1 Introduction

Biodiversity loss and climate change are deeply intertwined, forming a complex and interdependent crisis [86, 123]. One cannot be addressed without addressing the other [65]. The biosphere plays a role in regulating the climate system, and a stable climate is important for life as we know it. However, the imperative to mutually protect climate and biodiversity has not yet been sufficiently integrated in environmental governance. Climate change and biodiversity loss continue to be treated as separate issues and addressed in isolation in the policy arena [99]. This policy fragmentation has particular implications for biodiversity. While most biodiversity policies and measures are associated with positive effects on the climate, some climate policies and measures may have negative effects on biodiversity [93]. Research has called for the integration of climate and biodiversity policies and has increasingly highlighted the need to integrate biodiversity concerns into climate policies [7, 24, 93]. The role of climate actors in this climate-biodiversity nexus has become particularly critical, which may require a shift away from the mindset that climate change is the single most important problem towards more integrative environmental governance [113]. However, addressing cross-cutting issues has proven challenging for governmental actors, who are often fragmented and siloed [25].

Are non-governmental organisations (NGOs) any different? As non-profit organisations promoting public good, NGOs have emerged as integral actors in environmental governance [5, 95]. In particular, they have gained significant influence in national and international climate and biodiversity policy processes [43, 61, 75, 87]. Optimists would argue that this is a positive development for strengthening the climate-biodiversity nexus. NGOs are seen as more systemic in their policy approaches to environmental issues [121], with the ability to connect different issues across time and space. NGOs are also often critical of short-term solutions that create long-term problems, such as deep seabed mining for green energy transitions [56, 114]. They can act as pioneers or “vehicles of change”, challenging the status quo and providing opportunities to foster social change that may not be attainable through governments [8, 64]. Overall, NGOs are expected to be a driving force in advancing ambitions to link the two issues and promote an integrated approach to climate and biodiversity protection. They could be important actors in avoiding a scenario where climate efforts come at the expense of biodiversity, and where we miss opportunities to leverage ecosystem-based approaches to climate action.

However, at the same time, NGOs have become increasingly specialised [98], serving as advocates for specific interests while pursuing their own agendas and objectives. Many NGOs focus on specific issues such as climate change and biodiversity conservation, which is in turn refined into specific areas like forests, birds, wetlands, and others. Even the largest NGOs are internally organised into distinct issue-based departments that reflect the fragmented governance landscape (e.g., WWF [117]). These NGOs also compete for limited resources to ensure their survival and growth [47, 72], much like government ministries and international institutions. They tend to have tunnel vision and lack the incentive to promote issues beyond their remit or to cooperate with other NGOs.

Against the backdrop of these contrasting views, and in response to broader calls for more research on the role of non-state actors in advancing a nexus approach to climate change and biodiversity loss [35, 104, 121], we address the following question: To what extent do NGOs facilitate the integration of climate and biodiversity policies and measures? Our analysis focuses on climate-related NGOs operating in Germany. Given the long history of NGO engagement and their significant role in shaping German climate policy [17, 54], German climate NGOs represent a mature case for analysis. We first identified 107 German NGOs with a policy focus on climate change and categorised them based on their specific area of focus. We then examined the extent and manner in which these NGOs address the relationship between climate and biodiversity, and tracked how their approaches have changed over time. For this analysis, we developed a typology of the climate-biodiversity nexus, consisting of two distinct types of issue linkage: (1) how the issues themselves are linked, and (2) how responses to one issue influence the other. Considering the directionality of these interactions, we delineated seven types of climate-biodiversity interactions. For our dataset, we used 190 annual reports published by the 107 German climate NGOs spanning two periods, 2016/2017 and 2021/2022, to enable longitudinal analysis. We identified references to climate-biodiversity interactions within these reports and classified them into one of the seven types.

