Increased dry-season length over southern Amazonia in recent decades and its implication for future climate projection.
Proc Natl Acad Sci U S A
; 110(45): 18110-5, 2013 Nov 05.
Article
em En
| MEDLINE
| ID: mdl-24145443
ABSTRACT
We have observed that the dry-season length (DSL) has increased over southern Amazonia since 1979, primarily owing to a delay of its ending dates (dry-season end, DSE), and is accompanied by a prolonged fire season. A poleward shift of the subtropical jet over South America and an increase of local convective inhibition energy in austral winter (June-August) seem to cause the delay of the DSE in austral spring (September-November). These changes cannot be simply linked to the variability of the tropical Pacific and Atlantic Oceans. Although they show some resemblance to the effects of anthropogenic forcings reported in the literature, we cannot attribute them to this cause because of inadequate representation of these processes in the global climate models that were presented in the Intergovernmental Panel on Climate Change's Fifth Assessment Report. These models significantly underestimate the variability of the DSE and DSL and their controlling processes. Such biases imply that the future change of the DSE and DSL may be underestimated by the climate projections provided by the Intergovernmental Panel on Climate Change's Fifth Assessment Report models. Although it is not clear whether the observed increase of the DSL will continue in the future, were it to continue at half the rate of that observed, the long DSL and fire season that contributed to the 2005 drought would become the new norm by the late 21st century. The large uncertainty shown in this study highlights the need for a focused effort to better understand and simulate these changes over southern Amazonia.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estações do Ano
/
Mudança Climática
/
Modelos Teóricos
Tipo de estudo:
Prognostic_studies
País/Região como assunto:
America do sul
/
Brasil
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2013
Tipo de documento:
Article