Three-Toed Sloth

"Statistics for the Past Millennium" (Tomorrow at the Statistics Seminar)

This should be interesting:

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 results.

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