The United Nations’ Climate Summit of 2022, also known as Conference of the Parties 27 (COP27), ended on November 20, 2022 in Sharm El Sheikh, Egypt (unfccc.int/cop27). Since 1995, the United Nations (UN) has taken the lead in bringing together almost every country to the COP (unfccc.int/process/bodies/supreme-bodies/conference-of-the-parties-cop) to find strategies for each country working together to commit to reducing greenhouse gas (GHG) emissions. Thirty years later, we are still working on it while trying to find new strategies to adapt to climate change and mitigate its impact. 

The 10-page decision text of COP27 (unfccc.int/sites/default/files/resource/1CMA4_1CMP17_1COP27_preliminary_draft_text.pdf) emphasizes the importance of limiting the global mean temperature to increase up to 1.5°C above pre-industrial levels to avoid catastrophic climate change impact. This agreement was already reached at COP21 in Paris seven years ago (cop21paris.org/). It also restates the goal would require substantial and rapid reductions in GHG emissions by 2030, reaching net-zero CO2 by around 2050 and further ongoing net-CO2 removals thereafter (1, 2). However, researchers are disappointed at the lack of calls to phase out fossil fuels. Meanwhile, COP27 closed with a breakthrough agreement on “Loss and Damage” funds for the vulnerable countries. The fund would support less-developed countries that have experienced adverse impact of climate change, such as Somalia where seven millions of people are facing hunger because of an ongoing drought and Pakistan where extreme precipitation left around 1/3 of the country flooded and millions of people displaced this year (nature.com/articles/d41586-022-03807-0). COP27 also made history by including topics such as food, water, and the controversial concept of nature-based solutions (NBS). The term NBS reached the center of the agenda at the COP26 (ukcop26.org/) in 2021 and was a major priority for the UK. However, it was included in and removed from the decision text back-and-forth, eventually being replaced with “protecting, conserving and restoring nature and ecosystems” in the final decision text, the Glasgow Climate Pact. At this year’s COP27, the decision text has one line referring to NBS, showing a breakthrough in global climate change mitigation strategies, because NBS are key complementary methods to reach net zero carbon emissions when implemented with rapid cuts in fossil fuel emissions together (1, 3). NBS become even more important when no concrete steps are in place to cut fossil fuel use. 

The term NBS was first mentioned by the World Bank in 2008 (openknowledge.worldbank.org/handle/10986/6216) (4,5). NBS can generate multiple ecological, social, and economic benefits. First, they can reduce socio-economic exposure to effects of climate change, such as heatwaves and flooding (6). NBS can also reduce socioeconomic sensitivity. Through NBS, individuals, communities and societies can rely on ecosystem services that support human wellbeing and livelihoods. Furthermore, NBS support socio-economic adaptive capacity through improved biodiversity and the involvement of diverse stakeholders, including communities, governments, and researchers. 

A question remains. Why is it taking so long for the term to be adopted? 

Despite the consensus that NBS can play an important role in resolving environmental, societal problems, and mitigating the impact of climate change, there is still not a uniform definition (5). Thanks to a 2022 review of the twenty papers that defined NBS, scientists tried to clarify some ambiguity and identified the core criteria in NBS (5). The conclusion is that NBS are efficient planning and design of solutions inspired and powered by nature to address environmental challenges that are urgent, and provide multiple benefits. This will hopefully facilitate differentiation of NBS from those that do not belong. For example, urban green infrastructure projects can cause gentrification and displacement of low-income residents as governments and developers could use these projects to boost property values (7). These types of projects may provide environmental benefits of reducing flooding risks for some communities but cause social inequity, and they should not be considered or promoted as NBS. 