The analysis shows a considerable increase in the extent to which German climate NGOs recognise the interconnectedness between climate and biodiversity. However, some types of linkages remain insufficiently addressed. Critical gaps remain, particularly concerning the role of biodiversity in stabilising the climate and the unintended negative consequences of climate policies and measures on biodiversity. Overall, German climate NGOs are trailing in addressing the climate-biodiversity nexus, falling short of a holistic approach to environmental protection. We stress the importance of coordinating issue-specific departments within individual organisations as well as cooperation among NGOs. Joint efforts would enable complementary approaches and facilitate progress towards a climate-biodiversity nexus.

This article is structured as follows. We first briefly discuss the issue linkages between climate and biodiversity and the role of NGOs in linking the two. We then explain the methods used to analyse how German climate NGOs address the climate-biodiversity nexus. The findings are then presented, highlighting the evolution of how NGOs address the different ways in which climate and biodiversity are linked, and which themes and narratives are dominant. Finally, we put the findings into perspective and explore the implications for the role of NGOs in addressing the climate-biodiversity nexus.

2 Conceptual framework

2.1 The interconnectedness of climate and biodiversity

Climate change and biodiversity loss are closely coupled, with one inevitably exacerbating and influencing the other [34, 70, 123]. Scientific evidence has long pointed to the threat that climate change poses to biodiversity, as severe climatic changes are likely to result in unsuitable living conditions for many species [9, 10, 55, 68, 84, 107]. Increasing biodiversity loss can in turn exacerbate climate change by disrupting the functioning of ecosystems and reducing their ability to sequester and store carbon [49, 50]. Those concerned about biodiversity loss have called for urgent action to mitigate climate change [42, 101, 107, 119].

Although there are many synergies, climate policies and measures can also have negative impacts on biodiversity, while most efforts to protect biodiversity do not have such impacts on the climate system [7, 93]. According to the Problem Shifts Database, 21% of the cases collected through a global survey involve a shift from climate to biodiversity [58]. An example is reforestation with plantation forests as a climate mitigation measure to increase carbon sequestration, which can accelerate biodiversity loss due to suppression and conversion of natural forests [36, 45]. Renewable energy can also negatively impact biodiversity, as wind turbines can harm birds and bats [3, 26] and solar panels require large areas of land, leading to the clearing of ecosystems and land use change [33, 48]. To safeguard climate and biodiversity simultaneously, it is crucial not only to identify promising win–win solutions, but also to identify and prevent inappropriate interventions that could potentially harm one or even both of these issues [93, 101].

To avoid such negative outcomes and maximise synergies, responses to climate change must be designed with potential impacts on biodiversity in mind [34, 92]. This starts with recognising the interconnected nature of climate change and biodiversity loss, and that neither can be stopped without stopping the other [28, 123]. It is also about understanding the different ways in which climate change can affect biodiversity and vice versa, and how climate policies and measures may impact biodiversity and vice versa. Appropriate policy interventions would need to be devised and their impacts assessed before implementation. They would also need to be regularly reviewed to evaluate their effectiveness in preventing or mitigating dangerous trade-offs and maximising co-benefits [34, 101].

Supporting the integration of ambitious climate and biodiversity action requires coordination and assistance from various stakeholders in science, governance, and civil society [29], suggesting that NGOs, as key civil society actors, are potentially relevant stakeholders in the integration of climate and biodiversity protection efforts.

2.2 NGO involvement in climate governance and their potential role in linking issue areas

NGOs have emerged as key actors in climate governance, playing diverse and critical roles at different levels of governance [62]. Governments increasingly recognise NGOs as important partners in governance processes, acknowledging their legitimacy and contributions [40, 75]. These organisations serve as key connectors, bridging levels of governance from local initiatives to global agendas [5, 75, 76, 97]. In addition, NGOs are actively involved in multilateral processes ranging from the local to the global level. For example, they contribute to the formulation of national climate plans, monitoring national climate efforts, and testing mitigation and adaptation strategies [20]. Their expanding role extends to participation in treaty-making and implementation processes within prominent international regimes and organisations [76]. In particular, NGOs play an important role in the Conferences of the Parties to the United Nations Framework Convention on Climate Change [20, 66].

