The Mayans incorrectly predicted the end of the world — as well as their own downfall.

What destroyed the Mayan civilization continues to be a hotly debated topic, with researchers offering evidence of everything from disease to a deadly foreign invasion. Now a new study suggests that climate change caused their collapse.

Researchers looked at 144 violence-depicting inscriptions on monuments from over 30 Mayan centers from a 500-year period. Then they cross-referenced those with temperature and rainfall records in areas of modern-day Mexico, Guatemala and Belize.

“The change in conflict levels between 350 and 900 AD was considerable,” the authors wrote in the report, published March 31 in Quaternary Science Reviews.

This is around the period when temperatures began to increase and the Mayans sweltered through more 86° F days. Preceding eras saw temperatures hover between 82 and 84 degrees.

Hotter temperatures likely caused two things: crops started to fail and leaders became more aggressive. (Research has shown that warmer temps can make people more violent.)

Dying crops meant that Mayan leaders couldn’t rely on festivals or new building projects (not enough food to feed the laborers) to keep their subjects happy. So they turned war in order to keep their power and maintain support from their starving public. And also, because they probably hot and angry.

The report notes how climate change continues to be a controversial topic, but stresses the importance of studying how it might impact our future.

“Small year-to-year changes in climate can result in large, negative effects over the long term,” Mark Collard, one of the study’s authors, told Seeker. “We run the risk of ignoring changes that will affect our children and grandchildren, because we can’t perceive those changes.”