I live in Cape Town, South Africa where it is a very real possibility that not a single drop of water will be left in our dams come March 2018.

THIS is a news article that suggests that at a government level, such a situation has not been discounted. And an overview of our current dam levels can be found HERE; we have about 900 000 ML of water left, with usage unlikely to fall below 500 ML / day. And we are almost completely reliant on water from damns. It is pretty easy to find other news about this.

I was recently reading a book on chaos theory where climate and weather models were discussed in terms of how sensitive they are to changing variables. If the earth experienced a slight axis shift and rotation change, what could be the effect on weather patterns?

An article by NASA suggests that such a change did occur in 2011 (that the figure axis was altered and that days were shortened) and the question I'm asking is:

Could such an alteration permanently change Cape Town's weather?

My (probably incorrect) understanding of Cape Town's weather is that rain is the result of clockwise-rotating low pressure cells approaching the continent from the South-West. It seems to me that slight changes in geographical properties (such as earth rotation and axis') could result in changing the paths of these cells as they migrate across the earth from west to east.

If that were so, is it feasible that Cape Town is likely to become MUCH dryer than it has historically been because low pressure cells continuously 'miss' the landmass, whereas before these cells were migrating OVER the landmass (and causing rain)?

This is in addition to the effects of climate change, which I'm not sure how would effect the Western Cape's (the province where Cap Town is) weather.

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    $\begingroup$ Are you asking about a real world scenario (Is this why Cape Town is drier) or a hypothetical one (could Cape Town become drier because if this)? $\endgroup$
    – Joe Bloggs
    Commented Oct 9, 2017 at 12:02
  • $\begingroup$ well Cape Town definitely is dryer this year. I'm asking if, hypothetically, this could be the result of an earthquake $\endgroup$
    – Zach Smith
    Commented Oct 9, 2017 at 12:03
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    $\begingroup$ Perhaps, because you are looking for a scientific instead of fictional answer, you may consider EarthSciences.SE. +1 for the well-resourced question. $\endgroup$
    – AliceD
    Commented Oct 9, 2017 at 12:19
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    $\begingroup$ Well asked but you'd probably get better answers over on one of the hard science SEs like Earthscience.SE $\endgroup$
    – Ash
    Commented Oct 9, 2017 at 12:46
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    $\begingroup$ If you’ve got a real world event and you’re asking about a real world effect then your question is a better fit for earth science. Not sure how to flag this for migration, but I’ll check. :-) $\endgroup$
    – Joe Bloggs
    Commented Oct 9, 2017 at 13:22

1 Answer 1


World climate is a very complex and chaotic system so it’s hard to be certain about what effects might or might not occur, but general trends can be observed as we are beginning to see with global warming.

Given the tiny effect even a magnitude 9 earth quake had on the earth’s rotational period (1.8 micro seconds), it’s unlikely that one such quake could be reasonably blamed for any significant short term effects. That said all affects build upon on another, tiny changes like that together with a myriad of other changes together over the long term do have significant effect, but you can’t pin the reason for these changes to one specific cause.

Other effects that come to mind are global warming, the effect of small variations in solar output, volcanic activity, earths axial precession and the movement of the magnetic poles to name but a few.

Although the effect of this particular earth quake is only a tiny part of the story if added to all other tectonic activity and all the other factors over a long period of time the effect can be significant but hard to predict. There have been many climate changes over the years for instance parts of the Sahara around the upper Nile were grass land 7000 years ago but became drier and drier as the rains repeatedly failed until 5-6000 years ago it was a desert. There is no reason to suppose that long term climatic changes are not still in progress (even without considering global warming).

  • $\begingroup$ Thanks. that is a much better answer than I on the earth science site (which I've flagged as a duplicate) $\endgroup$
    – Zach Smith
    Commented Oct 10, 2017 at 11:20

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