Course
Description
In this
course we will provide an introduction to the broad field of
“Paleoclimatology” by focusing on the examination of three important
and unsolved problems: the toggling between glacial and interglacial
conditions over the past two million years; the remarkably abrupt,
possibly global scale climate changes seen throughout the last glacial
period; the relative stability of the climate of the past 10,000 years.
We will first examine the ice-age problem. The ice-age cycles are
clearly paced by changes in insolation that occur because of changes in
the properties of the Earth’s orbit around the Sun: this is the
so-called Milankovitch theory. There is a close relationship between
insolation, ice volume and carbon dioxide. The processes that link
these variables are still uncertain. Hence, it is not surprising that
several theories for the ice ages exist, some of which are not
complimentary. We will examine the climate proxy data, the theories and
the modeling to determine what is known and what is uncertain about the
ice-age cycles, and to illuminate the key questions that are being
asked by investigators working on this problem today. [The state of
affairs is such that one can seriously entertain two mutually exclusive
theories: the ice-age cycles are fundamentally about interactions
between atmosphere/ocean dynamics and the carbon cycle (with the ice
being incidental), and the ice-age cycles are fundamentally about land
ice (with carbon dioxide and atmosphere/ocean dynamics being
incidental).]
The second problem we will examine is the causes for the remarkable
abrupt climate changes seen during the last ice age, that have not been
since: the so-called Dansgaard-Oescgher events and the Heinrich events
(iceberg discharges) that may be associated with them. We will
summarize and critiqued the observations that define theses events and
the current ideas of the processes responsible for them.
In the final section of the course, we will turn to the Holocene.
The Holocene starts about 10,000 years ago, at the end of the last ice
age, when the amount of terrestrial ice is about the same as that
today. It is widely believed that the climate during the Holocene is
less variable in comparison to the climate during the ice-age climate.
We will examine the proxy data and modeling evidence that challenges
that paradigm. In particular, it appears the climate in the tropical
regions during the early Holocene (5-10k yr BP) was much different than
that during the late Holocene (5ky BP to present). Finally, we
will examine the efficacy of the widely held assumption that the
leading patterns of year-to-year climate variability observed in the
instrumental record are useful in identifying and understanding the
climate variability on interannual to centennial time scales throughout
the Holocene.
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Evaluation
An important feature of the class is discussion sessions, each
one focusing on a key topic. These discussions will center on the
results from key papers. Two or three students will be responsible for
leading each focus discussion session, though everyone is expected to
contribute to the discussion. The discussion leaders will also be
responsible for additional papers that resolve issues raised in the key
papers, and summarize the current issues/challenges in this area of
research. At least 24 hours prior to the prior to each discussion
section, all students who are not assigned to lead that discussion will
submit to the discussion leaders and the instructors three questions
that stem from reading the key papers. The leaders should address the
most important questions during the discussion session.
In addition to the student-led discussion session, there will be
several mandatory problem sets.
There are no exams in this course.
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Required
Readings
See Syllabus
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