Abstract
Wetland ecosystems, freshwater, coastal and coral reefs, are important ecosystems as they provide many ecological services and ensure livelihood of people. The increase in carbon dioxide and global temperatures change in precipitation patterns, and acidification of oceans can adversely affect these ecosystems. It is expected that increase in temperature in lakes, reservoirs and coastal seas will affect flora, fauna and fisheries. The increase in sea level can erode shorelines and coastal habitats. Coral reefs can degrade due to increase in temperature, sea level rise and acidification. The ecological services provided by these ecosystems have economic value and thus any loss of these habitats can affect livelihood of communities. The global watershed and coastal management approaches such as the 1971 Ramsar Convention and 2030 Sustainable Development Goals (SDGs) provide key tools to protect these ecosystems. A robust global wetland information repository system needs to be developed for providing necessary data to effectively model climate change impacts at local and regional levels. The knowledge about climate risks to wetlands, integrated with effective governance at national, regional and global levels along with informed people, are key elements for protection and sustainable future of wetlands. It is in this global context and decisions of the successive Ramsar Conference of Parties (COP), within the limits of time and space, this study has sought to examine the climatic risks to the wetland’s ecosystems. The data and the situation in the Indian sub-continent have been used as an example for the purpose. We need to look for concrete ideas and solutions to address the challenge of climate change risks to the wetland ecosystem at the juncture of Stockholm+50 (2022) and beyond.
Keywords
Introduction
Human life depends on various goods and services provided by the ecosystems and thus economy of a country or world depends on health of ecosystems. During last two centuries, the human and social systems have significantly affected our environment and has become major driver of influencing the Earth system, especially the water, carbon, and nitrogen cycles, on which life depends. Wetland ecosystems, comprising both coastal and inland systems, are regions of remarkable biological productivity and diversity and have been centre of human activities. They produce fish, shellfish, and seaweeds, and most important they host ports for commerce. They store and cycle nutrients, filter pollutants and help to protect shoreline from erosion and storms. People are attracted to wetlands because of it’s beauty and thus provide recreation and facilitate tourism.
How these ecosystems are likely to respond to climate variability and change? Climate change, in terms of changes in carbon dioxide, temperature of atmosphere and ocean, sea level and precipitation patterns, are likely to affect many ecosystem services, e. g. fisheries, biodiversity, etc. The observed and projected changes of these parameters are as follows.
The warming of our atmosphere and sea has been unequivocal. In India, during the last century, the atmosphere has warmed by 0.6°C, with greater warming of 0.2°C per decade after 1980s. 1 Both maximum and minimum temperatures are increasing but maximum temperature is increasing at faster rate (1°C). The warming has changed the precipitation patterns in many regions. In India, the monsoon does not show any significant trend, but frequencies of light rain have decreased, and very heavy and extreme rainfalls have increased. 2
Ocean has been absorbing more than 80 % of heat and contributing to sea level rise. The tropical Indian Ocean is warming at 0.2°C per decade which is at faster rate compared to other tropical oceans. 3 The sea level rise over the Arabian Sea and Bay of Bengal is 0.5-3 mm/y and 0.75-6 mm/y, respectively, and is of steric origin 4 The increased sea level will modify shorelines and will affect biodiversity. The increased temperature will affect physical, chemical, and biological properties of wetlands, lakes and rivers and impact species distribution, community composition and water quality 5
The increasing carbon dioxide concentration affect the leaf physiology and thus photosynthesis. The stomatal conductance decreases by about 20 % across wide range of vegetation types with increase in carbon dioxide 6 , 7 and will lead to an increase in leaf area and net primary production. 8 It is necessary to study mid-Pliocene vegetation when the carbon dioxide levels were similar as of today which will provide an insight into response of vegetation to increased carbon dioxide levels.
The projected changes over the Indian subcontinent and surrounding ocean by the Earth System Science Organization (ESSO) - Indian Institute of Tropical Meteorology –Earth System Model (IITM-ESM) CMIP6 (Coupled Model Intercomparison Project Phase 6) simulations up to 2099.
