World lines: A framework for exploring global pathways

Sustainability research studies the dynamics and prospects of co-evolving human and ecological systems, a subject of inherent complexity and deep uncertainty. While work proceeds on facets of the overall problem, an overarching theoretical framework for giving coherence to this new discipline is lacking. Scenario analysis has been proposed as a promising integrative approach, while a recent wave of studies has significantly improved scenario methods. Still, these studies remain most compelling in their opening frames, where quantitative modeling can track unfolding trends, and their closing frames, where qualitative description can provide rich descriptions of long-term social visions. Not surprisingly, given the formidable uncertainties, the trajectories between "now" and "then", remain poorly specified, if addressed at all. This paper suggests ways of thinking about these pathways and pivots, the "world lines" through the terra incognita between current global realities and alternative futures. It outlines and illustrates a macro-framework, drawing fresh insight into the requirements for a transition to sustainability. It discusses major analytic elements - a systemic perspective, a scenario structure, critical uncertainties, human agency - and combines them into depictions of the broad contours of possible pathways. The analysis highlights two key uncertainties: the form of forthcoming crises and the quality of human response to global challenges. If institutional and cultural innovation fails to mute the precursor stressors of a systemic crisis, the world line could pivot toward a venal future. However, if the world begins to act with foresight, unity, and resolve, development would bend toward a resilient global civilization. This transition requires a sharp upswing in public awareness and engagement, a development that the evolving conditions of our planetary phase of history make possible, but by no means inevitable. Here, sustainability scenarios have a role in changing the future, as well as illuminating it, by expanding the horizon of what is thought possible and deemed desirable. The world lines framework offers a conceptual arena for advancing this effort.