Planetary boundaries are defined from a functional perspective. Only biodiversity appears as also having a value in its own. The original publication contains the laconic note: ‘Massive loss of biodiversity [is] unacceptable for ethical reasons’ (Rockström et al. Reference Rockström, Steffen and Noone2009). Remarkably, this brief reference is only to be found in a table that characterizes the nine proposed planetary boundaries. Nowhere else in the document do the authors name ethical concerns. They do mention that establishing values for the respective boundaries depends on value judgements or normative judgements. However, the idea that crossing a particular boundary is morally wrong per se only occurs in relation to biodiversity.

For scholars who study ‘biodiversity’ from a theoretical perspective, this reference to ethics comes as no surprise. The concept of biodiversity has been morally impregnated from the beginning. It was coined at the interface of biology and politics to send a wake-up call to decision-makers and has never seen itself as a value-free scientific concept (Eser Reference Eser2001). Nevertheless, like the closely related concept of ecosystem services, it appears in public discourse with the full authority of scientific knowledge. The concept of planetary boundaries presents itself as a ‘science-based analysis’, too. However, under the guise of ‘Science’ the values that underpin conservation efforts largely remain hidden. My chapter aims to address this shortcoming.

Section 9.1 will characterize the term ‘biodiversity’ as a concept that is situated in the borderland between biology, ethics, and politics and has factual, evaluative, and normative dimensions. Section 9.2 presents critique that has been made of biodiversity as planetary boundary, and how this has been addressed in more recent versions of the framework. The main section focuses on the different values of biodiversity, which I consider to be insufficiently reflected in the PB approach. Besides its instrumental value for humanity’s safe operating space, the diversity of living beings also has intrinsic and relational value. I will present these different value concepts and discuss them with regard to the PB framework (Section 9.3). Finally, I will argue for a more inclusive perspective on biodiversity that recognizes and takes into account differences between the manifold ways in which humans live from, with, in, and as nature (Section 9.4).

9.1 Biodiversity: A Boundary Concept

The term ‘biodiversity’ comes from conservation biology (Maclaurin & Sterelny Reference Maclaurin and Sterelny2008). It is a shorthand of ‘biological diversity’ or ‘biotic diversity’ (Faith Reference Faith and Zalta2021) and was coined in the course of the Washington Conference on BioDiversity in 1986 in order to raise public awareness of the ongoing mass extinction (Wilson Reference Wilson1988). In extensive interviews with protagonists of the concept, David Takacs, a scholar of science studies, has shown that the invention of the term was associated with remarkable boundary work (Takacs Reference Takacs1996). Both the established separation of science and politics and the common concepts of scientific objectivity and value-neutrality were explicitly challenged in the scientific advocacy for a more resolute policy in favour of biodiversity.

The Conference on BioDiversity itself was a political, rather than a scientific, endeavour. Dan Janzen, one of the many renowned biologists involved, remembers in his interview: ‘That was an explicit political event, explicitly designed to make Congress aware of this complexity of species that we’re losing . … A lot of us went to that talk with a political mission’ (Takacs Reference Takacs1996: 37). Part and parcel of the message that biodiversity is under threat is the message that biodiversity is important, that is to say: It has value. Such a statement is obviously at odds with the conventional understanding of science as being value-neutral. Accordingly, Takacs’ interviewees question this scientific norm. ‘One of the silly things is the idea that science is somehow separate from society. There is no value-neutral science,’ says Paul Ehrlich (Takacs Reference Takacs1996: 181). With regard to both intricate knowledge and imminent danger, biologists feel obliged to bridge the gap between ‘Is’ and ‘Ought’ that is so well established in philosophy.

This combination of expertise and urgency drives the protagonists of the planetary boundaries framework, too.

In his seminal book, Takacs illustrates that the commitment of biologists to biodiversity was accompanied by an attempt to shift the boundaries between science, politics, and ethics. Biodiversity was associated with ‘a new ethic, in which biodiversity’s multiplicity of values will be respected, appreciated, and perhaps even worshiped’ (Takacs Reference Takacs1996: 9).

