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The past is the key to the future: Ice core isotope data,
glacial fluctuations, decadal sea surface temperature
changes, solar variations, and historic measurements.
Don J Easterbrook
Dept of Geology,
Western Wash Univ.
Bellingham, WA
THE PAST IS THE KEY
TO THE FUTURE

Charles Lyell (1797) – “The present is the
key to the past.”
 To
understand present-day climate changes,
we need to know how climate has behaved
in the past.
 In
order to predict where we are heading, we
need to know where we’ve been.
Measuring climatic warming/cooling
in the geologic past
 Historic
temperature
measurements
 Oxygen
isotope ratios in
deep ice cores.
 Advance
glaciers.
and retreat of
Data in this presentation
may be found in this volume
 Periods
of
warming and
cooling during
the past
century
GREENLAND GISP2 ICE CORE

The ratio of 18O to 16O depends on the temperature at the time
snow crystals formed in the atmosphere. The oxygen isotopic
composition of a sample is expressed as a departure of the 18O/16O
ratio from a standard.
 δ18O
= (18O/16O)sample ‒ (18O/16O)
_________________________________
x 103
(18O/16O)standard


where δ18O is the of ratio 18O/16O expressed as per mil (0/00)
The GISP2 isotope data reflects Greenland temperatures but
excellent correlation with global glacier fluctuations makes it
a good proxy for global temperatures.
Periods of warming and cooling in the past 500 years
Isotope data from Greenland ice cores shows 40 periods
of warming/cooling, none of which could be caused by CO2
Warm/cool periods over the past 5,000 years
The Medieval
Warm Period and
Little Ice Age
2400 publications
including many books
(Loehle, 2007)
Mann et al. (1998)
Little Ice Age moraines
Periods of warming and cooling in the past 10,00 years
Abrupt, intense
periods of
global warming
10-15,000years
ago
Global warming/cooling in past 25,000 years
1. Global warming has occurred
many times in the last 25,000
years, all caused by natural,
recurring processes.
2. The magnitude and intensity of
global warming during the past
century is insignificant
compared to the magnitude and
intensity of the profound
natural climate reversals over
the past 25,000 years,
Some examples of intense global warming and cooling




1. About 24,000 years ago, while huge continental glaciers covered large areas, a sudden
warming of about 20°F occurred. Soon thereafter, temperatures dropped abruptly about
11°F and temperatures remained cold for several thousand years but oscillated between
about 5°F warmer and cooler.
2. About 15,000 years ago, a sudden, intense, climatic warming (about 21°F, ~12° C;) caused
dramatic melting of the large ice sheets that covered most of the world.
3. A few centuries later, temps plummeted~ 20° F (~11°C) and ice sheets readvanced.
4. About 14,000 years ago, temperatures rose rapidly, about 8° F (~4.5°C), and the ice
sheets receded.

4. About 13,400 years ago, temperatures plunged, ~14° F (~8°C) and ice sheets readvanced.

5. About 13,200 years ago, temps rose rapidly, 9° F (~5°C), and ice sheets receded.


6. 12,700 yrs ago temperatures plunged sharply, 14° F (~8°C) and a 1300-year cold period,
the Younger Dryas, began.
7. After 1300 years of cold climate, temperatures rose sharply, ~21° F (~12° C), 11,500
years ago, marking the end of the Younger Dryas cold period and the end of the
Pleistocene Ice Age.
Significant periods of warming and cooling that
occurred within climatic events are recorded in
ice sheet advances and retreats
Conclusions about global warming from the
past few centuries to 25,000 years ago
1. Global warming has occurred many times in the last
25,000 years, all caused by natural, recurring processes.
2. The magnitude and intensity of global warming during the
past century is insignificant compared to the magnitude
and intensity of the profound natural climate reversals
over the past 25,000 years,
3. All of these periods of global warming occurred long
before any significant rise in human CO2 emissions and
cannot have been caused by them.
4. CO2 plays a minor, insignificant role in climate change.
The cause of global warming and cooling
 Relationship
of climate
change and
sea surface
temperature
—the PDO
and AMO
PDO and glacier fluctuations
PDO and sea
surface
temperature
GLACIER FLUCTUATIONS
CLIMATE CHANGES
PDO-AMO MODE CHANGES
WHAT DRIVES PDO-AMO MODES?
PDO COLD MODE (1945-77)
PDO WARM MODE (1977-98
Weather patterns for El Nino and La Nina
Sea surface temperatures
1997
1999
2001
2007
March,
2009
October
2011
Setting up of
the PDO cold
phase assures
global cooling
for the next
~25-30 years.
How cold will it get?
Cold PDO firmly entrenched since 1999
IPCC predictions vs. reality
Computer models are the
only basis for claiming
CO2 is causing global
warming. IPCC models
predicted 1ºF warming
from 2000 to 2011.
However, temperatures
have cooled so the
models have been
proven wrong.
GLACIER FLUCTUATIONS
CLIMATE CHANGES
PDO-AMO MODE CHANGES
WHAT DRIVES PDO-AMO MODES?
Maunder Sunspot Minimum
Global cooling occurs during times of few
sunspots and low solar irradiance
Correlation
between solar
activity and
climate
Change in
production
rate of
radiocarbon
and
temperature
Correlation of SOI and solar activity
Svensmark, CERN experiments
 Variations
in the sun’s magnetic field affects
cosmic radiation received by the Earth.
 Cosmic rays produce ions that act as seeds of
condensation (clouds).
 Increased cloudiness results in climatic
cooling.
Cloud cover and cosmic rays
CONCLUSIONS








Many periods of natural warming and cooling have occurred in the past
15,000 years, long before CO2 could have caused them.
More than 40 periods of global warming/cooling have occurred in the past 500
years, none of which could have been caused by CO2.
Many periods of far more intense warming have occurred from natural causes
in the past 15,000 years, some as great as 20°F in 40 years.
Almost all of the past 10,000 years has been warmer than present.
The Medieval Warm Period and Little Ice Age did occur—the ‘hockey stick’ is
a bad joke.
The climate has been warming gradually since the Little Ice Age began about
500 years ago.
Recurring patterns of cyclic global climate change form a reliable basis for
predicting future climate changes—the past is the key to the future.
Computer models have failed badly in predicting temperatures.

Glacier fluctuations result from climate changes.

Climate changes result from changes in the PDO and AMO.





The PDO flipped from cool to warm in 1977 and climate warmed;
the PDO flipped from warm to cool in 1999 and climate cooled.
Changes in ocean temperatures correlate well with solar changes.
Changes in the solar magnetic field affect incidence of cosmic rays
on Earth. Changes in cosmic ray intensity affects cloudiness,
which affects global temperatures.
The sun is now in a solar minimum and seems to be heading for the
Dalton Minimum (1790-1820), during which global
temperatures declined sharply.
The 1977-1998 global warming period is over and we are now in a
period of global cooling that will last several decades, similar to
continuing natural cycles dating back thousands of years.
Dogma is an impediment
to the free exercise of
thought. It paralyses
the intelligence.
Conclusions based upon
preconceived ideas are
valueless. It is only the
open mind that really
thinks. Patricia Wentworth, 1949
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