Transcript – Millennial-Scale Hurricane Activity on the Yucatan Peninsula: Climate Drivers and Cultural Impact

Of the one hundred and twenty two storms that have hit Mexico’s Yucatan Peninsula since the 50s, nearly half of advanced to strike the US mainland. Hurricane Dennis is location and track are influenced by the very position of the Intertropical Convergence Zone, a trough of warm, moist air that follows the Earth’s thermal equator shifting north and south of the seasons. The purpose of this project is to examine if past variations in hurricane activity across the Yucatan reflect past ITCZ displacements doesn’t more northerly shifted its direction. This is a relevant question today, since the warming northern hemisphere is expected to further displace the south to the north. To answer these questions, we’ve collected sediment cores from two sinkholes in the Yucatan lagoon and oil to the north and black hole 180 kilometers to the south. Each location has been struck by multiple hurricanes since modern record keeping began. These passing storms mobilize coarse grain sediment from the shallow waters adjacent to the holes, depositing them within. Once quiescent conditions return, these coarse deposits become buried in the finer grain matrix that dominates in these environments. Of course, collected in twenty seventeen show down core variability in grain size, reflecting episodes of high energy deposition. By comparing the most recent, of course, beds with historically observed storms, we can work to decipher the full sediment record. Moyal is sensitive to events category three or greater passing within 50 kilometers of the site.

Black holes appear sensitive to storms passing nearby to the south. This makes sense as black holes positioned against a hill and connected to the lake system via a narrow pass, a storm would need to strike at the proper angle to drive surge into the hole rather than away. Together, these records show that over the past two thousand years, each site has recorded periods of heightened storm activity. Most notably, we see that during the Mayan terminal classic period, a time of prolonged drought, we have active and inactive storm intervals from seven hundred and fifty to eight hundred fifty C. We have suppressed storm activity and suppressed rainfall. But during the final phases of the mine collapse, around one thousand feet, we have persistent drought and more frequent storm strikes. While local rainfall might have become disentangled from ITCZ positioning, perhaps due to extensive deforestation, storm frequency did track with ITCZ displacements, as indicated by the Kayako Basin reconstructions. Our work indicates that hurricane passage over the Yucatan does correlate positively with ITCZ position and that during the terminal classic mine collapse, rainfall became detached from hurricane activity. This work may also suggest that increasing tropical cyclone frequency may have contributed to the mine collapse by adding an additional stressor to a culture already grappling with prolonged drought.