Re: OT ~ Kevin's Thread Stolen?......

JanOrme99@xxxxxxx wrote:

<snip>

Here's an interesting study that speaks to the question of Man's influence
on global warming:

http://www.fs.fed.us/rm/pubs/rmrs_p015_3/rmrs_p015_3_027_032.pdf

I quote a portion here:

"Mann and others (1998, 1999) recently published a 1,000-
year long record of Northern Hemisphere temperature that
provides the first strong evidence that 20th century temperature
trends in the northern hemisphere exceed those that
would be expected from natural variability alone. These new
results represent a synthesis of a global network of hundreds
of proxy climate records derived from tree rings, glacial ice
and lake and ocean sediments, the vast majority of which
were collected in wilderness and other protected areas
where such climatic proxy data are preserved. Mann and
collaborators validated their temperature inferences by demonstrating
that the proxy temperature observations are
strongly correlated with observational data during the 20th
century.
Prior to the 20th century, the 1,000-year record shows slow
oscillations of warm and cool temperatures superimposed on
a 900-year cooling trend of approximately 1°C (Fig. 5).
Comparison of these oscillations with patterns of solar
variability and volcanic dust in the atmosphere strongly
indicates that these two factors combined to produce the
long-term cooling trend, as well as the shorter-term fluctuations
in temperature before 1900. The 20th century, in
contrast, is dominated by an abrupt increase of approximately
0.5°C. The remarkable nature of recent temperature
trends in clear: The decade of the 1990s is the warmest of the
last millennium and 1998 is the warmest year observed in
the full 1000-year record. The 20th century temperature
Figure 5-A 1,000-year record of Northern Hemisphere annual temperature
inferred from tree rings,
glacial ice, corals, and historical records (modified from Mann and others
1999).
trend mirrors the rate of accumulation of greenhouse gases.
There is no correspondence between the 20th century temperature
trends and other possible natural forcing factors
such as solar variability. In sum, the 1,000-year Northern
Hemisphere temperature reconstruction is the first strong
indication that we are now entering a period of Earth's
history when human imprint on climate can be detected.
This finding adds urgency to the call for including potential
climate change scenarios into planning for the management
of wilderness areas."


--
Kevin W. Miller
http://www.bluemoongemworks.com/rv/index.asp


.

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