NGOs engage in climate governance through a variety of activities and roles. They act as experts, mediators, and brokers in negotiations, or are perceived as legitimising policy outcomes [23, 75, 125]. Lewis [63] highlights the catalytic role of NGOs in global governance, which is characterised by an NGO’s ability to stimulate, facilitate, or contribute to societal transformation. NGOs do this by engaging with government representatives and seeking to influence political processes [12, 23, 44], including international climate negotiations [5, 75, 85, 95]. This has been possible due to alternative sources of power that NGOs possess, including knowledge and information sharing [6, 11, 75]. NGOs often use their expertise in international environmental negotiations to influence policymakers and decision-making processes. As international environmental issues such as climate change are characterised by a high level of complexity, expertise is a valuable resource of NGOs, and policymakers often consult NGOs to get advice on national negotiating positions and information on negotiation strategy and process [23].

Environmental NGOs play a crucial role in bridging disparate sustainability issues. This role is exemplified both by NGOs with a broad focus and by collaborations between specialised NGOs. Greenpeace and Friends of the Earth are large organisations working on a wide range of issues, from climate change to biodiversity conservation. These organisations typically have specialist departments dedicated to specific issues and work through internal coordination. For example, the World Wide Fund for Nature (WWF) office in Germany has departments focusing on climate and energy, forests, biodiversity, and plastics [117]. However, as environmental challenges have become more complex, NGOs have increasingly specialised in a single environmental issue. Their distinctiveness lies not only in their specific issue, but also in the nature of their activities, such as research or activism. Notable examples include The Nature Conservancy, which prioritises land and water conservation alongside extensive research, and the Climate Action Network, which focuses on advocacy and activism on climate change.

There is a risk of fragmentation in the NGO landscape due to specialisation, but there are also benefits to be gained from such focused expertise. What is important is that NGOs need to prioritise collaboration and maintain a holistic approach, avoiding tunnel vision on their individual issues and objectives. Encouragingly, positive steps are being taken to address environmental issues, where NGOs have been expanding their scope, reflecting a shift towards recognising and addressing the complex interplay of various issues. An illustrative example is the growing cooperation between human rights and environmental NGOs in recent decades. Their cooperation has led many humanitarian NGOs, such as the German NGOs Brot für die Welt or MISEREOR, to incorporate environmental concerns, including climate change, into their programmes [18, 67]. These NGOs have progressively recognised their common goals and the benefits of developing collective strategies and uniting their constituencies. In particular, they acknowledge that such efforts increase their influence with international corporations, governments, and international organisations [81]. These joint initiatives go beyond mere mutual support and involve active and sustained participation in long-term collaborative advocacy. By pooling resources and expertise, NGOs amplify their impact and gain significant leverage in promoting positive change [71].

Similar trends can be observed among environmental NGOs, as some of these organisations have broadened their purview to explore the intersections between their primary concerns and those of other NGOs. For example, numerous climate NGOs have become accredited to the Convention on Biological Diversity and regularly participate in its Conferences of the Parties. Their efforts are helping to identify key areas for coordinated action on both climate and biodiversity. However, the extent to which these NGOs recognise and integrate the different issues they address remains unclear. This represents a critical gap in the existing literature that we aim to fill.

3 Methods and data

We define climate NGOs in Germany as non-profit organisations headquartered in Germany and working independently from the government on climate-related issues or driven by the goal to protect the climate. Notably, these NGOs do not need to have climate protection as the primary objective, but we cast the net wide to include NGOs with activities in relation to climate change. Our analysis began with identifying these NGOs, which added up to 107 in total (Appendix I). The process started with the list of German NGOs working on climate change extracted from the EU transparency register, and was supplemented by the German NGOs that have been approved as observers to the UNFCCC. These NGOs were then screened to ensure they are NGOs registered as associations or similar non-profit organisational forms with headquarters in Germany. We consulted every organisation’s website to examine whether climate change or issues clearly related to climate change, such as climate justice, are listed as one of the NGO’s thematic foci, if the organisation lists combating climate change as its goal/mission, or if it implements projects that are thematically related to climate protection. Most of these NGOs have at least one publicly available annual report from either the years 2016/2017 or 2021/2022, which we used for analysis, but those that do not were removed. Lastly, snowball sampling was applied whereby we included a small number of German climate NGOs additionally identified during the analysis of the annual reports.

