The following exchange occurred on Speculations Rumor
Mill, my favorite Web hangout for genre fiction writers. This
particular discussion concerns what might happen if Earth suddenly lost
one-half of all her water! It's amazing the ideas these Rumor Millers
generate! I've done a teeny bit of editing just for typos and maybe the
odd spelling correction, otherwise this is just as it developed on the
Mill.
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Message 465773 was posted by Fredrick Obermeyer on 2005-07-01 15:18:55.
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If 50% of Earth's total water supply were suddenly stolen or disppeared
one day, how would that affect Earth's ecology? Would the planet still
be able to sustain any life or would everybody and everything die? What
if all the water stolen was all salt water from the ocean, would that
make any difference? Would the planet become like the desert planet
Arrakis in Frank Herbert's Dune or would there be some pockets of green
left?
If there was still life, how many people and animals would die from
lack of water? Also could future humans and animals be genetically or
mechanically engineered to survive on less water?
Thanks.
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Message 465855 was posted by Gregory Koster on 2005-07-03 16:49:14.
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For Fred: Gee, I just stopped by for a minute to see Terry's
announcement of the Mark IV Hickman-Koster postage chart, and saw your
question. Doomed, that's all it took. Onward:
"If 50% of Earth's
total water supply were suddenly stolen or disppeared one day, how
would that affect Earth's ecology? Would the planet still be able to
sustain any life or would everybody and everything die? What if all the
water stolen was all salt water from the ocean, would that make any
difference? Would the planet become like the desert planet Arrakis in
Frank Herbert's Dune or would there be some pockets of green left?
If there was still life, how many people and animals would die from
lack of water? Also could future humans and animals be genetically or
mechanically engineered to survive on less water?"
Fred Obermeyer
Okay, let's think a little. First, I am told that there is enough water
to cover the earth to a depth of two miles, if all the continents,
valleys, and mountains were smoothed out. I remember this from the LIFE
Science Library THE SEA, but I can't find the reference on the spur of
the moment. So there will still be plenty of water on the planet.
What will happen to the planet's ecology? Fred does not specify how the
water vanishes, so let's try two ways:
a) A cosmic vacuum cleaner (hence CVC) is dumped down in the oceans,
switched on, and it's SKYWARD HO! for Flipper and Aquaman. This gets
around Mary's pertinent observation about the sudden increasing
salinity if the water goes, but the salt stays. However, the CVC is
going to take what is in the water along with the water (Fred has said
the disappearance is "sudden") so presumably, the sea life goes up with
the water) Unless the CVC covers the entire water surface of the
planet, though, presumably there will be areas where the fishies etc
swim along undisturbed. So suddenly, there's a great decrease in the
marine biosphere, but there's still life left to repopulate it. My
guess is that the repopulation would be fairly quick because a) the
nutrients in the water left behind would be able to cause the plankton
to grow like crazy, particularly since the larger predators that eat it
have been disproportionately taken by the CVC. But this brings us to
another effect: if a substantial amount of plankton disappears, the
photosynthesis that converts carbon dioxide to oxygen will be seriously
disrupted. I don't know how to run the math for this, but my guess is
that the carbon dioxide levels would rise substantially. Enough to
cause a runaway greenhouse effect? Could be? It's true, the land plants
are still cranking away, but a) land area only covers 30% of Earth,
water covering 70%, so any water catastrophe disproportionately affects
photosynthesis. And b) land plants have all kinds of structures (roots,
seeds flowers, etc) that are necessary to their survival, but
contribute nothing to photosynthesis. Pound for pound, plankton crank
out oxygen far more efficiently than any land plant.
b) Let's suppose the aliens use Mary's notion, and use a field that
brings up the water, but not anything in it. First thing, all land
life, including six billion humans get converted into slimy jerky, and
the aliens have a swell concession ready made for snacks. Second,
better than 95% of the mass of the water is going to come from the
oceans. Lakes, rivers and glaciers don't count for much. The esteemed
National Oceanographic and Atmospheric Administration website tells me
that Oceans average 3.5% salt content by mass. By comparison, the Great
Salt Lake in Utah test out at 10%. The higher levels of salinity will
cause much trouble. For example, the Salton Sea in California has no
outlet for its water. It can only get rid of water by evaporation,
which means it gets saltier over time. In the century since it was
created, it has gone from being a freshwater lake to 4.4% salt,
substantially saltier than ocean water. Result: no freshwater species
can live in it today (though there are many other reasons beside
salinity at play here.) Here's an NOAA map showing current salinity
levels:
No dam it, the map won't copy. It is at:
http://www.windows.ucar.edu/tour/link=/earth/Water/images/salinity_big_gif_image.html
Note that even the saltiest parts of the ocean are far under the 7%
level. So while there would be exceptions, I think Mary is quite right
to assume a mass dieout of oceanic life with this sudden rise. There
might be survivals near the mouths of great freshwater rivers, e.g. the
Mississippi The Amazon etc, where the water, instead of being brackish
as it is now, might be "normally" salty for saltwater life. Finally,
doubling the salinity will not precipitate salt from the water. The
valuable MERCK INDEX sez water can dissolve up to 33% of its weight in
salt, so Fred's scenario, which raises the content to 7%, well under
the limit.