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The projections are based on the Shared Socio-economic Pathways (SSPs), SSP2-4.5 (middle-of-the-road) and SSP5-8.5 (fossil-fuel-rich development). The projections are given below. The mean surface temperature will increase by 2.1°C and 3.3°C under immediate and high emission scenarios, respectively, by 2099. The precipitation is likely increase by 0.03 mm/day and 0.51 mm/day for corresponding scenarios. An increase in mean, extremes, and inter-annual variability of monsoon precipitation is expected by 2100.
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The mean sea surface temperature in the Indian Ocean will continue to rise in the 21st century. The sea-level-rise in the north Indian Ocean during last four decades has been due to weakening of summer monsoon winds
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and future changes in monsoon wind will have similar impact on sea-level-rise. The total seasonal snowfall has been reduced in the western Himalaya due to increase in both maximum and minimum temperatures.9 In view of these changes in precipitation pattern, it is expected that the mean water supply for the Indus, Ganges, and Brahmaputra likely to decrease by 8.4 %, 17.6 % and 19.6 % .
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In another study, it has been suggested that due to enhanced snow and glacier melting and resultant increased streamflow will lead to enhanced flooding risks in absence of appropriate adaptation and risk mitigation measures in the Indus, Ganges and Brahmputra basins.
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India has been witnessing higher frequency of flood and droughts during last 70 years. With increasing variability in monsoon rainfall, it is expected that there will be an increase in occurrence, severity, and area under drought.
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The increase in extremely heavy rainfall events, and melting in snow and glaciers, likely to lead to enhanced flooding events, especially in the Indus, Ganga and Brahmputra basins
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. The frequency and intensity of cyclone depends on sea surface temperature and heat content. It is expected that frequency and intensity of very severe cyclonic storms will increase in this century.
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These projected changes are likely to affect wetland ecosystems and may reduce ecological services. The impacts of climate change on aquatic, coastal and coral reef ecosystems as well as ecological services have been discussed in following sections. The efficacy of current approaches for conservation of these ecosystems vis-à-vis environmental changes have been analysed. The monitoring system in view of conversing wetlands in changing environment has been proposed. The sustainability of wetlands is a key to livelihood of people. How adaptation and mitigation efforts to be directed has been provided in concluding remarks. The Stockholm+50 Conference is expected to provide new insight in this regard.
Impacts of Climate Change on Wetlands
Aquatic Ecosystems
Freshwater, covering rivers and lakes, occupy only 0.8 % of the Earth’s surface but provide habitat for > 10 % of known species. 17 , 18 A detailed inventory of freshwater wetlands in India in space and time has been provided. 19 Satellite altimeter data have been used to monitor water levels in rivers, lakes, and reservoirs. 20
The warming of lakes and rivers likely to affect metabolism and foraging characteristics of individual ectothermic flora and fauna. 21 Many lakes may change from net autotrophic (carbon sinks) to net heterotrophic (carbon source). 22 In addition, anthropogenic activities also affect ecosystems and combined impacts can alter health of wetlands. A regular monitoring of lakes and reservoirs is necessary to record changes in aquatic ecosystems.
Human activities have altered freshwater systems through hydrological or geomorphological interventions, affected water quality and biological production. The construction of dams or withdrawal of large amount of water affect biodiversity and ecosystem services. 23 The likely reduction of 10-20% in water flows in rivers in India has already led to ingress of saltwater in the deltaic regions and increased salinity levels in groundwater. Apart from this aspect, most deltas are not receiving adequate sediment supply and/or water flow due to construction of dams across rivers, e. g. Kaveri delta. In view of this, it is expected that stronger wave and tidal action will lead to increased coastal erosion. Apart from reduced river flow, the reservoirs also retain nutrients such as C, N, P and Si and may modify marine ecosystems. 24 However, the actual impact of dam on coastal systems is yet to be studied and modeled. To mitigate impacts of climate change up to certain extent, it is necessary to maintain baseline flows in rivers so that freshwater, coastal and marine ecosystems can be sustained.
The agricultural runoff and domestic sewage, enriched in nutrients, nitrogen and phosphorus, lead to eutrophication and changes in ecosystem structure and function. As nutrient load increases, the phytoplankton communities change from diatoms and green algae to highly productive cyanobacteria or blue-green algae and leads to algal blooms. Many algal blooms are associated with depletion of oxygen or harmful toxins. The changes in phytoplankton community have impact on zooplankton species and ultimately affect fishery.
