"Stalagtites hold tight, stalagmites..."

Webster et al. (2007) also outlined a link between drought and Classic Maya collapse. This was done by presenting a climate record for the Maya region using evidence obtained from a stalagmite once located in the Macal Chasm in the Vacal Plateau, Belize (Figure 1).

Figure 1: Location map showing Macal Chasm and other important Mayan sites (Source: Webster et al. (2007))

Past climate was reconstructed from analysis of the reflectance, colour, luminescence, and carbon and oxygen stable isotope records for the period from 1225 B.C. to the present. The record thus encompassed the Maya Pre-Classic, Classic, and Post-Classic periods. 

The stalagmite record indicates that a series of droughts, which collectively form the most prolonged dry interval in the 3300-year record, lasted from A.D. 700 to 1135 and thus coincided with the collapse of the Maya civilization (Figure 2).  

Figure 2: Droughts in Belize indicated by a reduction in stalagmite luminescence compared with Maya monument production (Source: Webster et al., 2007)

For comparison and validation Webster et al. (2007) referenced the work of Keigwin (1996). Keigwin (1996) produced a record of the Holocene variability of sea surface temperatures (SSTs), salinity and flux of terrigenous material in the Sargasso Sea, within the North Atlantic Ocean. A sea-sediment core was taken in order to accomplish this, due to the high rates of sediment accumulation in the region. 

Keigwin (1996) observed that variation in SSTs in the record showed separate distinct rises in temperatures that correlate with the evidence for Mayan collapse. Though the Sargasso Sea is located a significant distance from the location of the Mayan empire, it is claimed that the record, most probably, corresponds to climate change at a “basin or hemispheric scale”. However, this conclusion is yet to be wholly substantiated and is open to debate.

Webster et al. (2007) compiled their own findings with those of Keigwin (1996) and Hodell et al. (1995) (discussed earlier in the blog), as shown in Figure 3.

Figure 3: Comparison of the Belize stalagmite record with Sargasso Sea and Lake Chichancanab data (Source: Webster et al., 2007)

Webster et al. (2007) state that these correlations demonstrate that the Macal Chasm stalagmite provides a regional record of climate, rather than a local record of land-use change or a record only of changes within the cave itself. More significantly, they demonstrate that the dry periods in the Macal Chasm record were widespread events that would have affected the entire Mayan civilization

It is apparent that all three studies show periods of drought occurring at the same time – the Classic Maya collapse. Webster et al. (2007) conclude that severe dryness affected a broad region of Mesoamerica most likely contributed to the collapse of the Maya civilization during the Late Classic period.

While this evidence is still not definitive for the entire Mayan region and does not explore the social implications of the drought, it can be said that the greater the number and spatial extent of the proof that drought did occur at the time of Mayan collapse, the more readily this factor can be accepted as a playing a key role in the demographic decline.