Given that history, ‘biodiversity’ can be regarded as a thick concept. ‘Thick’, in philosophy, are concepts that have a substantial degree of descriptive content but also are value-laden (Williams Reference Williams1985). With regard to biological concepts like biodiversity, ecology, or evolution, such thick concepts have been named ‘epistemic-moral hybrids’ (Potthast Reference Potthast and Potthast2007). In view of this hybrid character, biodiversity loss is not only a scientific matter of fact. The statement that we are losing biodiversity at unprecedented rates per se involves the value judgement that this loss is bad, and the normative statement that we ought to do something to halt it. In other words, the term has factual, evaluative, and normative dimensions.

Since its invention in the 1980s, the term ‘biodiversity’ has had a rapid career, in both the scientific and political arenas. Within science, the question of how to define biodiversity and how to measure it fills volumes. In the political arena, the term became the focus of global conservation efforts with the Convention on Biological Diversity (CBD), adopted at the first Earth Summit in Rio de Janeiro in 1992. The close entanglement of political and scientific dimensions of the term makes it both important and difficult to define biodiversity. According to the CBD, ‘“[b]iological diversity” means the variability among living organisms from all sources …; this includes diversity within species, between species and of ecosystems’ (1992: Art. 2). The UNESCO funded ‘Man and Biosphere’ Program described it as living variability: ‘Biodiversity is the property of living systems of being distinct, that is different, unlike. Biological diversity or biodiversity is defined here as the property of groups or classes of living entities to be varied’ (Solbrig Reference Solbrig1991: 9). An explanatory leaflet produced by the CBD’s clearinghouse mechanism for communication purposes explained: ‘The term “biological diversity” … is defined in terms of genes, species, and ecosystems, which are the outcome of over 3,000 million years of evolution. The human species depends on biological diversity for its own survival. Thus, the term can be considered a synonym for “life on earth”’ (CBD 1999). When asked for a definition of biodiversity, David Ehrenfeld stated, ‘I don’t have a definition of biodiversity … I think it’s one of those wonderful catchwords like sustainable development, that, because it’s vaguely defined, has a broad appeal, like motherhood’ (Takacs Reference Takacs1996: 46–47).

This indeterminacy of content contrasts with scientific exactness but is precisely why it enables practical cooperation. It is, therefore, helpful to understand biodiversity as a boundary object that is ‘both plastic enough to adapt to local needs and constraints of the several parties employing them, yet robust enough to maintain a common identity across sites’ (Star Reference Star, Gasser and Huhn1989: 46). While such objects can be very useful enablers of cooperation, it is hardly possible to pin them down to a single metric within a science-based framework. This becomes apparent when we look at the scientific debate on biodiversity as a planetary boundary.

9.2 Biodiversity as Planetary Boundary

How can an ill-defined concept as biodiversity be used within a framework that intends to be science-based? In particular: How is it possible to formulate a reliable boundary that separates the safe operating space from the danger zone? What are appropriate metrics for such a boundary? And how to deal with the huge amount of non-knowledge with regard to both the numbers of existing and endangered species and their relevance for ecosystem functioning?

The planetary boundaries framework uses extinction rate as a proxy for biodiversity loss. In calculating the boundary and the zone of uncertainty, the original paper made use of a rather rough rule of thumb: ‘The lower and upper bounds of extinction rates in the fossil record … provide the best estimates of the background extinction rates that have historically conserved global biodiversity’ (Rockström et al. Reference Rockström, Steffen and Noone2009). With regard to this natural extinction rate, the authors set the boundary at an extinction rate of less than 10 extinctions per million species per year (E/MSY), and the zone of uncertainty at 10–100 E/MSY. However, they admit, ‘it remains very difficult to define a boundary level for the rate of biodiversity loss that, if transgressed for long periods of time, could result in undesired, non-linear Earth System change at regional to global scales’ (Rockström et al. Reference Rockström, Steffen and Noone2009).

