Global wetland loss reconstruction over 1700-2020

This repository contains three datasets resulting from the reconstruction of global wetland loss over 1700-2020. The three datasets are listed here and described in more detail below:

• A. National and subnational statistics of drained or converted areas
• B. Regional wetland percentage loss estimates and geospatial polygons
• C. Gridded reconstruction

The scripts used to process input data, model and calibrate the wetland loss reconstruction, and produce the figures are publicly available at https://github.com/etiennefluetchouinard/wetland-loss-reconstruction.

A. National and subnational statistics of drained or converted areas

This tabular database containing national and subnational statistics of wetland area drained and peat mass extracted. The database includes four land use types: cropland, forestry, peat extraction and wetland cultivation. These data are used as input to the mapped wetland loss reconstruction. Column descriptions of drainage_db_v10.csv:

1. unit: Scale of administrative unit ("national" or "subnational").
2. type: Land use type ("Cropland", "Forestry", "Peat Extraction" or "Wetland Cultivation")
3. iso_a3: 3-letter code of each country.
4. region: Name of subnational unit. Blank if data is national scale.
5. HASC_1: Hierarchical Administrative Subdivisions Codes for the subnational units. Blank if data is national scale.
6. year: Year of data.
7. drained_area_1000ha: Cumulative area drained by the year specified, in thousands of hectares.
8. drained_weight_1000tonsyr: Annual peat extraction rate for the year, in thousand tons per year.
9. peatland_only: Label indicating whether the drained area applies to all wetlands or peatlands specifically ("Peatland only" or blank).
10. Comment: Additional description from original data source, or unit conversion, or data corrections.
11. Source: Reference of data source and/or compilers.

B. Regional wetland percentage loss estimates and geospatial polygons

A shapefile of 151 polygons projected in WGS84.  Columns description for polygon shapefile of the regional wetland loss percentage: regional_loss_poly.shp:

1. id: Numerical identifier.
2. name: Name of administrative unit, region or water feature the polygon area covers.
3. country: Name of country.
4. continent: Name of continent.
5. wet_categ: Broad category of wetlands included in the estimate (“Peatlands”, “Inland natural wetlands”, “Coastal natural wetlands”, “Unspecified natural type(s)” or “All wetlands”).
6. yr_start: Start year of the period over which wetland loss is estimated.
7. yr_end: End year of the period over which wetland loss is estimated.
8. area_mkm2: Surface area of the polygon, in million square kilometers (Mkm²).
9. perc_loss: Numerical value of percentage wetland loss (positive value represent loss of wetland area between start and end year.
10. comment: Additional description of estimate used or estimation method.
11. source: Citation of original data source.
12. compiler: Citation of intermediary data compiler.

C. Gridded reconstruction

Gridded outputs are stored in a separate NetCDF file for each of the 12 reconstructions of simulated wetland and present-day wetland maps. An ensemble average was also computed from the 12 reconstructions (only individual reconstructions were discussed in the manuscript). These data consist of global maps generated from the drainage reconstruction methodology for 33 decadal intervals (1700-2020 inclusive) for 9 variables:

The filenames of ensemble members are labelled to with the name of the input present-day and simulated wetland maps:

            “wetland_loss_1700-2020_” + simulated input + “_” + present-day input + “_v10.nc”

The 4 simulated wetland map inputs are: LPJwsl, SDGVM, ORCHIDEE, DLEM.  The 3 present-day wetland map inputs are: GIEMSv2, GLWD3, WAD2M.

Description of the 9 variables in each NCDF file:

1. wetland_loss: Cumulative wetland area lost (km² per grid cell). This variable is equivalent to the sum of area drained for the seven land uses drained
2. nat_wetland: Remaining natural wetland area (km² per grid cell)
3. cropland: Cropland area drained (km² per grid cell) leading to wetland loss
4. forestry: Forestry area drained (km² per grid cell) leading to wetland loss
5. peatextr: Peat harvest area drained (km² per grid cell) leading to wetland loss
6. wetcultiv: Wetland cultivation area (km² per grid cell) leading to wetland loss
7. ir_rice: Irrigated rice area leading to wetland loss (km² per grid cell)
8. pasture: Pasture area drained leading to wetland loss (km² per grid cell)
9. urban: Urban area drained leading to wetland loss (km² per grid cell)

All layers were capped below the land pixel area grid (from HYDE 3.2, excl. open water).

Time: 33 slices; numerical years spread at decadal intervals, ranging between 1700-2020 (inclusive)

Extent: Longitude: -180° to 180°.  Latitude: -56° to 84°.

See the README file for a more detailed description of this dataset. Anyone wishing to use this dataset should cite Fluet-Chouinard et al. 2023. Please contact Etienne Fluet-Chouinard  at etienne.fluet@gmail.com with any questions or comments with regards to the best usage of our dataset.

Fluet-Chouinard E., Stocker B., Zhang Z., Malhotra A., Melton J.R., Poulter B., Kaplan J., Goldewijk K.K., Siebert S., Minayeva T., Hugelius G., Prigent C., Aires F., Hoyt A., Davidson N., Finlayson C.M., Lehner B., Jackson R.B., McIntyre P.B.  Nature. Extensive global wetland loss over the last three centuries