On Wed, 27 January, 2010 8:14 am, Per Edman wrote:
>> Mankind's impacts were great enough to remove most of the large
>> megafauna from the Earth, especially in North America and that
>> occurred thousands of years ago. The resulting changes in the North
>> American ecosystems would also have impacted climate.
This is not definitively demonstrated. Some megafauna may have been
hunted to extinction. Others clearly were not. The evidence is
contradictory.
>> The repeated series of Ice Ages/Interglacials is thought to be due to
>> rather small changes in the distribution of solar energy, compounded
>> by changes in the atmospheric optical properties. Is there any reason
>> to think that these processes will be repeated? Yes and the latest
>> estimate of the driving forces suggests the Ice Ages won't return for
>> thousands of years. That is, the net impact of natural forcing won't
>> repeat for that long a period.
"Thought." "suggest."
In other words, we don't know.
>> > > Or, it may be that what we do could result in the start of
>> > > another Ice Age, even though the latest models do not make this
>> > > projection. I think it's possible that the Thermohaline
>> Circulation
>> > > is changing and this may result in one of those "tipping points",
>> > > i.e., a threshold event, which would change the Earth's weather in
>> > > ways human civilization has never experienced.
Anything is possible. What is the evidence to support the proposition
that the Thermohaline Circulation is changing; in reality, not in
mathematical models?
I'm not asking that the evidence be trotted out here. I'm curious if
this is a "thought" or a conclusion based on observation.
>> Your response again suggests you have no clue about the physics
>> involved. Your reply ignores the finding that the recent rise in
>> atmospheric CO2 is larger than any period since the beginning of the
>> present period of glacial/interglacial climate. I suggest that you
>> should learn some science before you spout off and demonstrate your
>> ignorance.
The nastiness of this response suggests a lack of trust in the science.
In fact, it is difficult to determine with any accuracy the
"largeness" of atmospheric CO2 variation over the past 500,000 years.
One cannot say with any certainty that CO2 levels were less or more
than present.
Furthermore, such a correlation is meaningless as there is no
established cause and effect relationship between atmospheric CO2
levels and average surface temperature. The fact in isolation that CO2
absorbs IR energy says nothing about "global warming," as other
chaotic factors involved in climate variability far outweigh the
effects of CO2.
This is what I mean by a narrow linear view of climate change: more
CO2 = higher surface temperatures. This is demonstrably untrue,
therefore this simplistic appeal to popular emotion has no merit.
hayduke
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