Does climate change affect the Earth's orbit ?

[Icemelt]

Current theories suggest that the major ice ages are caused by irregularities in the Earth’s orbit around the sun, it’s polar attitude, and an additional wobble for good measure. Calculations show that, given the Earth’s historical orbit and attitude, these correlate nicely with corresponding periods of glaciation, it would seem providing us with a basis to predict future ice ages. But how sure are we of our facts ?

 

As with many other factors relating to climate change, we really need to establish which changes lead and which changes lag. It seems very likely that the cyclic variation in the mass of ice building up at each of the poles disproportionately, would inevitably induce wobble and attitude changes, and most probably minor orbital changes.

 

We have to couple with this that, although the melting of Northern hemisphere ice might at first glances decrease the overall reflected energy and cause warming, if the Earth is tilted with the North Pole away from the Sun, as it is when we enter an ice age, the lack of an Arctic ice cap would have little or no effect. A build up of ice would then begin again, correcting and even reversing the tilt and producing the observed wobble.

[swansont]

We have to couple with this that, although the melting of Northern hemisphere ice might at first glances decrease the overall reflected energy and cause warming, if the Earth is tilted with the North Pole away from the Sun, as it is when we enter an ice age, the lack of an Arctic ice cap would have little or no effect. A build up of ice would then begin again, correcting and even reversing the tilt and producing the observed wobble.

emphasis added

 

We enter an ice age after September and before March?

[bascule]

Not to slippery slope you, but what's next... maybe the Sun doesn't heat up the earth... maybe when earth warms up, it causes solar luminosity to increase?

 

Can we really be sure which one causes the other???

 

Can I demonstrate the physical science basis of this hypothesis? No.

 

Can you demonstrate the physical science basis for your idea? Perhaps you could calculate the earth's precession as a function of the polar ice accumulation.

[insane_alien]

did you ever think that the orbital variations(which are well understtod and pretty simple) may be a cause for the natural heating and cooling of our planet?

[Icemelt]

We enter an ice age after September and before March?

 

Ah yes “swansont”, perhaps I should have added the word “further” to have avoided such an instant dismissal.

 

Let me therefore rephrase it as follows and add the explanation below:

 

"if the Earth is tilted with the North Pole further away from the Sun, as it is when we enter an ice age"

 

As you correctly point out, a normal tilt produces the seasonal effect, however as I’m sure you are aware the Earth circles the Sun in a flat plane. It is as if the spinning Earth is also rolling around the edge of a giant, flat plate, with the Sun in the center. The shape of the Earth’s orbit—the plate—changes from a nearly perfect circle to an oval shape on a 100,000-year cycle (eccentricity). Also, if you drew a line from the plate up through the Earth’s North and South Poles—Earth’s axis—the line would not rise straight up from the plate. Instead the axis is tilted, and the angle of the tilt varies between 22 and 24 degrees every 41,000 years (obliquity). Finally, the Earth wobbles on its axis as it spins. Like the handle of a toy top that wobbles toward you and away from you as the toy winds down, the “handle” of the Earth, the axis, wobbles toward and away from the Sun over the span of 19,000 to 23,000 years (precession). These small variations in Earth-Sun geometry change how much sunlight each hemisphere receives during the Earth’s year-long trek around the Sun, where in the orbit (the time of year) the seasons occur, and how extreme the seasonal changes are.

In the early 1900s, a Serbian mathematician named Milutin Milankovitch meticulously calculated the amount of sunlight each latitude received in every phase of Earth’s orbital variations. His work culminated in the 1930 publication of Mathematical Climatology and the Astronomical Theory of Climate Change. He theorized that the ice ages occurred when orbital variations caused the Northern Hemisphere around the latitude of the Hudson Bay and northern Europe to receive less sunshine in the summer. Short, cool summers failed to melt all of the winter’s snow. The snow would slowly accumulate from year to year, and its shiny, white surface would reflect more radiation back into space. Temperatures would drop even further, and eventually, an ice age would be in full swing. Based on the orbital variations, Milankovitch predicted that the ice ages would peak every 100,000 and 41,000 years, with additional “blips” every 19,000 to 23,000 years.

Evidence supporting Milankovitch’s theory of the precise timing of the ice ages first came from a series of fossil coral reefs that formed on a shallow ocean bench in the South Pacific during warm interglacial periods. As the ice ages came, more and more water froze into polar ice caps and the ocean levels dropped, leaving the reef exposed. When the ice melted, the ocean rose and warmed, and another reef formed. At the same time, the peninsula on which the reefs formed was steadily being pushed up by the motion of the Earth’s shifting tectonic plates. Today, the reefs form a visible series of steps along the shore of Papua New Guinea. The reefs, the age of which was well-defined because of the decaying uranium in the coral, measured out the millennia between ice ages. They also defined the maximum length of each ice age. The intervals fell exactly where Milankovitch said they would.