Urbanization also modifies rivers and streams and discharges wastewater from domestic and industrial use and non-point sources such as paved surfaces and affect water quality. The wastewater from sewage treatment plants is rich in organic material leading to increase in biological oxygen demand (BOD). Such changes affect ecosystem functioning and reduce biodiversity. Many synthetic compounds in pharmaceuticals, personal care products, etc. cannot be treated in such treatment plants, ecological effects of such chemicals are not fully known. 25
In Himalayas, the glaciers cover about 33,000 sq km. Global warming has affected glaciers and most glaciers are retreating. There is large variation in retreat of glaciers from few meters to 60 m per year. The total loss of glacier area has been estimated to be about 13 percent and the mean loss of mass has been doubled between 1975-1985 and 2000-2010. 26 The retreat of glaciers likely to lead to changes in species diversity, abundance, and structure of fauna and flora. 27
Based on CMIP5 (Coupled Model Intercomparison Project 5) projections, it is expected that about 10.6 and 27 per cent of glaciers may disappear under RCP (Representative Concentration Pathway) 2.6 (Low emission) and 8.5 (High emission) scenarios, respectively. 28 Hence, the river flow will increase, initially due higher melt, leading to floods. Later, when glaciers are lost, may lead to water shortages. Such scenarios will adversely impact on downstream aquatic ecosystems.
Coastal Ecosystems
The coastal ecosystems such as mangroves, seagrasses, and coral reefs are at increasing risk from sea level rise, storm surges and ocean acidification as well as other anthropogenic activities. The rising sea levels are already eroding shorelines, drowning low-lying areas, and changing shoreline configuration of coast. Human modification of the shoreline has altered currents and sediment delivery, enhancing coastlines in some areas and starving beaches in others. This coupled with high tides and waves and storm surges can cause excessive episodic flooding. This can affect the ecosystems, settlements, and port operations and ultimately livelihood of coastal communities. This can lead to migration of people to other areas. The people should be made aware of the changing environment and take adaptive and mitigation measures.
Mangroves, salt-tolerant plants, protect coast from storms and help in stabilizing the shoreline. During last three decades, mangroves on the Indian coast has substantially increased from 4046 sq km in 1987 to 4992 sq km in 2021, due increased conservation efforts (www.fsi.nic.in). The increase in area has also led to increase in carbon stock and an important step in mitigation of climate change impact apart from providing enhanced ecological services. Mangroves classified as pure and mixed categories in selected areas. 29 It has been recorded that cyclonic storm do damage mangroves, however they do recover in about six months as visualised in NDVI (Normalised Difference in Vegetation Index) images generated from OCEANSAT-1 OCM (Ocean Colour Monitor) and IRS WiFS (Wide Field Sensor). 30 Similarly, the damage due to tsunami was also recorded using satellite data. 31 As frequency and intensity of cyclones along with sea level likely to increase, it is necessary to model their impact on mangrove ecosystems.
What are likely impacts of sea level rise on coastal zone comprising landforms such as beach, mudflats, rocky coast, mangroves, lagoons, dunes, barrier islands, etc.? The effects of rising sea level on the Gujarat coast (NW coast of India) were studied. 32 Most beaches which are either undernourished or in equilibrium will get eroded and shoreline will move landwards. The rocky coasts are less likely to be affected. The dunes will be affected due to rising groundwater level and dune vegetation might change to salt-tolerant varieties. Due increase in tidal amplitude, estuarine dynamics will be altered. The barrier islands form in mouth of rivers and their evolution depends upon regional tectonics, sea level rise, vegetation, and wave activity. It is expected that the slow rise in the sea level will generate new barrier islands, while rapid rise will erode them. 33 The deltaic mangroves are being affected by reduced water flows and freshwater-loving mangroves will give way to salt-water tolerant mangroves as noticed in some parts of Sundarbans. The degradation of coastal habitats results in loss of nurseries for many species. This will affect the biodiversity as well as livelihood of people. The rate of rise of sea level is not uniform along the Indian coast. We are not yet been able to model the impact of sea level rise on coast and islands.
