Dry spells

Conversely, people in other places and times had to deal with drought.

Northern Arizona University professor Jaime Awe compares people's responses to droughts in ancient Mayan territories with other societies in different times, including Brazil in the 19th century, Spain in the 18th century and the southwestern United States in the 1930s.

Recent and ongoing research shows that the Maya adopted a range of agricultural approaches like raised and terraced fields and kitchen gardens to respond to droughts in the regions they inhabited in Central America's central lowlands from the eighth to the 10th centuries.

Moreover, they appealed for divine intervention.

"Use-intensity study indicates that there was a dramatic increase in cave ritual activities during the period," Awe says, adding that the Maya even offered human sacrifices in caves to pray for rain.

Measures adopted by people from other regions included increased grain storage, construction of dams and reservoirs, religious activities and reliance on "hard-time" foods — plants and animals they typically wouldn't eat, including certain reptiles, bats and vultures.

However, ancient Mayan efforts were in vain and the central lowlands were eventually abandoned. Awe says severe, multiyear droughts led to decreased food, increased competition for resources, and higher rates of conflict, violence and mortality, until they finally migrated.

"With almost all efforts failed, you have to put on your walking boots and move out. And it seems it's consistent. It did not just happen to the Maya. It happened all over the world. So, in some respects, the ancient Maya were some of the early climate refugees," says Awe.