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

Model orbital changes on your own compy

[HoneyBeeSpace]

We don't have animals in our climate model, but if you'd like to see how orbit effects climate, you can do so yourself.

The EdGCM project has wrapped a NASA GCM in a graphical interface. You can double-click to install, and if you'd like to turn the sun down a few percent or change the orbit, there are checkboxes and sliders. Press play, wait a while (hours to a day or so depending on your computer), and you can look at the results...

Disclaimer: I'm the developer.

Re:BTW

[regular_gonzalez]

http://en.wikipedia.org/wiki/Tipping_point

Not saying this necessarily applies; just pointing out that just because a process may be gradual does not mean that its consequences can't be sudden.

Re:BTW

[Dun Malg]

before anyone starts getting all 'see, all you global-warming believers, this is a perfectly rational natural explanation for the current warming trend,' the periods of these natural cycles are on the order of 1.2 and 2.4 million years. not exactly fast-acting.

Though is is worth noting that something happened either to the earth's orbit or its speed of rotation in the 8th century BCE. History shows civilizations around the world dumping their 360-day calender at right about the same time after having used it for over 1000 years, followed by a struggle to come up with a 365-day one. Attempts to hand-wave this away as "silly ancients couldn't make an accurate calendar" or "it was just a ceremonial calendar" are clearly wrong. With a 5 day variance like that the calender would become 180 degrees out of phase in only 36 years-- within one person's lifetime-- so obviously someone would've noticed and adjusted it and not just left it alone for 1000+ years. As for the second, that ignores the entire purpose of the calender: agricultural planning. A calender so inaccurate you can't plant crops by it is worthless. No, clearly the mechanics of earth's orbit were altered. Probably not enough to make any significant climatic difference, but an orbital alteration nonetheless, and within recorded history. Worth keeping in mind lest people get the idea that we live within a static system

Modifying the orbit of Earth is feasible!

[mrcgran]

"...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."

Yes, we have! And it's very interesting indeed!

http://www.space.com/scienceastronomy/planetearth/ earth_move_010207.html

A link to the paper: Korycansky, D. G.; Laughlin, Gregory; Adams, Fred C. Astronomical engineering: a strategy for modifying planetary orbits. Astrophys.Space Sci. 275 (2001) 349-366
http://arxiv.org/abs/astro-ph/0102126
Abstract:
"The Sun's gradual brightening will seriously compromise the Earth's biosphere within ~ 1E9 years. If Earth's orbit migrates outward, however, the biosphere could remain intact over the entire main-sequence lifetime of the Sun. In this paper, we explore the feasibility of engineering such a migration over a long time period. The basic mechanism uses gravitational assists to (in effect) transfer orbital energy from Jupiter to the Earth, and thereby enlarges the orbital radius of Earth. This transfer is accomplished by a suitable intermediate body, either a Kuiper Belt object or a main belt asteroid. The object first encounters Earth during an inward pass on its initial highly elliptical orbit of large (~ 300 AU) semimajor axis. The encounter transfers energy from the object to the Earth in standard gravity-assist fashion by passing close to the leading limb of the planet. The resulting outbound trajectory of the object must cross the orbit of Jupiter; with proper timing, the outbound object encounters Jupiter and picks up the energy it lost to Earth. With small corrections to the trajectory, or additional planetary encounters (e.g., with Saturn), the object can repeat this process over many encounters. To maintain its present flux of solar energy, the Earth must experience roughly one encounter every 6000 years (for an object mass of 1E22 g). We develop the details of this scheme and discuss its ramifications."