What really happened to the Maya civilization?

Question

Are there any reliable sources that explain the "disappearance" of the Maya? I am highly skeptical about the following account as it states that the cities were destroyed by the war when in actual fact the ruins are almost largely intact (taking time into consideration):

In the wake of new research, it appears that Mayan cities were locked in something similar to the Cold War, only hotter. Hieroglyphs in the area reveal that two metropolitan “super-powers,” Tikal and Calakmul, were bitter rivals for centuries. Skirmishes between the kings of each city grew increasingly violent, prompting both dynasties to build alliances with other cities via raids, conquest, and royal coups. But, as more and more cities got involved, the warfare spread.

In 2002, a few more clues came to light after archaeologists discovered a stunning new set of hieroglyphic texts carved into the steps of a palace staircase at Dos Pilas (uncovered thanks to an earthquake that hit the region the previous summer). The texts told the surprising story of renegade princes from Tikal, who tried to create an empire of their own by waging a full-force attack on their home city with the help of neighboring allies. Unfortunately, their timing was poor. The invasion occurred during the height of the drought, and the result was pure devastation. Pyramids and temples were torn apart to build fortifications, and what few trees were left in the razed rainforest were cut down to build fences. Eventually, farmers had to retreat to the fast-growing weeds. The war destroyed the cities, leaving behind ruins and refugees. The land could no longer support the population due to the drought, and the government was too weak to do anything about it due to the war. Rather than to remain in the cities and face death, the people scattered, and the jungle eventually reclaimed the land.

Answer 1

It appears that the real demise of the Mayan Empire was a number of factors, including drought, warfare, and disease. NASA archeologist Tom Sever used satellite images combined with archeological findings to piece together the most likely scenario. Using pollen trapped in layers of lake sediment, scientists learned that around 1,200 years ago, just before the civilization's collapse, tree pollen almost completely disappeared and was replaced by weed pollen. This indicates that the region had become almost completely deforested.

Without trees, erosion started carrying away fertile topsoil. The changing groundcover boosted average temperatures which dried out the land, making it less suitable for crops. In support of this, researchers find human bones from the last decades before the civilization's collapse showed signs of severe malnutrition. Rising temperatures would also cause a disruption in rainfall patterns. During the dry season water would be scarce, and the groundwater was too deep to reach with wells. Dying of thirst became an additional threat.

"Archeologists used to argue about whether the downfall of the Maya was due to drought or warfare or disease, or a number of other possibilities such as political instability," Sever says. "Now we think that all these things played a role, but that they were only symptoms. The root cause was a chronic food and water shortage, due to some combination of natural drought and deforestation by humans."