Re: realistic aliens and the necessities of storytelling

In article <1hx75bb.itsa051ht1qrmN%green_knight@xxxxxxxxxxxxxxxxxx>,
green_knight@xxxxxxxxxxxxxxxxxx (Catja Pafort) wrote:

Googling around, the average ocean depth is about 3-4 km, so the upper
limit of the IPCC prediction is an increase in depth by about one part
in 4000.

We don't live at the bottom of the sea. We live near the top of the sea,
and in some cases below the top of the sea, and when all that stands
between you and large amounts of water in your living room is a dam or
dike or levvee the top of which lies a meter above the highest
imaginable flood mark, and that flood mark rises by a meter and a half,
you would do right to be very very nervous indeed. (Coastal waters,
particularly when winds press water into bays get *much* higher rises
than 'the average'.)

So yes, it matters tremendously. To some of the Pacific islands which
consist almost entirely of very flat land indeed, this rise can mean the
difference between 'habitable' and 'inhabitable' and I'd say it matters
a whole lot to them.

All of which might be relevant if you were responding to a comment about
the effect of the rising sea level on flooding but, as you can easily
see if you bother to read it, what you quoted was part of a calculation
of how much dilution of salinity would result. The flooding of Pacific
islands is irrelevant to that question.

And the conclusion is that, on the IPCC figures, the average salinity
changes by less than from 35 parts per thousand to 34.9 parts per
thousand (I carelessly got the direction wrong in the post I quoted,
corrected it in a subsequent post). Can you offer any reason to believe,
given the time spans involved, that that average will involve "radical"
dilution in some areas? Just how long do you think you can maintain a
substantial difference in concentration along a front thousands of miles
long?

I wrote 'where that happens'

What you originally wrote was:

"But in point of fact a rise like that - IN TERMS OF OCEANS - would
mean aMAJOR change in the salinity of those oceans, and in habitat in
the frozen regions where species are already struggling to survive."

note "the salinity of those oceans." That claim was wildly wrong, as I
have now demonstrated.

and the reason for that formulation should
be obvious. Polar ice and glaciers do not melt evenly diffused through
the whole of the world's oceans, *they melt in place*. And where that
happens, you *will* get a large influx of fresh water in the ocean,
changing local conditions and thus influencing plankton, fish, and, to a
degree that is currently difficult to calculate, ocean circulation.

This will happen. What exactly the effects are is not something I would
want to predict with any degree of accuracy, but there will be changes,
and they will be quite drastical, and since the whole ecosystem is
connected, it is not unrealistic to assume that a major change in one
part of the ecosystem will create equally major changes elsewhere.

The 'spherical cow' argument of 'oh, if you spread the effect out over
the whole of the world's ocean's' is a ridiculous one and entirely
unhelpful, because that model will never apply to any segment of the
real world.

Unless, of course, the whole of the world's oceans form a connected
system and solutions diffuse from more concentrated to less concentrated.

Were you imagining the whole process happening in a week? Current
predictions call for a tiny bit of it happening in a century.

Take a look at the figures I quoted. Relative to the size of the oceans,
there is essentially no water in glaciers--down by four orders of
magnitude--it's all in the ice caps. The ice sheets melt into the
Atlantic and Pacific oceans, which between them contain most of the
world's water. If you can get one of them to melt into the Mediterranean
you might manage a radical dilution, but as a geographer you will
recognize the practical difficulties of doing so.

You can keep making assertions forever but you have offered no data to
support them, just a vivid imagination and unlimited self-confidence.
I've given the data that show that "the salinity of those oceans" would
change by a tiny bit on current predictions, two or three percent if you
melted all the world's ice.

Where is your data, or calculations of diffusion rates, or something, to
support your certainty that the effect would be so uneven as to cause
"radical" changes in the salinity of some areas?

--
http://www.daviddfriedman.com/ http://daviddfriedman.blogspot.com/
Author of _Harald_, a fantasy without magic.
Published by Baen, in bookstores now
.

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