Marshes occupy a mere 0.1% of the global terrestrial carbon budget. This tiny fraction of the Earth's surface holds the capacity to absorb high tides and mitigate the impacts of extreme weather. They function as disproportionately powerful engines for climate resilience and biological production.
Plants such as cattails, sedges, papyrus, and sawgrass possess aerenchyma, specialized channels within their stems that transport air from the leaves down to the rooting zone. These organisms also develop rhizomes for underground storage and reproduction to ensure persistence through fluctuating water levels. This biological engineering feat allows them to breathe in conditions that would suffocate most other vegetation.
Salt marshes dominate the mid to high latitudes of the globe and flourish in protected coastlines where the motion of the tides sporadically covers the land. These ecosystems are most commonly found in lagoons, estuaries, and on the sheltered side of shingle or sandspits. They form where currents carry fine particles to quiet areas to build up sediment.
Freshwater marshes represent the most diverse and common form of wetland in North America, ranging from wet meadows to vernal pools and playa lakes. Vernal pools are unique because they are covered in shallow water during the wetter months but can be completely dry by summer and fall. These temporary ponds provide a critical habitat free from fish, which would otherwise eat the eggs and young of amphibians like the endangered gopher frog.
Human attempts to conquer the water have resulted in the loss of 90% of wetlands in some areas to create agricultural land or accommodate urban sprawl. In Northern Germany, Scandinavia, and the Netherlands, large tracts of tidal marsh have been embanked and artificially drained to create polders. This transformation has led to a significant decline in the biological productivity that once characterized these regions.
As sea levels rise and erosion accelerates, most natural marshlands face an existential threat that could see them migrate upland or disappear entirely. The biological productivity that makes marshes so valuable is now under siege from the dual pressures of climate change and human development. The rate of sea level rise may outpace their ability to adapt, leading to the loss of these critical habitats.