Skip to content
Home » Removing Carbon Dioxide Removal At Scale – balancing urgency with caution

Removing Carbon Dioxide Removal At Scale – balancing urgency with caution

Shaun Fitzgerald

Shaun Fitzgerald

Director of Centre for Climate Repair at Cambridge University. Speaks and writes regularly about climate change & the need for repairing the climate.

Greenhouse gas concentrations are racing up with impacts touching the lives of many people and ecosystems in both the southern and northern hemisphere. How does the Centre for Climate Repair characterise the challenge with regard to ocean based large scale carbon dioxide removal?

The challenge that we have in terms of the levels of greenhouse gases, if we express things in carbon dioxide or carbon dioxide equivalent, we are currently at something like 420 parts per million of carbon dioxide levels in the atmosphere. If you add in other greenhouse gases, such as methane, then the atmosphere is something like 500 parts per million of carbon dioxide equivalent. 

Dr James Hansen has gone on record as saying that he thinks that in order for there to be an atmospheric concentration that is really satisfactory for life on Earth, as we know it, in terms of ecosystems, and also, things like the Antarctic ice levels, and things like this, we need to get it down to 350parts per million. So we’re already north of where we need to be. 

The biggest opportunity that we have is the oceans

The oceans occupy 70% of the surface of the world and therefore, I think that is an area that we should be investing research money into. But there are two challenges. One is understanding what the mechanisms are and how we might be able to get the oceans to do more for us, materially.

The second is making sure that we don’t harm the oceans but actually look at what opportunities there might be to support the oceans and actually have them functioning in a way they should be, taking into consideration that they are not because of human activities spoiling the oceans. We have got to repair the oceans. And as a function of that the side benefit being getting the oceans to do more for us, and in fact, doing what they should be doing.

Transparency is everything 

So doing things with a whole raft of different stakeholders, local communities, governments, agencies, NGOs, and other scientists to be able to provide critique on approaches. The areas that I think we should be working on first, within the oceans, are smaller areas to try and restore bits of the ocean that we have destroyed. For example, as a result of some of our fishing techniques, we have lost kelp beds. 

We need to work hard firstly at regenerating those kelp beds in the coastal vicinities and learn from our activities on how we might be able to regenerate areas in a local region that are easy to monitor, because just the act of trying to undo the damage that we have already inflicted on local scales will teach us about how we might then also approach tackling more larger parts of the ocean, which we have also impacted significantly as a result of human activity. So I would start small and it’s really important that at the Centre for Climate Repair, we work with local communities, thinking about how to do things in a local environment to start with.

Engaging local communities 

Working with local communities to think through and discuss is really important. There has to be discussion as opposed to imposing one set of beliefs or one set of views on a solution. So for example, a restoration of a local ecosystem might mean that a given practice that has been followed over the last few decades is no longer able to be pursued, because we found that, it is taking out the kelp beds, but what about the upside in terms of to them, the ecosystem, or, fish populations, or shellfish and things like this. 

Other things are also important for the economy, for people who harvest the oceans. It is working with communities to figure out how, not only can you help regenerate and restore ecosystems within coastal locations, but how that might also lead to increased commercial benefit, albeit perhaps in a slightly different form than has been used over the last few decades. 

Progress on restoring kelp beds 

There are a number of activities, the safest place to operate this in a room behind a computer screen. This means modelling the impact of what would happen if you were to stimulate and support the growth of giant kelp in surface waters of the deep ocean, for example. A lot is being learned from this. 

The different approaches that we have been exploring are point sources. Think of these as individual buoys supporting kelp in the surface waters of the deep ocean to allow the kelp to grow. And then for those buoys to have a biodegradable plug within them. So that after about nine months of growth, where kelp has grown from something like 5kgs to 300kgs, for the biodegradable plug to then go, allowing the whole mass to then sink to the bottom of the ocean. 

Antique Longcase Clocks
Howard Walwyn Clocks, Kensington, London

Critical factors for kelp harvesting

The modelling of this reveals that one of the critical factors behind the growth of kelp is the availability of nutrients, in addition to sunlight, in the surface waters of the deep ocean. And thinking about just how densely populated could you have, for example, individual buoys, starting with very diffuse dispersed buoy locations so that you’re not really affecting the local ecosystems at all. But the big question is: how much could you grow in a given area before you end up having to worry about those things? Modelling teaches us a huge amount about that. 

