During this scorching summer rainfall is quite scarce, and drought becomes more and more of a threat, thus undermining the stability of many parts of the world. This alarming meteorological situation has consequences which are, at the present time, still far below those suffered centuries ago by the Mayans.
A study published in the ‘Science’ journal has indeed revealed that a decrease in rainfall could have largely contributed to the disappearance of this pre-Columbian civilisation, a discovery that could finally explain the collapse of the Mayan empire. To reach this conclusion, researchers at the University of Cambridge in the United Kingdom and the University of Florida in the United States have developed a method to measure the different isotopes of water trapped in a particular mineral, known as gypsum.
Formed in times of drought when water levels drop, this so-called evaporite rock abounds in the lakes Chichancanab, a stretch of water located in the Yucatan peninsula, which was occupied by the Mayan people since they came to be in 2600 BCE.
Precise quantification of precipitation levels
Thanks to this isotopic measurement technique, researchers were able to quantify the decreases in rainfall that occurred during the collapse of the Mayan civilisation. These results leave little room for doubt about the role of drought in the annihilation of this secular culture.
At the time of the empire’s collapse, annual rainfall levels in the region fell from between 41% and 54%, with particularly intense periods of drought reaching a maximum of a 70% decrease in rainfall. Relative humidity was 2% to 7% lower than in the Mexican peninsula today.
‘The role of climate change in the collapse of the classical Mayan civilisation is controversial, in part because previous recordings are limited to qualitative reconstructions, such as if conditions were wetter or drier for example,’ the lead author of the work Nick Evans said, from the Department of Earth Sciences at the University of Cambridge.
This unprecedented evidence thus seems to shed new light on the collapse suffered by the Mayan civilisation during the ninth century, a period in which the famous stone cities were abandoned by their occupants in a context of political and economic decline.
Strong evidence to support a still fragile theory
This hypothesis of a climatic origin for the collapse of the empire is not a new one. In 1995, Professor David Hodell, director of the Godwin Laboratory for Paleoclimatic Research at the University of Cambridge, had already identified a correlation between the lakes Chichancanab drought periods and the Mayan empire's decline period.
But the scientist and his team have gone much further in their investigations, establishing a complete hydrological model of the context of the disappearance of the Mayans. ‘[Our] method is extremely accurate, and almost involves measuring the water itself,’ says Nick Evans. Nevertheless, this work does not yet make it possible to identify with certainty the causes of the decline and the collapse of this civilisation.
Scientists now plan to use this comprehensive hydrological data to identify the specific effects of drought on Mayan life. The researchers in particular can see consequences suffered by agriculture, among others, which certainly faced serious declines in yield. These disastrous effects are once again the subject of concern, several centuries after the collapse of the Mayan Empire.