Many areas on the Indian coast are eroded. About 30 per cent area of shoreline of India is under erosion. The loss of coastal habitats reduces key ecological services, e. g. fish and shellfish stocks may decline, and shoreline may be destabilized. The relationship between health of coastal habitats and fish stock is usually linear. The capability of coastal and marine ecosystems to produce fish for human harvest is likely to be reduced due to regime shift due to increased sea surface temperature and loss of coastal nursery areas. It has been observed that after 1985, there an increased availability of Sardines on the east coast and Northern west coast and reduction in catch on the Southern west coast of India. 34 This is an example of regime shift occurring on the Indian coast. Stock assessments of commercially important species are necessary to identify Maximum Sustainable Yield (MSY) on annual basis for sustainability of fishery. A program to assess potential for commercial fishery in the Indian EEZ has been undergoing at ESSO-Centre for Marine Living Resources (CMLRE), Kochi.
Mangroves sequester carbon much faster than tropical rainforests. There is little understanding of how coastal carbon accumulation rates will change in response to global warming. It has been demonstrated that competition between mineral sediment deposition and organic matter accumulation determines the net impact of carbon accumulation in intertidal wetlands. The direct impact of warming on soil carbon is more subtle than impact of warming-driven sea level rise. The simulations suggest that net impact of climate change will be increase carbon burial rates in the first half of the twenty-first century. 35
Coral Reefs
The information coral reefs types (fringing, platform, patch reefs, atoll, coral heads, etc.) and conditions have been assessed using satellite data 36 and ecological and morphological zoning has been carried out. 37 Coral reefs maps are available at www.vedas.sac.gov.in. The information on extent on live corals is limited. In a one study, hyperspectral data were used to distinguish healthy live corals and degraded corals. 38 The destruction of coral reefs due to tsunami of 2004 and their regeneration was recorded using satellite data. 39 , 40
Coral reefs are predicted to decline under the pressure of ocean warming. Coral reefs are associated with tropical seas having temperature around 28°C. Incidences of coral belching is increasing in our seas during last two decade, e. g. 1998 and 2020. According to one estimate, about 30 per cent coral reefs are severely damaged and it has been estimated that more than half will be lost in near future due to global warming. The health of coral reef needs to be routinely monitored due to rising temperature of sea. ESSO-Indian National Centre for Ocean Information Services (INCOIS), Hyderabad regularly provides bulletins about alerts for coral reef health (www.incois.gov.in).
However, there are studies which reported that many of these corals have been regenerated after bleaching events. It appears that soft corals, reproduced Acropora, normally first to succumb to increased temperature, has developed some resistance to bleaching or it may be zooxanthellae. It is too early to say that it an adaption to changing conditions. It is now realized that number of coral species can survive at a seawater temperature higher than predicted for the tropics during next century. In the Persian Gulf, corals survive seawater temperature up to 36°C during summer. A better understanding of how coral respond to rising temperature is important for predicting the fate of coral reefs. We need to investigate the molecular mechanism that allow corals to thrive at extreme temperatures. 41
Low-lying coral islands are sensitive to rise in sea level as it can modify shoreline processes and sediment movement around island 42 and may breach the natural berm which protects the island from inundation. In such conditions, population on islands may become vulnerable.
Ocean acidification resulting from the uptake of carbon dioxide by ocean water threatens corals, shellfish and other living things that form their shells and skeletons from calcium carbonate. We need to record condition of corals continuously to understand how changes are likely to happen.
Corals have survived almost 450 million years; however, many species became extinct and new species have emerged. Future corals may be quite different from those of today. 43 However, if such events become too common, corals will not be able to bounce back.
Water Pollution
Water quality of wetlands are affected by large scale land use/land cover changes, agricultural activities including irrigation, urbanisation and industrialisation and mining. The major activities include: Agriculture: Sediments from agricultural area, leaching of nutrients from excessive fertiliser use, and chemicals from pesticides. Animal Husbandry: Faecal bacteria from animal manure and veterinary medicines. Urbanisation: Sediments from construction sites, wastewater discharge, leaking septic systems, urban non-point sources. Mining: Sediments and mine’s waste.
