In the 1920’s a Serbian geophysicist and astronomer called Milutin Milankovitch suggested that long term variations in how the Earth travels in space may affect climate change because of the effect these changes have on the amount of solar radiation that hits the Earth’s surface. He recognized three long term cycles and these cycles are now referred to as Milankovitch Cycles.

Milankovitch Cycles

The three cycles are the variability of the Earth’s orbit, the position of the Earth when it’s closest to the sun, and the amount the Earth tilts on its axis.

Eccentricity of the Earth’s orbit

The first cycle is the variability or eccentricity of the Earth’s orbit which ranges from nearly circular to more elliptical and back every 90,000 to 100,000 years.

Milankovich cycles - orbit shape

Longitude of perihelion

The second cycle refers to the position of the Earth when it is closest to the sun referred to as the longitude of perihelion.  At the present time, the Earth is closest to the sun in its orbit during the southern hemisphere’s summer and furthest away from the sun during the northern hemisphere summer. This changes every 10,000 or so years, making the complete cycle around 21,000 years.

Obliquity of Axis

The third cycle refers to the “lean” or obliquity of the Earth on its axis. This lean changes the Earth’s tilt from 21.8° (closest to upright) to 24.4° (most inclined). The full cycle from 21.8° back to 21.8 ° takes about 40,000 years.




Where are we in the cycles now?

At the present time, the earth’s orbit is nearly circular and becoming more circular, the longitude of perihelion gives the southern hemisphere warmer summers (and cooler winters) than the northern hemisphere and the obliquity is decreasing tending to decrease the differences between the seasons.


So what does it really mean for climate change?

The Milankovitch cycles do have an influence on our climate, and there seems to be a good correlation between the cycles and the evidence we have for Earth’s ice ages.  However, there are times that the cycle prediction has failed, or when major climate events have taken place for which the cycles can’t explain.  This may mean that other factors, like atmospheric chemistry (greenhouse gases for example), volcanic eruptions, location of continues due to plate tectonics, the size of ocean basins, and ocean currents may play a stronger influence.

Milankovitch cycles – the Earth in space and climate.

4 thoughts on “Milankovitch cycles – the Earth in space and climate.

  • July 12, 2020 at 3:06 pm

    A brilliant explanation for the near clockwork like changes in our environment, which is also represented within the ice-core and ocean-core samples. Together they give a more accurate portrait of earths climate throughout it’s history.
    When I do talk to people about earths climate I liken it to the pendulum in an old fashioned clock I say to them “consider one side of the clock as hot the other side cold and the pendulum as the earth, as the pendulum moves back and forth so does the climate change with it over time .”
    The only variables as I see them are global CO2 and oxygen levels (affected by plant growth or lack there of) volcanic activity and meteor impact these things I believe account for the variations in the data.

  • January 27, 2021 at 5:56 am

    This is a matter of contention with someone i am in discourse with please note – i am stating that the relation ship when there was 6000ppm co2 effect was undermined by solar differences of around 4% so that an ice age could occur. He states to me – ‘ If CO2 was the most importat/strongest climate driver then it would have been impossible for there to have been an Ice Age with 6000 parts per million.

    I need some aid as it is in the comments section and it is really difficult to get a google link etc detail so if you can help please do. I personally believe this will be accounted for by IPCC type accounts but i can’t find the explanation.

    • January 28, 2021 at 3:48 am

      I think the short answer is that CO2 is not the only driver of climate change.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.