Fig. 1: Primary sources of pollution and proposed indicators for nutrient and pesticide pollution for the monitoring framework of the GBF. figure 1 a, Indicators for nutrient pollution. b, Indicators for pesticide pollution. Purple, current headline indicators; blue, current component and complementary indicators; yellow, new headline indicators proposed here. The current headline indicator for nutrients is the index of coastal eutrophication potential (ICEP) (Sustainable Development Goal indicator 14.1.1a); for pesticides, it is the pesticide environment concentration (note that pesticide use per active ingredient (also in purple) is necessary to calculate pesticide environment concentration). We suggest that the highest-priority indicators for the GBF should be indicators of nitrogen (N) and phosphorus (P) lost to the environment and risk-weighted pesticide use or environmental concentration. Additional complementary indicators are given in Supplementary Tables 1 and 2. Agriculture is shown topmost in both panels because it is by far the main source of nutrient and pesticide pollution. See ref. 29 for a quantitative ranking of nitrogen and phosphorus sources. Si, silicon.

Full size image Box 1 Indicator types in the GBF monitoring framework Headline indicators are a small set of high-level indicators that capture the overall scope of the GBF’s goals and targets to be used for communication, planning and tracking progress. Countries are requested to provide these indicators in their national reports to the CBD. Component indicators are a larger set of optional indicators to provide complete coverage of all facets of goals and targets. Complementary indicators are optional indicators for thematic or in-depth analysis.

Show more Nutrient pollution For nutrient pollution, the current headline indicator is the index of coastal eutrophication potential6. Although this is an established indicator for marine pollution in the UN Sustainable Development Goals, its narrow focus on the ratios of riverine nitrogen, phosphorus and silicon loading greatly limits its relevance to the broader problem of the effects of nitrogen and phosphorus pollution on biodiversity and ecosystem services. It is also an indicator of nutrient sinks and impacts, rather than sources of nutrient pollution (Fig. 1). There is good evidence that indicators of nutrient sources are much more effective in informing and implementing policy to reduce nutrient pollution7.

We urge the ad hoc technical expert group of the CBD (the CBD AHTEG) and governments to raise the profile of indicators that focus on the sources of nutrients lost to the environment in the GBF monitoring framework. This could include:

Promoting indicators of agricultural nitrogen and phosphorus surplus (an estimate of excess nitrogen and phosphorus agricultural fertilizer lost to the environment) to headline indicators;

Complementing these with additional component indicators of the sources of nitrogen and phosphorus pollution, including agricultural nitrogen and phosphorus efficiency (the per cent of nitrogen and phosphorus taken up by crops), nitrogen and phosphorus footprints8, and gaseous nitrogen emissions from agriculture, transport and industry; and

Encouraging further development of the component indicator on wastewater treatment so that it can be used to estimate nitrogen and phosphorus pollution.

Together, these indicators would be much better aligned with the objectives of target 7 and provide reasonably comprehensive coverage of nitrogen and phosphorus pollution sources (Fig. 1). These could be completed with a broad range of complementary indicators of nutrient pollution. Agricultural indicators are currently available at national, regional and global levels. For example, agricultural nitrogen and phosphorus efficiency data are directly available from FAOSTAT, and agricultural nitrogen and phosphorus surplus can easily be derived from FAOSTAT cropland nutrient budgets9 (see Supplementary Table 1 for an overview of available indicators, data sources and applications).

Pesticide pollution For pesticide pollution, the current headline indicator of pesticide environment concentration does not yet have agreed-upon methodology, so it will be up to the CBD AHTEG to work with partners to guide development3.

This indicator is intended to be based on the predicted environmental concentration of pesticides, which is one part of the methodology used by Tang et al.10 to calculate pesticide risk. It uses a modelling approach to estimating concentrations of pesticide active ingredients in the environment, taking into account active ingredient use and physicochemical properties as well as environmental data. It is an important first step in estimating risk for biodiversity but lacks the key final step of converting environmental concentrations of active ingredients into risk (as in Tang et al.10). Many governments are not yet willing to report pesticide risk using the risk score as in Tang et al.10 or total applied toxicity as in Schulz et al.11, in spite of the recent adoption of the risk score in the environmental performance index12.

Continued work can solidify the scientific foundations of these indicators and facilitate their wider use. These indicators should also be improved to account for risks related to pesticide mixtures, interactions with other stresses and sublethal effects, among others13. However, this should not be used as an argument for delaying the use of the objective and transparent indicators of pesticide risk that are currently available (Supplementary Table 2). Tang et al.10 highlight the value of analysing pesticide risks on a global level, and countries such as Denmark have demonstrated over the past decade that the regular reporting of pesticide risk is possible without large administrative barriers14.

Central to the use of pesticide risk indicators will be more precise reporting of pesticide use data on a product or active ingredient level, as there exist large differences in the toxicity of different pesticide active ingredients. We urge the scientific community, the CBD AHTEG and governments to work together to find a common means for reporting pesticide active ingredient- or product-level use, otherwise it will not be possible to compare and collate pesticide risk reported by countries and will leave the door open to using indicators of pesticide risk that do not have a strong scientific basis and are not sufficiently transparent. For example, the collection of active ingredient- or product-level pesticide use data could be coordinated by the Food and Agriculture Organization of the United Nations (FAO), which already collects aggregate country-level pesticide use data.

Translating global targets into national and regional contexts During the negotiations of the GBF and in our interactions with governments both leading up to and at COP15, many governments were explicitly or implicitly working under the assumptions that (1) nutrient and pesticide pollution targets referred only to agricultural sources and that (2) quantitative objectives would need to be directly translated from global to national scales. Global targets are important communication tools and policy drivers, emphasizing the widespread nature of nutrient and pesticide pollution. However, adapting these targets to national and regional levels is a challenging but necessary task, given the heterogeneous economic, cultural, political and environmental contexts that drive pollution, reduction potentials, trade-offs and their interconnectedness (as described, for example, in refs. 10,15,16,17).

As one example, Zhang et al.9 show how differences in national conditions can be taken into account when halving the global agricultural surplus of nitrogen, while simultaneously maintaining food security. Some countries, such as China and the Netherlands, have very high nitrogen surpluses that leave ample opportunity for reducing nitrogen losses from agriculture. However, other countries have insufficient agricultural nitrogen inputs, leading to a loss of soil fertility. Zhang et al.9 estimate that China could reduce nitrogen surplus by over 70% by 2050 while increasing food production by over 20%, whereas sub-Saharan Africa will need to almost triple its nitrogen inputs (with an ensuing doubling of nitrogen surplus) to improve soil fertility and double food production by 2050. Further, in many countries, large and cost-efficient reductions in nitrogen and phosphorus lost to the environment can be made through improving wastewater treatment and reducing NOx emissions from transport and industry18 with important benefits for human health.

Similarly, pesticide use and risks — as well as their drivers, reduction potentials and role in agricultural production — differ markedly, so global numerical objectives should not be applied directly to national levels10,19.

Reducing trade-offs with other policy goals requires a more holistic governance framework Addressing nutrient pollution requires a multisector approach that accounts for agricultural and non-agricultural sources such as wastewater and fossil fuel combustion. Similarly, pesticides are not exclusively used in agriculture, but are also used in forestry, aquaculture, municipal spaces and non-professional applications. However, the dominance of agriculture as the main driver of both nutrient and pesticide pollution means that a joint and systemic approach to the governance of pollution from agri-food systems is critical.

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