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NbSI talk: Value & limits of working with nature to address climate change

January 26, 2021
News item image NbS must be implemented with the full involvement and consent of local people, and must be supported by biodiverse, healthy ecosystems.

Professor Nathalie Seddon, Director of the NbSI, and Dr Cécile Girardin, Technical Director of the NbSI, gave an overview of the value and limits of working with nature to address climate change, as part of the Oxford Martin School series on Net Zero.

Key messages:

1. NbS can make significant contributions to both climate change adaptation and mitigation, alongside economic and ecological benefits. Implementation of NbS must be informed by understanding of all its potential effects on nature and people; a focus on just one outcome, such as mitigation, can lead to adverse consequences in other areas.

2. The cost effective (≤ $100/MgCO2e)  climate change mitigation potential of NbS on land is estimated to be 10 GtCO2/yr. If society achieves a trajectory to keep average temperatures at no more than 1.5°C above pre-industrial levels, then implementation of NbS at this scale could reduce peak warming by 0.1°C. Around half of this mitigation potential comes from avoided emissions (primarily through protecting intact ecosystems), with the remainder coming from enhancing sinks. Only about 20% of the total mitigation potential comes from restoring ecosystems, including forests and wetlands. Whilst these estimates account for constraints such as food security and biodiversity safeguards, they are cost-sensitive (a higher carbon price would increase the mitigation potential), exclude marine ecosystems, and do not account for the impacts of climate change on ecosystems’ ability to store carbon.

NbS can only make this contribution to climate change mitigation in tandem with decarbonisation of the global economy at an unprecedented rate. The ability of ecosystems to store carbon will be greatly compromised if we exceed 1.5°C of warming, because more frequent and severe fires, droughts and storms will lead to greater release of CO2 from ecosystems.

3. NbS contribute to climate change adaptation via three pathways:

  • Reducing exposure – e.g. mangrove forests, coral reefs, oyster reefs and saltmarshes protect coastlines from storm surges and erosion. This is the most intuitive and well-known pathway.
  • Reducing social sensitivity – e.g. marine protected areas can provide a source of food when crops fail due to drought.
  • Building adaptive capacity – e.g. participation in NbS projects can build social ties, trust, networks and participation in projects, increasing preparedness for future shocks.

4. NbS are economically viable:

  • They can be cost effective – e.g. benefits from mangrove restoration are up to 10x the costs.
  • They create jobs – e.g. for every $1 million invested in coastal habitat restoration in the US, 40 new jobs are created, compared to 19 for investment in aviation, 7 for finance and 5 for oil and gas.
  • Prioritising NbS in COVID recovery strategies could produce 400 million jobs and $10 trillion per year globally.

5. There are two key pitfalls of NbS that must be avoided:

  • Investing in NbS as carbon offsets is distracting from the need to decarbonise and phase out fossil fuels.
  • Over-emphasis on tree planting has adverse impacts on local communities, biodiversity, and creates unstable non-permanent carbon stores.

6. In the short-term, NbS may be financed through ‘offsetting’ schemes, so long as:

In the longer term, negative emissions will need to come from low-risk permanent geological storage, and funding for NbS will come from alternative sources such as public funding, risk management, blended finance.

Watch the recording of the session here.