To highlight the diversity of the NGOs analysed and to identify patterns in how different NGO types address the climate-biodiversity nexus, the NGOs were categorised into different groups. This was done primarily based on the constituencies outlined by the UNFCCC [111]. The category of humanitarian was added to better separate humanitarian NGOs from purely environmental NGOs. For the NGOs that were not UNFCCC-accredited, the classification into the categories was done by consulting the organisations' websites. Table 1 presents the categorisation of 107 NGOs. A list of all NGOs, including a brief description of each and whether they have a nature conservation focus, can be found in Appendix I.

Table 1 Classification of 107 German climate NGOs into seven different categories
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We then conducted an analysis of references to climate and biodiversity linkages found in the annual reports of the 107 NGOs. To facilitate a meaningful comparison over time, a five-year interval was selected, 2016/2017 and 2021/2022, which maximised the duration for longitudinal analysis without compromising data availability. Annual reports are a suitable source of data because most German NGOs publish them as part of Transparency International’s initiative Transparent Civil Society [109]. These reports provide information on the vision, mission, and goals of the organisations, as well as their key activities in the reporting period, such as fieldwork, campaigns, projects, and research initiatives. Appendix I lists the annual reports that were used for analysis per NGO. Through the data collection process, a total of 190 annual reports were gathered, comprising 85 reports from the years 2016 or 2017, and 105 reports from the years 2021 or 2022.

The analysis involved searching the annual reports for mentions of biodiversity, using the key words “biodiversity”, “biodiverse”, “biological diversity” and “species” (in their respective German translations). Once a statement containing such key words was found, the paragraph containing the statement was examined carefully to determine whether biodiversity was in some way linked to climate, and if so, in what ways the two issue areas were linked by the NGO. Through this process, and by drawing on relevant literature, we identified seven different types of climate and biodiversity issue linkages, which we present in Table 2 in the form of a typology. The types of issue linkages were then operationalised using the examples from the annual reports and literature.

Table 2 A typology of the climate-biodiversity nexus and examples from the annual reports to illustrate how the coding was done
Full size table

The seven types are organised into two broad groups. The first is a general recognition that climate change and biodiversity loss are linked, and that one may negatively affect the other. For example, a changing climate will reduce biodiversity, and reduced biodiversity will further exacerbate climate change. There are three such linkages in our typology, depending on the direction of the perceived negative impact. The other major group is the recognition that certain policies and measures for climate or biodiversity may have consequences for the other. There are four such types in our typology, depending on the direction and nature (positive or negative) of the impact. For example, windmills for renewable energy production may lead to collisions with birds and bats, and thus negatively affect biodiversity [3, 26]. The literature suggests that climate policies and measures can have both positive and negative impacts on biodiversity protection. However, biodiversity policies and measures only have positive effects on climate protection, so the other direction is not considered.

4 Results

4.1 NGOs increasingly recognise the nexus between climate and biodiversity, but overall recognition remains limited

The results show that references to the climate-biodiversity nexus have strongly increased in both total number and across all types of linkage (Table 3). In 2016/2017, only 22 NGOs recognise a linkage between climate and biodiversity; the majority of the NGOs (74%) does not refer to any of the climate and biodiversity linkages. In 2021/2022, however, 46 NGOs make a reference to the climate-biodiversity nexus, constituting 45% of the NGOs. The observed 20% increase over the period of five years is substantial, highlighting a strong increase in acknowledgement of the climate-biodiversity nexus amongst Germany’s climate NGOs. Notably, the recognition of the general issue linkage between climate change and biodiversity loss (i.e., “climate change ↔ biodiversity loss”) and of the interplay between climate and biodiversity policies and measures (i.e., "climate policy ↔ biodiversity policy") has experienced substantial increases, indicating an increasing awareness of the intertwined nature of the climate and biodiversity crises and the need for an integrative approach. Although there has been considerable progress, it is important to note that the significance of biodiversity has so far only reached half of the German NGOs working on climate change, indicating that overall knowledge among the NGOs remains limited.

