How Wetlands Keep Our Climate in Check

Irleen Kaur

When we think about powerful climate solutions, we often visualize clean technology or other engineered systems. Yet, we often overlook leveraging natural landscapes in helping regulate our planet’s climate. Wetlands, for example, play an important role in balancing the atmosphere's carbon levels and water purification. Understanding and protecting this ecosystem is a critical strategy in our response to climate change.

What is a Wetland?

Wetlands are areas where water covers the soil either completely, or almost completely. They rank among the most productive ecosystem types, supporting a remarkable level of biodiversity. The categorization of wetlands can vary based on hydrology (frequency of water presence & depth of water), hydrophytic plants, and soil characteristics (dependent on how frequently the soil is waterlogged), but there are two categories generally recognized by the EPA, coastal/tidal wetlands and inland/non-tidal wetlands.

Coastal/tidal wetlands are closely linked to estuaries, where sea water mixes with fresh water. Inland/non-tidal wetlands are commonly found on floodplains along rivers and streams, in isolated depressions surrounded by dry land, or in other low-lying areas where the groundwater intercepts the soil surface. Other wetland specifications include marshes, wet meadows, wet prairies, swamps, bogs, fens & seeps, vernal pools, and prairie potholes.

Wetlands also provide a multitude of ecosystem services to the environment and humans. They are not limited to, but include:

• Provisioning: food production (fish, wildlife, fruits), domestic water retention, agricultural & industrial use, log production, wood, fodder, peat

  
  

• Regulating: regulation of climate, regulation of water hydrology (recharge of groundwater), wastewater treatment, water purification/pollutant removal, regulation of erosion, flood/storm protection

  
  

• Cultural: aesthetics, tourism, spiritual source for various cultures

  
  

• Supporting: soil formation, cycling of nutrients

Wetlands cover about 5-8% of the world’s land surface, yet comprise 20-30% of the world’s carbon pool, illustrating the large carbon density present in wetlands.

Examples of wetlands in Massachusetts include the Great Marsh, which runs from Cape Ann in Massachusetts to the southeastern coast of New Hampshire, as well as the Back Bay Fens in Boston. The Fens are an example of an urban inland wetland, where peat, decayed plant material, develops and distinct habitats form.

How do Wetlands Contribute to Environmental Stability?

Wetlands actively sequester carbon as plant biomass or organic matter in soil via photosynthesis. The consistent waterlogged condition of wetlands and anoxic soil causes lowered rates of decomposition for organic matter. This matter accumulates instead of breaking down, locking carbon away for hundreds of years. This process makes wetlands one of nature's most powerful carbon sinks. In fact, according to the U.S. Global Change Research Program, wetlands in the United States store around 13.5 billion metric tons of carbon. They regulate concentrations of methane, carbon dioxide, and nitrous oxide as well, which are the most dominant greenhouse gases contributing to climate change. 

Wetlands also improve the quality of water that flows through the wetland. This is done through three pollutant removal processes, sediment trapping, nutrient removal, and chemical detoxification.

By reducing the velocity of water entering wetlands, roots of wetland plants trap sediments present in water. The suspended material settles to the wetland surface, and the root binds the accumulated sediment. Up to 90% of sediments can be removed from runoff or streamflow.

In addition, wetlands naturally recycle nutrients, so excess nitrogen or phosphorus from fertilizers accumulate in less harmful forms in wetlands. In a similar form, toxic chemicals can be trapped along with the settled soil particles or converted into less dangerous forms.

Current Protections

All wetlands were previously protected under the Clean Water Act. However, after the 2023 Supreme Court ruling in Sackett v. Environmental Protection Agency, the scope of protections for wetlands significantly narrowed down. Nonetheless, there are other federal protections for wetlands. The North American Wetlands Conservation Act, for one, provides grants for partnerships to conserve wetlands for wildlife. 

On a state level, the Executive Massachusetts Wetlands Protection Act “prohibits any filling, excavation or alteration of the land surface, water levels or vegetation in wetlands, floodplains, riverfront areas or other wetland resource areas, regardless of ownership, without a permit from the local Conservation Commission” (What Is the Wetlands Protection Act? | Town of Rehoboth MA, 2023). Passed in 1972, this act has continued to help preserve Massachusetts wetlands. Other states have similar protections for wetlands.

Current Threats & Future Steps

Climate change is the greatest threat to wetlands. Rising temperatures, changes in rainfall, and increase in extreme climatic events can change the biogeochemistry and function of a wetland to the point where certain ecosystem services may no longer be available. 

Warmer conditions increase microbial activity, allowing for a much more rapid breakdown of organic matter. This breakdown of organic matter releases carbon dioxide into the atmosphere. Nitrous oxide emissions also increase with warmer temperatures.

In addition, increased frequency in droughts can dry out waterlogged soil. This allows more oxygen to be present in the soil, once again, increasing the decomposition of organic matter. 

These phenomena change the function of a wetland from a carbon sink to a carbon source. This creates a positive feedback loop, in which more carbon release causes temperatures to rise more.

Wetland mesocosm experiments are conducted to better understand the changing dynamics of wetlands in response to climate change. Additional funding and time utilizing these experiments will help create effective conservation strategies.

Fortunately, wetlands are additionally supported by multiple non-profits and federal partners. Looking into current projects these organizations are working on and donating could contribute to the further protection of wetlands. General efforts include restoring drained wetlands and creating constructed or artificial wetlands.

Organizations in New England that support the conservation of wetlands include the Society of Wetland Scientists, the Association of Massachusetts Wetland Scientists, the Land Trust Alliance, New England Biological Assessment of Wetlands Workgroup, New England Interstate Water Pollution Control Commission, and Charles River Watershed Association. Federal partners include the USFWS, EPA, and U.S. Army Corps of Engineers New England District.

Conclusion

The relationship between wetlands and the climate is profound and complex. Wetlands store large amounts of carbon whilst providing habitats for a variety of organisms and water quality control. Climate change threatens to destroy these services, making the conservation of wetlands essential. Moving forward requires coordinated action across governments, organizations, and communities.

Seaside Sustainability aims to protect our wetlands. To see what we’re up to, visit our action tab on our website.

Citations

Department of Environmental Conservation. (2020). Wetland Functions and Values: Surface and Ground Water Protection | Department of Environmental Conservation. Vermont.gov; State of Vermont. https://dec.vermont.gov/watershed/wetlands/functions/water-quality

Protecting Wetlands in Massachusetts | Mass.gov. (n.d.). Www.mass.gov. https://www.mass.gov/info-details/protecting-wetlands-in-massachusetts

Reynolds, P. (2024, May 28). What are Wetlands? Why Should We Care? Conservation Law Foundation. https://www.clf.org/blog/what-are-wetlands-why-should-we-care/

Salimi, S., Almuktar, S. A. A. A. N., & Scholz, M. (2021). Impact of climate change on wetland ecosystems: A critical review of experimental wetlands. Journal of Environmental Management, 286(286), 112160. https://doi.org/10.1016/j.jenvman.2021.112160

The Wetlands Initiative. (n.d.). What Is A Wetland? The Wetlands Initiative. https://www.wetlands-initiative.org/what-is-a-wetland

US EPA. (2019, June 4). How Do Wetlands Function and Why Are They Valuable? | US EPA. US EPA. https://www.epa.gov/wetlands/how-do-wetlands-function-and-why-are-they-valuable

What is the Wetlands Protection Act? | Town of Rehoboth MA. (2023). Rehobothma.gov. https://www.rehobothma.gov/conservation-commission/faq/what-wetlands-protection-act