This book studies the history and gives an analysis of extreme climate
change on Earth. In order to provide a long-term perspective, the first
chapter briefly reviews some of the wild gyrations that occurred in the
Earth's climate hundreds of millions of years ago: snowball Earth and
hothouse Earth. Coming closer to modern times, the effects of
continental drift, particularly the closing of the Isthmus of Panama are
believed to have contributed to the advent of ice ages in the past three
million years. This first chapter sets the stage for a discussion of ice
ages in the geological recent past (i.e. within the last three million
years, with an emphasis on the last few hundred thousand years).
The second chapter discusses geological evidence for ice ages - how
geologists surmised their existence prior to actual subsurface data that
proved the theory. The following two chapters look at ice cores
(primarily from Greenland and Antarctica). Chapter 3 discusses how ice
core data is processed and Chapter 4 summarizes data obtained from ice
cores. Chapter 5 discusses the processing of data obtained from ocean
sediments, and summarizes the results, while the following chapter
discusses data from other sources, such as Devil's Cave.
Chapter 7 summarizes the experimental results from Chapters 4, 5, and 6.
It provides the foundation for comparison with theories in later
chapters. In a perfect world, this data would be totally separate and
disconnected from theory. Unfortunately, as the author shows, dating of
much of the data was accomplished by tuning to the astronomical theory,
which introduces circular reasoning.
Chapter 8 provides a brief overview of the various theories that have
been devised to explain the patterns of alternating ice ages and
interglacials that have occurred over the past three million years. This
serves as an introduction to the following three chapters which presents
the astronomical theory in its various manifestations,
compare the astronomical theory with data, and then compare other
theories with data. Finally, Chapter 12 summarizes what we think we know
about ice ages and, more importantly, what we don't know.