Many national and regional monitoring programs exist for variety of pollutants. In India, coastal water quality is being measured for last 30 years along the selected transects. The data is available on www.incois.gov.in/portal.comaps/home.jsp. It has been observed increased nutrient inputs to coastal waters due to rise in coastal population and agriculture intensification and has led to reduced oxygen levels. The frequency of Harmful Algal Blooms (HAB), resulting in mass mortality and morbidity of marine organisms has increased significantly. The increase in frequency of heavy and extremely heavy rainfall have enhanced river runoff, polluting coastal waters with more nitrogen and phosphorus, sediments, and other contaminants. Increased direct monitoring of water quality parameters, coupled with satellite data, will improve our knowledge of condition of coastal and ocean waters.
The increase in population and economic development likely to impact water quality in future. An integrated model comprising climate change and impacts, land use policy and socio-economic conditions to address issues related water quality of wetlands.
Ecosystem Services of Wetlands
Global warming and sea level rise are likely to lead to changes in precipitation and humidity, increase in intensity and frequency of episodic events, and saltwater intrusion and will affect ecosystem services provided by wetlands. What are these services which are likely to be affected by climate change? The Millennium Ecosystem Assessment 44 approach can be used to identify wide range of ecosystem services at local, regional, and global scales. Such approach allows one to trace the benefit from wetland ecosystem to humans. These services can be classified as provisioning, regulating, cultural and supporting services. 45
The provisioning services are mainly related to food (fish, shellfish, and other edible biota), fodder for grazing animals and fuel (firewood, peat). Other important services are related biodiversity, and many species provide biochemicals and bioactive molecules to be used in medicine. Wetland regulates flow of water by storing water in floodplains, and lowlands, and recharging ground water. The sediment transport in rivers and along the coast develop flood plains and beaches, respectively, and control erosion. They also recycle nutrients and assimilate waste production and reduce the pollution. The wetlands and beach have aesthetic values and thus have a recreation value as well as support research and education. Many wetland areas are popular sites for angling. The primary and secondary production in wetland areas support fishery and other biota.
All these ecological services have economic value. However, the value of all these services have not accounted for. There have been some attempts to compute economic value of different type of wetlands. In one such study, the economic benefits from In the Koshi Tappu Wildlife Reserve, Nepal, the economic benefits computed are order of US $ 16 million per year out of which 85 % value is from provisioning services (food, timber, fodder, fisheries, thatch, and water). 46 Carbon sequestration, flood protection and ecotourism are other important economic benefits.
Mangroves provide many ecological services and thus very valuable not only to the ecology of the area but also economy of a country. The value of mangroves of Gujarat State (north-west coast of India) has been computed. 47 The value of provisioning services (fishery, fodder, fuel, timber, etc.) and supporting services (carbon sequestration, shoreline stabilisation) from mangroves has been estimated about US $ 3300 per ha per year. A study conducted in Pichavaram mangroves (SE coast of India) after the 2004 tsunami recognised the role of mangroves as a bio-shield as coastal villages behind the mangroves forest were least affected by tsunami, followed by its function as a nursery for fishery resources. 48
Coral reef ecosystem is very productive and provide valuable economic goods and services such as fisheries, tourism, biodiversity, etc. Its economic benefits are yet to be fully understood. In a one such study in Indonesia, it was estimated that the total economic benefit of coral reef is US $ 3 million per ha in 2014. 49 The destruction or degradation of coral reefs will lead to huge economic losses.
The economic value of wetlands, mangroves and coral reefs should be used as a reference to protect and conserve them for sustainable use. The program of declaring wetland areas as Protected Area (PA) is an ideal tool to protect ecosystems as well as to ensure recovery of degraded systems.
Approaches for Wetland Conservation
The Ramsar Convention on Wetlands of International importance, an international treaty, has been a prime vehicle for conservation and sustainable use of wetlands. During last 50 years, the convention has drawn attention of policy makers and able to advocate protection and wise use of wetlands. Over the years, almost 2500 sites world over are covered under this treaty. In India, 51 wetland sites have been identified as ‘Ramsar Sites.’ These sites cover lakes, coastal lagoons, reservoirs, river channels, mangroves, national parks and bird and wildlife sanctuaries. Thus, this convention has also helped to protect wildlife, birds, biodiversity and promoted ecotourism in these regions.
