Changes in Earth's Orbit Linked to Extinctions

Josh Fink writes "A group of Dutch Scientists have recently released a study stating that they have found that changes in Earth's orbit around the sun are linked to mammal extinctions. From the article: '"Extinctions in rodent species occur in pulses which are spaced by intervals controlled by astronomical variations and their effects on climate change..." The cycles are associated with lower temperatures, changes in precipitation, habitats, vegetation and food availability which are the main factors influencing the extinction peaks, the study published in the journal Nature said.' So on top of worrying about global warming, it seems we should also worry about the physics that govern the orbit of Earth around the sun. Too bad we don't have a way of keeping the Earth in the same orbit/on the same axis of rotation."

Comments

Vague article

[novus ordo]

More info in nature. It seems to do with something called Milankovich cycles. But i guess 'wobble' is specific enough for stuff that matters.

Re:Move Along

[guycouch]

Here's a quick link to some other studies: http://earthobservatory.nasa.gov/Study/Paleoclimat ology_Evidence/

Freaked out

[wurp]

The whole tone of this /. post freaked me out. There's no way for there to be 'irregularities' in the Earth's orbit without something with both really high mass and really high velocity interacting with the earth or the sun.

So I read up on Milankovich cycles, and it turns out it's just precession. It's perfectly regular, it's just that in the case of something the size & slow angular velocity of the earth, it takes a really long time to change.

When you spin a top, you can see the axis of spin describe a circle. This is precession.

Likewise as the Earth rotates, there is precession. Also, as the earth orbits the sun, there is precession. These have cycles on the order of tens of thousands of years. Both can affect the climate by changing the angle of sunlight. There are cycles on the order of millions of years long in which the two effects both affect the climate the same way, and so produce a bigger net effect.

I guess wobble is an accurate term, except that to me it implies something irregular. In a system as big and isolated as the Earth's orbit around the Sun, or the Earth's rotation, momentum is king, and very little could cause an irregular change. These changes are just precession, and they're perfectly regular.

I am not a physicist, but I do have a Bachelor of Science in Physics.

Re:BTW

[mwlewis]

Then there's the fact that North-West Europe (in particular us Brits) is kept warm by the Gulf Stream (look it up)

OK. I think you'll find that there is some doubt about this.

Re:BTW

[FhnuZoag]

Man, why do people like you just draw random assertions out of a hat and pretend that's the divine truth. Let's actually look at the science, eh?

http://en.wikipedia.org/wiki/Permian-Triassic_exti nction_event

70% of all vertebrate species died in under a million years, leaving fungi dominant. Something of a mass extinction event, eh? (In fact, Earth's worst mass extinction event.) Observe the big temperature spike at PETM. (Top right corner)

http://upload.wikimedia.org/wikipedia/en/1/1b/65_M yr_Climate_Change.png

Thank you and goodnight.