In Which Daisy Uses Her Ancient Blog to Lifehack University Technology

Wet, Muddy and Saving the World

An Ode to a Natural Superhero

By Daisy Frabell

For Dr. Jay Kaufman

GEOL489r: Geoscience Communications

Messy and Magnificent: the value of the salt marsh is all about mud.

The edge of the sea has long fascinated humanity, as rocky cliffs inspired lyric poems and alluring beaches fed the fire of transportation technology. The salt marsh, however, with its knee-deep sludge and scent of rotten eggs, is hardly a popular favorite. Boggy wetlands are just not as valuable to us as warm sand and breathtaking overlooks.

But they should be.

Yes, salt marshes and other coastal wetlands (like tropical mangroves and shallow sea grasses) are home to rare, beautiful birds; they shield the young fish that will one day feed our economy and our appetites. But, even more incredible are the endless grasses themselves. Coastal wetlands lead global environments in shear amount of living material, or biomass. Rain forests may claim a long list of exotic species, but the living mats of roots and residents underlying a tidal wetland are vastly more full of life.

And here on Earth, life means carbon.

Carbon is the fourth most common element making up our planet, and it is the essential ingredient in all living things. Unique properties of the bonds formed by carbon atoms make it the conductor of the energy that makes our cells work. In fact, carbon is both the frame and the fuel of all plants and animals, and it cycles through air, food chains and organic decay in loops usually measured in decades. This, geologically, is the fast carbon cycle.

The slow carbon cycle is the realm of rocks, and is measured in millions, or hundreds of millions, of years. Common rocks like limestone, thick blankets of innumerable tiny marine shells hardened by time, contain two-thirds of Earth’s buried carbon. Limestone will be familiar to some readers, but it would be difficult to avoid the other major player. When organic, once-living material is layered with mud in a shallow sea or lake and turned to stone, the resulting products take on a familiar name: fossil fuel.

An organic-rich wetland buried deep underground will become a future fossil fuel.

Most fuel that powers modern industry is simply made of very old biomass, heated and compressed underground. Coal is born of ancient algal blooms in stagnant water, while petroleum and natural gas are formed by ancient swamp plants that grew and died more quickly than they could rot. When this dead stuff is drowned in still water, the microbes that would usually decompose it into soil and release its carbon do not have enough oxygen to work, replaced by slow-working specialist bacteria that smell of sulfur. This condition is called hypoxia, literally ‘low oxygen,’ and is the source for both the marsh’s stink and it’s superpower. In a hypoxic environment, carbon is transferred from the fast cycle into the relative dormancy of the slow cycle. This physical burial is called sequestration, because it separates the element from the atmosphere and ocean for many millions of years.

Carbon gathered into wetlands by the 'photosynthesis' and 'plant biomass'
arrows, the fuel and frame of plants, cannot be fully decomposed in 
low oxygen conditions, and does not quickly return to the air.
 It is instead sequestered long-term into fossil fuels.

Booming human societies have thrown a wrench into this balanced molecular dance. We dig up and burn any sequestered carbon found, returning a hundred million years of carbon into the air as carbon dioxide gas in the blink of a geologic eye. Fossil fuels hold 20-30% of the Earth’s buried carbon, so this is a massive change. As carbon dioxide is a greenhouse gas, one that acts as a energy-trapping blanket around the atmosphere, heat mounts as Earth soaks up solar energy but can’t shed it. So, unless the carbon cycle becomes re-balanced, we will continue to experience runaway global climate change, eventually destabilizing every natural system on the planet.

And so, a talent for carbon sequestration becomes a superpower, and smelly marshes could save the world.

Narrow strips of coastal wetland are a tiny part of the planet’s surface: only around 2% by area. And yet, they have always accomplished one third of the downward sweep of the slow carbon cycle. In the historic past, people have filled, drained and built over marshes, an artifact of the unpopularity of damp, odoriferous muck. Only now, when rising ocean water threatens to drown these lowlands, can we finally see that the seashore least inspiring to us may be the most valuable ecosystem of them all. 

There are many necessary adjustments to be made in economy, industry and habitual consumption: perhaps savoring our swamps is a pleasant point to start this perception shift. Society can place the cultural, economic and scientific worth on wetlands that they deserve. If we can protect and restore wetlands to maximize their carbon sequestration potential, we will gain a powerful advantage in bringing our runaway climate back on track.

And if a salt marsh has the power to balance the human species, maybe it deserves some poetry after all.

Read more:
Hopkinson, C. S., W.-J. Cai, et al. (2012). "Carbon sequestration in wetland dominated coastal systems - a global sink of rapidly diminishing magnitude."

Mcleod, E., G. L. Chmura, et al. (2011). "A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2."

Mitsch, W. J., B. Bernal, et al. (2013). "Wetlands, carbon, and climate change."