Frieze (carved stucco pattern) on the side of the El Castillo structure at Xunantunich site in Cayo.

Team Investigates Climate Change Impacts on Maya Civilization

Dr. Jason Polk, a faculty member in WKU’s Hoffman Environmental Research Institute, led a research expedition to Belize in August as part of an ongoing project investigating the socio-environmental dynamics of drought and climate change on the collapse of the ancient Maya civilization many centuries ago. Dr. Polk and several graduate students have been working with colleagues since 2009 from around the world, including archaeologists, environmental scientists, paleoclimatologists and geologists from London, Canada, Florida, Arizona, Georgia, the U.S EPA and the Institute of Archaeology in Belize, as part of a concerted effort to collect various data to help shed light on the much debated question of the environmental circumstances surrounding the decline of the Maya throughout Mesoamerica. This mystery is discussed often in popular literature; for example, it was featured in Jared Diamond’s best-selling novel Collapse a few years back, and recently in an issue of National Geographic, among many other scientific and popular publications. Renewed interest was seen this year with the relevance of 2012 being linked to the end of a Maya calendar cycle, with much speculation about what this may mean for modern civilization. The purpose of Dr. Polk’s research in the larger project is to refine the paleoenvironmental record of land use, vegetation change and climate variability through the use of deposits found preserved in caves in Belize near the archaeological sites Minanha and Ix Chel, on the Vaca Plateau. These sites are partially excavated and located in a region thought to be one of the last to be abandoned by the Maya as droughts pressured their ability to survive in the region.

Nick Lawhon in Jose Cueva near a broken Maya pot.

Dr. Gyles Iannone from Trent University and Dr. Jaime Awe of the Institute of Archaeology in Belize are the principal investigators of the project, which is funded through the Alphawood Foundation, and they are leading the excavations of these two sites to better understand the archaeological record about Mayan past occupations. Dr. Polk is working with colleagues from the University of Georgia and the University of South Florida to analyze sediments and mineral deposits, known as stalagmites, from within caves in the study area to reconstruct environmental changes that occurred over the past few thousand years. Much like tree rings, these deposits record past changes in the land and climate above the caves, and can be analyzed using isotopes to reveal the history of the local and regional paleoenvironment. In particular, Dr. Polk’s research focuses on the sediments within the caves, which accumulate over time, and record the vegetation and land-use history of what is occurring on the surface. Accompanied by geosciences graduate student Nick Lawhon of Gallatin, Tenn., and Hoffman Institute staff member Ben Miller, Dr. Polk visited several caves on the Vaca Plateau during this research trip, taking sediment core samples, surveying and mapping several caves, and visiting multiple Maya sites to better understand the spatial connections with respect to the cave locations and their place within the landscape. The Maya used most of these caves heavily for rituals and ceremony, with artifacts, such as pottery and stone tools, found throughout the caves, along with human remains. During the expedition, the Hoffman team also participated in the making of a documentary about the research and the excavation of the Maya ruins at Lower Dover Field Station, where the team bases its expeditions, with Make-Belize Films. WKU geosciences graduate student Kegan McClanahan of Loveland, Ohio, and undergraduate students Travis Garmon of Burkesville and Lowell Neeper of Morehead are working to analyze the sediment core samples. In conducting this research, the team hopes to be able to reconstruct climate events and land-use patterns that may provide insight on the Maya and how the environment in which they lived changed over a thousand years ago.

Jason Polk and Nick Lawhon taking a sediment core sample in Actun Chapat Cave.

The very presence of caves, which occur in karst landscapes, provides a clue as to how prolonged drought may have impacted that Maya more intensely in the study area than elsewhere. In karst landscapes, the soils are often well-drained and there is little access to surface water, since most of it is found deeper underground in aquifers or flowing through caves as underground rivers. Both of these conditions would have enhanced the negative effects of drought conditions in the region with respect to the Maya’s survival. “We are excited to be involved in this research, and it continues to unveil clues as to how past climate change influenced a fairly advanced civilization,” said Dr. Polk. “The fact that these climate events could impact such a large population should serve as an indicator that future climate variability could have significant impacts in developing areas. With this research, we hope to dig deeper into how this sequence of events took place and continue to add pieces to the puzzle.”