The Earth's Precessional motion

plutoisacomet

Could the Earth's Precessional motion {40,000 years for one loop} cause or contribute to Global warming?

jim mcnamara

See Milankovitch cycle (google)

The earth's orbit around the sun is an ellipse, and the aphelion and perihelion shift over time and with respect to the solstices. In short, when summer occurs and the earth is furthest away (aphelion), the northern hemisphere gets colder because there is less insolation. When summer occurs at perihelion the reverse is true, things heat up. That is the idea anyway.

DaveC426913

Would you care to postulate a hypothesis as to how it might?

(Incidentally, IIRC it's more like 26,000 years)

wysard

I'll bite.

The roughly 47.5 degrees of swing with respect to the equinoxes causes seasons. No big surprise there. The perturbation caused by precession of the poles is a tad under 0.7 degrees. So that would mean that the pole precession depending on the angle with respect to the sun would cycle between adding about 0.75% to the severity of seasons to lessening them by 0.75% and back over about 26,000 years.

With such a tiny addition or subtraction I don't see how it could have a lasting effect. We probably see more severe disturbances in weather due to sunspot activity, but that's just conjecture on my part.

So poster, here's a question, what is the current angle of precession with respect to the sun? Is the Earth tilted farther in towards the sun, out away from it, or is the current effect precession tending more to leading the earth in orbit or following it? That would make a huge difference on even as small a number as you are looking at.