The Physical Evidence Of Earth's Unstoppable 1, Ochrona środowiska, Environmentalism Engl, Pl
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The Physical Evidence of Earth’s
Unstoppable 1,500-Year Climate Cycle
by
S. Fred Singer
President, Science and Environmental Policy Project
Adjunct Scholar
National Center for Policy Analysis
and
Dennis T. Avery
Senior Fellow
Hudson Institute
Adapted from their forthcoming book,
Unstoppable Global Warming—Every 1,500 Years
NCPA Policy Report No. 279
September 2005
ISBN #1-56808-149-9
Web site: www.ncpa.org/pub/st/st279
National Center for Policy Analysis
12770 Coit Rd., Suite 800
Dallas, Texas 75251
(972) 386-6272
Executive Summary
The Earth currently is experiencing a warming trend, but there is scientific evidence that human
activities have little to do with it. Instead, the warming seems to be part of a 1,500-year cycle (plus or
minus 500 years) of moderate temperature swings.
It has long been accepted that the Earth has experienced climate cycles, most notably the 90,000-
year Ice Age cycles. But in the past 20 years or so, modern science has discovered evidence that within
those broad Ice Age cycles, the Earth also experiences 1,500-year warming-cooling cycles. The Earth
has been in the Modern Warming portion of the current cycle since about 1850, following a Little Ice Age
from about 1300 to 1850. It appears likely that warming will continue for some time into the future, per-
haps 200 years or more, regardless of human activity.
Evidence of the global nature of the 1,500-year climate cycles includes very long-term proxies for
temperature change — ice cores, seabed and lake sediments, and fossils of pollen grains and tiny sea crea-
tures. There are also shorter-term proxies — cave stalagmites, tree rings from trees both living and buried,
boreholes and a wide variety of other temperature proxies.
Scientists got the first unequivocal evidence of a continuing moderate natural climate cycle in the
1980s, when Willi Dansgaard of Denmark and Hans Oeschger of Switzerland first saw two mile-long ice
cores from Greenland representing 250,000 years of Earth’s frozen, layered climate history. From their
initial examination, Dansgaard and Oeschger estimated the smaller temperature cycles at 2,550 years.
Subsequent research shortened the estimated length of the cycles to 1,500 years (plus or minus 500 years).
Other substantiating findings followed:
●
An ice core from the Antarctic’s Vostok Glacier — at the other end of the world from Green-
land — showed the same 1,500-year cycle through its 400,000-year length.
●
The ice-core findings correlated with known glacier advances and retreats in northern Europe.
●
Independent data in a seabed sediment core from the Atlantic Ocean west of Ireland, reported
in 1997, showed nine of the 1,500-year cycles in the last 12,000 years.
Other seabed sediment cores of varying ages near Iceland, in the Norwegian and Baltic seas, off
Alaska, in the eastern Mediterranean, in the Arabian Sea, near the Philippines and off the northern tip of
the Antarctic Peninsula all also showed evidence of the 1,500-year cycles. So did lake sediment cores
from Switzerland, Alaska, various parts of Africa and Argentina, as did cave stalagmites in Europe, Asia
and Africa, and fossilized pollen, boreholes, tree rings and mountain tree lines.
None of these pieces of evidence would be convincing in and of themselves. However, to dismiss
the evidence of the 1,500-year climate cycle, it is necessary to dismiss not only the known human histories
from the past 2,000 years but also an enormous range and variety of physical evidence found by a huge
body of serious researchers.
The Physical Evidence of Earth’s Unstoppable 1,500-Year Climate Control
1
Introduction
Is the Earth currently experiencing a warming trend? Yes.
Are human activities, including the burning of fossil fuel and forest
conversion, the primary — or even significant — drivers of this current tem-
perature trend? The scientifically appropriate answer — cautious and con-
forming to the known facts — is: probably not.
“The Earth’s climate cycles
through 90,000-year Ice Ages
interspersed with shorter
warm periods.”
Indeed, the current warming cycle is not unusual: Evidence from
around the world shows that the Earth has experienced numerous climate
cycles throughout its history. These cycles include glacial periods (more com-
monly known as Ice Ages) and interglacial periods, as well as smaller, though
significant, fluctuations. During the past 20 years, scientists have been ac-
cumulating strong physical evidence that the Earth consistently goes through
a climate cycle marked by alternating warmer and cooler periods over 1,500
years (plus or minus 500 years). The evidence indicates that:
●
The Earth experienced a Little Ice Age from 1300 to 1850.
●
A Modern Warming period began about 1850 and continues to the
present.
Figure I tracks the Medieval Warming and Little Ice Age that preceded
today’s Modern Warming.
We have long had physical evidence that the Earth has experienced
numerous climate cycles throughout its history. The best-known of these is
the Ice Age cycle, with 90,000-year Ice Ages interspersed with far shorter
interglacial periods. What is new is the evidence of more moderate, persistent
climate cycles within these broader cycles.
