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past thousand years, compared with more modern instrumental temperatures beginning in the seventeenth century. One vertical tick mark
spacing corresponds roughly to a 1°C temperature variation. [Adapted from Jones et al., “High-Resolution Paleoclimatology of the Last
Millennium: A Review of Current Status and Future Prospects,”
Holocene
(2009): 34.]
Toward the Abyss
As I was completing my Ph.D. in 1996, I remained interested in using proxy climate records to study
the longer-term patterns of natural climate variability. I remained intrigued not only about the role of
what I had termed the Atlantic Multidecadal Oscillation, but also how the El Niño phenomenon had
behaved in centuries past. I was also interested in teasing out the role of natural “forcing” factors
(that is, natural external factors that force the climate to change), such as volcanoes and changes in
solar output, in explaining past climate changes. Though I accepted the mainstream view that there
was now a detectable human influence on the climate and I was vaguely aware of some of the
contentiousness that surrounded that conclusion, anthropogenic climate change was barely on my
radar screen. That was about to change, however. If I had avoided entanglement in the thorny issue of
humanity's role in global warming thus far, I would soon collide with it head on.
