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12/14/1999
Weird Ice And Our Warm Future
How often has your spouse or significant other gone to the
refrigerator for ice cubes for his or her gin and tonic, only to find
that you used the last ones? No doubt, a few caustic comments
followed about your failure to replenish the supply. (Ok, you''re
the more advanced technology type with automatic ice
maker/dispenser. We tried, but it was going to be a major
plumbing event.) At any rate, how about that huge ice cube the
size of Rhode Island (1214 square miles) that broke off the
Antarctic shelf and is floating around down in the South Atlantic?
The threat to shipping in the area may be exacerbated when the
monstrous iceberg breaks up into many smaller Manhattan-size
(22 square miles) pieces. Global warming may or may not be
responsible for this spectacular event. If it is, our children and
grandchildren may be in for all the predicted environmental fallout
predicted by the greenhouse models for our future climate.
Which brings me to another form of ice. I''ll segue into this form
by way of the polished brownish paperweight that I keep on my
desk. The specimen, with whitish and dark brown black stripes
traversing through it, has the name Tosco etched into the top.
Tosco is in the news recently, taking over a fairly large number of
the Mobil stations in our area as a result of the Exxon-Mobil
merger. Back in the ''70s, I owned stock in Tosco, which was
looking into the prospect of extracting oil from shale, a sample of
which comprises my paperweight. I have never tried, but I
understand that if I light a match to the shale, it will start to burn.
The extraction of oil from shale has not been pursued vigorously
since the ''70s because of the lower oil prices.
What''s this got to do with ice? Well, it turns out that, if you''re
looking for new sources of energy there''s a form of ice that is so
abundant on this planet that it purportedly contains more energy,
in the form of methane gas, than all the fossil fuels in the world
combined! This "ice" is methane hydrate, a whitish icy material
that consists of methane molecules trapped in "cages" of frozen
water. Methane gas is the major component of natural gas and
also is found as "marsh gas", a product of decaying vegetative
matter in swamps, etc. Methane is a known contributor to
greenhouse warming. Indeed, I''m reasonably sure I''ve seen
speculation that bovine flatulence has been considered as a major
source of methane in the atmosphere. I have no personal
experience in this field, nor do I wish to!
Like my oil shale, the methane ice will burn when lit. Now, you
might think that flammable ice is like green eggs and ham, a
figment of the late Dr. Seuss''s imagination. Actually, you''d be
close. A leading authority on methane hydrate is Dr. Erwin Suess
(spellings are correct), director of the Research Center for Marine
Geosciences in Kiel, Germany. He is the lead author of an
interesting article entitled "Flammable Ice" in the November issue
of Scientific American. The article not only considers the
properties of methane ice but also describes an expedition off the
coast of Oregon to dredge up some of the material from the
bottom of the ocean. Oh, I forgot to mention, this methane ice is
not too stable, to put it mildly. It can only exist at near-freezing
temperatures and under high pressure. This means that it only
exists naturally under pressures found at ocean depths of at least
500 meters (over a thousand feet) below the surface. So, raise
the temperature or move the methane ice to shallower water and
methane gas will escape and bubble up to the surface. Suess and
his colleagues were able to scoop up about a hundred pounds of
the stuff and dump it, hissing away as the methane escaped, into
liquid nitrogen. They did manage to take a chunk, light it with a
match and it did indeed burn with a reddish flame, leaving behind
a puddle of water.
I certainly never heard of methane hydrate in my chemistry
courses and I was unsuccessful in finding any mention of it in my
chemistry handbooks. It apparently has only been since 1970 that
anyone knew that it existed under the ocean. Now it has been
found all over the world, even off our New Jersey coast. If we
express the energy content of various items in terms of the
organic carbon content, the Scientific American article estimates
that gas hydrates contain 10 trillion tons of carbon compared to 5
trillion tons for fossil fuels. Other carbon sources such as soil,
peat and living organisms are quoted as containing nearly 4
trillion tons of carbon. It wasn''t stated how big a percentage of
the living organisms were us! After my cannibalism column, who
knows? We could be cannibalized as fuel some day.
