The history of conversion by humans is well documented (Davidson 2014), yet rates of change of wetland and surface water extent from satellite imagery since the 1990s indicates 6-Y% decrease (Prigent et al. 2012; Schroeder et al. 2015). Site-based meta-analyses over a longer time horizon indicate a 25-30% decline since 1970 (Dixon et al. 2016), of 55.6% since 1900 and 70.6% since 1700 (Davidson 2014). The rate from these meta-analyses exceeds previously held belief that 50% of the world's wetland had been lost since 1900 (Dahl 1990). The distribution of site records could be biased toward certain highly degraded sites and regions, possibly not directly extrapolated to global wetland cover (Hu et al. 2017).
- Estimate natural wetland extent converted to cropland and rice culture.
- Analyze changes in wetland area, rates of change across geographic regions and over time.
121 Independent estimates of wetland loss over specified areas and time periods. Databases of historical records of wetland conversion have been compiled for meta-analyses of wetland conversion rates (Asselen et al. 2013; Davidson 2014; Dixon et al. 2016; Paudel et al. 2012). Older records cover larger ill-defined areas associated with current day borders.
- WAD2M
- GIEMSv2
- GLWD level-3
- Simulations from WETCHIMP: ORCHIDEE, SDGVM & DLEM (Wania et al. 2013; Melton et al. 2013)
- LPJ-Wsl (Zhang et al. 2016)
- Cropland
- Rice cultivation
- Pasture
- Urban area
- Forestry (primary & secondary)
c
