文档介绍：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 ing book,
Unstoppable Global Warming—Every 1,500 Years
NCPA Policy Report No. 279
September 2005
ISBN #1-56808-149-9
Web site: /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 Gre