Tracing the effects of the Little Ice Age in the tropical lowlands of eastern Mesoamerica

doi:10.1073/pnas.0707896104

Tracing the effects of the Little Ice Age in the tropical lowlands of eastern Mesoamerica

*Instituto de Geología,
^‡Instituto de Geofísica, and
^§Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México D.F., 04510, México

Communicated by Linda Manzanilla, National Autonomous University of Mexico, Mexico, D.F., Mexico, August 21, 2007 (received for review May 10, 2007)

Abstract

The causes of late-Holocene centennial to millennial scale climatic variability and the impact that such variability had on tropical ecosystems are still poorly understood. Here, we present a high-resolution, multiproxy record from lowland eastern Mesoamerica, studied to reconstruct climate and vegetation history during the last 2,000 years, in particular to evaluate the response of tropical vegetation to the cooling event of the Little Ice Age (LIA). Our data provide evidence that the densest tropical forest cover and the deepest lake of the last two millennia were coeval with the LIA, with two deep lake phases that follow the Spörer and Maunder minima in solar activity. The high tropical pollen accumulation rates limit LIA's winter cooling to a maximum of 2°C. Tropical vegetation expansion during the LIA is best explained by a reduction in the extent of the dry season as a consequence of increased meridional flow leading to higher winter precipitation. These results highlight the importance of seasonal responses to climatic variability, a factor that could be of relevance when evaluating the impact of recent climate change.

Footnotes

^†To whom correspondence should be addressed. E-mail: mslozano{at}servidor.unam.mx
Author contributions: M.d.S.L.-G., M.C., and B.O. designed research; M.d.S.L.-G., M.C., B.O., A.R., and S.S. performed research; M.d.S.L.-G., M.C., B.O., A.R., and S.S. analyzed data; and M.d.S.L.-G. and M.C. wrote the paper.
The authors declare no conflict of interest.
Abbreviations:

LIA,

Little Ice Age;

ITCZ,

intertropical convergence zone;

PAR,

pollen accumulation rate;

TF,

tropical forest;

STF,

secondary tropical forest;

UF,

upland forest.
Freely available online through the PNAS open access option.