Can Seaweed Save The World?

Yes, it undoubtedly can help to...and in a very, very big way. It is said if we use just 10% of the ocean to farm seaweed, we can safely store up to 40 gigatons of carbon dioxide per year. That's the equivalent of what the whole world emits on an annual basis.

Last month, February 2019 there was the highest reading of carbon dioxide taken in our atmosphere yet by NOAA; 411.75 parts per million (ppm). It is predicted if we keep on our current trajectory, emissions could rise over 600ppm over the next 30 years. This would lock ourselves in to at least another 2-3 degrees of warming on top of the 1 degree warming we have currently. This is not an article highlighting what 2-3 degrees of warming would look like, as that scenario will potentially be catastrophic to the human civilisation. This an article about a major solution to help reverse the growth in atmospheric carbon, something I along with other scientists are working on.

What we need is to look for ways to rapidly get that carbon dioxide out of the atmosphere that's causing the warming, right? Well...Professor Brian Von Herzen has found a way to do just that.

Brian Herzen of the Climate Foundation has found a way to farm large amounts of seaweed in the open ocean, which was up until now, basically impossible. This couldn't be done previously because of the following:

• Lack of nutrients on the ocean surface - the ocean is basically a 'marine desert', with all nutrients dwelling in the deeper parts below the surface not allowing plant growth
• The ocean 'desert' is expanding from phytoplankton die off due to human induced climate change
• Warming ocean surface waters impacting plant growth - the ocean takes in up to 93% of the extra global warming heat, making plant growth difficult

Brian's seaweed farming model that he refers to as 'marine permaculture' overcomes these challenges by using wave driven 'pumps' or large pipes that are run from the surface down to a 300 metre depth. They function using wave energy (renewable) to draw the cooler, nutrient rich waters to the surface. This brings phytoplankton and other aquatic microbiological life to the surface first then eventually turns the 'marine desert' into an entire ecosystem bursting with life. This model has been proven to reverse the following impacts of climate change:

• Reduction in ocean acidification - by producing more phytoplankton to help neutralise the increasing carbon dioxide levels that cause rapid ocean acidification
• Reduction in ocean temperature rise - by circulating the cooler waters from the bottom to the surface

Long ropes are hung off floating buoys in the ocean in hectare farms for the seaweed to grow on for a period of 90 days. Yes, 3 months is all it takes because kelp or algae (as seaweed is commonly referred to as) can grow 30-60 times faster than any land based plant. Now, keep the economy in mind here because my next paragraphs will talk about the carbon sequestration rates that can be turned into profitable carbon credits. We all know how fast our economy moves, so we also need fast moving plants to keep up.

Herzen's model uses a particular type of seaweed called macrocytosis pyrifera that is most suited for carbon sequestration because of it's size. Herzen has calculated that 3000 tonnes of carbon could be safely stored using the seaweed over 100 hectares of seaweed farms. That's 3000 carbon credits that can be sold and traded as a product or value under current carbon farming schemes. This particular methodology is referred to as 'blue carbon' (ocean or freshwater developed carbon credits).

The seaweed, once grown...has a number of different uses, including the following:

1.    Climate change mitigation - The carbon in the seaweed can be stored safely by cutting the ropes on which they grow on and sinking the seaweed 1000 metres below the surface to close off the 'carbon loop' (meaning it won't re-enter the carbon cycle for 1000's of years).

2.  Seaweed cattle/sheep feed - CSIRO and Meat Livestock Australia have undertaken trials to that prove if you incorporate just 2% of seaweed into their diet it can reduce methane levels up to 99%.

3. Soil carbon - trials have been undertaken by using seaweed waste to turn into biochar, an organic product that can be used in soil to hold nutrients, carbon and increase water storage potential.

3. Alternative food source for millions of people - with a growing population, decreasing fish numbers and extreme weather events such as drought impacting agriculture, we could look to farm seaweed as a solution to the food crisis.

4. Alternative for plastic - there are currently business's working on using seaweed to make materials that will ultimately replace plastics.

What if you could line the Great Barrier Reef with the seaweed farms to act as a 'barrier' that protects them from the marine heat waves that cause severe bleaching and further threats to ocean acidification? What if...what if seaweed farms could reduce the intensity of cyclones because of the surrounding cooler waters? What if you could feed all the cattle in the world seaweed to completely eliminate the methane emissions? What if you could use the waste products to make biochar to store the carbon in soil to enhance agricultural production? The list is actually endless...I will keep this one reasonably brief.

Challenges

The open ocean seaweed model that Herzen has developed comes with a significant start up price per hectare. All of the mentioned uses of seaweed above can be used to trade carbon credits, which is essentially a way to incentivise the safe storage of carbon and encourage effective action on climate change. However, there is no current price on carbon because of a lack of political will (for use of a better word), it is currently a voluntary market. Which means the price per 'carbon credit' is not high enough to make the open ocean seaweed farm model profitable. I am hopeful this will change within the decade, as the Paris Climate Agreement sets an International Framework policy that finally allows this to happen so carbon can be traded like gold or any other commodity. Other social pressures such as the recent world wide school climate strikes will in fact put pressure on governments to act with more integrity and speed on this growing challenge that we all face.

Conclusion

Do I think that seaweed can solve climate change alone? No, of course not...there is no silver bullet and we must stop thinking like there is. We must transition to renewable energy as soon as possible, but simultaneously we have to learn ways to mine the harmful gases we have already released...and we must act with the same urgency as if we were in an emergency, because we are. This is to avoid the unthinkable from happening - the oceans becoming so warm and acidic that we lose all ability to grow anything and the opportunity to create wealth in our economy, society and environment will be gone.

There is a very small window of hope, and we must collectively act on it...because it is quickly closing.