**2. The ontology of sustainability and concept of sustainable leadership**

The concept of sustainable leadership is complex as it combines two key aspects: Sustainability and leadership. First, it is crucial to delve into the ontology of

sustainability in terms of its complexity and multi-dimensional nature before focusing on the concept of sustainable leadership.

### **2.1 Ontology of sustainability**

According to Layman, sustainability refers to the capacity and thresholds to maintain and protect a particular entity, process or outcome at a certain level over some time [8]. In more technical and specific parlance, sustainability is conceived in terms of the triple bottom line, namely the social, economic and environmental [5]. First, the environmental aspect of sustainability includes the reduction of people's negative impacts on the environment and the protection of nature and ecosystems [3]. Human beings must act responsibly and sensitively to use all resources as they have a limit. Second, the social dimension refers to sustainability's human, institutional, cultural and societal aspects. Lastly, the economic dimension relates to the link between economic activities, growth and effects. Sustainability in business dwells on reducing or avoiding unsustainable business models with adverse effects on the environment and society [1]. Sustainability's environmental, economic and social dimensions are interdependent and interconnected and interact in non-linear ways. A shift in one can, in turn, cause a series of knock-on effects in the others. This interconnection brings to the fore the dynamic and temporal aspects of sustainability, where the cause and effect are subtle, and the results of interventions are not immediately apparent. Sustainability entails a conscious effort to create shared value in the mutual balance of all interests. Shared value reflects a win-win scenario that differs from the concept of 'trade-offs' as a 'win/lose' scenario.

The Brundtland report for the World Commission on Environment and Development (WCED) [9] defines sustainability as 'meeting the needs of the present without compromising the ability of future generations to meet their own needs'. This definition has aspects of dynamic and temporal complexity. At its core, sustainability implies the continued flourishing of human societies in a constantly changing world competing for social, economic and environmental conditions. Complexity arises from 'inter-relationship, inter-action and inter-connectivity of elements within a system' among elements that make up the system (micro-level) and different systems (macro-level) [10]. Sustainability is a complex process of continuous adaptation to change. The processual perspective opposes the view of sustainability as an outcome or a specific end state, best captured by static outcome indicators [11].

Path dependencies help deal with sustainability problems but may stifle an organisation or society from reflexively adapting to existing change or allowing radically new conditions to be possible. Complexity may also arise from counterintuitiveness, which occurs when interactions intended to produce the desired outcome generate opposite results [9].

The ontological view of sustainability depicts multiple dimensions. Four dimensions of sustainability decipherable in Refs. [1, 9, 12] are (1) environmental-based sustainability, (2) corporate sustainability, (3) business-related sustainability and (4) sustainability in education. Proactive and environmentally friendly behaviours that people perform in the natural environment or that try to reduce the negative impact of their activities on the natural environment are termed pro-environmental behaviours [12]. Employees can choose whether or not to implement pro-environmental

behaviours in the workplace (e.g. actively recycling paper and saving water and electricity). In pursuit of sustainability, short- and long-term objectives are complementary rather than incompatible.
