As per the Global Wetland Outlook: state of the world's wetlands and their services to people Ramsar Convention 2018, “The most recent estimate of global inland and coastal wetland area is more than 12.1 million km 2 , an area almost as large as Greenland. Of this, 54% is permanently inundated, and 46% seasonally flooded. An estimated further 5.2 million km 2 are intermittently or occasionally inundated, but this is believed to include areas of formerly converted wetlands affected by extreme storm events. Approximately 93% of wetlands are inland systems, with 7% marine and coastal – although this coastal estimate does not include a number of wetland groups, such as near shore sub tidal wetlands, which also fall under the Ramsar definition. Global wetland areas are small in comparison: wetlands occupy an estimated 0.3 million km2 and rice paddy 1.3 million km2 (Davidson et al. 2018; Davidson and Finlayson 2018). The size of the global wetlands has increased considerably since the 1980s, primarily due to advancement in remote sensing, geographical information system tools and mapping methods but there has not been an increase in the actual size of the wetlands (Davidson et al. 2018). The largest wetlands region at the continental level are distributed in (Figure 1.2) Asia (32%), North America (27%) and Latin America & Caribbean (16 %), Europe (13%), Africa (10%) and Oceania (3%) (Davidson et al. 2018).
Table 1.1 Classification of wetlands as defined by Ramsar Convention Bureau, 2010
Source: Ramsar wetland‐type classification retrieved from: https://www.environment.gov.au/water/wetlands/ramsar/wetland‐type‐classification © Department of Agriculture, Water and the Environment(Southern Australia). Licensed under CC BY 4.0.
| A ‐ Permanent shallow marine waters in most cases less than six m deep at low tide; includes sea bays and straits |
| B ‐ Marine sub‐tidal aquatic beds; includes kelp beds, sea‐grass beds, and tropical marine meadows |
| C ‐ Coral reefs |
| D ‐ Rocky marine shores; includes rocky offshore islands, sea cliffs |
| E ‐ Sand, shingle or pebble shores; includes sand bars, spits and sandy islets; includes dune systems and humid dune slacks |
| F ‐ Estuarine waters; permanent water of estuaries and estuarine systems of deltas |
| G ‐ Intertidal mud, sand or salt flats |
| H ‐ Intertidal marshes; includes salt marshes, salt meadows, saltings, raised salt marshes; includes tidal brackish and freshwater marshes |
| I ‐ Intertidal forested wetlands; includes mangrove swamps, nipah swamps and tidal freshwater swamp forests |
| J ‐ Coastal brackish/saline lagoons; brackish to saline lagoons with at least one relatively narrow connection to the sea |
| K ‐ Coastal freshwater lagoons; includes freshwater delta lagoons. Zk (a) – Karst and other subterranean hydrological systems, marine/coastal |
| L ‐ Permanent inland deltas. |
| M ‐ Permanent rivers/streams/creeks; includes waterfalls. |
| N ‐ Seasonal/intermittent/irregular rivers/streams/creeks. |
| O ‐ Permanent freshwater lakes (over 8 ha); includes large oxbow lakes. |
| P ‐ Seasonal/intermittent freshwater lakes (over 8 ha); includes floodplain lakes. |
| Q ‐ Permanent saline/brackish/alkaline lakes. |
| R ‐ Seasonal/intermittent saline/brackish/alkaline lakes and flats. |
| Sp ‐ Permanent saline/brackish/alkaline marshes/pools. |
| Ss ‐ Seasonal/intermittent saline/brackish/alkaline marshes/pools. |
| Tp ‐ Permanent freshwater marshes/pools; ponds (below 8 ha), marshes and swamps on inorganic soils; emergent vegetation water‐logged for at least most of the growing season. |
| Ts ‐ Seasonal/intermittent freshwater marshes/pools on inorganic soils; includes sloughs, potholes, seasonally flooded meadows, sedge marshes. |
| U ‐ Non‐forested peatlands; includes shrub or open bogs, swamps, fens. |
| Va ‐ Alpine wetlands; includes alpine meadows, temporary waters from snowmelt. |
| Vt ‐ Tundra wetlands; includes tundra pools, temporary waters from snowmelt. |
| W ‐ Shrub‐dominated wetlands; shrub swamps, shrub‐dominated freshwater marshes, shrub carr, alder thicket on inorganic soils. |
| Xf ‐ Freshwater, tree‐dominated wetlands; includes freshwater swamp forests, seasonally flooded forests, wooded swamps on inorganic soils. |
| Xp ‐ Forested peatlands; peat swamp forests. |
| Y ‐ Freshwater springs; oases. |
| Zg ‐Geothermal wetlands |
| Zk (b) – Karst and other subterranean hydrological systems, inland |
Figure 1.2 Regional distribution (%) of the wetland area
Source: Davidson et al. (2018) and Ramsar Convention on Wetlands; WORLD OUTLOOK, 2018 (2018). © Ramsar Convention Secretariat.
1.4 Status and Impacts on the Wetlands Ecosystem
The wetland ecosystem is a very sensitive aspect of the ecological landscape. The health of flora and fauna species is associated with the conditions and distribution of the wetlands. Any change on a small and large scale in the wetland ecological system impacts the biodiversity and habitat of the species. The changes in wetlands leads to changes in number of species, distribution of the species, alteration in migratory bird routes, and changes in community structures and species interconnection (Erwin 2009). Rapid changes in population dynamics or any other environmental or climate change often result in wetland encroachment due to increasing demand for ecosystem services in wetlands (Mitchell 2013; Davidson 2014; Dixon et al. 2016). These wetlands are increasingly degraded, and the provision of wetlands services is at serious risk. Based on an analysis of 189 reports on change in wetlands system, Davidson outlined in 2014, that ‘over a long period wetlands have been converted to other land‐use practices and have lost more than 50% since 1900 AD and more than 87% since the beginning of the 18th century’. Trustworthy information on the spatial distribution of wetlands would help academics, policymakers, scientists, and environmental conservationists understand the location, area, distribution and current physio‐biological status of global wetlands and develop efficient conservation policies measures and management plans. However, globally (Davidson 2014; Dixon et al. 2016) and at regional levels some work has been done on recent changes in global wetlands, distribution, loss and status.
Wetlands are currently at higher risk of climate change for example alternations have
