Could nature ‘solve’ climate change?
By Paul Rouse / 22 October 2019
If we are to keep global heating to under 1.5°C, the IPCC tells us we need not only to reduce emissions, but to remove billions of tonnes of carbon dioxide from the atmosphere. A new commitment by 77 governments to reach net zero by 2050 similarly requires a massive amount of CO2 removal.
How would we do this in practice? This is one of the biggest challenges facing the international community today, and we are a long way from resolving it.
For some, the biggest potential lies in ‘nature-based solutions’, a subset of approaches to the CO2 removal challenge which have attracted growing attention over recent months.
But how true is this?
To what extent could nature alone – under the most ambitious deployment scenarios – remove the necessary amount of CO2 to achieve international goals. Or might other, more technological approaches also be needed?
Let’s start with a definition. While nature-based solutions vary considerably – you can learn more about their forms in our new evidence and policy briefs – they share one core feature: they seek to enhance the capacity that natural ecosystems already have to remove and store carbon dioxide.
Perhaps we might describe them as ‘working with nature rather than against nature’.
Also sometimes known as ‘natural climate solutions’, they include techniques such as very large-scale forest planting, restoring wetlands (such as peatlands and mangrove swamps), and improving land management to increase carbon sequestration in soils.
The good news is that these are generally things we appreciate for their own sake. More nature has all sorts of benefits. If it can help tackle the climate crisis as well, it looks like a clear win-win.
But on closer inspection, the picture is less simple.
Are nature-based solutions actually ‘solutions’?
In fact, the very name used to describe nature-based solutions might be misleading.
If deploying nature at scale requires massive human intervention, to what extent is it natural? Perhaps more importantly, to what extent do nature-based solutions actually provide a ‘solution’ to the climate crisis?
The United Nations Environment Programme has estimated that forests, wetlands and soils – if humanity took all possible measures to enhance their carbon storage potential – could remove up to 4–12 gigatons per year.
This falls far short of balancing out the 37 gigatons of CO2 (and rising) which humans release from fossil fuel sources annually. Other studies indicate nature-based solutions could have a significantly higher potential, but that they still would not amount to a silver bullet.
Also, whilst these approaches can remove carbon in the short-term, permanent storage is much more challenging. Trees die and decay, or can burn down, releasing carbon back into the atmosphere. Land management policies change. Keeping CO2 out of the air at the time-scales needed is difficult.
And the sheer scale is daunting. Over the course of this century, the IPCC suggests that we need to remove between 100-1000 gigatons of CO2 to stay under 1.5°C warming. Analyses by other organisations suggest the most realistic figure lies at the higher end of that scale.
The simple reality is that nature-based solutions are unlikely to achieve this by themselves.
That is why in most of the IPCC scenarios, technological approaches, like Bioenergy with Carbon Capture and Storage, play a major part – especially where emissions fall more slowly.
If nature-based solutions aren’t the solution, are they still useful?
Even if they aren’t the whole solution, nature-based solutions could make a crucial contribution to CO2 removal. This is especially so given the current underdevelopment of technological options, which are unproven at scale, and lack compelling business models.
One of the key attractions of nature-based solutions is their co-benefits, which could advance international goals beyond temperature change. These include preserving and enhancing biodiversity, which is of particular concern as we live through Earth’s sixth mass extinction event.
Unfortunately, the large-scale deployment of nature-based solutions also brings considerable trade-offs and risks. These include potential damage to essential ecosystems services, oxygen and food supply, income generation and flood and storm protection.
It may be that interfering with natural systems to remove large amounts of atmospheric CO2 has large unintended consequences on the capacity to deliver the sustainable development goals. As we think about any potential approach, it is essential to consider any potential negative effects.
Why nature-based solutions need governing
So how would we protect against harm, while maximising the synergies and benefits of nature-based solutions? The answer is governance.
For the moment, governance mechanisms appropriate for nature-based solutions are inadequate for the scale under consideration, and many important questions remain.
Who might deploy, monitor and pay for them? How might the effects on trade, food production and delivery of the sustainable development goals be tracked and reported? Who would pay compensation in case things go wrong?
As the window closes to keep warming below 1.5° or even 2°C, these and many other conversations are increasingly important.
Perhaps the starting point is the realisation that there are no risk-free options ahead.
All approaches have risks and costs, as well as potential benefits – and nature-based solutions, as attractive as they appear, are no exception.
That is why C2G is working to ensure that all forms of carbon dioxide removal, even nature-based solutions, are discussed by the UNFCCC and other appropriate international bodies.
Whatever society decides, there will still be risks, and they will need to be managed.
As benign as nature-based solutions may sound, they are no exception.