibly epidemics) are the results of climactic upheaval. The two are linked, and often seem at odds in the short-term efforts to tackle them.
For I come from an ardent race
That has subsisted on defiance and visions.


Return to “The Poetry and Prose of Science and Science Fiction”

Who is online

Users browsing this forum: No registered users and 1 guest