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Cambridge Centre for Carbon Credits (4C)

A butterfly sits on a leaf in a tropical rainforest setting.

How can we measure biodiversity and compare it across conservation projects? And is it possible to judge biodiversity remotely? Dr Alison Eyres is helping 4C to develop a quantitative metric of the biodiversity impact of projects.

With a background in macroecology and the evolutionary ecology of plants and birds, Ali completed a PhD at the Senckenberg Biodiversity and Climate Research Centre on the evolutionary dynamics of climate niches in birds before joining the Cambridge Conservation Initiative to work on a collaborative fund project. 

Interview by James Millerstudent environmental activist, film-maker. Text lightly edited for clarity.

I’d love to know a bit about your background. What did you do before getting involved in 4C, and tell me about how you first got involved in 4C?

I did biology as an undergrad in Oxford, then I did a PhD in Germany on how birds are responding to climate change. Much as I enjoyed that, it was very theoretical, and detached from having an impact. So when I finished, I took up a position at the Cambridge Conservation Initiative on a collaborative project quantifying the impact of tree planting schemes. Andrew Balmford was also on that project - I really enjoyed working with him, and was excited by 4C, which was just starting then.
How does your research feed into 4C’s work?

One element of carbon projects that is often neglected is biodiversity – previously projects haven’t really assessed biodiversity, or haven’t done it in a consistent standardised way. I’m working with Andrew and Tom to incorporate an assessment that quantifies the added value to biodiversity of each project. The other element that we’re starting to develop is leakage – the potential of any project to displace harmful activities to other areas.

To what extent can you quantify biodiversity? It’s so multifaceted, what would a single number tell us?

That’s what we’re thinking a lot about at the moment! It’s a difficult question, and I’m cautious about putting numbers on biodiversity. We use persistence. This is a measure based on the area of remaining habitat – as species lose their habitat, they become more at risk of extinction. Conversely, as they increase their habitat, they are able to survive longer. 

We are using remote sensing to track habitat change and the resulting impact on individual species extinction risk within Tom’s framework of additionality, compared to counterfactual scenarios. We’re keen to improve - the metric currently only incorporates habitat change, and rests on the assumption that if the habitat is there, species will be able to use it and it will be suitable. There are other factors to consider like hunting, invasive species and pollution which can affect habitat quality and biodiversity. We are working on some of these – Hamish, a Masters student is looking at ways of assessing hunting pressure. 

You also need to think about how you express this information, too. We’re looking at the net gain. But if you restore agricultural land to forest, you lose agricultural species as you gain forest ones. It’s how you present that information that is really difficult.

Much as it might feel simplistic tying biodiversity to a single number, I guess the reason you’re doing that is so that buyers can compare across projects?

Yes. Although, to an extent it still depends on what you’re interested in. There’s probably the greatest potential for biodiversity improvements in moist tropical forests around the world, but that doesn’t mean that other regions aren’t important.

Is this all able to be done in an automated fashion remotely? Do some bits have to be done manually still?

We’re working on it. It’s pretty automated, but it’s still not as quick as we would like. In theory you can use the methodology on any project using remote sensing data for those areas. But we also need to consider that this is a hypothesis, and we need to gather ground truth data for the projects to make sure that what we think is happening is really happening. That’s something you can’t get away from.

James Ball has done a lot of linking of remote sensing with ground surveys and camera trap data, for example linking forest structure with vertebrate diversity. And Dr Sarab Sethi has been using acoustic monitoring of diversity to link Tom’s remote sensing with species diversity too – that was reassuring. We’re really keen to continue that audio work as a method of ground truthing.

So there are people testing each link in the chain from the ground truth to the top?

Yes. But you’re right in saying that one of the problems is that it has been based on field surveys, which are quite resource-intensive and not scalable enough for the amount of projects we need to make a difference for carbon sequestration. It’s a balance between what is good enough and what we can do on a practical scale. 

You can’t just trust remote sensing for everything. The intention I think is that there will be people visiting the projects and monitoring what’s going on. This could also be really important for ensuring that the local people are happy and not being mistreated, which is really hard to do with remote sensing.

Is the data about species ranges/niches always available? Are there biases that might affect the results?

Yes, good question. We’re using data from the International Union for Conservation of Nature (IUCN), which has species range maps and information on what habitats they can tolerate. One of the things that’s really an issue is that we don’t have as much data from plants, and they’re a huge component of biodiversity. That’s what James Ball and David are doing. We can currently remotely assess a few species of plants, and we need to determine how representative these species are of total biodiversity, how much we can infer from them. We have this data from the IUCN, but we know it is more certain in Europe and America than in Africa, for example.

Are your current methods of assessing biodiversity purely applicable to tropical rainforests? Do they work for other ecosystems? 

It’s harder to distinguish between some habitat types using remote sensing. Forest is particularly well done, and is also a habitat which is really important for carbon and biodiversity – that is why the project so far has been mainly looking at forest extent. We do have some projects just starting which are looking at other habitat types like the Great Fen, but we’re less good at distinguishing those sorts of habitats using remote sensing. Hamish is going to be doing his PhD on peatland, so hopefully he will develop ways of monitoring them using satellites.

What do you think are the main obstacles that you’re encountering/have left to solve?

The communication of it – on the biodiversity aspect we’ve been locked in an academic bubble and we need to think of a way to explain it to people that is true to what it is doing but also engages people. The leakage aspect is also something that we need to develop, but that’s a data limitation. Leakage can occur anywhere, it’s a problem of trying to get that data.

Do you see there being people that will want to buy credits not for carbon but for pure biodiversity value instead?

Yeah I think definitely. People aren’t necessarily motivated by the best carbon project, it’s also nice to have a link to something tangible - we’ve had people picking sites that are good for biodiversity and are very charismatic rather than absolutely the best for carbon. For me, that is more of a motivator; if I were choosing what to buy carbon credits for, I would be more motivated by seeing benefits to biodiversity than for carbon. Numbers are really hard for people to relate to, but one advantage of our biodiversity metric is that it is additive and can be broken down into contributions towards individual species. Although that’s less scientific, it might be more relatable. Someone can say ‘I’m really passionate about this species, which projects contribute towards its recovery?’

Talking about other important aspects of carbon offset projects – what’s the story with social justice?

This is definitely an area we’re lacking in so far. We’re lacking in sociologists and need to improve on that - there is nobody dedicated to it. In September we’ll get a researcher looking at the impact on food production as a result of these sites, which might involve contacting local people. There is also a new professor joining the Geography department looking at quantitative social science . Collaboration with experts such as her will be key. 

Why is the timing right for Cambridge to develop solutions?

This funding that has come from the Tezos Foundation makes it possible to do something like this that you couldn’t do with traditional research money. They are excited by the principle but it’s up to us to develop it how we like. I think that funding was critical in allowing people like Andrew, Anil, Keshav and David, who are all motivated by the same thing, to actually be able to come together to work on it. 

What is it like working for 4C?

It’s really exciting - I really like it. It’s the most real work that I’ve ever done. It’s going to have real implications, and I haven’t really found that anywhere else. I also consider myself very privileged to be working with really good researchers who are doing high quality research that is going to have a wide impact.

What do you see as the potential impact that 4C’s work could have on nature and biodiversity?

I think the potential of this project for carbon is going to be huge, but can’t promise enough carbon sequestration to solve climate change. So I’m really excited about the opportunity to leverage money from carbon credits towards areas where we can also have an impact on conservation, which is really exciting for biodiversity.