Table 3 Number of NGOs referring to each type of climate and biodiversity linkage in 2016/2017 and 2021/2022
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There is also considerable variation in the extent to which different types of linkages are addressed. While linkages are generally and increasingly recognised, most types are barely acknowledged by NGOs and crucial topics receive little attention. For example, NGOs rarely acknowledge how biodiversity loss exacerbates climate change (i.e., “biodiversity loss → climate change”) and how biodiversity policies and measures help protect the climate (i.e., “biodiversity policy → climate protection”), indicating that the role of biodiversity in stabilising the climate is generally underappreciated. In addition, the possibility that climate policies and measures may have negative impacts on biodiversity (i.e., "climate policy → biodiversity loss") has gained slightly more attention over the five years, but is still a very under-recognised type of issue linkage.

There are differences in how different types of German climate NGOs address the climate-biodiversity nexus. Environmental NGOs show an above-average frequency of references to the climate-biodiversity nexus in both the 2016/2017 and 2021/2022 periods, placing them at the forefront of NGOs in recognising this link. Conversely, other groups categorised as “farmers” or “business and industry” appear to lag behind in this regard. It is noteworthy that all six organisations that highlight the problem shift from climate to biodiversity in both time periods advocate for both nature conservation and climate protection. Furthermore, most of these NGOs tend to be smaller in size.

4.2 NGOs increasingly acknowledge the adverse effects of climate change on biodiversity, yet overlook biodiversity loss as a driver of climate change

There is some recognition of the negative impact of climate change on biodiversity (i.e., “climate change → biodiversity loss”), and this is also increasing over time, albeit by a small margin. For instance, Bodensee-Stiftung [14] highlights the adverse effects of climate change on biodiversity, as does the Münchener Rück Stiftung [73], which takes this approach in the context of the Panguana tropical rainforest. Additionally, two research institutes, Thünen-Institut [108] and Alfred-Wegener-Institut [4], specifically study the impacts of climate change on biodiversity, the former focusing on agriculture and the latter addressing the issue in the context of marine biodiversity. The German Institute of Development and Sustainability [37] and Öko-Institut [82] argue that climate change will have a strong impact on biodiversity, citing the Intergovernmental Panel on Climate Change. Other German climate NGOs have also expressed concern about the consequences of climate change for species (GermanZero [38], Greenpeace [41], Heinrich-Böll-Stiftung [46], Institut für Klimaschutz, Energie und Mobilität [52], Klima-Allianz Deutschland [60], Naturschutzbund Deutschland [78]), and call for a rapid phase-out of fossil fuels “in order to prevent a further worsening of the climate crisis—not at least because it also endangers biodiversity” ([78], p. 10).

An increasing number of NGOs is addressing the interplay between the climate crisis and biodiversity loss (i.e., “climate change ↔ biodiversity loss”). A notable number of NGOs recognises the linkage in the sense that the same anthropogenic activities are causing both problems. For example, Heinrich-Böll-Stiftung [46], OroVerde [83], Südwind [105], Deutsche Umwelthilfe [30], Greenpeace [41], Transport & Environment [110], and Campact [22] point to mining, natural rubber production, deforestation, fast fashion, biofuels, and highway construction as leading to biodiversity loss and climate change. Agriculture in particular is underscored as a key driver by Naturschutzbund Deutschland [78], Klima-Allianz [60], Bodensee Stiftung [15], ProVeg [91], and the Institut für ökologische Wirtschaftsforschung [53].

