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GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 23, 2199, doi:10.1029/2003GL018600, 2003

A new climate-vegetation equilibrium state for Tropical South America

Marcos Daisuke Oyama

Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, SP, Brazil


Carlos Afonso Nobre

Centro de Previsão de Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Cachoeira Paulista, SP, Brazil


Abstract

The existence of multiple climate-vegetation equilibria in Tropical South America is investigated under present-day climate conditions with the use of an atmospheric general circulation model coupled to a potential vegetation model. Two stable equilibria were found. One corresponds to the current biome distribution. The second is a new equilibrium state: savannas replace eastern Amazonian forests and a semi-desert area appears in the driest portion of Northeast Brazil. If sustainable development and conservation policies were not able to halt the increasing environmental degradation in those areas, then land use changes could, per se, tip the climate-vegetation system towards this new alternative drier stable equilibrium state, with savannization of parts of Amazonia and desertification of the driest area of Northeast Brazil, and with potential adverse impacts on the rich species diversity in the former region and water resources in the latter.

Received 10 September 2003; accepted 29 October 2003; published 5 December 2003.

Index Terms: 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions; 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); 9360 Information Related to Geographic Region: South America.

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Citation: Oyama, M. D., and C. A. Nobre (2003), A new climate-vegetation equilibrium state for Tropical South America, Geophys. Res. Lett., 30(23), 2199, doi:10.1029/2003GL018600.