Climate change is upon us

It can be seen in melting Antarctic and mountain glaciers, multi-year long droughts in the North American West that spawn year after year of devastating wildfires, floods in Germany where this spring a year’s worth of rain fell in a few days and record heat seen across most of the northern hemisphere.

Reducing greenhouse gas emissions is clearly the first priority

If we are to have any hope of meeting the 2015 Paris Climate Accord’s goal of keeping average global temperatures from rising more than 1.5 degrees centigrade above pre-industrial level (1.1 degrees so far), we must, first and foremost, reduce greenhouse gas emissions. This will require a transition away from the fossil fuel economy at the heart of the global warming crisis via the development of alternative technologies. As discussed in the thesis article with which I started this blog, this means moving away from the linear first industrial revolution economic system characterized by extraction, production, consumption and waste to a circular system that more closely imitates nature and places value on the natural capital which is the basis of all life on earth. Several of my blog articles have already explored different angles of this initiative, from controlling methane emissions to changing how we make steel to adopting regenerative agriculture techniques. Please have a look at them.

But reducing global greenhouse gas emissions will take time and, even if successful, will not be enough, on its own, to meet our goals. We also need to find ways to achieve negative emissions–ie reduce the amount of carbon already in the atmosphere.

Carbon capture and storage is getting a lot of attention and tends to elicit thoughts of huge machines pulling carbon out of the air and pumping it below the earth where it will hopefully remain. These methods are a long way from being implemented in any scale and are vastly expensive. This is typical of our species… we use our brains to develop mechanical ideas for dealing with a problem rather than opting for the solutions nature already offers us. The three great natural carbon sinks are soil, the world’s forests and the oceans. Employing these to absorb carbon from the atmosphere will be far more effective and less expensive than any mechanical solution.

Of the world’s carbon sinks, the oceans are by far the largest

Half of the CO2 that is captured from the atmosphere goes into the oceans which in turn produce over 50% of the earth’s oxygen. Over 90% of the heat caused by global warming is absorbed by surface waters. This warming results in ocean temperatures rising which is steadily undermining the marine food chain. Oceans are most productive where cold, nutrient-rich water upwells from the deep sea toward the surface, for example in the Grand Banks of Newfoundland, once one of the richest fishing grounds in the world until it was overexploited by humanity. As waters heat up, this overturning circulation of water reduces, currents slow, acidity increases which undermine coral and shellfish systems, phytoplankton production drops and marine life systems diminish. Vast amounts of subtropical and tropical oceans are now largely devoid of life… deserts in the middle of water. But what if we could change this?

A 2030 prediction of the scale of the ocean economy and its environmental benefits.

This is where seaweed comes into the picture

Who has not marveled at the giant beds of kelp waving in the ocean off of the California coast or in many other parts of the world? What if these seaweed beds were also capable of being part of the fight against global warming? Like plants on land, seaweed uses photosynthesis to absorb CO2 and grow biomass, but it is more efficient. Coastal marine systems can absorb carbon at rates up to 50 times greater than forests on land, according to Conservation International. Globally, seaweed is thought to sequester nearly 200 million tons of CO2 annually–as much as New York State’s annual emissions. The average square kilometer of seaweed can sequester more than a thousand metric tons of CO2. And seaweed doesn’t burn… a real issue in these climate warming times. So what if we were to plant kelp and other seaweed extensively with the aim of increasing its role in natural carbon capture?

What is the potential?

Halley Froelich, a marine scientist at the University of Santa Barbara, is the lead author of a study that found that farming seaweed in just 3.8% of federal waters off the California coast could offset all the carbon emissions from the state's $50 billion agriculture industry. The study concluded that 48 million sq km (18.5 million sq miles) of the world's oceans are suitable for seaweed cultivation – an area about six times the size of Australia. If we could plant even a small percentage of this area with kelp, it could massively increase the overall absorption rate of CO2 with positive effects on global warming, assuming we can make sure the life cycle ends with the bulk of the carbon-based plant material descending into the ocean’s depths where it would remain.

The need for sinking

The key, of course, is not just to absorb carbon out of the air but to then keep it from reverting back to the atmosphere down the road. Trees in the forest draw huge amounts of CO2 from the atmosphere and convert it via photosynthesis into carbon in their roots, trunks and leaves. But if those trees then burn in a fire, the carbon is released back into the atmosphere again. The same process happens in the world’s seas as part of a natural carbon cycle via the degradation of plant and animal material. However, if the plants that convert CO2 into their bodies then fall to the ocean floor when they die, the carbon sinks with them and can stay there for hundreds if not thousands of years. (This, after all, is how oil was formed in the first place.)