Enough of this ghoulish speculation. Let''s turn to something
really worrisome. What happens to the methane gas released
from these weird icy deposits? Some of the methane reacts in the
sea to form carbon dioxide, which in turn forms the calcium
carbonate shells of various sea creatures. Methane that escapes
the ocean also reacts in the atmosphere to form carbon dioxide,
the greenhouse gas we''re all concerned about. Any methane that
doesn''t react also contributes to greenhouse warming. Not a
good scenario! A number of workers ranging from Australia to
Rutgers University, where I have a connection, have been looking
into cases of relatively sudden global warming of a rather
spectacular nature over the past 100 million years or so. Their
opinion is that there were vast releases of methane into the
atmosphere which caused a spectacular warming about 55 million
years ago, after the extinction of the dinosaurs. The temperature
rose a remarkable 9 to 12 degrees Fahrenheit. This caused the
extinction of many species but at the same time the number and
variety of mammal species exploded. It was from some of these
species that primates and, eventually, good old Homo sapiens
evolved. Could it be that we owe our existence to both the
dinosaur extinction and this weird methane ice?
How did this sudden extinction/evolution occur? Miriam Katz, of
Rutgers, and her colleagues from Rutgers and the University of
California at Santa Barbara believe that there was a gradual
warming which changed the ocean currents sufficiently to push
relatively warm water down to the sea bottom. As we mentioned,
methane ice isn''t happy at temperatures much above freezing.
There would be a burst of methane gas, which could have
generated enough pressure to create mudslides and allow rapid
release of the methane. The methane in the atmosphere would
then react to give carbon dioxide and the temperature would heat
up more. The cycle would feed on itself and the result would be a
greatly accelerated rate of warming. Katz''s proposal is that
frozen landmasses would have warmed up enough to allow the
expansion of the mammals'' habitat and spur the observed
explosion of new species.
Well, need I go on to tell you the possible scenario for our own
future if the global warming trend, now pretty well established as
being a real concern, continues? Dr. Gerald Dickens of Australia,
a co-author of the Science paper, calculates that in the next
hundred years about two-thirds of the amount of carbon
responsible for the heat-up 55 million years ago will be released
into the atmosphere if we continue on our merry way, burning
those fossil fuels. This could tip the balance and, with additional
release of methane from the ice, could alter things rapidly, even in
decades rather than thousands or millions of years! Perhaps we
should be hoping for a really tremendous volcanic eruption or two
to balance the heating with a cool-down from the debris that
would circulate in the atmosphere.
I have been searching for something other than volcanoes that
would bring a note of optimism as to our future climatic state.
What I was hoping was that maybe an ice age was on its way to
counter the greenhouse effect. At first I thought there was some
hope based on work reported by Dr. Wallace Broecker and
colleagues at Columbia University, who looked into ocean
sediments to find a correlation of the sediment composition with
climate changes in the past. They found evidence that led them to
propose oscillations in a global "conveyor belt", a global deep
ocean current that runs all the way from the North Atlantic down
past Antarctica into the Pacific up near Alaska. This system
operates by cool ocean water being brought up to the surface,
where it warms and becomes saltier and denser and eventually
sinks back down to lower depths. As it sinks it is replaced by
other water and a conveyer-like movement is engendered. This
sinking is called the "production of deep water" in the trade and
apparently takes place most heavily in the North Atlantic and in
the Weddell Sea near Antarctica. It had been thought that the
amount of the production of deep water was about the same in
both places but the Columbia workers have concluded that there
is actually an oscillation between these two producing areas. This
oscillation is believed to be responsible for a 1500-year cycle of
cooling and heating.
The most recent visible product of this oscillation is thought to be
the "little ice age" which spanned a period from the 14th to 18th
centuries. This was a period of unusual cold and poor harvests
responsible for famines in Europe during those years. These
1500-year cycles have been traced back to the last "big" ice age
10,000 years ago. Unfortunately, we are just emerging from the
last little ice age so I can''t foresee any relief for many centuries.
If anything, I suspect there would be a reinforcement of the
greenhouse effect.
I''ll make one more try for optimism. That flammable ice, if it can
be "mined" for methane to be used as fuel, can serve to generate
electricity for air conditioning for the more fortunate people still
around during the Greenhouse Age. Ok, that was a pretty sick
suggestion but try to come up with a better one!
After all this, I''m ready for something a bit stronger than a gin and
tonic, perhaps bourbon on the rocks. Now if I can only find those
ice cubes.
Allen F. Bortrum
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