Within conservation biology, there have been controversial debates for years about whether biodiversity is an end or a means of conservation, and how biodiversity helps in the selection and prioritization of conservation objects (Maclaurin & Sterelny Reference Maclaurin and Sterelny2008; NRC 1999; Sarkar Reference Sarkar2005). Due to massive conceptual and methodological difficulties, some even argued for abandoning the term altogether (Santana Reference Santana2014). Accordingly, the biodiversity community’s response to the planetary boundaries framework was mixed. The reactions range from constructive criticisms (Mace et al. Reference Mace, Reyers and Alkemade2014) to harsh verdicts (Montoya et al. Reference Montoya, Donohue and Pimm2018). Mace et al. (Reference Mace, Reyers and Alkemade2014) argued that extinction rate and species richness were weak metrics and suggested alternative approaches to determine biodiversity loss boundaries. In response to their critique, the PB framework was adjusted and the initial boundary ‘biodiversity loss’ was replaced by ‘biosphere integrity’ (Steffen et al. Reference Steffen, Richardson and Rockström2015). Biosphere integrity has two components: genetic diversity, with extinction rate as control variable, and functional diversity with a Biodiversity Intactness Index (BII) as control variable. The updated table no longer contains the remark on ethics but the note: ‘These are interim control variables until more appropriate ones are developed’ (Steffen et al. Reference Steffen, Richardson and Rockström2015), thus acknowledging practical and theoretical challenges of finding appropriate control variables at regional or global scales.

Despite these adjustments, some still doubt the practical utility of the concept. ‘[N]otions of planetary boundaries add no insight into our understanding of the threats to biodiversity and ecosystem functioning, have no evidence to support them, are too vague for use by those who manage biodiversity, and promote pernicious policies’ (Montoya et al. Reference Montoya, Donohue and Pimm2018). In addition to practical conservation concerns, the authors of this verdict also express moral and political concerns. In the face of boundaries that are difficult to operationalize, they consider the talk of a ‘safe operating space’ problematic because it could encourage policymakers to assume ‘if the planet is not obviously collapsing around us, then surely we can continue to deplete it’ (Montoya et al. Reference Montoya, Donohue and Pimm2018).

I will leave the question of a proper metric for biodiversity here and turn to the ethical implications of a concept that considers the diversity of living beings exclusively in terms of a safe operating space for humanity.Footnote ¹

9.3 The Value(s) of Biodiversity

‘Our primary reason for including biological diversity as a planetary boundary is its role in providing ecological functions that support biophysical sub-systems of the Earth’ (Rockström et al. Reference Rockström, Steffen and Noone2009). Apart from the marginal note in the first table, the planetary boundaries framework considers biodiversity for functional reasons. The only value of biodiversity taken into account is its instrumental value: Biodiversity is valued as a means to humanity’s continued existence. Genetic diversity is appreciated as a database that allows adaptation to an uncertain future, and functional diversity is treasured for its contribution to ecosystem services (Steffen et al. Reference Steffen, Richardson and Rockström2015). There is no doubt that this functional perspective contains essential reasons for the protection of biological diversity. However, it ignores other, equally important reasons: it does not take into account the possible intrinsic value of other than human living beings (Instrumental vs. Intrinsic value), nor does it adequately address the diversity of meaningful relationships between humans and nature (Relational Value).

9.4 A More Inclusive Perspective on Biodiversity

For decades, environmental discourse has been framed as a conflict between humans and nature. Such a framing ignores that in environmental protection and nature conservation we are usually not dealing with conflicts between ‘man’ and ‘nature’, but with conflicts between different people with different interests and needs – and different potentials to achieve those. One consequence of this binary framing is that the exclusion of people is often seen as the best way to protect nature. One recent example of such a preference is the Kumming-Montreal biodiversity framework adopted at the 15th Conference of the Parties to the CBD in Montreal in December 2022. It established the 30 by 30-target of global biodiversity conservation, to ‘[e]nsure and enable that by 2030 at least 30 per cent of terrestrial, inland water, and of coastal and marine areas, … are effectively conserved and managed through … systems of protected areas and other effective area-based conservation’ (CBD 2022). Only after fierce debates and in response to serious concerns with regard to: Indigenous people and local communities, the document finally explicitly recognizes and respects the rights of these groups. As long as we conceive of biodiversity loss as a conflict between humans and nature, crucial distinctions between different lifestyles and economies and their impacts on biodiversity cannot come into view – and hence cannot be adequately addressed in the political arena.

