From JoNova

By Jo Nova

13 year megadrought during Medieval Warm Period may have finished off the Maya

A slightly spooky new paper shows annual rainfall patterns from a thousand years ago on the Yucatán Peninsula, Mexico. It’s so detailed, they list every drought by year, including 13 unbroken years of drought from 929 to 942AD.  It’s a bit like someone unearthed the Maya Bureau of Meteorology records from a thousand years ago (except it’s better, because it’s a rock with no politics).

This is one of the highest-resolution tropical stalagmite records ever published. Each year the stalagmite grew by as much as a millimeter, allowing for a year by year analysis — or indeed 12 datapoints within each year.

During this era of perfect CO2, for some reason that no climate model can explain, the poor sods in Maya suffered through extreme swings from wet to dry, stacked back-to-back. The climate was chaotic. Droughts were followed by floods. It’s uncannily like “climate extremes” we are told man-made emissions are going to bring.

It is sobering to think the Maya civilization lasted nearly 3,700 years. At it’s peak it was thought there were around 5 million people, but more recent estimates with lidar mapping suggest there might have been as many as 10 or even 16 million people. The Maya civilization started around 2,000BC and peaked somewhere around 700AD before declining in “the terminal collapse period” from 800AD-1000AD. Little pockets of the civilization lingered on for centuries until the Spanish conquest of 1697. Even today some 6 million people still speak Mayan languages.

The Southern lowlands (where this cave is) would never be re-urbanized after 1000AD. The megadroughts appear to be the coup de grace.

“Even with the water management techniques that the Maya had, a drought that long would have had major impacts on society.”

Nobody mentions the Medieval Warm Period but this is the same time as things were warming up in Europe:

Mexican cave stalagmites reveal the deadly droughts behind the Maya collapse

[ScienceDaily] Chemical evidence from a stalagmite in Mexico has revealed that the Classic Maya civilization’s decline coincided with repeated severe wet-season droughts, including one that lasted 13 years. These prolonged droughts corresponded with halted monument construction and political disruption at key Maya sites, suggesting that climate stress played a major role in the collapse. The findings demonstrate how stalagmites offer unmatched precision for linking environmental change to historical events.

According to the information contained in the stalagmite, there were eight wet season droughts lasting for at least three years between 871 and 1021 CE. The longest drought of the period lasted for 13 years. Even with the water management techniques that the Maya had, a drought that long would have had major impacts on society.

The climate information contained in the stalagmite lines up with the dates inscribed by the Maya on their monuments. In the periods of prolonged and severe drought, date inscription at sites such as Chichén Itzá stopped entirely.

The growth hiatus mentioned in 1020AD was found in other studies and apparently so dry the stalagmites dramatically slowed down their growth. Just imagine, the whole region was in severe hydroclimate stress, even without any four-wheel drives, oil rigs, or coal plants.

In other words, no matter when or where you lived, a witchdoctor somewhere could say the climate was changing. 

As well as the stalagmite being a freakishly fast growing one, they also used multiple proxies (δ¹⁸O, δ¹³C, Mg/Ca, Sr/Ca ratios, as well as the U-Th ratios to date the layers). They were able to line up the layers with other studies and also with carvings on monuments and other archeological finds. The researchers claim there is ±6-year age uncertainty on the dating.

REFERENCE

Daniel H. James, Stacy A. Carolin, Sebastian F. M. Breitenbach, Julie A. Hoggarth, Fernanda Lases-Hernández, Erin A. Endsley, Jason H. Curtis, Christina D. Gallup, Susan Milbrath, John Nicolson, James Rolfe, Ola Kwiecien, Christopher J. Ottley, Alexander A. Iveson, James U. L. Baldini, Mark Brenner, Gideon M. Henderson, David A. Hodell. Classic Maya response to multiyear seasonal droughts in Northwest Yucatán, Mexico. Science Advances, 2025; 11 (33) DOI: 10.1126/sciadv.adw7661

The stalagmite in question, called Tzab06-1, was obtained in 2006 from Grutas Tzabnah near Tecoh, Yucatán, Mexico