Germanwatch in particular has long emphasised that climate change and biodiversity loss should not be considered as separate issues, but rather as “interconnected crisis landscapes” ([39], p. 7). While such an explicit recognition of the direct issue linkage was scarce in 2016/2017, this joint/double crisis narrative has become prevalent in 2021/2022. This seems to have been noticed by Rettet den Regenwald, which states that “the climate crisis has finally become a top issue in society, while the mass extinction of animal and plant species is often overlooked or considered less urgent; this now seems to be changing” ([94], p. 10), see also Bund für Umwelt und Naturschutz Deutschland [19], Deutscher Naturschutzring [32], Germanwatch [39], Greenpeace [41], Klima-Allianz [59], Naturschutzbund Deutschland [78], WWF Deutschland [115]. And it is not only the large NGOs that have taken up the narrative, but also smaller NGOs such as Nationale Naturlandschaften [77], Institut für ökologische Wirtschaftsforschung [53], and Bodensee-Stiftung [15].

However, climate NGOs in Germany have not yet fully recognised biodiversity loss as a key driver of climate change (i.e., “biodiversity loss → climate change”). Only one NGO, Heinrich-Böll-Stiftung, mentions biodiversity loss as a driver of the climate crisis [46]. This may be due to the fact that the issue of biodiversity loss is not one of their primary concerns.

4.3 Awareness among NGOs of the link between climate and biodiversity policies is increasing, but attention to negative impacts such as problem shifting from climate to biodiversity remains limited

In 2016/2017, several NGOs recognise the nexus between climate protection and biodiversity conservation and the positive impact that protecting one can have on the other (i.e., “climate policy ↔ biodiversity policy”). This number has increased substantially between 2016/2017 and 2021/2022, with NGOs increasingly recognising the synergies between climate and biodiversity policies and measures.

In particular, there has been a marked increase in the number of NGOs highlighting the positive effects that climate policies and measures can have on biodiversity (i.e., “climate policy → biodiversity protection”). For example, Bioland Stiftung [13] emphasises the role of soil in storing carbon but also in protecting biodiversity, and the farmers NGO IFOAM underscores the importance of climate-friendly agriculture for biodiversity protection [51]. Several NGOs such as AGDW [2] and Rettet den Regenwald [94] emphasise the benefits that sustainable forest management as a climate protection measure can have on biodiversity conservation. Fairtrade Germany, OroVerde, Stiftung Naturlandschaften Brandenburg and Naturschutzbund Deutschland run reforestation initiatives in this context. Several NGOs have climate projects in the Global South that also contribute to enhanced biodiversity protection on the ground, including Münchener Rück Stiftung [74], WasserStiftung [120], and Stiftung Allianz für Entwicklung und Klima [102].

Some NGOs have also taken initiatives to protect biodiversity for the climate (i.e., “biodiversity policy → climate protection”). For example, BUND has undertaken a floodplain restoration project to protect carbon sinks [19]; Plant for the Planet is planting trees to increase carbon sequestration [88]. A common theme is the importance of ecosystems for climate regulation (e.g., CDP Europe [21]). Stiftung Naturlandschaften Brandenburg [103] protects wilderness areas for existing species and carbon sequestrating ecosystems, while Michael Succow Stiftung ([69], p. 37) is particularly committed to the preservation of peatlands as they "make a significant contribution to climate protection and preserve unique plant and animal species". Similarly, Zoologische Gesellschaft Frankfurt ([126], p. 6) considers protected areas and wilderness to be "the foundation for biodiversity conservation and our best tool for mitigating climate change". The WWF Deutschland [116] campaigns for rainforest protection in the same vein (see also AGDW [1], Naturstiftung David 80], OroVerde [83], Robin Wood [96]). Furthermore, Institut für ökologische Wirtschaftsforschung [53] argues that wind and solar energy can contribute to species conservation if the systems are properly implemented, while other NGOs advocate for biodiversity-friendly agriculture and food systems that benefit the climate system (Umweltinstitut München [112], Heinrich-Böll-Stiftung [46, Slow Food Deutschland 100]).

However, the negative impacts of climate policies or measures on biodiversity (i.e., “climate policy → biodiversity loss”) remain insufficiently addressed by German climate NGOs. So far, the focus has been on the positive effects, or “climate protection is biodiversity protection” ([124], p. 13), even though climate policies and measures can sometimes lead to adverse impacts on biodiversity, a phenomenon known as environmental problem shifting [57, 122]. Yet a small but growing number of NGOs recognises the risk of problem shifting and points to relevant examples in the German context. Deutsche Umwelthilfe [31] expresses concern about the negative impacts of the expansion of renewable energy, such as wind turbines and power lines. Similarly, Naturstiftung David [79] recognises the impact of hydropower on various species. These NGOs argue that, while climate protection and nature conservation should complement each other, “all too often they stand in opposition to each other” and collide (Naturstiftung David [80], p. 28, see also Rettet den Regenwald [94]).

NGOs concerned about the risk of problem shifting report on what they see as potential solutions to the issue. These include careful planning in the development of solar parks by taking into account ecology and biodiversity (Bodensee-Stiftung [15]); data collection by, for example, setting up a platform for reporting bird fatalities caused by power lines (The Renewables Grid Initiative [106]); and critical analysis of climate policies for unintended consequences (Rettet den Regenwald [94]). More fundamentally, some NGOs argue that societies need to give “equal priority to the aspects of climate protection and nature conservation” ([80], p. 28), and argue against prioritising one issue over the other, stressing that climate protection should not be pursued uncompromisingly at the expense of biodiversity [94].

The call for joint protection of climate and biodiversity is growing. In contrast to 2016/2017, when only one NGO made this demand, this narrative is more prominent in 2021/2022. The Carbon Disclosure Project underlines this viewpoint by stating that “there is increasing realization that the global effort to combat climate change cannot be effective without addressing the nature crisis simultaneously” ([21], p. 6). BUND ([14], p. 22) also echoes this message by calling for “holistic protection of different environmental goods”, including the climate and biodiversity. Deutsche Umwelthilfe ([30], p. 2) argues that “climate protection and biodiversity belong closely together”, underscoring the significance of intact ecosystems in mitigating the impacts of global warming and at the same time slowing down species extinction. Heinrich-Böll-Stiftung recognises that “the world faces the enormous challenge of embarking on a new, sustainable development path that protects the climate and preserves biodiversity” ([46], p. 13). The Potsdam-Institut für Klimafolgenforschung also acknowledges the need for holistic environmental protection [89] and, along with Rettet den Regenwald [94], refers to the joint scientific outcome of the Intergovernmental Panel on Climate Change and the Intergovernmental Platform on Biodiversity and Ecosystem Services and their key finding that neither problem can be successfully tackled unless both are tackled together [92].

5 Discussion

German NGOs working on climate change have made substantial strides in addressing the climate-biodiversity nexus in recent years. They have expanded their focus beyond single issues to a more holistic view of environmental concerns. In doing so, they have assumed the role of intermediaries, linking various issues and recognising the complex interdependencies among them. NGOs appear to have the potential to be more progressive in recognising the nexus than other governmental and intergovernmental actors that are highly siloed [16].

However, there is still room for improvement, as these NGOs may not fully recognise the climate-biodiversity nexus. In particular, the vital role of biodiversity in stabilising the climate is not given sufficient attention, and the negative impacts of climate policies and measures on biodiversity are often overlooked. As a result, our study suggests that these NGOs have yet to take a leading role in integrated environmental protection. To move forward, they need to bridge different issues and advocate for transformative changes in environmental governance. To achieve this, climate NGOs should recognise the interplay between climate and biodiversity objectives and align their objectives accordingly, promoting synergies and mitigating trade-offs between climate and biodiversity policies. This can be done at two levels: within NGOs and between NGOs.

Exchange and cooperation between different departments within the same organisation could be encouraged to achieve co-benefits and ensure that biodiversity is not undermined. As the analysis has shown, it is helpful to have NGOs working on a wide range of environmental issues, rather than focusing solely on climate advocacy, as they are more likely to be aware of the issue linkages. They also stand out as the only type of NGO that recognises the potential negative effects of climate policies and measures on biodiversity. NGOs that have integrated climate and biodiversity protection within their organisation are at the forefront of holistic climate and biodiversity protection. Although internal coordination has its inherent limitations, this indicates that integration of environmental issues within NGOs could be effective in advancing efforts to promote the climate-biodiversity nexus. This is particularly relevant for large NGOs that work on multiple issues through specialised departments.

We also suggest that there is an opportunity for German climate NGOs to collaborate both within the climate domain and beyond. Increasingly, NGOs are collaborating in order to increase their impact and achieve shared goals [27, 72]. This collaboration facilitates information exchange and distribution, creating a network that allows them to complement each other’s expertise and fill knowledge gaps. In theory, cooperation could support the integration of climate and biodiversity actions in environmental governance, particularly if different types of NGOs recognise different types of issue linkages between climate and biodiversity. An example of such cooperation is the joint report by WWF International and Climate Focus that examines the synergies between Nationally Determined Contributions and National Biodiversity Strategies and Action Plans, promoting an integrated approach to climate and biodiversity action [118].

Existing NGO alliances, such as Klima Allianz Germany, could serve as a forum for connecting climate NGOs and facilitating knowledge exchange. Large, multi-sectoral NGOs could also play a prominent role. They have an above-average understanding of the climate-biodiversity nexus and a broader knowledge of the issues involved, while smaller NGOs have specialised knowledge that has not yet reached the majority, particularly on the issue of problem shifting from climate to biodiversity. Overall, increased cooperation between these NGOs would raise awareness of specific aspects of the climate-biodiversity nexus, notably the role of biodiversity in climate stabilisation and the negative consequences of climate policies and measures on biodiversity, facets that have been largely overlooked by most NGOs. Should these ideas and actions continue to propagate, climate NGOs are well-positioned to become influential advocates for holistic climate policies that consider biodiversity.

Additional research is needed on non-state actors and their work in linking issues that are considered separate, such as climate and biodiversity. Further research into the factors that explain why certain NGOs are more likely than others to recognise the linkages would be beneficial. The geographical scope of NGOs may be an influential factor, for example, with local NGOs more likely to recognise the climate-biodiversity nexus than global NGOs.

6 Conclusion

In recent years, research has called for better alignment of climate and biodiversity policies and increasingly emphasised the need to integrate or mainstream biodiversity into climate policies to create co-benefits and avoid trade-offs. However, little is known about the extent to which NGOs, as critical actors in this endeavour, recognise the climate-biodiversity nexus. Our study has contributed to filling this knowledge gap, using 107 climate NGOs headquartered in Germany as an illustrative case and their 190 annual reports published five years apart as a data source.

The analysis revealed a growing recognition of the interdependence between climate and biodiversity within German climate NGOs. Notably, there is a growing acceptance of narratives that stress the joint crisis of climate change and biodiversity loss, and the need for coordinated efforts to effectively protect both. However, this awareness is not consistent across all types of climate-biodiversity linkages. Certain crucial aspects, such as the role of biodiversity in stabilising the climate and the potential negative repercussions of climate policies and measures on biodiversity, continue to receive insufficient attention, demonstrating that NGOs are still far from being holistic environmental stewards.

Further efforts are needed to give NGOs a leading role in advocating for an integrated approach to the interconnected challenges of climate and biodiversity in environmental governance. In this context, we stress the need to strengthen intra-organisational exchange and cooperation between issue-specific departments. We also underscore the potential of harnessing collaboration across and beyond climate NGOs. While individual NGOs may still have tunnel vision, their collective strength can lead to a valuable synergy of knowledge and expertise. In this way, they could make a significant contribution to finding integrated solutions for climate and biodiversity protection and ensure that biodiversity concerns are firmly integrated into climate policy.