FIGURE I
Climate Cycle
1
5
“Within the longer cycle, the
climate warms and cools in
1,500 year-cycles (plus or
minus 500 years).”
Little Ice Age
0
Medieval Warm Period
-0.5
-1
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900
Year (A.D.)
Bradley and J. A. Eddy (
EarthQuest
, vol. 5, no. 1, 1991) based on J. T.
Houghton et al. (1990).
2
The National Center for Policy Analysis
The message that the 1,500-year climate cycle is real, broad — and
sudden — is being dug up from the Earth itself by modern science. The key
evidence comes from very long-term proxies for temperature change, especial-
ly ice cores, seabed and lake sediments, and fossils of pollen grains and tiny
sea creatures that document even small changes in Earth’s temperature over
many thousands of years.
In addition, we have a number of shorter-term proxies (cave stalag-
mites, tree rings from trees both living and buried, boreholes and a wide vari-
ety of other temperature proxies) that testify to the global nature of the 1,500-
year climate cycles.
A striking example of the effect of this 1,500-year climate cycle can be
seen in the temperature-sensitive history of wine-growing in England.
“Evidence from every conti-
nent and ocean confirms the
1,500-year cycle.”
The Romans grew wine grapes in England when they occupied it from
the first through the fourth centuries. Aerial photography, remote sensing and
large-scale excavation have recently revealed seven Roman-era vineyards in
south central England. One site contains nearly four miles of bedding trenches
that could have supported some 4,000 grapevines.
1
A thousand years later, during the Medieval Warming of 950-1300,
the Britons themselves grew wine grapes in England. The
Domesday Book
,
compiled in the 11th century, recorded 46 places in southern England growing
wine grapes. (Richard Tkachuck of the Geosciences Research Institute notes
that German vineyards were found as high as 780 meters in elevation during
the Medieval Warming, but are found today up to only 560 meters — indicat-
ing a temperature difference of 1° to 1.4° C.
2
) During the Little Ice Age (1300-
1850), England was too cold to grow wine grapes. Instead, London often held
ice festivals on the frozen Thames River, which hasn’t frozen in the last 150
years.
Now that the Little Ice Age has given way to the Modern Warming, a
few hardy Britons have again begun serious efforts to grow good wine grapes
in England — but thus far with spotty success. The Web site www.english-
wine.com admits that British wine-making is still a very chancy proposition.
Only two years in 10 will the wine be very good, and during four of the other
years it will be terrible, “largely due to weather....”
British vintners should be hopeful, however. The Modern Warming is
still young, and likely to eventually give them several centuries of good wine
production. The Earth is apparently having its third natural, moderate — and
unstoppable — warming in 2,000 years.
Taken by itself, the cycle of wine-grape growing in England might be
seen as an aberration. However, this is just one bit of the emerging body of
physical evidence of a natural climate cycle — a cycle too moderate and too
long to have been reported in the Viking sagas and earlier oral histories from
people without thermometers.
The Physical Evidence of Earth’s Unstoppable 1,500-Year Climate Control
3
FIGURE II
Change in Oxygen-18 Ratio in
Greenland Ice Cores, A.D. 820-1985
“The changing concentration
of oxygen-18 in Greenland
ice cores corresponds to the
1,500-year cycle.”
Note: The vertical axis shows the mean bidecadal change in oxygen-18 in the Green-
land ice cores. The horizontal lines through the graph of the data give the aver-
age annual change in
18
0 for the Medieval Warming Period (MWP) and Little
Ice Age (LIA).
Source: Sallie Baliunas and Willie Soon, “Climate History and the Sun,” George
C. Marshall Institute, June 5, 2001; from Minze Stuiver, Pieter M. Grootes
and Thomas F. Braziunas et al., “The GISP2δ
18
O Climate Record of the Past
16,500 Years and the Role of the Sun, Ocean and Volcanoes,”
Quaternary
Research
, vol. 44, 1995, pages 341-344, Figure 4.
None of these pieces of evidence would be convincing in and of them-
selves. However, in order to dismiss the huge impact of the 1500-year climate
cycle, we would have to dismiss not only the human histories from those pe-
riods, but also the enormous range and variety of physical evidence presented
here.
Importantly, if the current warming trend is, as the evidence suggests,
part of an entirely natural climate cycle, actions proposed to prevent further
warming would be futile and could, by imposing substantial costs upon the
global economy, lessen the ability of people to adapt to the impacts — both
positive and negative — of climate change.
The Ice Cores
In the 1980s scientists got the first unequivocal evidence of a continu-
ing, moderate natural climate cycle.
The 1,500-year climate cycle emerged
almost full-blown
from Greenland in 1983.
Denmark’s Willi Dansgaard and Switzerland’s Hans Oeschger were
among the first people in the world to see two mile-long ice cores that brought
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