Wetland Loss/Degradation

Primary reference(s)

Olsson, L., H. Barbosa, S. Bhadwal, A. Cowie, K. Delusca, D. Flores-Renteria, K. Hermans, E.
Jobbagy, W. Kurz, D. Li, D.J. Sonwa, L. Stringer, 2019. Land degradation. In: Climate Change and Land: an IPCC Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems. Accessed 21 January 2025.

Convention on Wetlands of International Importance Especially as Waterfowl Habitat, 2 February 1971 (amended 1982 & 1987). Accessed 21 January 2025.

Annotations

Key relevant UN convention / multilateral treaty

The Convention on Wetlands is an intergovernmental treaty whose mission is the conservation and wise use of all wetlands through local and national actions and international cooperation, as a contribution towards achieving sustainable development throughout the world (Convention on Wetlands, 2016). As of August 2023, 172 nations had joined the Convention as Contracting Parties, and more than 2,400 wetlands of international importance, covering over 2.5 million km2, have been designated for inclusion in the List of Wetlands of International Importance.

The United Nations Educational, Scientific and Cultural Organization (UNESCO) serves as the depositary for the Convention. However, the Convention on Wetlands is not part of the United Nations or UNESCO system of environmental conventions and agreements. The Convention is responsible only to its Conference of the Contracting Parties (COP), and its day-to-day administration has been entrusted to a secretariat under the authority of a standing committee elected by the COP. The Secretariat to the Convention on Wetlands is hosted under contract by the International Union for Conservation of Nature

Drivers

Overexploitation of freshwater resources jeopardises human wellbeing and the environment. Wetlands, critical ecosystems for biodiversity, water purification and flood control, are increasingly under threat from a complex interplay of socio-economic and environmental hazards. The multi-hazard context of wetland loss and degradation involves a combination of natural and anthropogenic factors that exacerbate their vulnerability.

Human activities are a primary driver of wetland loss, in particular land use change and agriculture. Agricultural expansion results in direct habitat loss and fragmentation. Agricultural practices represent a significant driver of wetland loss, primarily through conversion for agricultural land, water extraction and pollution. The expansion of agricultural land often necessitates the drainage and infilling of wetlands, disrupting their natural hydrology and ecological functions. Furthermore, agricultural activities can lead to increased nutrient pollution, sedimentation and habitat fragmentation, further degrading wetland ecosystems. These impacts can have severe consequences for biodiversity, water quality and the provision of ecosystem services (Convention on Wetlands, 2022).

Climate change also contributes to wetland loss, manifesting through rising temperatures, altered precipitation patterns and increased frequency of extreme weather events such as storms and droughts. These climatic shifts disrupt hydrological regimes, leading to either prolonged inundation or excessive drying, both detrimental to wetland health. For instance, intensified storms can cause physical damage and increase sedimentation rates, while droughts can reduce water availability, impacting the flora and fauna dependent on wetland habitats (Humpenöder et al., 2020; Gitay et al., 2011).

Moreover, socio-economic factors such as poverty and inadequate environmental governance can exacerbate wetland degradation. In many regions, wetlands are exploited for their resources-such as timber, fish and water-without sustainable management practices, leading to over-extraction and habitat destruction (Ghosh et al., 2023).

Impacts

Access to safe water, human health, food production, economic development and geopolitical stability are made less secure by the degradation of wetlands driven by the rapidly widening gap between water demand and supply. Even with current attempts to maintain minimum water flows for ecosystems, the capacity of wetlands to continue to deliver benefits to people and biodiversity—including clean and reliable water supplies—is declining. Efforts to support water allocation to ecosystems, such as environmental flow requirements, placing upper limits on water allocations and new water management legislation, must be strengthened (Convention on Wetlands, 2016). 

Wetland loss/degradation results in associated reductions in ecosystem services delivered by wetlands, such as: provisioning services including food and freshwater; regulating services such as flood control, storm protection, drought buffering, groundwater recharge and discharge, and carbon sequestration; cultural services such as recreation; and supporting services such as purification of water supplies, shoreline stabilisation and erosion control, retention of nutrients, sediments and pollutants, and stabilisation of local climate conditions—particularly rainfall and temperature. The ecosystem services related to human health primarily cover the supply of water, food, nutrition and medicine; purification of waste products; and buffering against adverse flooding and climate effects (Convention on Wetlands, 2005; 2016). 

The cumulative effects of these hazards create a feedback loop, where the degradation of wetlands reduces their resilience to future threats, thereby increasing their susceptibility to ongoing environmental changes. Addressing this multi-hazard context requires integrated management approaches that consider the interconnections between climatic, environmental and socio-economic factors to protect and restore these vital ecosystems (Convention on Wetlands, 2012; Docherty et al., 2020).

Multi-hazard context

The figure below summarises common interactions between wetland loss or degradation and other hazards. This information should be used with caution and not be solely relied upon in disaster risk management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Multi-hazard diagram

Risk Management

Preserving wetlands requires an integrated approach, which not only addresses wetland conservation and restoration but also the implementation of effective climate change solutions and the achievement of the Sustainable Development Goals. This is particularly important given that water-related hazards constitute around 74% of all natural hazards (Chen, 2022; UNESCO 2020; Priscoli et al., 2015). Many Contracting Parties to the Convention on Wetlands, recognising the importance of the conservation and wise use of wetlands, have adopted some form of an avoid-mitigate-compensate approach to wetland loss and degradation. In this context, national, regional, and local laws and policies emphasise that negative wetland impacts should be avoided if at all possible. If such negative impacts cannot be avoided or prevented, actions should be taken to mitigate (minimise or reduce) this wetland loss or degradation. Finally, if wetland loss or degradation remains after such mitigation, actions should be taken to compensate for (i.e., offset) these residual impacts (Gardner et al., 2012).    

Wetlands themselves can act as early warning systems for broader catchment changes. Alterations in wetland hydrology, such as changes in water levels or flow regimes, can signal broader hydrological shifts that may impact water resources and downstream ecosystems (Grenfell et al., 2005). 

Monitoring

The section and the table below provide an overview of monitoring for wetland loss or degradation. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency or authority responsible for disaster management.