8
$\begingroup$

In thinking about the question, Why is earth's axis tilted?, and reading articles about Earth's axial tilt, I came across the website Snowball Earth which describes an alternate theory for global glaciation proposed by George Williams, from the University of Adelaide - what is proposed is that the Earth had a considerably higher axial obliquity (greater than 54°) up to about 600 million years ago.

Professor Williams proposes that this could be a mechanism for Snowball Earth events and cites the 'explosion' of life occurring after the axial tilt stabilised, thus causing the seasonal changes to become less severe with lower obliquity.

This is related to the question What sort of climate zones would be present if Earth was tilted like Uranus?, but asks the question if there is evidence that Earth did have a greater axial obliquity in the Proterozoic?

$\endgroup$
8
$\begingroup$

There is no evidence that Earth had a much greater axial tilt so long ago. To my knowledge, the evidence for changes in the axial tilt of the Earth is based on ocean sediment cores (see http://en.wikipedia.org/wiki/James_Hays ) and ice cores ( see http://en.wikipedia.org/wiki/Milankovitch_cycles#Axial_tilt_.28obliquity.29 ). However, these only go back 100s of thousands of years. There is no record that I know of that could be used to assess the axial tilt of Earth 100s of millions of years ago. However, you could speculate that after the collision that Earth had that led to our moon, the axial tilt could have been much greater as a result. However, all records that I have seen show that the axial tilt fluctuates from 22.1 to 24.5 degrees.

$\endgroup$
  • 1
    $\begingroup$ do you have non-Wikipedia resources? $\endgroup$ – user889 Nov 29 '14 at 3:42
  • 2
    $\begingroup$ Check out the paper by James Hays: mantleplumes.org/WebDocuments/Hays1976.pdf "Variations in the Earth's orbit: Pacemaker of the ice ages." $\endgroup$ – farrenthorpe Nov 29 '14 at 20:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy