When my kids were younger we'd often vacation in Mexico and I took the opportunity to learn about the Maya. Talk about a puzzle wrapped in an enigma, wow the Maya were a puzzle without a doubt.
This new evidence seems to coincide with several other theories concerning the collapse of the Mayan civilization. And in a word, it comes down to water.
Examining ancient tree rings suggest to scientists that Mexico and Central America experienced long periods of drought. It follows then that: no rain, no crops, no civilization. The new evidence merely suggests that instead of a "big bang" of a collapse, their civilization experienced various waves of collapse, some waves being more dramatic than others.
If these theories are true and lack of water caused the downfall of the Maya, the next question then becomes, "what happened to the water?" This is where things get dicey. With oceans relatively close by geographically speaking then one would have to assume the Mayans would receive some rainfall, at least a little. Moisture soaked clouds would be coming off the oceans all the time. It seems logical therefore that both coasts received enough rain to sustain crops.
But lands further towards the interior may have been a different story. Today much of that land is dense jungle, so dense you have to hack your way through with a machete. It is akin to the Rain Forest, just a version that is a bit lower to the ground, extending maybe only 40 feet or so up. Still, it is extremely dense packed with every type of plant under the sun.
During normal conditions this shorter Rain Forest creates its own ecosystem. Each day the jungle plants emit a fair amount of moisture into the air. That moisture is the primary driving force behind afternoon rain showers that don't last long, but long enough to give the ground a good soaking.
The cycle repeats most every day where the jungle takes moisture from the ground and eventually emits it back into the air. But what happens if there is no jungle? No jungle, no afternoon rain showers.
It is quite possible that the Mayans created their own downfall by clearing the jungle as their civilization expanded. We know the Mayan civilization was very successful and stretched from North America to the tip of South America. We have to assume they cleared vast jungle areas as they expanded. Their huge population simply required very large areas to live in and grow their crops. Yet they had no way of understanding that it was the jungle itself that provided the daily rainfall their crops required.
It's a fairly safe hunch therefore to deduct that the Mayans unwittingly did themselves in when they cleared the jungle.