Key messages
- Nature-based Solutions (NbS) can offer multiple benefits to climate, ecosystems and societies, but must not replace or delay decarbonization efforts in other sectors.
- With further warming, Earth System feedbacks may increasingly destabilize ecosystems and undermine the long-term mitigation potential of NbS.
- Investing in NbS now to protect biodiversity will make them more climate resilient and strengthen their ability to act as long-term carbon sinks.
- Much potential for NbS is situated in the less developed and developing countries and in areas inhabited by indigenous peoples who often have limited land rights. Effective decentralized governance and robust regulation and finance can be particularly challenging in these contexts.
- To successfully include NbS in National Determined Contributions (NDCs) and effectively implement policies and direct funding, comprehensive metrics and monitoring, reporting and verification (MRV) are needed that include biodiversity, ecosystem services and local livelihoods, alongside carbon sequestration.
Insight explained
Recent findings highlight that NbS, next to opportunities for carbon dioxide removal, contribute considerably to climate adaptation and risk mitigation. Positive effects include flood control, increased resilience to droughts, biodiversity conservation, socio-economic development and improvements to human health and wellbeing. See insight 10 for more on the benefits of NbS.
One expectation for NbS – offsetting residual emissions – has been set into context within the scientific debate. Scenarios that limit warming to 1.5°C are based on significant assumptions: full decarbonization within 30-40 years, shifting agriculture from carbon source to sink, considerable carbon dioxide removal and maintained resilience of natural ecosystems. Well-designed NbS play a pivotal role – not as a means to delay the phase-out of fossil fuels, but as a much-needed supplement that can contribute to a range of Sustainable Development Goals (SDGs). Importantly, further warming risks altering Earth System feedbacks and destabilizing ecosystems, which may undermine the long-term mitigation contribution of NbS and their benefits to people and the planet. Evidently, this makes rapid decarbonization ever more urgent, and highlights the need to strengthen the resilience of ecosystems through protection and restoration (see Insight 9).
At COP26, parties have an opportunity to address questions of equity and procedural justice that are central to the success of NbS. While cumulative emissions predominantly come from more industrialized countries, much of the carbon-saving potential of NbS has been identified within less industrialized countries, particularly in areas occupied by indigenous communities with insecure rights. There is a risk that NbS could shift the responsibility for decarbonization onto vulnerable communities if there is insufficient regulation.
Extreme events threaten the climate-mitigation potential of forests
- Wildfires have become more extreme both in intensity and frequency, and are burning now in regions that are not typically prone to wildfires. While normal wildfires are often assumed to be “net zero” with regards to CO2 emissions (all CO2 emitted would be taken up by regrowing vegetation), the more frequent occurrence of megafires that burn very large areas (Insight 3) is now likely to change this balance due to ecosystem degradation.
- Events such as the 2015/2016 El Niño caused an extreme and prolonged drought, which fueled extensive and damaging fires. This put some regions of the Amazon under such pressure that plant mortality rates remained elevated for 2-3 years after the event – particularly where forests had already been modified by human activities.
- Even though the net biome exchange of carbon with the atmosphere in most parts of the Amazon still works as a carbon sink, the effects from fire in association with other environmental changes have already turned large parts into an effective net source of carbon to the atmosphere. The south-eastern part of the Amazon basin, particularly, is a net carbon emitter even if the effect of fires is ignored. Here, temperatures during the dry season have strongly increased, precipitation has decreased and deforestation has been especially severe.
These effects reduce the climate-mitigation potentials of forests and other vegetation prone to fires. This needs to be taken into account when assessing the effect of forest-related NbS on CO2 emissions. In the case of the Amazon, wildfires contribute to potentially triggering a climate regime shift towards an open and degraded state in some parts of the basin (Insight 4).
Background
NbS are systems-based approaches to societal challenges such as climate change, biodiversity loss, and social inequality. They are actions that protect, restore and better manage natural or modified ecosystems. Research has shown that NbS can provide relatively low-cost and readily available opportunities for carbon dioxide removal compared to other options. But more than that, well-designed and implemented NbS can deliver multiple benefits for climate change mitigation and adaptation, biodiversity conservation and local livelihoods. Under the mitigation umbrella, however, parties to the UNFCCC increasingly fund the expansion of plantations with non-native species, even though they remove little carbon and place local livelihoods and ecosystems at risk, especially in non-forested ecosystems.
Implications & Recommendations
Fulfilling the Paris Agreement requires rapid emissions reductions in tandem with well-designed carbon dioxide removal, including NbS. COP26 is an opportunity to align the goals and procedures of the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention of Biological Diversity, for instance by adjusting metrics and MRV for NbS.
At a global level, it is suggested that parties at COP26:
- set clear reporting guidelines under Article 6 of the Paris Agreement, as NbS are increasingly included in NDCs. These should be based on comprehensive performance metrics for climate, biodiversity and livelihood outcomes, as well as science-based and transparent MRV;
- tackle the disproportionately small share of NbS in mitigation finance and lack of appropriate multilateral finance and governance structures.
At a national and local level, policy-makers must:
- regulate NbS to avoid shifting the responsibility for decarbonization onto vulnerable communities.
