Land-Cover and surface water change drive large albedo increases in south america

Albedo is an important factor affecting global climate, but uncertainty in the sources and magnitudes of albedo change has led tosimplistic treatments of albedo in climate models. Here, the authors examine nine years (2000-08) of historical 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) albedo estimates across South America toadvance understanding of the magnitude and sources of large-scale albedo changes. The authors use the magnitude of albedo change fromthe arc of deforestation along the southeastern edge of the Brazilian Amazon (+2.8%) as a benchmark for comparison. Large albedo increases (>+2.8%) were 2.2 times more prevalent than similar decreases throughout South America. Changes in surface water drove most large albedo changes that were not caused by vegetative cover change. Decreased surface water in the Santa Fe and Buenos Aires regions of Argentina was responsible for albedo increases exceeding that of the arc of deforestation in magnitude and extent. Although variations in the natural flooding regimes were likely the dominant mechanism driving changes in surface water, it is possible that human manipulations through damsandother agriculture infrastructure contributed. This study demonstratesthe substantial role that landcover and surface water change canplay incontinental-scale albedo trends and suggests ways to better incorporate these processes into global climate models.