This critique of generalization also applies to the concept of planetary boundaries. ‘Human activities increasingly influence the Earth’s climate … and ecosystems’, ‘humans are effectively pushing the planet outside the Holocene range of variability …’, ‘humanity has already entered deep into a danger zone’ (Rockström et al. Reference Rockström, Steffen and Noone2009, emphasis added): These quotes demonstrate the shortcomings of a planetary perspective mentioned earlier. Different human activities influence climate and ecosystems in very different ways – not ‘human activities’ as such but particular activities of particular persons. Not ‘humans’ are pushing ‘the planet’ outside of the comfort zone, but some humans with specific lifestyles and policies are pushing other humans – and other species – ‘deep into the danger zone’.

Talk of ‘humanity’ tends to ignore morally relevant differences between originators and victims of the depletion of nature. Those who are responsible for the decline of species and those who suffer from this decline more often than not are different persons. As the Human Development Report 1998 pointed out, responsibility for environmental damage, including biodiversity loss, lies mainly with the top global consumers (UNDP 1998). Increasing consumption not only puts strains on the environment but also reflects and increases global inequality. The richest fifth of the world’s population account for 86 per cent of total private consumption expenditures – and the related environmental and social burdens (UNDP 1998). On the other hand, consequences of biodiversity loss ‘will be felt disproportionately by the poor’ (Díaz et al. Reference Díaz, Fargione, Chapin and Tilman2006). Degradation of the Earth’s life support systems ‘is threatening the fulfillment of basic needs and aspiration of humanity as a whole but especially, and most immediately, those of the most disadvantaged segments of society’ (Díaz et al. Reference Díaz, Fargione, Chapin and Tilman2006). Both with regard to the polluter pays principle and with regard to responsibility for particularly vulnerable groups, the unifying talk of humanity is inadequate from an ethical perspective.

Talk of ‘humanity’ also tends to ignore conflicting interests: on the one hand, conflicts between interests in different kinds of use (e.g. provision of food vs. provision of housing); on the other hand, conflicts between interests in use and interests in other kinds of relations with nature (e.g. aesthetic, cultural, or spiritual). In order to overcome the unsatisfactory frontline between humans and nature and to recognize the diversity of human-nature relationships, IPBES initiated an assessment on the multiple values of nature and its contributions to human well-being in 2018. Over a period of four years, a multidisciplinary and multinational team of nearly a hundred authors scrutinized different concepts of value and methods of evaluation, analysed the values underlying current decision-making, and inquired if the inclusion of multiple values might lead to better decision outcomes. The results, published in July 2022, provide extensive evidence that ‘decisions based on [a] narrow set of market values of nature underpin the global biodiversity crisis’ (IPBES 2022b). The Summary for Policy Makers establishes that decisions are (too) often made on the basis of monetary values, neglecting other values. ‘Despite the diversity of nature’s values, most policymaking approaches have prioritized a narrow set of values at the expense of both nature and society, as well as future generations, and have often ignored values associated to indigenous peoples and local communities’ worldviews’ (IPBES 2022c). According to the Values Assessment, dominance of market values and ignorance of non-instrumental values are to be seen as root causes of the biodiversity crisis. To overcome this restriction, the assessment suggests a value typology that leaves room for different ways in which humans can relate to nature. It discriminates four ‘live-frames’: living from, living in, living with and living as nature. Living from nature designates the instrumental perspective on nature as a resource. Living with nature emphasizes relational bonds between humans and other than human beings. Living in nature highlights place-based connections between people and nature while Living as nature underlines the inseparability of humans and nature.

The findings of the IPBES Values Assessment may shed new light on the planetary boundary approach. By taking a functional perspective on biodiversity, it is clearly situated within the living-from frame. Within that frame, it provides powerful reasons for action. However, this achievement comes at the expense of neglecting other perceptions. A more inclusive perspective on biodiversity needs to take into account diverse values and to address social aspects such as power, poverty, and inequality. As long as such an inclusion is missing, it is doubtful whether the planetary boundaries approach can provide adequate solutions to the ongoing crisis of biodiversity.