The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing

Image via WikipediaThe Little Ice Age, a period of global cooling that occurred between 1500 and 1750, has been the subject of much scientific debate about what roles do people play in global climate change, and if natural variation has been the source of past warming and cooling periods.  The Little Ice Age has been previously attributed exclusively to natural variations through mechanisms like decrease in solar irradiance (the amount of sunlight which reaches the Earth), increase in global volcanic activity, and changes in ocean circulations.  The current article "The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing" by Robert Dull and other leading researchers argue that anthropogenic causes played a larger role then once anticipated.  They conclude that the rapid population crash of indigenous people of the new world after the Columbian Encounter lead to a reforestation of the Neotropics creating a terrestrial biospheric carbon sequestration in the order of 2 to 5 billion tons.  A carbon sequestration event of this magnitude would be a significant forcing mechanism for global cooling during the Little Ice Age period.  Dull et al. reviewed fire history and reported high-resolution charcoal records to support the idea that the Neotropical lowlands went from being a net source of carbon dioxide to a net sink in the centuries following the Columbian encounters.   This article furthers the concept of anthropogenic forcing of climate before the Industral Revolution, and shows that people have a longer history on global climate change.

The Columbian Encounter and the Little Ice Age:Abrupt Land Use Change, Fire, and Greenhouse Forcing is avilable in the Annuals of the Assocation of American Geographers Special Issue on Climate Change October 2010


Dull, Robert A. , Nevle, Richard J. , Woods, William I. , Bird, Dennis K. , Avnery, Shiri and Denevan, William M.(2010) 'The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing', Annals of the Association of American Geographers,, First published on: 01 September 2010 (iFirst)

http://dx.doi.org/10.1080/00045608.2010.502432

Robert A. Dull's UT Faculty Profile