The wise ecosystem management is one of the important steps to manage risks of climate change. The conservation and restoration of wetlands, mangrove and other plantations on coast, watershed management, reducing fragmentation of habitats and sustaining biodiversity are vital tasks in this regard.
In India, watershed management programs are undergoing for last thirty years. Remote sensing and field-based inputs were utilised to prepare land use, geomorphology, and soil maps for each watershed. A detailed action plans and locale-specific and grass-root level solutions for managing land water resources have been developed. 50 In many areas, these actions have been implemented or being implemented. Such an integrated approach is likely to help to conserve aquatic ecosystems and reduce the impacts of extreme events of flooding and droughts.
The declaration of wetland areas as national parks, sanctuaries, biosphere reserves, etc. does help to protect them and act as natural barriers and can reduce the impacts of hazards. It was shown that degradation of mangroves and coral reefs can be reversed using appropriate conservation measures on the part of Gujarat coast (NW coast of India). 51 The declaration of this region in 1983 as the Marine National Park and initiation of suitable conservation measures allowed recovery of mangrove and coral reef ecosystems despite increased industrial activities. 52 The restoration of mangrove ecosystems not only provided protection from coastal erosion but also support increased productivity of fishery and thus livelihood to local communities. In addition, mangroves provided mitigation benefits through carbon sequestration. The restoration of fragmented or degraded ecosystems not only conserved biodiversity but also supported nutrient cycling. It has been recognised that healthy mangrove and coral reef ecosystems has capability to mitigate impacts of rising sea level to a large extent. 53
In India, Coastal Regulation Zone (CRZ) Notification, issued in 1992 and subsequently modified in 2011 and 2019 (The Gazette of India: Extraordinary, Part II, Sec 3 (i), dated Jan. 6, 2011, and Jan. 17, 2019) has paved a way for protecting coastal ecosystems and regulated the use of coastal zone for industrial, municipal, and recreational purposes. The areas between high and low tide lines (HTL, LTL) and 500 m from HTL have been identified as CRZ and prohibited or restricted industrial and construction activities. One of the objectives was to protect settlements from rising sea levels and associated hazards. The management plans for the entire Indian coast have been prepared by the National Centre for Sustainable Coastal Zone Management (under the Ministry of Environment & Forests and Climate Change, Govt. of India) based on ecologically sensitive areas, urban or agricultural areas and islands (www.ncscm.res.in). ESSO-National Centre for Coastal Research (NCCR), Chennai, have been providing information of areas under deposition and erosion for the entire country’s coastline (www.nccr.gov.in). These measures have conserved coastal habitats to large extent and ensured livelihood of fishers, provided resilience from coastal hazards, and promoted socio-economic development of communities. 54 The data based on biennial monitoring of mangroves using satellite data by the Forest Survey of India (FSI) have shown improved extent of mangroves during last 30 years.
Coastal vulnerability to cyclones, storms, sea level rise, tsunami, etc. is one of the important steps for the adaptation to climate change and is indicative of likely physical changes that may occur and ability of coastal ecosystems to respond to changed climatic conditions. It has been defined based geomorphological setting viz. on long-term shoreline changes, tidal range and wave height, coastal elevation and slope and projected sea level rise. 55 Vulnerability maps have been prepared for the entire Indian coast and hot spots have been identified (www.incois.gov.in).
The timely, accurate and reliable advisory services for cyclone, tsunami, flood, drought, etc. are important for alleviating misery of people. The cyclone advisory comprising information on track, location and time of landfall, intensity, storm surge provided for all north Indian Ocean countries helped to initiate timely action by national, state, and local governments and minimise loss of lives. 56 , 57 , 58 A state-of-art tsunami warning system set up in 2007 provides information about travel time and runup heights at 1800 coastal forecast points within 15 minutes to all stakeholders in India and the Indian Ocean Rim countries through web-based system. 59 , 60 , 61 , 62 The performance of the system during last fifteen years is exemplary and no false warning has been given.
