Addressing water issues effectively requires transboundary action because the connectedness of these systems goes beyond political boundaries. Globally, there are over 270 transboundary river basins and 200 transboundary aquifers. 39 countries have more than 90% of their territory within one or more transboundary river basins and 21 lie entirely within one or more of these watersheds. These watersheds cover about one-half of the earth's land surfaces and are home to about 40% of the world population. The majority of the world 's Large Marine Ecosystems (LMEs), responsible for over 85% of the world's fish catch and provide a suite of ecosystem services such as essential spawning habitats, natural coastal protection, and carbon sequestration and storage, are shared by two or more countries.