state, causing increased carbon dioxide uptake. Other researchers have supported depopulation in the Americas as a factor and have asserted that humans cleared considerable amounts of forest to support agriculture there before the arrival of Europeans brought on a population collapse. Richard Nevle, Robert Dull and colleagues further suggested not only that anthropogenic forest clearance played a role in reducing the amount of carbon sequestered in Neotropical forests but also that human-set fires played a central role in reducing biomass in Amazonian and Central American forests before the arrival of the Europeans and the concomitant spread of diseases during the Columbian exchange. Dull and Nevle calculated that reforestation in the tropical biomes of the Americas alone from 1500 to 1650 accounted for net carbon sequestration of 2–5 Pg. Brierley conjectured that the European arrival in the Americas caused mass deaths from epidemic disease, which caused much abandonment of farmland. That caused much forest to return, which sequestered more CO2. A study of sediment cores and soil samples further suggests that CO2 uptake via reforestation in the Americas could have contributed to the Little Ice Age. The depopulation is linked to a drop in CO2 levels observed at Law Dome, Antarctica. Population increases at mid- to high latitudes It is suggested that during the Little Ice Age, increased deforestation had enough effect on the Earth's albedo (reflectiveness) to cause regional and global temperature decreases. Changes in albedo were caused by widespread deforestation at high latitudes, which exposed more snow cover and thus increased reflectiveness of the Earth's surface, as land was cleared for agricultural use. The theory implies that over the course of the Little Ice Age, enough land was cleared to make deforestation a possible cause of climate change. It has been proposed that the Land Use Intensification theory could explain this effect. The theory was originally proposed by Ester Boserup and suggests that agriculture advances only as the population demands it. Furthermore, there is evidence of rapid population and agricultural expansion, which could warrant some of the changes observed in the climate during this period. This theory is still under speculation for multiple reasons: primarily, the difficulty of recreating climate simulations outside of a narrow set of land in those regions; so that one cannot rely on data to explain sweeping changes or to account for the wide variety of other sources of climate change globally. As an extension