Subbasin-wise quantitative precipitation forecasts for next five days by the ESSO-India Meteorological Department (IMD) (www.mausam.imd.gov.in) are used to issue flood warnings by the Central Water Commission (CWC), New Delhi. An integrated urban warning system indicating likely areas to be inundated, has been developed based on weather, tide and storm forecasts, and hydrological and flood modelling 63 and has been operational in Chennai and Mumbai. In India, droughts occur regularly, and many times cover large areas. The National Agricultural Drought Assessment and Monitoring System (NADAMS) provide monthly drought assessment at district/sub district level. 64 These services will help in mitigating impacts of climate change..
The Sustainable Development Goals (SDGs) set up by the United Nations General Assembly in 2015 and to be achieved by 2030 is a vital framework for sustainable future. The SDG 13, 14 and 15 related to Climate Action, Life below Water and Life on Land are relevant to conservation and protection of wetlands. The targets are related to protection of terrestrial and inland freshwater systems, marine and coastal ecosystems, and their ecological services; reducing marine pollution and ocean acidification; strengthening the resilience to climate related hazards; and development of appropriate policies are key factors for protecting wetlands and ecological services and thus safeguarding livelihood of people.
Monitoring of Wetlands
The most important aspect of managing ecosystems is monitor their extent, condition, and capacity to continue to provide various services. A regular monitoring of wetlands through remote sensing and field methods to assess its condition is a pre-requisite for conservation of wetlands. Remote sensing has greatly enhanced our knowledge on spatial pattern and extent of ecosystems, on their physical structure and attributes, and on rates of changes in the landscape. It is proposed that all wetlands should be monitored using the Indian satellite series, IRS, RESOURCESAT, CARTOSAT, RISAT and EOS, data for providing spatial extent, structure and condition of aquatic ecosystems, coastal wetlands, and coral reefs. The changes in plant characteristics such as leaf area and biomass, phytoplankton species, etc. needs to be recorded. The change in wetlands is essentially due to exchanges of mass and energy between hydrosphere, biosphere, geosphere, atmosphere, and cryosphere. 65 Satellite data provide major input to study these exchanges.
Monitoring of water quality of wetlands at appropriate frequency is another important input for assessment of its health and for conservation of wetlands. Water quality not only of surface flow but also groundwater should be assessed. Both satellite-based and in situ measurements of water quality are required. Following parameters are vital for the assessment of water quality. Turbidity: Suspended sediments, the Secchi disc depth (in m) Chlorophyll, Coloured Dissolved Organic Matter (CDOM) Temperature Dissolved inorganic substances Hydrogen ions (pH) Dissolved gases: Dissolved oxygen and CO2. Biological oxygen Demand (BOD) and Chemical Oxygen Demand (COD) Trophic Status based on mean annual chlorophyll (microgram/l), phosphorus (microgram per litre) and the Secchi disc depth (in m).
The measurement of water levels and its monitoring is a critical parameter to understand variation of water level. The proposed mission, the Surface Water Ocean Topography (SWOT), to be launched in 2022, by NASA, CNES, Canadian Space Agency and UK Space Agency, will measure water height of surface water bodies and seas with accuracy of few cm at every 100 m across the globe every 10 or 11 days (www.swot.jpl.nasa.gov). It is expected that these datasets will hugely improve our understanding about health of wetlands.
All these datasets should be organised around geographic information system to develop wetland biographical information system focusing on structure, function, and vulnerability. This will be an important step towards protecting wetlands from climate change impacts.
The Global Regulatory Framework
The Ramsar Convention on wetlands adopted in 1971, one of the first global environmental treaties to promote conservation and wise use of wetlands to achieve sustainable development. The national governments have prepared inventory of their wetlands and many sites of ecological importance were designated as ‘Ramsar Sites.’ Each year, February 2 is celebrated as ‘World Wetland Day’ to renew our commitments to wetlands towards their sustainable use and providing livelihood to local communities. During last 50 years, it has been observed that most Ramsar sites have either improved or maintained their ecological conditions compared to other wetlands. The partnership between the Ramsar Convention and Convention for Biodiversity and other multilateral environmental agreements have ensured the implementation of various decisions related to wetlands in a coordinated manner.
