How much wetland has the world lost? Long-term and recent trends in global wetland area

Abstract

It has been frequently stated, but without provision of supporting evidence, that the world has lost 50% of its wetlands (or 50% since 1900 AD). This review of 189 reports of change in wetland area finds that the reported long-term loss of natural wetlands averages between 54-57% but loss may have been as high as 87% since 1700 AD. There has been a much (3.7 times) faster rate of wetland loss during the 20th and early 21st centuries, with a loss of 64-71% of wetlands since 1900 AD. Losses have been larger and faster for inland than coastal natural wetlands. Although the rate of wetland loss in Europe has slowed, and in North America has remained low since the 1980s, the rate has remained high in Asia, where large-scale and rapid conversion of coastal and inland natural wetlands is continuing. It is unclear whether the investment by national governments in the Ramsar Convention on Wetlands has influenced these rates of loss. There is a need to improve the knowledge of change in wetland areas worldwide, particularly for Africa, the Neotropics and Oceania, and to improve the consistency of data on change in wetland areas in published papers and reports.

Three decades of Landsat-derived spring surface water dynamics in an agricultural wetland mosaic; Implications for migratory shorebirds

“…Most migratory shorebird species are entirely dependent on wetlands for food and rest during long-distance journeys in the spring and fall (Brown et al, 2001); many face dual threats of habitat loss and climate change (Davidson, 2014;Morrison et al, 2006). Under ongoing climate change, inland nontidal wetlands are at increased risk from future drought severity, and they will increase in importance for migratory shorebirds when sea level rise reduces access to coastal wetlands (Galbraith et al, 2002;Werner et al, 2013).…”

Understanding change in the ecological character of Ramsar wetlands: perspectives from a deeper time – synthesis

“…The need for clear evidence about change prompts a discussion of how the Ramsar Convention can create more nuanced processes to deal with past and future, natural and anthropogenic, internal and imposed, change to the world's wetlands of international importance, and in doing so enhance its role in enabling wise use to support people and protect the natural values of wetlands. This is particularly important given the paradox whereby the extensive effort to develop and implement international policy, supported by a substantial and expanding information base, has not stopped and reversed the global loss and/or degradation of wetlands (Finlayson 2012;Davidson 2014). Ralph et al (2016) also point out that it can be difficult to determine whether change is anthropogenic or not, or whether is it positive, negative or neutral.…”

“…Building from this understanding, the provision of guidance for wetland managers on the appropriate use of palaeoecology in their management planning and preparation of ecological character descriptions would support enhanced implementation of the wise-use provisions of the Ramsar Convention, including mechanisms for determining when adverse change has occurred, or is likely to occur. Given the extent of wetland loss and degradation over recent times (Davidson 2014;Gardner et al 2015) and the likelihood that many baseline or past reference conditions may not be suitable for future management purposes (Kopf et al 2015), it is difficult to see how the Convention can ensure the conservation and wise use of all wetlands unless every possible step is taken to better understand the nature and trajectory of change in wetlands.…”

“…Further, by linking wise use with ecological character in this manner it applies to all wetlands, and not just to designated Ramsar Sites, as had previously been the case (Pittock et al 2010). These are important changes as it extends the imperative of maintaining the ecological character, including the combination of the ecosystem components, processes and services, to all wetlands, and yet there is ample evidence, including from the cases shown in Table 1, that this has proven difficult for many Ramsar sites, the jewels in the crown of the Convention, let alone others (Finlayson and D'Cruz 2005;Davidson 2014).…”

Land Use Change Trajectories for Wetland Management (Mogi-Guaçu Floodplan River, Southern Brazil)

“…However, the information about the level of natural condition and the changes in land use trajectory, as well as the dynamics of the wetlands are little known and very restricted to the current years. The main attention for purpose management is thus often a reference when the wetland is perceived to the return of initial natural condition [39].…”