Population Pressure Impacts World Wetlands

The area of the globe covered by wetlands (swamps, marshes, lakes, etc.) has dropped by 6% in fifteen years. This decline is particularly severe in tropical and subtropical regions, and in areas that have experienced the largest increases in population in recent decades. Although they cover less than 5% of Earth's land surface, these areas play a key role in human  activities, biodiversity, climate and the water cycle. Indeed, they produce one third of atmospheric methane, a major greenhouse gas. Moreover, these regions impact the transfer of continental freshwater to the sea and alter local weather by enhancing evaporation. This observation suggests that population pressure impacts hydrological cycles at the global scale. This pressure may stem from the draining of wetlands for urban development and the increase in water extraction from wetlands.

http://www.sciencedaily.com/releases/2012/05/120511122101.htm