1 00:00:07,200 --> 00:00:20,180 A new NASA climate model simulation that dates back to the Aztec and Mayan era shows deforestation by these ancient empires could have intensified periods of drought that contributed to the decline of these once mighty civilizations. 2 00:00:20,200 --> 00:00:30,590 According to the model, regions of Central America inhabited by the Aztecs and Mayans received less rainfall when population levels were high and deforestation was widespread. 3 00:00:30,610 --> 00:00:42,580 Years later, as indigenous populations declined following the arrival of Europeans, the regrowth of forests in areas once used by the natives for farming resulted in a much wetter climate. 4 00:00:42,600 --> 00:00:52,800 Scientists believe the conversion from farmland to forest modified the surface reflectance of sunlight in those regions, which led to local changes in temperature and rainfall.