"Statistics for the Past Millennium" (Tomorrow at the Statistics Seminar)
- Julien Emile-Geay, "Statistics for the Past Millennium"
- Abstract: In 1998, a seminal study by Mann, Bradley, and Hughes
took advantage of climate signals embedded in an array of high-resolution
paleoclimate proxy data to conclude that "Northern Hemisphere mean annual
temperatures for three of the past eight years are warmer than any other year
since (at least) AD 1400." The so-called "hockey stick" reconstruction showed
relatively stable temperatures for most of the millennium, until the start of
the Industrial Revolution, when reconstructed temperatures began a rise to a
level not seen in the last millennium.
- Since 2001, when the third assessment report by the IPCC featured the
"hockey stick" prominently, this graph has become the emblem of the debate on
anthropogenic global warming. No other picture conveys how anomalous recent
climate change is in the context of natural variations in temperature over the
past millennium. Defended as definitive proof of global warming by many
climate scientists and sympathetic members of the public, hailed as a
"misguided and illegitimate investigation" by some politicians, it remains one
of the most hotly debated climate studies ever published. After a
congressional inquiry was conducted under the aegis of the respectable
Dr. Wegman, most statisticians are now convinced that the "hockey stick" is a
fluke due to the overfitting of noisy data.
- Have paleoclimatologists been wasting their time all along? In this talk,
I will describe the most recent statistical methods used by climate scientists
to reconstruct past climates; explain how their performance can be assessed in
a realistic geophysical context; show that some climate scientists are, in
fact, working hand-in-hand with professional statisticians, with some promising
- Time and place: 4:30--5:30 pm on Thursday, 11 November 2010, in the Adamson Wing of Baker Hall (entry through 136)
As always, the seminar is free and open to the public, but I should probably
add, considering the topic, that if you come and talk like a crazy person you
will be ignored
and/or mocked and rebuked.
Enigmas of Chance
Posted by crshalizi at November 10, 2010 11:00 | permanent link