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Green Shoots: A Burning Embers for biodiversity?

2023; Wiley; Volume: 29; Issue: 14 Linguagem: Inglês

10.1111/gcb.16727

1365-2486

Richard T. Corlett,

Ecology and Vegetation Dynamics Studies

Conservationists were generally pleased with the agreement reached at the UN Biodiversity Conference in Montreal last December (CBD, 2022). The Kunming-Montreal Global Biodiversity Framework—the GBF, for short—was 2 years late, but it was more ambitious than many expected and, for a time, focused global attention on the perilous state of wild species and ecosystems. However, the agreement is just one step towards halting global biodiversity loss and its full and effective implementation is by no means guaranteed. The GBF is haunted by the ghost of the previous global framework, the Strategic Plan for Biodiversity 2011–2020, agreed by Parties to the CBD in Nagoya in 2010. This plan included 20 'Aichi Targets', none of which were fully met by 2020, although considerable progress was made on some. Among the key reasons for these failures were the lack of clarity in the targets and the fact that most were difficult or impossible to monitor (Butchart et al., 2016). It is no coincidence that one target which was almost achieved was the agreement, as part of Aichi Target 11, to protect at least 17% of the terrestrial and inland water area for biodiversity. This goal was ecologically arbitrary, but it was clear and easily monitored at the national and global level. Target 11 also had additional, qualitative targets, requiring the new protected areas to be 'effectively and equitably managed, ecologically representative and well connected…', but few, if any, countries met these in full. Although the problems with the Aichi targets were in everyone's mind when the GBF was being drafted, Target 3 of the new agreement is basically an upgrade of Aichi Target 11, with 17% by 2020 increased to 30% by 2030, and with a similar range of qualitative targets, including that these areas are 'effectively conserved and managed through ecologically representative, well-connected and equitably governed systems of protected areas…'. Inevitably, '30 by 30' has become the most cited component of the GBF, giving the impression that if this quantitative target is achieved the agreement will have been a success, however, the additional area is chosen and managed. The review by Arneth et al. (2023) in this issue addresses this excessive focus on area coverage at the expense of protected area effectiveness. It considers not only impacts on biodiversity—the focus of the GBF—but also impacts on the interconnected issues of nature-based climate mitigation, through carbon fixation and storage, and food production. Land and sea are both treated, since the 30% target applies also to marine areas, and they attempt to simplify the complex synergies and trade-offs between biodiversity, carbon and food in a way that can be summarized and communicated visually. Although their own analysis is global, the same approach could be used at the national and regional scale. Effectiveness in the context of this study means effectiveness for biodiversity conservation and is defined to include where protected areas are sited as well as how they are protected and managed. A highly effective protected area is optimally sited, well protected and well managed, while an ineffective one is in the wrong place and/or poorly protected and managed. The paper's 'Green Shoots' visualization (their Figure 1)—inspired by the IPCC reports' iconic 'Burning Embers' diagram for risks from climate change—is therefore based on two axes, the percentage of the total terrestrial or marine area covered by protected areas (from 0% to 50%) and the effectiveness of these areas for biodiversity conservation (from low to high). This rectangle is then coloured from grey to green to indicate increasingly positive outcomes for the three objectives: biodiversity, climate and food. This is done separately for terrestrial and marine areas because the impacts and outcomes differ, giving a total of six visualizations (their Figure 2). These colour transitions represent the judgement of the authors, informed by the conservation literature. Possible futures, such as 30% or 50% protected area coverage with varying effectiveness, can then be plotted on these figures to illustrate likely outcomes for the issues of concern. The relationship between terrestrial biodiversity conservation and protected area coverage and effectiveness is easiest to describe. Increasing coverage at low effectiveness achieves little extra biodiversity conservation, while increasing either coverage with high effectiveness or effectiveness with any level of coverage leads to large gains. If current effectiveness is low and resources for conservation are limited, the best outcomes in their analysis are achieved by increasing effectiveness rather than coverage, which, noticeably, is not an option suggested in the GBF. Carbon storage and biodiversity are generally positively related at large spatial scales (Di Marco et al., 2018), so the global outcomes for climate are similar to those for biodiversity. However, the carbon–biodiversity relationship has considerable scatter, so a protected area system optimized only for biodiversity will not usually be optimal for carbon and the best outcome for climate will therefore be achieved at less than maximum effectiveness for biodiversity conservation. The relationship for food production is more complex, with both synergies and trade-offs (Baldwin-Cantello et al., 2023), and here the graphics are particularly helpful. At low coverage, protected areas benefit agriculture by providing services, such as pollination and pest control, but as coverage increases competition for land is inevitable. For a given coverage, this competition is minimized if the protected areas are concentrated on the land least useful for food production—usually poor soils, steep slopes and high altitudes—but this results in low effectiveness for biodiversity conservation. Maximizing effectiveness requires the ecological representativeness called for in the GBF's Target 3, which means including at least some of the areas that farmers want—fertile soils, shallow slopes and low altitudes. The effects of achieving the '30 by 30' target on food production thus depend critically on how the expansion in coverage is achieved and compromises are inevitable. For marine systems, the projected outcomes for biodiversity and carbon are generally similar to those on land, although the concentration of known carbon pools near the coast (salt marshes, mangroves and seagrasses) mean that large gains can be achieved with small areas. For food, the benefits of increasing marine protected area coverage and effectiveness through replenishing fish populations are expected to outweigh any competition for space, at least up to the GBF's 2030 target. The Burning Embers diagrams in the IPCC reports use colour transitions to show changes in the level of risk for natural and human systems with rising global mean temperatures (Zommers et al., 2020). The risk levels associated with each temperature are aggregated globally and reflect expert judgment, based on the literature. The diagrams are intended to be simple, intuitive and easily understood with only the captions, and have appeared in most IPCC reports since the Third Assessment Report in 2001. This longevity shows their usefulness in communicating complex ideas to a nonspecialist audience, but they have also been subject to criticism, with concerns expressed for their consistency and comparability, and for the lack of transparency in the use of expert judgements. In response, the process for producing the diagrams has become more formalized and standardized. The Sixth Assessment Report in 2022 used an expert elicitation protocol involving a first round of independent, anonymous, judgments, followed by group discussion to develop a consensus (O'Neill et al., 2022). The Green Shoots differ from the Burning Embers in covering two dimensions, area and effectiveness, rather than just one, global mean temperature, but the colour transition from grey to green is simpler and the results appears to be intuitive and easily understood. They also go further than the Burning Embers in not only showing risks but also allowing exploration of the impacts of possible solutions (Arneth et al., 2023). However, the global aggregation of studies makes considerably less sense for biodiversity—particularly terrestrial biodiversity—than for climate, since patterns of biodiversity loss are much less uniform than those for climate change, as also are the relationships between biodiversity, carbon and food production. The Green Shoots are therefore likely to be most useful for analysis and communication at national or subnational scales. Their application to less heterogeneous regions will also go some way to addressing potential criticisms of the reliance on expert judgment. The use of a formal expert elicitation protocol with diverse local experts, literature and other inputs, such as modelling studies, seems more likely to lead to a defendable consensus than trying to aggregate differing experiences and opinions at a global scale. The world is faced with a triple challenge: biodiversity, climate and human well-being (Baldwin-Cantello et al., 2023). We need to communicate the broader consequences of major changes in policy focussed on just one element, such as the GBF, to the nonspecialists who will implement them. Successful communication, visually or in writing, requires simplification, with a trade-off between clarity and accuracy. The compromises made by Arneth et al. (2023) are only one possibility, but their approach is well-argued and ready for immediate application. The author declares no conflict of interest. No data were used in this commentary.