NBS can be challenging to implement, with issues like lack of investment and barriers for actions over broad landscapes and seascapes crossing jurisdictional boundaries (6). We live in a highly engineered world. About sixty percent of the world’s major rivers have dams and diversion activities (nationalgeographic.com/environment/article/worlds-free-flowing-rivers-mapped-hydropower), 56% of people on earth live in urban areas dominated by impervious surface (weforum.org/agenda/2020/11/global-continent-urban-population-urbanisation-percent/), and 14% of shorelines in the U.S. are hardened (8). We are so used to relying on gray infrastructure for economic development, energy production, water use, and disaster protection that we neglect the observed negative impact such as loss of biodiversity, reduced carbon sequestration, and failure of protection. For example, dam failures in New Orleans during Hurricane Katrina claimed over 1,800 lives and $81 billion in damage (9). In a world where economic development is the priority, we often forget that nature can provide important buffers against extreme weather by protecting houses, crops, water supplies, and vital infrastructure. Although research on NBS has sped up over the last ten years (1), we need more research to evaluate different types of NBS. We also need to see how NBS compare against traditional solutions such as gray infrastructure. We need to compare cost and benefits in the short and long terms at multiple spatial scales to improve understanding of where, when, how, and for whom NBS can support (1). NBS may require a large initial investment, but the smaller maintenance cost and increased benefits because of functioning ecosystems from the NBS in the long term should justify this initial investment. Such research across broad scales and jurisdiction boundaries will provide the basis and incentives for governments to work together. The research often requires multidisciplinary collaboration: physics, chemistry, hydrology, economics, engineering etc., therefore the supporting agencies should consider an effective approach to encourage research across disciplines to promote implementation of NBS. 

We also need to acknowledge that NBS are complementary and need to work with direct fossil fuel emission reduction. Some large GHG emitters tried to get away from more expensive GHG reduction in the routine operations by investing in less expensive NBS (1). We should avoid trying to “greenwash” potential false solutions to climate change.

We must involve indigenous people and consider their land rights when adopting NBS. Indigenous people comprise 5% of the world’s population, yet they use 22% of the world’s land that are home to 80% of the planet’s biodiversity (greenpeace.org/usa/stories/why-indigenous-environmentalism-is-more-important-than-ever/). The peer-reviewed papers on NBS have increased exponentially over time, but only 0.13% considered indigenous peoples or their traditional ecological knowledge (TEK) (10) based on a search at the Web of Science. It is critical to apply a participatory network to involve the indigenous people in harnessing their TEK and protect their land rights. The capacity building is the key to the success of NBS (1). 

With challenges acknowledged and continuously being addressed, we hope to see the incoming COP28 in 2023 refers to NBS in more than one line in its decision pact.

References

1. Seddon, N. Harnessing the potential of nature-based solutions for mitigating and adapting to climate change. Science (80-. ). 376, 1410–1416 (2022).

2. Intergovernmental Panel on Climate. Climate Change 2022 - Mitigation of Climate Change. ipcc.ch/report/ar6/wg3/ (2022).

3. Seddon, N. et al. Getting the message right on nature-based solutions to climate change. Glob. Chang. Biol. 27, 1518–1546 (2021).

4. Mackinnon, K., Sobrevila, C. & Hickey, V. Biodiversity, climate change, and adaptation: nature-based solutions from the World Bank portfolio. Clim. Chang. Adapt. 1–381 (2008).

5.       Sowińska-Świerkosz, B. & García, J. What are Nature-based solutions (NBS)? Setting core ideas for concept clarification. Nature-Based Solut. 2, 100009 (2022).

6.       Seddon, N. et al. Understanding the value and limits of nature-based solutions to climate change and other global challenges. Philos. Trans. R. Soc. B Biol. Sci. 375, (2020).

7.        Shi, L. Beyond flood risk reduction: How can green infrastructure advance both social justice and regional impact? Socio-Ecological Pract. Res. 2, 311–320 (2020).

8. Tavares, K. D., Fletcher, C. H. & Anderson, T. R. Risk of shoreline hardening and associated beach loss peaks before mid-century: Oʻahu, Hawaiʻi. Sci. Rep. 10, 1–10 (2020).

9. Pielke, R. A. et al. Normalized Hurricane Damage in the United States: 1900–2005. Nat. Hazards Rev. 9, 29–42 (2008).

10.      Huntington, H. P. Using traditional ecological knowledge in science: Methods and applications. Ecol. Appl. 10, 1270–1274 (2000).