Download Maya May Have Caused Civilization

Maya May Have Caused Civilization-Ending
Climate Change
Anne Minard
National Geographic
Self-induced drought and climate change may have caused the destruction of the Maya
civilization, say scientists working with new satellite technology that monitors Central America's
environment.
Researchers from the Marshall Space Flight Center in Huntsville, Alabama, launched the satellite
program, known as SERVIR, in early 2005 to help combat wildfires, improve land use, and
assist with natural disaster responses.
The researchers occasionally refer to the project as environmental diplomacy.
But the program also found traces of the Maya's hidden, possibly disastrous agricultural past—
and is now using those lessons to help ensure that today's civilizations fare better in the face of
modern-day climate change.
SERVIR stands to warn leaders in Central and South America where climate change might
deliver the hardest hits to their ecosystems and biodiversity, say developers Tom Sever and
Daniel Irwin.
If the governments heed the warnings, the data may truly save lives, the experts add.
Secret Farms
More than a hundred reasons have been proposed for the downfall of the Maya, among them
hurricanes, overpopulation, disease, warfare, and peasant revolt. (Read "Maya Rise and Fall" in
National Geographic magazine (August 2007).
But Sever, NASA's only archaeologist, adds to evidence for another explanation.
"Our recent research shows that another factor may have been climate change," he said during a
meeting of the American Association of the Advancement of Science in Boston, Massachusetts,
earlier this month.
One conventional theory has it that the Maya relied on slash-and-burn agriculture. But Sever and
his colleagues say such methods couldn't have sustained a population that reached 60,000 at its
peak.
The researchers think the Maya also exploited seasonal wetlands called bajos, which make up
more than 40 percent of the Petén landscape that the ancient empire called home.
In most cases, Maya cities encircled the bajos, so archaeologists thought the culture made no use
of them. But groundbreaking satellite images show that the bajos harbor ancient drainage canals
and long-overgrown fields.
That ingenious method of agriculture may have backfired.
The data suggest that the combination of slash-and-burn agriculture and conversion of the
wetlands induced local drought and turned up the thermostat. (Related: "Climate Change Killed
off Maya Civilization, Study Says" [March 13, 2003].)
And that could have fueled many of the suspected factors that led to the Maya decline—even
seemingly unrelated issues like disease and war.
Climate Change Killed off Maya Civilization,
Study Says
Stefan Lovgren
for National Geographic News
March 13, 2003
With their awe-inspiring architecture and sophisticated concepts of astronomy and mathematics,
the Maya were undoubtedly among the great ancient civilizations of Mesoamerica. At the peak
of their glory, around 800 A.D., the Maya ranged from Mexico's Yucatán peninsula to Honduras.
Then, almost in an instant, a society of some 15 million people imploded, leaving deserted cities,
trade routes, and immense pyramids in ruins. The sudden demise is one of the greatest
archeological mysteries of our time. What caused the collapse of the great Maya civilization?
The answer, say researchers, is climate change. According to a new study published in the
current issue of Science, a long period of dry climate, punctuated by three intense droughts, led
to the end of the Maya society. "Climate change is to blame for one of the most catastrophic
collapses in human history," said Gerald Haug, a professor of geology at the University of
Potsdam, Germany, and one of the study's authors.
Identifying the Culprit
The drought hypothesis is not new. Sediments taken by scientists in 2001 from a lake on the
Yucatan peninsula showed that a series of extended droughts coincided with major cultural
upheavals among the Maya people.
But the study of that lake also found man-made effects, such as deforestation and soil erosion,
and therefore didn't reflect a "pure climate signal," according to Haug. For the new study, the
scientists instead analyzed sediment core from the Cariaco Basin off northern Venezuela, where
the record is cleaner.
Identifying annual titanium levels, which reflect the amount of rainfall each year, the Swiss and
U.S. researchers found that the pristine sediment layers in the basin formed distinct bands that
correspond to dry and wet seasons. According to the scientists, there were three large droughts
occurring between 810 and 910 A.D., each lasting less than a decade.
The timing of the droughts matched periodic downturns in the Maya culture, as demonstrated by
abandonment of cities or diminished stone carving and building activity.
Experts say the Maya were particularly susceptible to long droughts because about 95 percent of
their population centers depended solely on lakes, ponds, and rivers containing on average an 18month supply of water for drinking and agriculture.
Reading the Sun
The Maya were skilled astronomers who constantly followed the movements of the sun and the
moon. They predicted eclipses, explained the movements of planets, and devised a sophisticated
calendar of the solar year.
Scientists have found that the recurrence of the drought was remarkably cyclical, occurring every
208 years. That interval is almost identical to a known cycle in which the sun is at its most
intense every 206 years. Nothing suggests the Maya knew anything about the sun's change in
intensity.
The drought theory is still controversial among some archeologists who believe a combination of
overpopulation, an internecine struggle for control among the nobles, a weak economic base, and
a political system that didn't foster power-sharing led to the Maya's collapse. One hypothesis
suggests the Maya people themselves were responsible for their downfall as a result of
environmental degradation, including deforestation.
Defenders of the climate change theory, however, say the droughts sparked a chain of events that
led to the demise of the Maya. "Sunny days, in and of themselves, don't kill people," said
Richardson B. Gill, author of The Great Maya Droughts: Water, Life, and Death. "But when
people run out of food and water, they die."
Living on the Edge
In their twilight days, the Maya were a society in deep trouble, according to the authors of the
new study. Densely populated cities strained resources. Agricultural production became crucial
in order to feed the people. "They were living on the absolute edge," said Hoag.
While the Maya had learned to live with shorter droughts, the study indicates that a more subtle,
long-term drying trend was ongoing during the collapse. The three specific droughts may have
been what pushed the Mayan society over the edge.
"Not only did the Maya have to face an intense climatic catastrophe, but the duration was
something that they had never experienced before," said Hoag. "If they had stayed for another
two years, they may have survived. But how could they know that the drought would end?"
Learning from the Past
Other human societies have succumbed to climate swings. In Mesopotamia, a canal-supported
agricultural society collapsed after a severe 200-year drought about 3,400 years ago. With wetter
conditions, civilizations thrived in the Mediterranean, Egypt, and West Asia. Ten years after
their economic peak in 2,300 B.C., however, catastrophic droughts and cooling hurt agricultural
production and caused regional collapse.
Other societies, however, have survived past climate changes by changing their behavior in
response to environmental change. About 300 years after the Mayan collapse, the Chumash
people on California's Channel Islands survived severe droughts by transforming themselves
from hunter-gatherers into traders.
Experts say the Maya collapse could serve as a valuable lesson today to societies in Africa and
elsewhere that are vulnerable to droughts. When droughts strike, they can trigger a chain reaction
beginning with crop failures, leading to malnutrition, increased disease and competition for
resources, and ultimately causing warfare between nations and sociopolitical upheaval.
"We can handle climate change if we're prepared for it," said Hoag. "The Maya were not
prepared."
Questions to be answered on a separate sheet of paper in complete sentences:
1)
2)
3)
4)
What could the Mayans have done in order to be prepared for the climate change?
What lessons can we learn from the Mayan collapse?
How did climate change cause Mayan collapse?
Were the Maya at fault for the climate change and resulting disaster or were they simply
victims of bad luck?