# Tag Info

11

During the 20th century, the global mean temperature in January was 12°C while it was 15.8°C in July. This is a bit paradoxical as insolation is currently about 7% higher during January than it is in July. So why is July warmer than January? The solution to this apparent paradox and the answer your question (how does apsidal precession alone affect the ...

10

In short: No. Unless multi-million timescales are considered. The reason we keep teaching Newtonian mechanics, is because it is a VERY accurate approximation of a more general theory (general relativity) within the regimes of speed and gravity acceleration found in everyday life. Therefore, all the relativistic corrections to Newtonian mechanics in the ...

9

The link between orbital parameters and CO2 levels is, as you wrote, the temperature. Orbital parameters may change, via feedback mechanisms, the atmospheric temperature. To my knowledge the most important feedback mechanism with respect to the Milankovich cycles is the ice-albedo feedback. The temperature, however, is an important player in geochemical ...

8

It thus seems reasonable to say we are entering another Ice Age according to Milankovitch cycles. Some of the Milankovitch conditions would appear to make the Earth ripe for a new glacial epoch starting now, or perhaps a few hundred years ago. In particular, aphelion occurs in early July, and obliquity is low. Both of these make for mild northern hemisphere ...

6

Your question is framed as if any model of glaciation were only allowed to consider one of those influences. I think practically any palaeoclimatologist would accept that astronomical forcing, solar output, and volcanic eruptions all have effects on glaciation. It's true, however, that on long timescales (tens of kiloyears and up), Milankovitch forcing ...

6

The Earth's climate switches between "hothouse Earth", where ice is nearly absent worldwide, and "icehouse Earth" where the Earth intermittently has ice that stretches far from the poles. Periods when the Earth is in the icehouse Earth phase are called ice ages. The most recent ice age began about 2.6 million years ago and has not yet ended. We are still in ...

4

The precessional effect on climate is caused due to two factors: (1) Axial Precession (2) Apsidal Precession The precession of the apses doesn't cause a change in climatic state by itself. However, this motion is in the same sense as the axial precession (gyroscopic motion of the earth's axes). This effect reduces the period of precession from 26kyr to ~...

4

It's a little dated and brief, but it's a cool article and I believe it's overall sound in it's predictions and arguments presented. On the overall point, the author isn't predicting an ice age in 2,000 years, so the answer to your title question is that he didn't really say that, though he writes the article somewhat poorly because that's not very clear, ...

4

The tidal effect over time tends to circularize orbits. It's well known that Moon is being tidally pushed away from the Earth over time (about 1.5 inches a year). This effect is stronger when the moon is closer and weaker when the moon is farther, so there is a very gradual tidal circularizing of orbits over time, unless the orbit is highly eccentric, ...

3

What is usually shown in cyclic plots showing precession is the precession index ($e \cdot \sin\varpi$ where $e$ is the eccentricity and $\varpi$ is the moving longitude of the perihelion). It is dimensionless ($e$ and $\sin \varpi$ being ratios). Here is the precession index for the last 2 Myrs that I plotted using data from Laskar et al. (2004) (in the ...

3

I don't see this point made, so I'll just add it. In very high gravitation situations orbital energy can be lost to "relativity" or more specifically, gravity waves. The primary relativistic effect that the Sun's gravity has on Mercury is an increase in it's precession, as @CamiloRada pointed out, and see more details here. A secondary relativistic ...

3

The latest positions that I am aware of say yes, but not in any useful way. From what I have read, the current prevailing opinion is that the weather of Earth is a chaotic system. Chaotic systems are known to be very sensitive to initial conditions. Eddys in the atmosphere that are mere milimeters in size may change whether it rains or shines on the other ...

2

First, let us try to understand how precession affects climate: The precessional effect on climate is caused due to two factors:- (1) Axial Precession (2) Apsidal Precession The precession of the apses doesn't cause a change in climatic state by itself. However, this motion is in the same sense as the axial precession (gyroscopic motion of the earth's axes)...

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