Can kelp forests save us?

Is ocean afforestation the most important and overlooked solution to global warming?

By turning the open seas into vast ocean forests and farms we could cool our planet, feed the world’s growing population and provide carbon neutral and negative energy for all. How? Thanks to floating kelp and algae forests.

The oceans have already absorbed 90% of heat and 50% of carbon dioxide from the atmosphere, which causes acidification and collapse of the up-swell of cold and nutrient rich water from the ocean depths.

But what if the up-swell of nutrient-rich water could be re-established and used to irrigate vast floating kelp forests? These kelp forests would absorb so much carbon dioxide that acidification and global warming could be reversed.

This is what Brian Von Herzen, Ph.D proposes to do with thousands of Marine Permaculture floating kelp forests. Marine Permaculture is one of Project Drawdown’s coming attractions.

“The key technology involves marine permaculture arrays (MPAs), lightweight latticed structures roughly half a square mile in size, submerged 80 feet (27 meter) below sea level, to which kelp can attach. Attached buoys rise and fall with the waves, powering pumps that bring up colder, nutrient-rich waters from far below. Kelp soak up the nutrients and grow, establishing a trophic pyramid rich in plant and animal life.Plants that are not consumed die off and drop into the deep sea, sequestering carbon for centuries in the form of dissolved carbon and carbonates. Floating kelp forests could sequester billions of tons of carbon dioxide, while providing food, feed, fertilizer, fiber, and biofuels to the world.” Source: Drawdown, edited by Paul Hawken (2017)

How does ocean afforestation fit with other global warming solutions?

In its simplest form global warming is an “area under the curve” problem, whereby positive and negative emissions must add up to a budget. A carbon budget in turn corresponds to a level of atmospheric concentration of greenhouse gases to stay within 1.5°C global warming (for which there are the following 5 science-based plans to do so):

Whether it is 1) Project Drawdown modelled 80 solutions 2) The One Earth Climate Model 100% renewables, protect land and oceans 3) The Exponential Climate Action Roadmap grow climate solutions exponentially 4) The Solutions Project 100% renewable energy or 5) IPCC 1.5°C report the shape of projections in emissions is similar (See The One Earth Climate Model graph below).

Fossil fuels’ and cement use drop dramatically and sharply (replaced by exponential growth in renewable energy & electrification and cement alternatives) AND human’s use of land goes from being a positive emissions’ contributor to a significant negative contributor.

Ocean human carbon sinks do not feature prominently as a carbon sink in the models (Project Drawdown has just 1 ocean solution in its modeled 80 solutions and a further 3 in its “coming attractions”). Yet oceans do not have the disadvantages of land-based solutions (under direct pressure from human encroachment and global warming on a smaller -less than a third- of earth’s surface area).

Ocean Afforestation through preserving and extending  Coastal wetlands (e.g. mangrove swamps, seagrass), marine permaculture (e.g kelp ) that sequester carbon (up to 5 x rain forests), regenerative  ocean farming of shellfish, algae and seaweed (as opposed to industrial mono-cultural fish farming) that provide carbon neutral food, bio-fuels and algae that reduce cow methane emissions (  a cow walks on a beach ) can contribute to massively reducing. avoiding and sequestering emissions.  These ocean-based natural climate solutions:

• increase the value of oceans in terms of the positive externalities they provide (e.g. pollution control, food, fuels and jobs)
• do not suffer from the problems land-based solutions suffer such as rain forests that are being deforested (driven by livestock, livestock agriculture, palm oil, human settlement etc.)
• could be invested in & developed by countries to grow their economies and increase Paris plans to reduce emissions

How big is ocean afforestation’s potential?

Negative Carbon Via Ocean Afforestation, a landmark 2012 study, shows the vast potential of Ocean Afforestation -of which Marine Permaculture would play an important part- to produce 12 Gt /year of biomethane (that would replace fossil fuels responsible for 40 Gt CO2/year) by 2035 while storing 19 Gt CO2/year directly from bio-gas production, plus 17 Gt CO2/year from carbon capture of the biomethane combustion exhaust (total 76 Gt CO2/year). These rates are based on macro-algae forests covering 9% of the world’s ocean surface in 2050, which could produce sufficient biomethane to replace all of today’s needs in fossil fuel energy, while removing 53 Gt CO2/year from the atmosphere, restoring pre-industrial levels. This amount of biomass could also increase sustainable fish production to potentially provide 200 kg/yr/person for 10 billion people. Additional benefits are reduction in ocean acidification and increased ocean primary productivity and biodiversity.

A 2016 World Bank study uses the 3 million tons of algae produced in 2012 as its starting point and asks what would happen if production grew by 14%/year until 2050 to reach 500 million tons. These “bottom up” results are “of course” more modest and most interesting in terms of nitrogen & phosphorus removal, land sparing and freshwater sparing (as most algae is used for animal feed). In terms of carbon dioxide equivalents 495 million tons or about 1% of current emissions would be sequestered. The key positive externalities are summarized in the table from the world bank study.

Conclusions

If Ocean Afforestation were a Drawdown solution it would rank about number 36 delivering about 7.5 Gt CO2e reductions -using data from the World Bank study on Algae farming- and a “silver bullet” solution delivering well over 1,000 Gt CO2e reductions if fully exploited as per the Negative Carbon Via Ocean Afforestation. The marine permaculture (kelp forest) solution alone would provide hundreds of Gigatons of carbon storage as well as significant economic, social, environmental and financial co-benefits. Marine permaculture is an exponential growth business opportunity that should be invested in massively and scaled up rapidly to help cool our planet, feed the world’s growing population and provide carbon neutral and negative energy for all.