Purposeful, anthropogenic carbon sequestration is a fairly recent endeavor to mitigate carbon releases from industrial processes. The theory is that, by actively removing carbon dioxide from the atmosphere, the effects of manmade climate change can be reduced.

This is not only seen as a necessity for general global health, but also as a lucrative business opportunity. Many companies purchase carbon credits to account for the release of carbon from their particular manufacturing processes.

This offset has been accomplished and credits created by planting new forests, forest preservation, injection of carbon dioxide into geologic formations, and conservation-minded agricultural practices, etc.  One of the newer ideas for how to handle the “carbon crisis” is Blue Carbon, which we will discuss more thoroughly in just a moment.

But, before we start discussing how to handle today’s atmospheric carbon, we ought to start with where it came from in the first place. Most of the fossil fuels we use today were deposited during the Carboniferous Period of the Paleozoic Era (359 to 299 million years ago), and the coal beds and oil fields we know of today were formed by the plants alive during this period.

In the Carboniferous Period, the climate was mild (temperatures a lot like what we know today) and the Earth was covered by inland seas and swamps. Over 35 percent of the continents were covered by in-land seas – so everything west of the Rockies would be under water! The atmospheric carbon dioxide in the early Carboniferous was between 2,000 and 4,000 parts per million (ppm), compared to our 300 to 400 ppm today. Abundant water and carbon dioxide led to an explosion of plant life. Not only were the inland seas full of algae in a kind of primordial pea soup, but on land ferns were the size of oak trees or tall buildings.

Carbon sequestration in flooded areas is the result of anaerobic conditions present underwater and in saturated soils, which slows the decaying process and allows for the accumulation of organic matter. The breakdown of carbon by microorganisms in the absence of oxygen occurs almost 18 times slower than when oxygen is present. Because the critters eating the plants can’t keep up, the continued inflow of dead plants and sediment buries the layers beneath. Over time, this results in the permanent removal of the material. Over geologic time, these organic deposits became the sedimentary rock with the coal and oil deposits we consume today.

But you probably learned most of this in school, right? What has this got to do with Blue Carbon?

One of the best, natural, long-term carbon sequestration areas (i.e. sinks) are wetlands and open water. Some examples include your good old-fashioned swamps, bayous, mangrove forests, salt marshes, and seagrass beds. The restoration of these areas for carbon sequestration (carbon credits for purchase as offsets) is Blue Carbon.

Think about it.  If nature has already proven these ecosystems as highly effective carbon sinks (see the Carboniferous Period), it seems logical to focus our current carbon sequestration efforts there, too.

Although smaller in size, wetlands absorb carbon at much faster rates than adjacent forests by the mechanisms explained above. Not only is carbon stored, but the wetlands are still acting as biogeochemical filters. Many other pollutants can also be trapped and stored, which reduces pollution entering streams, lakes, and oceans.

We are all aware of the need for coastal and wetland habitat conservation and restoration. Wetlands offer critical habitat for wildlife and plants that evolved to call these areas home. These ecosystems reduce inland flooding and erosion by acting as a buffer during storm surges from hurricanes; support commercial fishing by providing nurseries for young fish; and provide ecotourism attractions.

Carbon sequestration is yet another example of the critical role our wetlands and coastal areas play in overall ecosystem health. The implementation of a Blue Carbon scenario would include the same wetland mitigation related improvements, but because they are offsetting a mutually exclusive impact, wetland surface area would increase at a possibly exponential rate.

The potential benefit of Blue Carbon to the Gulf Coast could be crucial to the continued existence of the vast fresh, brackish, and saline marshes and swamps found there. Rates of wetland loss in southern Louisiana are estimated at 1 acre every hour!

The purchase of Blue Carbon credits could provide the additional economic drive needed for saving and restoring these invaluable wetland resources that provide so much more than we often realize. By burning fossil fuels, we are taking carbon captured from the air in the Carboniferous Period and re-releasing it back into the atmosphere. If we decide we need to catch, capture, and hold it again, perhaps instead of reinventing the wheel, we should look to the mechanisms that caught it in the first place.

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Austin Russell
Austin serves as an Environmental Specialist for RS&H’s Transportation-Infrastructure Practice.
Austin Russell

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