Nature
Wetlands, Peatlands and Freshwater Ecosystems
The capacity of natural systems to store and sequester carbon are all heavily influenced by water. Maintaining and restoring wetlands and peatlands is the single most effective use of water to lower emissions.
The Challenge
The capacity of natural systems to store and sequester carbon are all heavily influenced by water. Water is a critical factor in forest-based mitigation, impacting the effectiveness of sequestration and also can be impacted by demand for water for plant growth. Wetlands — and especially peatlands — store two to three times the amount of carbon than forests by area, while they are being depleted even faster. They can also emit significant greenhouse gases when dried and damaged; degraded peatlands alone account for 5% of total anthropogenic global greenhouse gas emissions. Moreover, wetland and peatland systems’ critical functions, including storage of carbon, can be vulnerable to climate shifts in wet and dry periods. Measures to ensure they maintain and maximize these functions require higher priority in policy, planning, and investment.
Recent studies on GHG emissions from inland waters (rivers, lakes, reservoirs, ponds) are revealing emission rates higher than previously estimated and that these are impacted by human activities. The key accelerators of methane emissions are impoundments, pollution, as well as sediment, organic carbon and nutrient loads from agriculture. One challenge is that freshwater systems are scattered across different sectors and programs in climate plans. For example, countries that do include targets on wetlands in their Nationally Determined Contributions (NDCs) often have not set targets for emission reduction or sequestration through wetland restoration and management.
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• Emissions from drained peatlands are estimated at 1.9 gigatonnes of CO2e annually. This is equivalent to 5% of global anthropogenic greenhouse gas emissions, solutions require halting agricultural conversion and drainage and restoring the waterlogged conditions required for peat formation (IUCN 2021).
• We have lost 35% of the world’s wetlands in the last five decades – since 1970 – and we continue to lose them at a rate faster than we’re losing forests.
Solutions
The IPCC outlines conservation of high-carbon ecosystems such as wetlands, including peatlands and mangroves, as mitigation response options with high impacts.
At COP28, 45 countries officially agreed to the Freshwater Challenge which aims to ensure 300,000 km of degraded rivers — equivalent to more than seven times around the Earth — and 350 million hectares of degraded wetlands — an area larger than India — are committed to restoration by 2030, as well as conserve intact ecosystems. To reach these targets, the drivers of wetland loss such as conversion for agriculture, urbanization, aquaculture, or coastal development must also be addressed. Countries will need to include wetland management targets in their NDC portfolio and develop a Measurement, Reporting, and Verification (MRV) methodology for their emissions and carbon stock changes.
To address emissions from inland waters, measures that can be taken include: nutrient and organic matter control for eutrophication management; improved management of older dams and dam removal processes; adoption of technologies for methane capture or reduction via installing aerating devices in the water; and smarter conception and planning of new hydropower dams to avoid reservoir based emissions (both before and after impoundment). There are further a range of technologies that can reduce and capture the release of methane from freshwater bodies.