15 Sep 2021

The second webinar in our latest Future Focus series examines the nature-based solutions to climate change, from financial, biodiversity and societal points of view.

This is part two of our second Future Focus event in partnership with Oxfordshire Greentech. For part one of this session, featuring Nicky Chambers presentation on “How can nature help itself?”, click here.

Having explored the challenges around financing nature-positive initiatives with Nicky Chambers, we now hear from Cécile Girardin, Science Lead – Oxford Biodiversity Network and Technical Director – Nature based Solutions Initiative.

Nature-based solutions in the race to net zero

At the moment, how we define nature-based solutions (NBS) and how much nature-based solutions contribute to mitigating climate change are grey areas and subject to much discussion, so it’s important to protect the definitions.

Simply put, nature-based solutions involve working with nature to address societal challenges, as Nicky said. The important point is that they provide a benefit for both human well-being and biodiversity; not just protecting or restoring biodiversity. How humans interact with biodiversity is a key aspect.

Specifically, nature-based solutions involve the protection, restoration and management of natural or semi-natural ecosystems. That includes sustainable management of working lands, regenerative agriculture, aquatic systems, the creation of ecosystems in urban areas – anything that involves working with nature to address the societal change.

Examples include kelp forest restoration, wetlands, seagrass, and agroforestry such as planting trees on cocoa farms. It’s important to show the links between biodiversity, humans and the sustainable development goal and how working with nature and people can address these links. There are decades of evidence to support that nature-based solutions can reduce greenhouse gases and provide flood and erosion control, coastal defences, and cooling and shading in urban areas.

Land use change is one of the biggest drivers of biodiversity loss. It accounts for about 30% of biodiversity loss, according to IPBES reports. It’s also the second highest source of greenhouse gas emissions according to the IPCC (Intergovernmental Panel on Climate Change), so addressing land use change through NBS can help us contribute to mitigating climate change and address biodiversity loss – if it’s done well. And that’s the catch.

NBS in action

Cocoa agroforestry is a good example of an effective nature based solution. In Sierra Leone, planting trees in cocoa farms increased profits, improved local livelihood, avoided deforestation, protected biodiversity and reduced carbon emissions. There are examples of community protected areas and wetland restoration in the Andes or urban forest in the US and all these you can find on the Nature Based Solutions Initiative website, where there are many more examples.

Reducing emissions

How much can nature-based solutions contribute to mitigating climate change? This is a question we’ve been asking in the scientific community for a while. There has been a lot of controversy over this subject; some say it’s the best solution to climate change, others say it’s a dangerous distraction. Most of the models provide a wide range of estimates over a range of timeframes with different models and assumptions. Currently the focus is on emissions, so how much do NBS reduce emissions?

We tried to address this question by looking at it in terms relevant to the Paris Agreement. The Paris Agreement asks us to limit peak warming to well below 2 degrees this century, whilst attempting to limit it to 1.5 degrees. So in terms of temperature, how much can nature based solutions minimise peak warmings?

We looked at the widely-accepted model by Bronson Griscom, which talks about natural climate solutions. Just a little side note here: nature-based solutions include all the multiple benefits they provide for adaptation, water regulation and nutrient cycling, etc. When you’re talking about natural climate solutions, it’s really focusing on nature-based solutions for climate mitigation – so the carbon benefits. This model estimates that we can avoid emissions and enhanced sinks by up to 10 gigaton of CO2 per year.

That’s at a cost-effective rate of less than $100 per Megagram CO2 equivalent per year. This is important, because the cost constraint really does make a difference to how much you’re estimating you’re reducing here. If we increase what we are willing to pay for up to $200 per Megagram CO2 equivalent per year, this contribution will go up to 20 gigatons of CO2 per year. It’s very sensitive to cost and how much we willing to pay for these solutions.

Avoiding emissions

The model shows that about half the reduction comes from avoided emissions (5 gigaton of CO2 per year) and half comes from enhanced sink. It’s important to recognise this because not all nature-based solutions absorb carbon, as is often said.

Avoided emissions means protecting the lands we have. As Nicky said, rather than deforesting and planting trees, it’s far better to protect the ecosystems we already have. It doesn’t only include forests, which are of course a major factor, but also wetlands, grasslands and all the thriving ecosystems such as kelp forest, seagrass that are important in the geological carbon cycle.

Half of the emission reductions come from enhanced sinks, resulting from better management of working lands and sustainable agriculture, better management of grazing lands, timberlands, croplands, and restoring native covers. When we talk about restoring native covers it should be not only forests but all the multitude of ecosystems we talk about.

Is it achievable?

How much land would we need to achieve these targets? Not as much as you might think, because 40% from protecting intact lands. We are already using this land for the ecosystems it supports. A further 40% of the target comes from better management of existing, working land. That leaves only 20% (678 million hectares, about double the size of India) to come from restoring ecosystems.

As you can see, a small proportion of the mitigation benefits come from restoring forests, which shows that all this enthusiasm going into planting trees may be misplaced at times. Much more comes from protecting and managing the working land we already have.

