The Collapse of the Classic Maya: A Case for the Role of Water Control

We analyzed lake-sediment cores from the Yucatan Peninsula, Mexico, to reconstruct the climate history of the region over the past 2600 years. Time series analysis of sediment proxies, which are sensitive to the changing ratio of evaporation to precipitation (oxygen isotopes and gypsum precipitation), reveal a recurrent pattern of drought with a dominant periodicity of 208 years. This cycle is similar to the documented 206-year period in records of cosmogenic nuclide production (carbon-14 and beryllium-10) that is thought to reflect variations in solar activity. We conclude that a significant component of century-scale variability in Yucatan droughts is explained by solar forcing. Furthermore, some of the maxima in the 208-year drought cycle correspond with discontinuities in Maya cultural evolution, suggesting that the Maya were affected by these bicentennial oscillations in precipitation.

Climate variability on the Yucatan Peninsula during the past 3500 yrs is reconstructed from the measurement of δ 18 O in monospecific ostracods and gastropods in a 6.3-m sediment core from Lake Punta Laguna, Mexico. This late Holocene record is divided into three periods based on changes in mean δ 18 O values. From ∼3310 to ∼1785 14 C yr B.P. (Period I), low mean δ 18 O values indicate relatively wet conditions (i.e., low evaporation to precipitation ratio, E / P ). Mean oxygen isotopic values increased ∼1785 14 C yr B.P., and the interval between ∼1785 and ∼930 14 C yr B.P. (Period II) was distinctly drier than the periods before or after. The climate during the latter part of Period II was persistently dry, with exceptionally arid events centered at ∼1171, 1019, and 943 14 C yr B.P. (equivalent to 862, 986, and 1051 A.D.). This interval of frequent drought was recorded at several other localities in Mexico and Central America, and coincided with the collapse of Classic Maya civilization. Following the last arid event, δ 18 O values decreased abruptly at ∼930 14 C yr B.P. (beginning of Period III), signaling a return to wetter conditions that have generally prevailed to the present, with the exception of a dry episode centered at 559 14 C yr B.P. (1391 A.D.). The paleoclimatic record from Punta Laguna provides evidence that multi-decadal and millennial-scale changes in E / P occurred on the Yucatan Peninsula during the late Holocene. These wet/dry episodes may have influenced cultural evolution in Mesoamerica.