The other scenario is where instead of having individual buoys supporting kelp, you create rafts, upon which kelp forests can grow. This has a very different impact on the ecosystem and a different model behind it because when you put a large infrastructure into surface waters of the deep ocean, the idea is that you don’t just get funded for the infrastructure by carbon credits, but can consider what other businesses might be interested? 

So if you can have a a kelp farm supported with a raft, then you can harvest some of the kelp and there is economic value behind this, Then allowing some of the kelp to slough off after its natural period where the fragments go to the bottom of the deep ocean. 

So modelling is the first step and the second is working closely with partners who are undertaking physical research into this area. So there’s an organisation called Running Tide, off the east coast of the US that’s looking at the possibility of buoys in the in the North Atlantic. 

We are also working with Kelp Blue and the Kelp Forests Foundation. Their model is looking at the raft supporting the growth of giant kelp. They are operating first in an upwelling zone, reasonably close to shore, off the coast of Namibia. The reason I really like this is that it is reasonably close to shore and involves the local communities. It is learning by doing but not on a large scale to start with. So it’s working with communities. And starting small there are plans clearly, as we learn more as they learn more or collectively as a society, we learn more, that this activity then might be allowed to grow further. But it’s working with both physical experiments out in the open ocean, as well as doing modelling. That’s how we’re pursuing this.

Scaling to a Gigatonne (billion tonnes) of carbon removal

We are only interested in carbon dioxide removal or greenhouse gas removal approaches that have the opportunity to actually get to the gigatonne scale. Because if they don’t, we should be finding those that do. We have not ruled out kelp yet at all but it’s still very much in the research phase.

Using Ocean Iron Fertilisation to restore the ocean chemistry

The essence of ocean iron fertilisation is identifying parts of the ocean that could be growing more phytoplankton. One of the common missing micronutrients is iron and that is why there is a field called Ocean Iron Fertilisation. The reason why it is controversial is that the idea of adding chemicals to the ocean begs a whole raft of different questions. The bigger question that we have is, why might certain parts of the ocean be devoid of certain nutrients? And, are there regions of the ocean which are devoid of micronutrients? If the reason is basically a result of human activity, so what we have done? 

Then we need to think very carefully about how might we be able to restore and regenerate those parts of the oceans so that they can then fulfil a function of a more healthy ecosystem with the concomitant benefits of sequestering more carbon dioxide. 

The bigger question is really identifying not just zones of the ocean that are missing in micronutrients, but trying to understand why that is the case. If those are areas that we have inadvertently affected through activities, whether it’s through whaling or other types of extensive impacts on the ocean. 

Where we have just been taking from the ocean for economic benefits, for health or food reasons but not supporting the ecosystem itself, we need to think carefully about how we counter that. One of the solutions could be through careful distribution of micronutrients for a given limited of time, and that might be many decades in order to regenerate an ecosystem. But we need to think very carefully about why we are doing this. The ultimate objective is to try and allow those natural systems to fulfil the function they should be doing if we had not disrupted them in the first place.

Reason for caution

There are many examples in history where humankind has intervened with nature, thinking we understand it but actually, we have made things even worse. No matter how clever we think we are as human beings, nature itself is incredibly complicated and we need to be sensitive to that. However, the flip-side is that we have made significant progress in many areas of society and the lifestyles that we have created. It isn’t all about just destroying nature. There have been very good examples where, as a result of learning more about nature, that we have been able to go and regenerate parts of our natural world, and see those come back and to see them come back more quickly as a result of certain activities, where we’ve been having a more caring approach rather than a taking approach. 

The Knepp Estate in Sussex, UK, for example, is an example of where there’s been an intention to try and tend the land and manage and care for it to regenerate a more natural ecosystem and to see all the benefits from that. Those are the kinds of approaches that we need to be thinking about to the oceans as well.

Leave a Reply

Your email address will not be published. Required fields are marked *