Reply To: Iconography

[Phil’s Dad]

Greetings digh,

digh wrote:
Your explanation of how tsunamis have been cuased(sic) by techtonic plate shift is fine, but your statement “tsunamis have never been caused by climate change” indiactes(more sic) premature closure of inquiry.

We will see. It may in fact be that my line of enquiry has reached and surpassed the point you have paused at here. Shall we both keep dighing and find out?

I don’t think many would rationally deny the melting of polar ice when there are massive changes in glaciers, the effects of which are pronounced.

The position I think you are taking (do please correct me if I am wrong in this) is that melting continues to the present day and has maybe even accelerated recently along with the much reported accelerated warming of the second half of the 20th century. You refer to it as “the rapid pace of deglaciation”.

We are interested in land based ice of course, as water ice does not change the overall mass or distribution of mass when it melts. (Volume yes, mass no)

The theory you propound, which had a resurgence of popularity in 2006 if my memory serves, certainly makes superficial sense.

Techtonic plates are affected as a result of changes in isostasy/eustasy and post glacial rebound on glacial isostatic adjustment. This can have an effect on seismic activity(i.e.: volcanic activity, earthquakes and, yes…tsunamis).

Now a few diagrams if I may. The first from the Global Volcanism Program and the last two from the National Earthquake Information Center of the U.S. Geological Survey(NEIC).

They show something remarkable. Despite all that melting there has been no statistically significant increase in seismic activity (i.e.: volcanic activity, earthquakes and, yes…tsunamis). In fact the trend, if any, is downward.

I note also that Earth Science professor John Clague at Simon Fraser University, a leading light in this area, said that even if the Greenland ice sheet melted, “plate motions… would continue, as they had prior to the melting.”

Granted all this is a worst case scenario, current thinking is that the impact takes place over a hundred years or more, but we can’t say with certainty, given the current rapid pace of deglaciation.

I think based on the evidence I would side here with “current thinking”. I am afraid I do not count a hundred year (or more) change in water levels a “tsunami”. Nor the 20,000 year increase (averaging 6.25mm/yr) given in your second reference.

We, hopefully, have time to change our energy infrastructure..

On this we agree.

Thank you digh, for giving me pause to think.

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