Once extint, things are extinct. I think the point is to avoid that.
Nothing more, nothing less.
Have a nice night,
Lisa Dangutis
In a message dated 05/01/01 4:06:00 PM Eastern Daylight Time,
[log in to unmask] writes:
> 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
>
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