Pilot analysis of global ecosystems: Freshwater systemsby , , , and -
Reveals that the world's freshwater systems are so degraded that their ability to support human, plant and animal life is greatly in peril.
The PAGE reports show that human action has profoundly changed the extent, distribution, and condition of all major ecosystem types. Agriculture has expanded at the expense of grasslands and forests, engineering projects have al- tered the hydrological regime of most of the world’s major rivers, settlement and other forms of development have converted habitats around the world’s coastlines. The picture we get from PAGE results is complex. Ecosystems are in good condition for producing some goods and services but in poor condition for producing others. Overall, however, there are many signs that the capacity of eco- systems to continue to produce many of the goods and services on which we de- pend is declining. Human activities have significantly disturbed the global water, carbon, and nitrogen cycles on which all life depends. Agriculture, in- dustry, and the spread of human settle- ments have permanently converted ex- tensive areas of natural habitat and con- tributed to ecosystem degradation through fragmentation, pollution, and increased incidence of pest attacks, fires, and invasion by nonnative species.