10 Nov 09 - Recent laser
imaging of the Earth’s surface provides new evidence for abrupt,
fluctuating, warm and cool climatic episodes that could not have
been caused by changes in atmospheric CO2, nor by humans.
In a
paper presented at the national meeting of the Geological Society of
America in Portland, Oregon, Professor Don J. Easterbrook, Professor
of Geology at Western Washington University, presented new data
showing that at least 9 significant, abrupt periods of climate
warming occurred between 11,700 and 10,250 years ago. These warmings
triggered retreat of the Cordilleran Ice Sheet.
Such
fluctuating periods of warming and cooling persist to this day
(with no help from humans), and there is every reason to expect them
to continue.
"Isotope data from Greenland ice cores show a consistent pattern of
fluctuating warm and cool periods over the past 500 years (Fig. 2),"
says Easterbook. "The average period of warming/cooling
oscillations over the past 500 years is 27 years, remarkably similar
to the period of alternation between warm and cool Pacific Decadal
Oscillation."
Figure
2. Paleotemperatures derived from oxygen isotope measurements of
the
GISP2 Greenland ice core. Red peaks are times of warming and blue
are times of cooling. The average time period for each climatic
oscillation is 27 years.
"What we can learn
from this geologic climate changes is that the past is indeed the
key to the future," Easterbrook continues. "In 1999, the year after
the warmest year of recent times, I projected the climate pattern
from the past century and past 500 years into the future and
predicted that we would be due for 25–30 years of global cooling
beginning about 2000. The PDO changed from its warm to cool mode in
1999 and since then we have had global cooling, quite moderate to
flat (interrupted by two warm El Ninos) and intensifying since
2007."
Figure 4. Projection of climate changes of the last century and
past 500 years
into the future. The black curve is temperature variation from 1900
to
2009; the red line is the IPCC projected warming from the IPCC
website in 2000; the blue curves are several possible projections of
climate change to 2040+ based on past global cooling periods
(1945-1977; 1880 to 1915; and 1790 to 1820). The lack of sun spots
during the past solar cycle has surpassed all records since the
Dalton Minimum and some solar physicists have suggested we may
be headed for a Dalton or Maunder type minimum with severe
cooling.
See
entire paper by Don Easterbrook entitled
"New geologic evidence of
past periods of oscillating, abrupt warming, and cooling"
Abrupt warming
and cooling - Easterbrook