The successive Ramsar Conferences of Parties (COP) such as COP 8 (2002), 11 (2012), 12 (2015), and 13 (2018) have adopted resolutions related to potential implications of climate change for the conservation and wise use of wetlands. These resolutions have cumulatively emphasised on developing inventory, classification and monitoring of wetlands, so that their vulnerability to climate change can be assessed.
The climate change and its impacts are likely to affect wetlands apart from other threats such as habitat loss, water pollution, water flow modification and species invasion. At the same time, healthy wetland ecosystems such as mangroves and coral reefs likely to provide protection from storm surges while inland wetlands can provide resilience to floods and droughts. In view of these characteristics, it is of vital importance to have an appropriate governance mechanism having suitable policies and laws, participation of global, regional, national and local institutions along with local communities to address climate risks. The 1972 Stockholm Conference (UNCHE; 5-16 June) addressed the environmental issues and recognised role of the governments as well as non-governmental organisations. The establishment of United Nations Environment Program (UNEP) was the outcome of this Conference. The scientific knowledge became the basis for protection of environment through the global and national governance system along with active support of civil society. However, it has been realised now that environmental protection cannot be achieved without removing poverty, inequality and hunger from the world and focus has been shifted to sustainable development to ensure livelihood while protecting environment.
Stockholm+50 Conference (2-3 June 2022) will take place while the world is again at crossroads due to impacts of climate change and COVID 19 on world economy and looming security threats. The wetland ecosystem is an important aspect in ensuring livelihood of millions in the world and it may be necessary to develop an effective monitoring and governance system of wetlands. The role of industries is going to be crucial, especially following environmental rules and regulations. The capacity building of small nations is another aspect which needs to be addressed. The focus on sustainability of wetlands should one of the important areas should be debated and discussed in this Conference.
Conclusion
Historical data describing previous extent of wetlands against which we measure change are very limited, especially on lakes, mangroves, coral reef, etc. The effects of human disturbances on ecosystems have been poorly recorded. We need to carry out predictive mapping, using existing climatic, oceanographic, and topographic data combined with biogeographic information, where historical data is available.
There is a need for enhancing understanding about how wetland ecosystems are being affected by climate change and variability as well as anthropogenic changes and developing robust models. However, ability of such models to project climate variability and change, especially extreme events at local levels is rather limited. The current climate models have large uncertainty and will need tremendous improvements to provide valuable insight and useful predictions for future. Despite these limitations of climate change and impact models, effective climate services to combat and minimize the impact of climate changes need to be introduced. Some of possible services can be related to Fishery resources: Poleward shift of marine fisheries due to changes in temperature. The warming of seas, rivers and lakes threaten fish stock, especially to pressure from overfishing, pollution, and habitat loss. Seasonal forecast of fish stock to be provided for regulated fishing. Water management: Changes in water cycle, especially monsoon, can increase or decrease, freshwater availability. The current monsoon forecast model has a skill of 0.71.
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Continuous investments in terms of finance and human resources improvement in forecast models are required. Improved forecasts will have impact on prediction of occurrences of drought, floods, etc. Droughts: There is a need to integrate hydrological and socio-economic data to assess impact on communities. Sea-level Rise: The projections of sea level rise along with tides and storm surges are required at local levels and for small islands to plan effective mitigation measures.
This would possibly call for setting up of a special program for assessment and monitoring as well as suggesting policy, legal and institutional measures to address the global climatic risks to the wetlands ecosystems. It would be advisable to have an international impact assessment panel on wetlands. As a corollary, it would be advisable to constitute specialized national regulatory authorities on wetlands for their conservation, protection and wise use.
It seems, the sustainable management of wetland depends not only on scientific knowledge but also on nature of social and human systems. The social system comprising governance structure, industrial capability, infrastructure development and its linkages with wetland conservation. The economic development and technological advancement during last two centuries have affected the environment including wetlands. The earth system processes of carbon cycle, sea level changes, ocean acidification and agriculture-induced pollution of nitrogen and phosphorous have capability of damaging entire earth system including wetlands 67 and we have been witnessing these changes at many places. The consciousness of human system to these changes as well as its capability to adapt to these changes and introducing mitigation measures is a key to healthy wetlands and sustainable future. We need to strive for managing wetlands for our better equitable future at the Stockholm+50 Conference (2022) and beyond.
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