These estimates come well-constrained and involve many years of negotiations about what land can we include. It must include biodiversity safeguards: you only restore forest ecosystems in areas that are ecologically appropriate for them. So we’re not planting trees on the savanna, for example, or anywhere else where there shouldn’t be forest. We exclude boreal biomes due to albedo effect and we look at saturation of ecosystem carbon sequestration rate, food security, fibre security and then the complex governance issues. There’s always room for improvement in these models, but we’re considering all these, and of course the sensitivity to cost.

Peak warming and beyond

The big question is how much nature-based solutions can contribute to limiting peak warming to below 2.0° this century, and preferably limit to 1.5°. We’ve based our projections on the IPCC model, where in the best case scenario we peak at 1.5°C by 2055 and then emissions start to reduce.

The same model also shows what happens when we peak at 2°, around 2088. Adding the contribution from nature-based solutions shows their impact on mitigating climate change is time sensitive. The more time available for them to take effect, the greater the benefit. Looking at the 1.5° scenario, NBS should reduce the peak of the warming trajectory by 0.1°C.

With the longer time period of the 2° scenario, however, we reduce warming by 0.3°. Beyond that, one of the most important finding is that nature-based solutions would continue to cool our planet long after we reach peak warming. So right up to the end of the century, they would make a crucial contribution to cooling our planet.

A long term commitment

We need to stress that we must invest in nature-based solutions for the long term. Focusing on short-term carbon gains is not going to get us there. If we are to achieve our targets, we need to ensure our projects’ longevity by designing them to be ecologically sound, socially equitable and in sync with local communities.

They must be designed to provide these multiple benefits over a century and more, and not jeopardise other climate measures. They should not be at the expense of decarbonising, because if we don’t achieve the 1.5° or 2° degree targets, then frankly ‘our goose is cooked’ and none of this matters. We can’t compromise on decarbonising our economy and we can’t rely on nature-based solutions to offset emissions if they’re not already aligned to net zero. So the key point is that all investments we make must be net zero aligned.

The critical value of NBS

We’ve focused extensively on carbon here, but there’s strong evidence across decades of to show the value of nature-based solutions for adapting to climate change and delivering a many local ecological and socio-economic benefits. These are summarised in an analytical review by Chausson on nature-based solutions published in 2020, which shows how NBS can help people adapt and achieve sustainable goals protecting biodiversity and mitigating climate change.

Similarly, the Dasgupta Review puts the business case for biodiversity and shows how we are dependent on it for our economy and our society. Nicky has already mentioned this, and the Mark Carney task force for climate finance.

Financial support for nature

Mark Carney’s COP26 report on Building a Private Finance System for Net Zero shows how signatory countries to the Paris Agreement can turn its targets into credible climate policies and legislated objectives. This then provides certainty for future investment, encouraging companies to innovate and implement transition plans to adjust their business to a net zero world.

I’m hoping Nicky’s task force on nature-related finance disclosures will provide the equivalent impetus for nature, so we will have clear targets for biodiversity, in the same way we have global targets from the Paris agreement for climate. This will then feed into business, private finance and public finance, and will go from there.

The challenge of carbon offsets

In the meantime the carbon offset market is booming (Taskforce on Scaling Voluntary Carbon Market). This makes it even more imperative that the offset market doesn’t become a distraction from decarbonizing our economy. Shell, BP and other huge emitters are investing heavily in planting or even restoring ecosystems to offset emissions, but without decarbonising their operations.

We urgently need to highlight the potential pitfalls of ecological carbon offsets. Investing in nature-based solutions for carbon offsets may be distracting from the need for the rapid phase-out of fossil fuels. Over-emphasis on tree-planting for rapid carbon gain rather than a wide range of nature-based solutions has impacts on local communities, biodiversity and the climate.

In some cases we’re replacing pristine rainforest by plantation forest to get the carbon credits. In that situation you have a negative impact on climate mitigation directly. You’re not only cutting down a very biodiverse thriving rainforest but also you are losing the carbon gains from it. There are examples of this from several studies from around the world, such as Chile, in China and Laos.

So we must caution against focussing on carbon as the main metric of success for nature-based projects. Instead, we must find metrics that capture the biodiversity and social benefits, as well as the climate benefits of these projects. Ultimately, we must make sure that all finance going towards nature-based solutions is directed to ecologically sound, socially just projects that are there for the long term.

Summing up:

  • NBS Guidelines (NbSI, 2020)
  • FEBA Framework for EBA criteria and standards (Bertram et al., 2017)
  • World Bank principles on NBS for disaster risk reduction and water management (World Bank 2017)
  • WWF principles (WWF, 2020)
  • IUCN Global Standard for NBS (IUCN2020)

These are useful examples of papers and guidelines on defining nature-based solutions. The first on the list, from the Nature-based Solutions Initiative, set out the four guiding principles for nature-based solutions, which are backed up by a number of institutions:

  1. NBS are not substitutes for the rapid phase-out of fossil fuels.
  2. They involve a wide range of ecosystems on land and sea.
  3. They should be implemented with the full engagement and consent of indigenous peoples and local communities.
  4. They should be explicitly designed to provide measurable benefits for biodiversity.

They may all seem obvious, but only by constantly repeating and referring to them can we make nature-based solutions work for our planet.

You can go back to Part One of this session, featuring Nicky Chambers’ presentation on ‘How can nature help itself?’ using this link.