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Re: Human vs. natural influences on the environment
In article <321FE2E4.1F4BFB4B@math.nwu.edu>,
Leonard Evens <len@math.nwu.edu> wrote:
>charliew wrote:
>>
>> In article <4vn2e4$9h3@igc.apc.org>, tomgray
>> <tomgray@igc.apc.org> wrote:
>> >brshears@whale.st.usm.edu (Harold Brashears) wrote:
>> >>kowens@teleport.com (Jeff Owens) wrote for all to see:
>> >>
>> >>[edited]
>> >>
>> >>>There are thousands of subjects we do not have full
>> understanding
>> >>>of, but that should not stop people from trying.
>> Knowledge is
>> >>>gained by suggesting a model and then trying to
disprove
>> it.
>> >>>The real issue here is: do we have enough information
to
>> suggest
>> >>>models. The answer from the scientific community is a
>> clear YES.
>> >>
>> >>While I think it is always worth it to build models and
to
>> test them
>> >>(otherwise, I would have been in some other business), I
do
>> not
>> >>believe that means we must act on the output of these
>> models at this
>> >>time. If you have some reason to believe that the
models
>> under
>> >>discussion are accurate, tell everyone about those
reasons.
>> >
>> >Well, far be it from me to quarrel with anyone's
religious
>> beliefs.
>> >
>> >I don't know that a strong belief in models is required,
>> though, to
>> >simply note that we are clearly changing atmospheric CO2
>> concentrations
>> >and therefore the earth's energy balance.
>>
>> Tom,
>>
>> This is where I continue to disagree with you. We know
that
>> we are changing the amount of CO2 in the atmosphere.
>> However, we don't know if it will keep increasing in
>> concentration, and we don't know if there is a threshold
>> concentration above which "it is bad". You are making a
BIG
>> assumption that we are changing the energy balance of the
>> earth at this point, because there is no clear documented
set
>> of measurements that indicate that this is so.
>>
>
>What we know by direct observation is that CO_2 levels have
increased
>siginficantly since the late 50s. We also know by
examination of
>ice cores that this started at the beginning of the
industrial
>revolution, and that CO_2 levels remained relatively
constant for the
>thousand years before that. (This is from the latest Report
of
>the IPCC Working Group I.) Climate modelers also have a
fairly
>good idea of how the Carbon cycle works, albeit with some
undertainites,
>and there is virtually no doubt that the obsrved increase is
due
>to human activities in burning fossil fuels, cement
production, and
>changes in land use. As to the future, we can't of course
be sure the
>models may continue to be explanatory. Unexpected events
could occur.
>Let us assume that no controls on emissions of fossil fuels
are put
>in place. Then it is clear that human emissions will grow
>exponentially for the next century of so. There are some
possibilities
>one can envision. Plants might become much more efficient
at removing
>CO_2 from the atmosphere than they have been until now.
Then quite a
>bit of the emitted CO_2 might be absorbed by the biosphere.
However,
>there is no particular reason to believe that will happen.
A more
>plausible scenario is that Carbon in soils in northern
latitudes will be
>emitted as temperatures increase, so the level of CO_2 will
go up
>even faster than it would just by burning of fossil fuels,
etc.
>Similarly, do you think there is any reason to expect the
CO_2 levels
>to change sigificantly if we stabilize emissions at current
levels?
>Why would the Carbon cycle suddenly change its basic
structure? Hence,
>when you say that we don't know that the CO_2 concentration
will keep
>increasing, it is right now a pretty good bet. The odds
that anything
>different will happen on the basis of what we know are very
small.
>What you suggest is that a very large change may suddenly
produce
>a sudden and beneficial effect, while keeping things more or
less
>the way they are may lead to serious problems. Is this
really very
>plausible? Your experiences in chemical engineering might
be
>relevant if you chose the right analogy. If you have some
elaborate
>chemical process and it appears to have been in steady state
for a
>very long time, making a sudden radical change in its nature
and
>then arguing that if you didn't, something unexpected might
happen
>or if you do, something else unexpected, which you have no
basis to
>predict, might lead to stability seems strange to me. I
would think
>that in the absence of knowledge, it would be safer to
continue the
>status quo than to undertake a radical change in the nature
of the
>process. Moreover, since there is considerable knowledge,
emphasizing
>that something unexpected might happen doesn't make much
sense.
>
Just what is the status quo? At the present time, it is
continuing to do what we are doing. If you had it your way,
what would you propose? Stop burning all fossil fuel? What
would we do for the time that it takes to replace our energy
sources with something clean and renewable? Do you have
enough patience to wait for a replacement (over fossil fuel
burning) to be widely developed?
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