Global environmental change

This dissertation tests an original hybrid methodology to explore the rapid spread
of the idea of human-made climate change that began in the 1950s after the idea had lain
dormant for half a century. It describes the 1950s rhetorical events that triggered the
idea’s diffusion, then traces how its rhetorical uses gradually gave root to the end-of-thecentury
political impasse over how to respond to the societal implications of the idea.
The research methodology rests on the simple logic that an idea can only spread
by being used in human discourses. It combines traditions of rhetorical historiography
with a philosophical view of intellectual history as the cumulative effect of a “natural
selection” of ideas and their spread by human individuals over time and geography. It
calls for sampling and analyzing rhetorical artifacts in light of the rhetorical situations in
which they originate, focusing on how the idea of human-made climate change is used
rhetorically in scientific and other discourses. The analyses form the basis of a narrative giving emphasis both to rhetorical continuities and to conversation-changing rhetorical
events. They also show how these rhetorical dynamics involve interactions of human
communities using or attacking the idea for their communal purposes.
The results challenge science-focused understandings of the history of the idea
itself and also suggest that the methodology may be more broadly useful.
As to the history, the analyses highlight how changes in the rhetorical uses of the
idea made possible its 1950s breakout in climate science, then led to uses that spread it
into other sciences and into environmentalism in the 1960s, attached it to apocalyptic
environmentalism in the 1970s, injected it into partisan politics in 1980s and shaped the
political impasse during the 1990s.
The data show that the methodology reveals elements of the discourses missed in
histories emphasizing the “power of ideas,” suggesting that a focus on the usefulness of
ideas may be more fruitful. A focus on rhetorical uses of ideas grounds the causation of
intellectual change in human motivation and agency, expressed in material acts that
multiply and disperse naturally through communities and populations.

Oxygen and Carbon stable isotope ratios were used to analyze and compare growth histories of six Recent and fossil genera of mollusks: three genera of gastropods---Triplofusus, Fasciolaria, and Beringius, and three genera of bivalves--- Dosinia, Anadara, and Codakia. Taxa were selected to check for compatibility of results between different fossil genera from the same environment. Comparison between isotopic signatures in recent and fossil congeneric species allowed substantial insight into growth rates. Recent specimens were collected from the Gulf of Aniva, Gulf of California, Bahamas, Florida Keys, and Gulf of Mexico. Fossil specimens were collected from the Middle Miocene of Kamchatka and the Pleistocene of Florida. Oxygen isotope ratios were also used to infer ambient seawater temperatures during the deposition of each shell. The calculated temperatures offer significant insight into the Pleistocene southern Florida embayment and Middle Miocene climatic optimum in the North Pacific.