The "Bad Guy" in the Everglades

If you were to name some good things about wetlands, what would you say? Maybe you would mention their role in climate change mitigation -- that they serve as a buffer for sea level rise, and that they have a strong carbon sequestration ability. Or you might talk about their role as habitats for millions of organisms. However, if you needed to name some “bad things” about wetlands… What would you say? Today, let’s get to know the “bad guy” in the Everglades – methane.

Methane (CH4) is a greenhouse gas that is more potent than the better-known gas carbon dioxide (CO2), since it has 25-36 times the global warming potential of CO2. In addition, the atmospheric methane concentration has increased 2.6 times from the preindustrial period. Methane is produced in soil with no oxygen conditions, therefore, since wetlands are commonly inundated with water, they are a perfect ecosystem to produce methane since water prevents oxygen from going to the soil. Methane is released into the atmosphere through diffusion, ebullition (bubbles), and plants. Getting to know the pattern of methane release, and what factors would impact future methane emissions, will help us better understand the global methane budget. The Everglades, the largest subtropical wetland in the United States, is a perfect place to research methane fluxes.

On June 27th, 2021, we visited two sites in the Everglades– saltwater marsh site SE-1 and freshwater marsh site TS/Ph-1. Although June is during the wet season, it was very sunny, and SE-1 had dried out, with no obvious water on top of the soil. The site had some low mangroves, and the marshes were mostly dead. After padding through muddy soil, we reached our Eddy Covariance tower and collected our flux data, including CO2, methane, water, and meteorological variables such as temperature, rain, water level, etc. The Eddy Covariance technique allows us to see air movement and to check the direction and concentration of gasses like methane. Thus, we can figure out the exchange rate of gas between the atmosphere and the ecosystem. After spending around an hour at SE-1, we drove to TS/Ph1. The soil type in TS/Ph1 is a thin layer of marl which is much more slippery. Due to the low water level, most of the marshes were exposed. We also collected data and said hi to the wasp family that lived inside one of our instrument boxes!

As a student from a university outside of Florida, this has only been my second time visiting the Everglades since 2019. However, visiting the sites is always fun, and by observing the sites, I could truly understand how dynamic the Everglades is. Researching the “bad” side of the Everglades showed me that we must also consider the potential negative impacts of wetlands. Wetlands can help mitigate climate change, but they are also a big source of methane. Therefore, we cannot expect nature to fix climate change for us. We must take responsibility for reducing our greenhouse gas emissions ourselves instead of relying on nature.