What else would happen in such a rise of salinity as option b) states?
Well, salt tends to reduce evaporation rates, so the air would tend to
be drier. Lots of effects on the weather here, which I leave to others
to work out. There would be much more land/ compared to water. What
would this do to Earth's albedo, that is, the amount of light it
reflects from the Sun? I don't know if land reflects more light than
land, or vice versa. But whichever way it goes, the effect would be
substantial. This effect, in combination with the less evaporative
rate, might cause either a runaway greenhouse, or an ice age.
Far more weight should be given to the collapse of photosynthesis. The
relatively rapid rise of carbon dioxide, a notorious greenhouse gas,
would cause climate change fastfastfast.
Fred, as to the rest of your questions:
1. The doubling of salinity would not kill all marine life, but it
would give a hell of a wallop to it. Freshwater life in option b) would
be largely unaffected at first. More so later on should climate changes
and hence rain- and snowfall, which make lakes and rivers what they are.
2. Could animals/humans be genetically engineered to survive on less
water? I think what you mean is on saltier water. Humans would not be
affected at all, at first. We'd still get fresh water from rain, lakes
rivers etc, and I don't think there are any commercial desalinization
plants producing drinkable water. So far as genetic engineering, I
think that could be done. Also, the marine species that could survive
in high salinity water would likely be transplanted from their present
locations to the rest of the planet and be told to go forth and
multiply, in an effort to get photosynthesis going again. The ecology
of the planet has already had a hell of a wallop, so the ecological
effects of transplantation would be seen as minor.
3. I don't think the sudden disappearance of the water would turn the
planet into a sandheap. But the climatic changes that resulted from the
disappearance might do the job within our lifetimes.
You have not asked what would happened to the geography of the planet,
but you don't think that's going to stop me, do you? The sudden loss of
all that water would expand the coastlines. The very fine Oxford ATLAS
OF THE WORLD, pages 5-6 has a feast for speculations. Countries with
shallow littorals would suddenly get much bigger:
a) in South America, Argentina would suddenly have 50% more area
b) the Caribbean Sea and Gulf of Mexico would be less than a quarter
the size they are now. Castro would drive across the land bridge to
Tallahassee and tell Jeb Bush that he's annexing Florida to Cuba, and
is prepared to discuss surrender terms.
c) The East Coast of the United States would extend out another hundred
miles, particularly in the southern half. This effect would be even
more pronounced in Canada, which would likely annex Greenland.
Greenland in turn would annex Iceland, which would annex the British
Isles, which would annex Europe. Jumping to the Bering Strait, that
would vanish, with Siberia and Alaska merging. Result: the Arctic Ocean
becomes landlocked. The climate changes resulting from that would be
even greater than those caused by photosynthesis at first.
d) the Mediterranean would become landlocked, with 80+% of it
disappearing. Doubltelss it would be renamed in honor of its creator,
the Fred Sea, because:
e) The Red sea and the Persian Gulf would vanish, making it harder to
get that Middle East oil exported.
f) Southeast Asia and Australia would merge.
The upshot of a)-f) means an enthusiastic hiker could start walking
along the shore at Melbourne Australia north around New Guinea, north
along Singapore, Vietnam, China, Korea (Japan being absorbed by
mainland Asia) north to Alaska, ten thousand miles south along the
western shore of North and South America, north ten sand miles along
the eastern shore of North and South America, four thousand miles west
in a great circle along the southern coasts of Greenland, Iceland and
the British Isles to Europe, eight thousand miles south along the
western coasts of Europe and Africa, four thousand miles north along
the eastern coast of Africa, six thousand miles west along the southern
coast of Asia and India, and finally six thousand miles along the coast
of the newly merged Southeast Asia and Australia to Melbourne again.
What a hike! It has tired me out enough that I will let someone else
take up these speculations, noting in passing that all ocean ports have
just become landlocked and hence ruined by this theft, and nuclear
power, because it doesn't produce greenhouse gases, would become the
power source of the day.
Best regards,
Gregory Koster
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Message 465862 was posted by Marie Brennan on 2005-07-03 17:21:42.
