In the Gray article is a reference to the acknowledged scientific fact that
there was a cataclysmic decline in species during the Devonian period,
approximately 400 million years ago. Gray argues in a round about way that
this is an example of what Nature herself can do without the help of man.
Now the argument that he uses to support his thesis is based on a theory
that the cause of this extinction about 400 million years ago was a meteor
that struck earth in Central Americas.
The last argument is actually is based on a current theory. There are other
possible explanations. One of which is that during this time when a massive
extinction occurred was that there were numerous large volcanic eruptions on
the Indian subcontinent which spewed massive amounts of aerosols and carbon
dioxide into the troposphere and the next upper layer of atmosphere. It has
not been established yet what was the exact cause of the large species die
off. However it is speculated that in North America the forests were all
burned off. This lead to additional amounts of CO2 being deposited into the
atmosphere and along with vastly lower rates of insolation that temperatures
fell considerably. The result was that in the Northern hemisphere all
animals larger than about the size of a rat died off. In the southern
hemisphere the effects were not as severe simply because it takes about 2
years for the earth's air masses to exchange between hemispheres. Now the
point that I wanted to make is this:
Gray argues that if nature is doing this, then it makes no sense to take
precautions at all to protect species nor their habitats. The only
environmental values that should be protected are immediate values, rather
than values expressed in terms of geological time scales. In fact he cites
an auther who claims that there were once more phyla on earth prior to
nature causing this extinction. The error here is obvious for any scientist
in climates. The accepted hypothesis is that during this major extinction
the direct cause of extinction was due to cool temperatures, low oxygen
levels and a serious shortage of food or prey. Now at this time in
geological history there was vastly more forest covering the earth. This was
*before* any of the ice ages occurred. The Antarctic was still forested. The
probability of recovery from the a large meteor landing in Central America
therefore was much greater than it is now assuming a similar meteor or
volcanic event was to ensue today. If a meteor or volcanic event of similar
magnitude occurred today, the probability of the earth's tropospheric
conditions (oxgyen levels, CO2, etc.) recovering to levels that would
support large animals would be very much reduced. One of the reasons for
this lack of recovery is related to the diminished extent of the world's
forested areas caused in main part by man. The quickest way for the oxygen
content of the troposphere recovering is through photosynthesis. The amount
of photosynthesis is directly proportional to the area of forest, and the
rate of photosynthesis of the oceans. Since dying and dead trees emit vast
amounts of CO2, there would be a very great increase in CO2 (magnitudes
larger than that from erupting volcanos or the direct effects of a large
meteor) and a corresponding decline in oxygen after a meteor or a severe
volcanic event. The chances of a rapid recovery occurring today given the
fact that over 50% of the worlds forests have been removed means that the
ability of the earth's biosphere to survive would be reduced simply because
it would take that much longer for the oxygen levels to recover to an
optimum or minimum level required by some life forms. In fact the current
speculation by climate scientists <some of whom are contrarians> is that the
oxygen levels in the atmosphere are currently below the optimum, therefore
to stimulate the evolution of more oxygen some anthropic generation of CO2
would be beneficial because it is felt that the current levels are
dangerously low for many species....therefore an increase in CO2 would
stimulate photosynthesis and therefore there would be more O2 in the
atmosphere.
The only long term carbon storage (sink) other than in protected forests
exists in oceans, but the rate of absorption compared to that sequestered in
forest biomass is much slower. The argument that if nature does something,
then it is okay for humans is therefore unscientific and therefore unsound.
This argument would suggest that it is okay to permit industry that has an
accumulative net negative effect on coral reefs. Gray disputes that coral
reefs have any benefit overall to life since he sees them as unimportant;
although he does not say this outright, he says it does not matter in the
long run if the Great Barrier Reef dies out. To say this also means that if
the coral reefs were wiped out by climate change induced by anthropogenic
green house gases via 'bleaching', then it is also okay. However the
ecological fact remains that coral reefs provide an important carbon sink or
source to the world's atmosphere and oceans of CO2. These reefs act like a
buffer and recovery system for life itself when a catastrophic natural
disaster takes place. So by arguing for a 'no virtue' approach to resource
management, ie., lets emulate natural events like volcano's and meteors,
then this approach may actually contribute to the improverishment of life on
earth.
Most if not all climate scientists are arguing for reforestation and
afforestation since this will increase the rate of carbon sinks in the
biosphere and diminish the impact of additional greenhouse gases on inducing
climate change. Even the contrarians are maintaining that this is a good
idea since trees capture solar energy and this energy can be used to fuel
electric plants, and to produce biofuels. Now does it make any sense to
argue for not restoring the biological productivity of previously forested
land simply because in the past it is hypothesized that a meteor caused the
atmosphere in the Northern Hemisphere to become so cold, oxygen deprived,
and inhospitable for a few short years?
Reforestation of the Amazon of 75 million hectares which were degraded and
denuded over the last 5 decades would contribute to the resilience of the
earth's biosphere and help to mitigate such natural disasters as volcanic
eruptions and meteors on the climate of the earth. Am I wrong on this?
chao
john foster
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