Here, kelp, in particular, has an advantage

Anyone who has seen it on beaches will know that the plants contain gas-filled bladders that help them float toward the surface where they receive more sunlight for photosynthesis. In the ocean, these bladders allow the plant, when uprooted, to float long distances. Because the bladders contain unpalatable compounds, they mostly remain uneaten until eventually the bladder bursts and the kelp sinks down towards the deep sea floor where its carbon can be sequestered for centuries in the right conditions. From macroalgae found in the guts of deep-sea crustaceans, it is clear that seaweed can travel far from where it is grown and make its way to depths of over 6000 meters underwater. And while it is difficult to measure exactly how much carbon is sequestered at these great depths, it can clearly be a big contributor to reducing greenhouse gases in the atmosphere.

This all sounds good, but how do we scale up seaweed production?

Mangroves and shoreline seagrass are very effective carbon absorbers, but they can easily be disturbed and killed off by storms or human activity such that their carbon leaks back into the atmosphere.
A better solution is to focus on kelp. Kelp is already one of the most commonly farmed types of seaweed. The large, brown alga, which is found in cold, coastal marine waters around the world, grows remarkably quickly–up to two feet a day and does not require fertilizer or weeding.
The question is how do we make this cultivation of seaweed happen on a scale that will make a difference.
Today, kelp forests cover some 19 million acres of the oceans’ near surface.
One way to expand this is to create floating arrays that can allow kelp to grow, much like grapevines do on trellises. Brian Von Herzen, executive director of the non-profit The Climate Foundation is one of the foremost proponents of this. He proposes creating marine permaculture arrays 4 miles wide, submerged deep enough to avoid blocking any shipping routes. A lightweight latticed structure of interconnected tubes hanging down into the deep would allow kelp to attach and thrive and with them mollusks and other sea creatures. Buoys attached on the surface would rise and fall with the waves, using this action or solar power to pump colder waters from hundreds of feet below up to near the surface through the tubes, thus fertilizing so to speak the entire marine system. This cool water infusion would re-create an ideal micro-environment for the tethered kelp to thrive; the kelp would then oxygenate the water; phytoplankton can thrive, which would attract creatures that feed on them and so on up the chain. It is like reforesting a desert, all the while absorbing carbon from the atmosphere via the water.
To prevent the release of stored carbon when a plant dies, it would need to be sunk at least 1,000 meters deep where it can decay but not rejoin the carbon cycle. How to sink it remains an open question, but it doesn’t seem insurmountable. If the kelp is raised using biodegradable buoys with long lines hanging down into the deep, when the buoys eventually degrade, they will sink and take the plant with them to the bottom. This would have to be done in a way that did not pose a threat to shipping, fish and other aquatic wildlife.
Running Tide Technologies in the Gulf of Maine is experimenting with just such a system: free-floating cellulose buoys, each tethered to a kelp-bearing rope. They are starting modestly with some 1,600 single buoy micro-farms to prove the concept. If it works, the project could be scaled to a very significant size. A consortium of oceanographers from MIT, Stanford and other top universities will review the project and its environmental risks– potential dangers include entangling whales or hindering shipping. See NPR article link here: 1 March 2021.

Other benefits of marine permaculture and seaforestation

A major food source:

Seaweed is a bountiful source of food in a planet desperately in need of it. Rich in protein, vitamins and minerals like calcium, iron, folic acid, and vitamin K, studies have shown significant health benefits from eating seaweed, including reduced blood pressure and improved digestive health. It’s no wonder seaweeds are trending as the new superfood.
Globally, around 12 million tonnes of seaweed is grown and harvested annually, about three-quarters of which comes from China. The current market value of the global crop is between $5-6 billion of which US$5 billion comes from sale for human consumption. Production is expanding very rapidly.
Besides its sustainability credentials, seaweed is cheap, easy to harvest and available worldwide, making it an attractive commercial proposition.
The World Bank estimates that if the sector is able to increase its harvest by 14% per year through to 2050, seaweed cultivation could lift the world's food supply by 10%. Given the inherent limitations to traditional farming, there is great potential for seaweed farming to supplant some of that pressure at a lower cost.

Enhancing biodiversity:

Seaweed provides a home for all sorts of sea creatures that are essential to the overall oceanic ecosystem and again can be a major food source

Reducing ocean acidity:

Seaweed raises the PH of ocean water locally and so can reduce the rising acidity of the ocean which is playing such havoc with coral reefs and mollusk shells.

Enhancing climate change resilience:

Seaweed aquaculture can also contribute to climate change resilience by damping wave energy and protecting shorelines.

Industrial uses:

It can be used in cosmetics, pharmaceuticals and, it is thought, could even be fashioned as a biodegradable replacement for plastic bags.

