Deforestation caused by the Mayans may have a long-lasting impact on a rainforest’s ability to keep carbon locked in the ground, according to recent research published in the journal Nature Geoscience.
The Mayans spread out across the Yucatán Peninsula roughly 3,000 years ago. During that time, they cleared rainforests for agriculture and chopped down trees to erect cities. That then affected the region’s tropical jungles by enabling more carbon to escape into the atmosphere.
That process reveals how much damage current climate change can cause to such regions.
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“What I think these data give us is a much longer term perspective,” lead author Peter Douglas, a geochemist at McGill University, told Gizmodo. “What they tell us is at least in this place…we seem to be losing a lot of this deep carbon over hundreds of years.”
Tropical rainforests, as a result of their plant density, actively soak up carbon dioxide. However, most of it goes into minerals in the soil, where it stays locked away for hundreds of thousands of years. In fact, current estimates guess that there are over 500 billion tons of carbon trapped in tropical soils. That is more than half of the total in the atmosphere.
By using the Mayans as a guide, researchers from McGill University attempted to shed light on how human activity could affect that large carbon store. To do that, they used radiocarbon dating to look at the age of hard-to-decompose plant waxes in sediment cores taken from three lakes in the former Maya lowlands.
That showed a 70 to 90 percent decrease in the age of plant waxes leaking out of the soil over the past 3,500 years. Such a decline falls right in line with deforestation caused by the Mayan expansion, which then suggests the Mayans reduced the soil’s ability to act as long-term carbon sinks.
Though the team is not exactly sure why the ancient civilization affected the tropical forests in that way, they do know that the ancient logging has extremely long-lasting ramifications.
Not only does that help scientists better understand how current deforestation could influence the future or our planet, but it also reveals that it may be too late for anything to be done. Some regions may stay altered, even if given time to recover.
“When you go to this area today, much of it looks like dense, old-growth rainforest,” added Douglas, according to Phys.org. “But when you look at soil carbon storage, it seems the ecosystem was fundamentally changed and never returned to its original state.”