Almost all Maya cities were abandoned after the 9th/10th century AD. How did that happen? In recent decades, there has been increasing evidence that climate change has brought civilization to the brink of collapse…
The Maya are known for their written language, architecture, art, mathematics and also their astronomy. They were mainly found on the Yucatán Peninsula (Mexico) and areas south of it in present-day Guatemala, Belize, El Salvador, and Honduras. Their culture had its heyday from 250-900 AD, the Classic Period. At the height of civilization, there were probably 13 million corn-eating Maya living in the region. Things went wrong at the end of the Classic Period. Cities were abandoned and there was chaos in the country. After 800 AD no less than 90-99% of the population disappeared.
The reasons for this have been a matter of great debate for nearly a century. The main reasons that scientists cite are war, rebellion, soil erosion and drought. The latter in particular has gained considerable popularity in science over the past decade. Learn more about the how and why in this article. Another article on Kennislink discusses the other theories.
Climate:how?
Those dry periods mainly occurred at the end of the Classic Period. Evidence comes, for example, from sediment cores from the lakes in Yucatán and even the Cariaco Basin, 2,500 km to the southeast. The Yucatán sediments show that the 750-850 AD period was the driest period in 7,000 years. The sediment cores from the Cariaco basin also show considerable drought for this period. In fact, with great precision, researchers led by Gerald Haug were able to pinpoint four 3-9 year periods of extreme drought within the dry season:~760, 810, 860 and 910 AD.
Archaeological artifacts also confirm drought. For example, Richardson Gill reported that the last chiseled dates on the stone monuments of important Maya centers coincide with three of the four dates mentioned:810 AD for the southwest, 860 for the southeast and 910 AD for the north. The droughts also affected the way the Maya approached their gods, at least for the eastern part, now Belize. In the late Classical period, the Maya performed more religious rituals in the caves to appease the gods based on the amount of charcoal and pots. Scientists call it a 'drought cult'.
Why so dry?
An important role in these droughts is played by the sun and the associated Intertropical Convergence Zone (ITCZ). This climatic equator migrates seasonally depending on the position of the sun relative to the Earth. Most rain falls in the summer period when the ITCZ is exactly above the former Mayaland. In winter, the ITCZ is further south and it is dry. Gerald Haug and colleagues think the ITCZ did not reach the Maya in the late summers of the late Classic Period. And that meant drought for the Maya.
Global climate variability
The drought in the Maya area is not an isolated incident. Also in other parts of the world there were temporary changes in the climate around the same period. In Europe it was cold in the 9th and early 10th century as well as in Greenland. For example, a study of tree rings from Sweden shows that it was extremely cold around AD 800, 860 and 910. Certainly for the last two years, this corresponds well with the periods of drought in 'Mayaland'. Africa also shared in the malaise:it was dry from 770-960 AD in Nigeria and in 829 the Nile even froze over. South of the Maya, wildfires raged in Costa Rica in the late 9th century, and ice from the Andean glaciers shows a dry spell around 900 AD. The global malaise shows that climate change in the land of the Maya is not strange.
All at once?
The demise of the Maya was therefore not a process of a few years or decades, but one of several hundred years. The towns and villages that survived into the Post-Classical Period were often located on a lake, sea or river. This was an ideal place to trade and water was almost always available. However, the general picture is that first the south (99% of the population disappeared in the Classic Period) was affected and later the northern areas of the Yucatán Peninsula were affected. This is strange because the northern part is drier than the southern part of Yucatán. In fact, it is so dry that it is a veritable desert in the dry season (January-May), especially in the north. In the northern part nowadays only 500 mm falls per year, while in the south it can go up to 4000 mm.
Scientists look for the reason for the failure to collapse simultaneously in the groundwater level. The subsoil of the Maya area consists for a large part of limestone. Over millions of years, part of this lime has dissolved, leaving behind all kinds of caves and trenches. So it's kind of like cheesecake. This allows the water from a rain shower to easily seep deep into the subsoil. This was not a problem in the lower northern areas because the groundwater was relatively shallow. In the higher southern part the water level was considerably lower. The water was therefore not nearly as accessible in the south.
The Mayans in the south therefore concentrated on building dams, canals and reservoirs to collect the water, such as for one of the largest cities called Tikal. The reservoir at Tikal had enough water to supply as many as 10,000 people for 18 months. This means that the Mayans in the south depended heavily on rainfall. Long droughts certainly meant a lack of water. In the north, for a while this could still be compensated by tapping groundwater. But the groundwater level can also drop considerably after a long dry period…
So many of the Maya died out at the end of the Classic Period. Not all, because descendants of the Maya still live in Central America. However, this is only a small part of the population compared to the Classic Period. This article shows once again that climate change plays a vital role in the demise of civilizations. Will that also be the case for our current society?
References:
Aimers, J.J. , 2007. What Maya Collapse? Terminal Classic Variation in the Maya Lowlands. Journal of Archaeological Research 15 :329-377.Diamond, J. , 2005. Collapse – how societies choose to fail or succeed, 157-177.Gill et al. , 2007. Drought and the Maya Collapse. Ancient Mesoamerica 18 :283-302. Haug et al. , 2003. Climate and the Collapse of Maya Civilization. Science 299 :1731-1735.Hodell et al. , 1995. Possible role of climate in the collapse of Classic Maya civilization. Nature 375 :391-394.Hodell et al. , 2001. Solar Forcing of Drought Frequency in the Maya Lowlands. Science 292 :1367-1370.Hodell et al. , 2007. Climate and cultural history of the Northeastern Yucatan Peninsula, Quintana Roo, Mexico. Climatic Change 83 :215–240.Peterson &Haug , 2005. Climate and the collapse of Maya civilization. American Scientist 93 :322-329.Webster et al. , 2007. Stalagmite evidence from Belize indicating significant droughts at the time of Preclassic Abandonment, the Maya Hiatus, and the Classic Maya collapse. Palaeogeography, Palaeoclimatology, Palaeoecology 250 :1-17.
- Demise of the Maya:Archeology (Knowledge Link Article)
- Sun Defeats Chinese Dynasties (Knowledge Link Article)
- Climate history points to important role of the sun (Knowledge link article)
- Climate Change (Knowledge Link Theme)
- Climate change is a timescale discussion (Knowledge Link Article)