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Physics department colloquium

Neotropical human landscape interactions, fire, and atmospheric CO2 during European conquest
Richard J. Nevle

Monday, November 8th, 2010
Daly Science 207

In this talk we'll look back in history to identify when the signature of human activities can be first be detected in the composition of Earth's atmosphere, and when such activity first began to affect Earth's climate system. We'll find an answer to this question in the European conquest of the Americas, which unleashed a torrent of deadly Old World diseases onto a virgin indigenous population. Introduced diseases, especially smallpox, killed tens of millions of Native Americans within a century and a half of European arrival, wiping out approximately 90% of the population. In the wake of the pandemics, reforestation of abandoned agricultural lands sequestered atmospheric carbon in quantities sufficient to decrease the concentration of atmospheric carbon dioxide. Evidence from reconstructions of fire history and ice core records support this hypothesis and suggest that changes in atmospheric composition wrought by reforestation may have contributed to the Little Ice Age, a period of global cooling that was most pronounced during the 16th-18th centuries.

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