Methane reducer:

Also, as discussed in my articles on regenerative agriculture and methane, adding a small amount of red seaweed called Asparagopsis taxiformis to cattle feed has been shown to reduce their methane output from belching by up to 80%. Compounds in the seaweed inhibit the enzymes in cows' stomachs that produce methane. As methane has a global warming impact 84 times higher than CO2 over a 20-year period, and livestock is one of the major causes of methane emissions, this in itself is an effective way to curb global warming.

Risks and obstacles

It seems like a simple solution: ramp up seaweed aquaculture to capture CO2 and slow down or reverse climate change, while also enhancing the health of our oceans and their food-producing capacity. So, where are all the climate change fighting seaweed farms? There are hurdles to cross before we get there.

First, for a seaweed carbon sequestration market to exist there must be someone willing to pay to store carbon in seaweed. Presently, there is no carbon credit exchange market for seaweed. Frankly, it shouldn’t be that hard to create one mirrored on existing carbon markets, but we are not there yet.

Second, government policies need to support industry development rather than be a barrier. This includes tax benefits for kelp and other seaweed farming, streamlining the permit process and incentivizing the development of the oceanic carbon market as mentioned above. To scale this industry with its carbon sinking ability will require governments and the private sector to work together. As yet, this cooperation is still embryonic. In some countries like the USA and Australia, it is easier to get a government concession to drill for oil and gas than it is to win approval for a kelp farm.

Third, climate change itself also can undermine efforts to build up the seaweed cultivation industry. Warming water and the removal of natural predators like sea otters have caused populations of kelp-eating sea urchins to explode in places like Santa Monica Bay, off the California coast. See photo below.

Taking stock

Any sequestration technology, of course, is only a tiny part of the overall solution to global warming. Even were we to multiply the current CO2 sequestration by seaweed by a factor of 10 or even 100, through intensive cultivation in the ocean, that would still only take us to c.2 to 20 billion tons of carbon dioxide pulled out of the atmosphere annually vs the nearly 50 billion tons that get emitted globally every year.

That would still be a huge achievement. And if we added carbon sequestration via regenerating our soils and terrestrial reforestation, the fight against global warming would really take off. Still, this has to be combined with cutting down emissions via re-engineering our economies away from fossil fuels (see my thesis article “About Confluence”).

The most effective way to sequester carbon is not to release it in the first place. But planting forests and seaweed can still be a useful part of the solution.

Appendix

Changes to fishing practices can also help reduce global warming (Sierra Magazine, summer 2021)

It is estimated that bottom trawling (where huge nets are dragged across the floor of the ocean, stirring it up while catching everything else in its path) releases as much carbon into the atmosphere as the entire aviation industry–over a billion tons a year. A global ban on this practice should be a priority for the representatives who meet for the climate conference in Glasgow in November.

Super Seagrass: (The Economist, 6 March 2021)

My article has focused on kelp as a major source of CO2 absorption. But there are other sea plants that can help as well. In the Spanish Mediterranean, a type of seagrass called Posidonia oceanica spreads by sending shoots out beneath the ocean sediment. A single organism can stretch for 15 kilometers from one end to the other, covering several hectares in total. And they are long-lived, some are thought to have been spreading for tens of thousands of years. Along with two other coastal ecosystems - mangrove swamps and tidal marshes - seagrass meadows are particularly good at taking in carbon dioxide from the air and converting it into plant material. This was written up in a UNESCO report dated 2 March this year. It estimated that as much as 33 billion tons of CO2 was locked away in these coastal carbon sinks–that’s about three-quarters of the world’s emissions in 2019. One hectare of seagrass can soak up as much carbon dioxide each year as 15 hectares of rainforest. In 2018, Apple partnered with Conservation International to protect 11,000 hectares of mangroves on the Columbian coast, which it estimates could lock away a million tons of CO2. Like kelp, these seagrasses and coastal marshes and mangroves, have the advantage that they do not burn, unlike our forests. They are, however, vulnerable to severe weather like cyclones and tidal waves that can uproot them or oil spills that poison them. A marine heatwave in Australian waters in 2010 damaged about one-third of the world’s largest seagrass meadow in Shark Bay, causing uprooted plants to release stored carbon into the atmosphere. Still, protecting existing coastal carbon sinks is important not only for greenhouse gas sequestration. It can also provide a buffer for vulnerable shorelines, dampening storm surges, building resilience in the face of climate change. And they can create their own ecosystems providing a home for a wide array of flora and fauna. Intentionally expanding such coastal carbon sinks, like stopping methane leaks across the planet, seems like a no-brainer action if we are serious about combatting climate change.