Question

How do the Milankovitch cycles affect climate change?

Answer 1

They clearly have little impact, or climatologists would have seen a repetitive 26 000 year cycle in their data as the fundamental period, they have not.

Explanation:

This is an increasingly popular 'get out' by people with a political view about climate change ... that it is "all just part of a natural cycle". [I posted similar views (with evidence) a couple of months ago in response to a very similar question and got a 'heated' response.]

I think it is true that Milankovitch cycles have some impact on climate, but it is dwarfed (currently) by human induced climate change due to `CO_2`, methane and other emissions.

Answer 2

The Milankovitch cycles can have a significant effect on climate change.

Explanation:

There are actually three distinct Milankovitch cycles. Each of which are very long and have significant effects on climate. The cycles are due to the fact that the Earth's orbit is continually changing due to the gravitational effects of the Sun, Moon and the other planets.

The Earth's orbit is currently almost circular. There is only a `3%` difference between the distance from the Sun at perihelion and aphelion. The Earth's orbit gets more and less elliptical over a period of 100,000 years. When the orbit is more elliptical the seasons are more extreme.

The axial tilt varies between `21.5^@` and `24.5^@` over a period of 41,000 years. It is currently at `23.5^@`. The greater the tilt, the more extreme the difference between seasons.

Finally the precession of perihelion which has a period of 23,000 years. Perihelion currently occurs around 4 January. As the southern hemisphere is mainly water it has little effect. When perihelion precesses until it is in July, there will again be significant differences between seasons.

So, the effects of the three cycles can have significant effects on climate, particularly if they align.

However, human production of `CO_2` has overridden these effects in recent year and needs to be stopped to prevent major climatic changes.