This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
Global extent and distribution of wetlands: trends and issues
We review estimates of global and regional wetland area from ‘bottom-up’ approaches of site or national wetland inventories and ‘top-down’ approaches from global mapping and remote-sensing. A trend of increasing wetland extent reported in the literature over time is a consequence of improving mapping technologies and methods rather than a real increase in wetland area, since a continuing trend of natural wetland loss and conversion is documented over the same time period. The most recent high-resolution estimate of global wetland area is in excess of 12.1 Million km2, of which 54% is permanently inundated and 46% temporarily inundated. Globally, 92.8% of continental wetland area is inland and only 7.2% is coastal. Regionally, the largest wetland areas are in Asia (31.8%), North America (27.1%) and Latin America & the Caribbean (Neotropics) (15.8%), with smaller areas in Europe (12.5%), Africa (9.9%) and Oceania (2.9%). It is likely that estimates of global wetland area published to date persist in underestimating the true wetland area. The “grand challenge” of a global inventory integrating all types of permanent and temporary wetlands at high spatial resolution has yet to be fully achieved.
MF17019 Accepted 16 September 2017
© CSIRO 2017