There's no doubt about drought

In addition to those already mentioned, Hodell et al.’s (1995) research prompted several paleoclimatic investigations into the Mayan region that suggest drought conditions were a feature of that period. Each focuses on different locations throughout the Mesoamerica and several proxies are employed. Instead of reviewing each in detail, a selection has been chosen and a summary of their findings is presented here.   

Curtis et al. (1996) reconstructed 3,500 years of climate for the Yucatan Peninsula using a 6.3 m lake sediment core taken from Lake Punta Laguna, Mexico (Figure 1). The proxies measured were δ¹⁸O in mono-specific ostracods and gastropods. 

Figure 1: Map showing location of Lake Punta Laguna in Quintana Roo, Mexico (Source: Curtis et al. 1996)

 The oxygen isotopic record from Punta Laguna indicated that the terminal Classic and earliest Post-classic period (800 to 1050 AD) was one of the driest intervals of the last 3,500 years. The high resolution record produced from Punta Laguna allows identification of peak drought conditions at 862 AD during the terminal Classic period (Figure 2). 

Figure 2: Comparison of the oxygen isotopic record from the Punta Laguna sediment core with Maya cultural periods (Source: Curtis et al. 1996)

 

Islebe and Sanchez (2002) also found there to be a drier period coincident with the period of Maya demographic decline. They analysed the pollen record of a sediment core taken form the Mexican Caribbean coast, showing the development and changes in the mangrove system (Figure 3). 

Figure 3: Location of the coring area along the Mexican Caribbean
coast (Source: Islebe and Sanchez 2002)

 

They found that the mangrove species Conocarpus erecta dominated during the period approximately 1500-1200 ¹⁴C yr BP while R. mangle almost disappeared and other taxa emerged, suggesting drier climatic conditions and generally more open vegetation.

A study by Carrillo-Bastos et al. (2010) once again found there to be drought conditions coincident with the collapse of the Classic Maya. They studied oxygen isotope measurements on a 2.5 m sediment core recovered from Lake Tzib central Quintana Roo, southeast Mexico (Figure 4). 

Figure 4: Map showing the location of Lake Tzib (Source: Carrillo-Bastos et al. 2010)

 

Their data indicated dry conditions between ~1300 and 1200 cal yr BP. They correlated the dry peak at 1200 cal yr BP with a dry period found using a marine core taken in the Cariaco Basin, north of Venezuela (Figure 5).

Figure 5: Correlation of  isotopes from Lake Tzib with Ti% data from the marine Cariaco Basin core (Source: Carrillo-Bastos et al. 2010)

  

It can be seen that the peaks in drought conditions found do correlate with the collapse of the Classic Maya.

 

With so many studies correlating drought conditions to the time of the Classic Mayan collapse, from such diverse parts of the empire, using such a wide variety of proxies, it seems very likely that drought conditions were experienced by all the Maya and caused population decline. Where there may be slight discrepancy in the chronology and exact dating of these is probably due to the differing dating techniques employed. It remains, however, to understand why this drought occurred and how much it affected different groups of Maya from around Central America.