Marine Permaculture Arrays
The source of half the Earth’s atmospheric oxygen…
Around half the organic matter in the oceans is comprised of kelp and phytoplankton. Through photosynthesis they produce at least half of the atmosphere’s oxygen, in the process sequestering gigatons of carbon deep into the ocean.
…depends on natural ocean upwellings
What makes oceans productive are upwellings of cold, nutrient-rich water from deep in the sea. Upwellings occur around the world such as in the Grand Banks of Newfoundland—the richest fishing ground in the world—where the icy Labrador Current meets the warm Gulf Stream. This phenomenon is known as overturning circulation.
Overturning circulation under threat
We often think of the ocean as a single fluid entity, but over 90 percent of the heat caused by global warming is absorbed by surface waters. As surface water temperature increases, overturning circulation is thwarted, and upwelling of nutrients decreases or stops altogether. Phytoplankton and seaweed production drops, leading to a decline in the aquatic food chain.
Surface acidification
Most of the carbon emitted by human activity is contained within the top five hundred feet of the oceans, causing surface acidification. Reversing this trend is mostly an issue of moving carbon from the near-surface photic zone into the middle and deep ocean. Oceans naturally send carbon from surface water into the depths, a process known as the biological pump.
ocean BIOMASS Declining
Unfortunately, today’s loss of overturning circulation and increased acidification is steadily erasing the marine food chain. Ninety-nine percent of the subtropical and tropical oceans are now largely devoid of marine life. Satellite imagery is detecting a 4 to 8 percent annual decline in biological activity in the Atlantic, a number that exceeds predictions from global warming models. The oceans’ plankton and kelp are estimated to be declining 1 percent annually.
A powerful solution – marine permaculture arrays
Marine permaculture arrays (MPAs) are lightweight latticed structures made of interconnected tubing, to which kelp can attach. They can be tethered near land, or guide themselves autonomously on the open sea. Since they are submerged 25 meters below sea level even the largest cargo ships and oil tankers can pass right over them with no damage, save some shredded kelp. A 0.4 square mile unit would recreate an entire marine ecosystem, akin to reforesting a desert.
How MPAs work…
Marine permaculture recreates the biological pump, enabling oceans to do the job they always have. Buoys attached to the MPAs rise and fall with the waves, powering very simple pumps that bring up colder waters from hundreds or even thousands of feet below sea level. As the nutrient-laden waters come to the sunlit surface, phytoplankton and kelp soak up the nutrients and grow.
…to support thriving ecosystems that sequester CO2.
With phytoplankton come algae, more kelp, and sea grass. These feed populations of herbivorous forage fish, filter feeders, crustaceans, and sea urchins. Carnivorous fish feast on the smaller herbivores, and seals and sea lions and sea otters feed on them. On top of this are seabirds, sharks… and fisher folk. The phytoplankton and kelp that is not consumed dies off and the majority drops into the deep sea, sequestering carbon for centuries in the form of dissolved carbon and carbonates.
This short film describes how marine permaculture arrays could artificially restore overturning circulation:
Bumper HarvestS of fish, FERTILISER and BIO-FUELS
MPAs could host the ultimate fish farms (free-range aquaculture), except the fish would be diverse, wild, untainted, and rich in omega-3 fatty acids.
Kelp harvests would produce abundant fish-feed, fertiliser (including nitrate, phosphate, and potash), and bio-fuels. Each dry ton of kelp sequesters around ton of carbon dioxide.
Coastal protection
MPAs in larger groups could seasonally protect coastlines from the worst effects of hurricanes by lowering the surface water temperature, and the latent heat energy upon which hurricanes depend. Given that Hurricane Katrina alone cost $105.7 billion, and 2015 saw twenty-two Category 5 hurricanes, this may be a cost-effective solution. In addition, coral reefs could be seasonally protected from thermally induced bleaching.
ScalEable Costs and benefits
The material costs are currently estimated at $5 million per square km. With a million MPAs active for thirty years, the carbon dioxide drawdown could be over 100 gigatons. The economic return is estimated to exceed $10 trillion. Restored fisheries could supply the protein needs of most of Earth’s 7.5+ billion people.
Conclusion
Today’s demise of living ecosystems needs to be reversed. But perhaps with the implementation of MPAs, human beings can be agents of restoration and increased productivity of fish and kelp forests. Overturning circulation can be restored by deploying marine permaculture arrays, increasing aquatic wildlife, diversity and marine fertility. In addition, bio-fuels and fertiliser can be harvested, and fishing economies and jobs boosted. Most importantly, done at scale MPAs could sequester a large fraction of today’s human caused CO2 emissions permanently into the deep ocean.
More here: Climate Foundation
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