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For clarity's sake, let me pull out and elaborate on Gregory's points
that are specific to climate patterns. I'm not by any stretch of the
imagination a serious student of the subject, but it seems to me that
there would be three factors mucking it up to the point where
environmental collapse would be pretty much guaranteed worldwide.
1) As Gregory pointed out, if you lose large volumes of plankton, your
CO2/O2 cycle gets gutted. Greenhouse gases proliferate, making the
planet hotter. Polar ice caps melt even more than they already have.
Are half of those getting stolen along with the liquid water? If so, I
could imagine not having any polar ice caps LEFT, once the CO2's gone
to work a little bit. Antarctica's soil sees the light of day for the
first time in a while . . . .
2) The shift in the coastlines would cut off the large-scale currents
in the oceans, which means that the circulation of cold and warm water
likewise gets gutted. These currents form a vast part of what's driving
our global weather patterns, I believe, so whacking them would have
VERY serious consequences. And even if the new patterns are survivable,
it's not going to be easy for people to rapidly change their tools and
crops and habits to suit whatever unfamiliar conditions they're now
facing.
3) The water cycle itself would, I imagine, be seriously gimped. No
matter how this water's being removed, if half of it is gone, then the
whole evaporation/condensation/precipitation cycle is suddenly way
off-kilter. It's probably even worse if the salt stays behind, because
of the effect on evaporation rates. Decrease in rainfall withers plant
life in various places, leaving the soil less shielded from the sun, so
I imagine you'd have a brand-new Dust Bowl, only worse. Water shortages
are already a large problem in the U.S. (see the most recent National
Geographic on the subject), so I'd expect crop failures, famine, and
terrible fires taking out the dead vegetation.
Then, if you really want to keep spinning out consequences, unless some
central authority works really hard to arrange for the disposal of all
the dead bodies (animal and human) caused by these problems, you're
going to have rotting corpses everywhere, which spreads disease, which
kills off even more people . . . .
(The Day After Tomorrow would have been a fantastic premise for an SF
novel if the story was about what happened AFTER the end of the movie.
The environmental and political consequences of that event would be
truly apocalyptic.)
As far as genetic engineering is concerned, I think the best bet would
be for people to retreat to places that still get some amount of
rainfall, and work with existing crops that do well under arid
conditions, engineering those to be more productive.
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Message 465875 was posted by Fredrick Obermeyer on 2005-07-03 23:17:26.
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I was thinking that the salt would be taken along with the water and
all the life in it. But it could also be left there.
What if most of the fresh water in the world was stolen or disappeared
rather than salt water? I imagine things would be a lot worse.
As for the genetic engineering question, I was wondering if a new human
being could be made that could literally survive on less water or could
be designed to absorb moisture out of the air. Or perhaps not waste
water through sweating and urination and find some other way to remove
wastes and keep cool.
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Message 465888 was posted by John Savage on 2005-07-04 09:50:39.
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Probably the biggest effect of suddenly removing half the oceans would
be a massive climate change due to the greenhouse effect. Half the
volume of water would result in half (well, somewhat more than half due
to depth/pressure based differences in solubility) the available volume
in which to hold carbon dioxide in solution. Even if one also posits
that all the carbon dioxide disappears with all the water, that's going
to cause a different equilibrium point. and, in the short run, oxygen
shortage as all of the blue-green algae die. Then one can watch
everything else crash, because that top 100 meters of ocean contains
something over 70% of the lifeforms on the planet.
Then, too, there's the whole fresh-water question. Particularly at the
mouths of the greater rivers, osmosis will drive salts farther upstream
(if the salts don't go with the water).
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Message 465889 was posted by Mary on 2005-07-04 09:59:06. Feedback: 0/0
If it's _fresh_ water, you can't take 50% of it. Maybe 50% of the fresh
water, which is a tiny fraction of the existing water.
How bad would it be? Assuming it didn't pull water out of plants and
things, water evaporating from the oceans would keep the water cycle
going. The problem being that it would have to go _massively_ to fill
up the waters again.
Expect massive extinction in the animals that live in marshes, ponds,
and swamps. Maybe even lakes and river, but they have more reserves.
Also, the absence would probably produce interesting effects on the
water cycle. Not as much as 50% of the water, but interesting.
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Message 465890 was posted by Mary on 2005-07-04 10:01:58. Feedback: 0/0
And for the seawater scenario -- would that water mean that the shore
is no longer on the continential shelf? I wonder because many of the
seashore ecologies are dependent on shallow water and, even more,
tides. You ain't going to get that on the drop-off.
(end of discussion on this subject)
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