Section: Overall Objectives

Sustainable development: issues and research opportunities

Sustainable development is often formulated in terms of a required balance between the environmental, economic and social dimensions of the problem, but public policies addressing sustainability are in practice oriented towards environmental issues in Western countries. However, the numerous and interrelated pressures exerted by human activity on the environment make the identification of sustainable development pathways arduous in a context of complex and sometimes conflicting stakeholders and Social-Ecological interactions.

On the one hand urban areas, as focal points of human activity, concentrate most of these pressures in a direct or indirect way. Our civilisation has turned worldwide into an urban one, with more than half the human population living in cities, an ever-increasing trend. Although urbanized areas still represent a very small fraction of the total terrestrial surface, urban resource consumption amounts to three-fourths of the annual total in energy, water, building materials, agricultural products etc, and pollution and waste management is a growing concern for urban planners worldwide. In France, for example, even if resource intensity (materials used divided by GDP) has been reduced by half since the 70s, the material use (total and per inhabitant) has remained essentially constant, and household wastes have grown by 20% since 1995; greenhouse gas emissions have been reduced by a few percent since 1990, but the transportation share (a major issue on this front) has been steadily growing over the same period.

Furthermore, urban sprawl is a ubiquitous phenomenon showing no sign of slackening yet, even in countries where rural depopulation has long been stabilized. Urban sprawl in industrialized countries is largely driven by residential peri-urban growth. The underlying dynamics has proven remarkably stable through a self-sustained positive feedback loop: the creation of suburban housing tracts creates a demand for transportation infrastructures and associated equipments such as parking lots, shopping centers, activity centers, land fills, etc, which in turn favour further suburban sprawl. In 2004, built and associated claimed surfaces amounted to 8% of the French territory. They have grown by 15% from 1994 to 2004 (the equivalent of a French département), and by more than 40% from 1982 to 2004; by comparison, the population growth over the 94-04 decade amounted to only 5%. This phenomenon results in an irreversible loss of cropland; it also induces a fragmentation of ecological habitat, with negative effects on biodiversity, creating a further indirect pressure on agricultural production, with further negative impacts on biodiversity. These trends raise new ethical questions in the global food security degrading context, especially that nearly 50% of agricultural surfaces in France are located in the immediate vicinity of urbanized areas. Controlling urban sprawl in a "climate friendly" framework is a key sustainability issue.

The issues just described require a panel of policy measures at all institutional levels, as they illustrate the existence of both local-local and local-global feedback loops. Nevertheless, the regional (sub-national) and more local levels are of particular importance for the transition to sustainability, especially in a "think global/act local" approach that is up to now mostly oriented towards local climate and energy territorial plans. Indeed, the time left for mitigation instead of adaptation actions is getting shorter by the day, and it is quite obvious that international negociations are making very slow progress if any on all fronts (not only climate change or biodiversity conservation). In this context, more local decision levels have real political and economic leverage, and are more and more proactive on sustainability issues, either individually or in organized nationwide of european-wide networks.

An interdisciplinary team like STEEP, with its strong background in various areas of applied mathematics and modelling, can be a game changer in at least two different but connected research areas : urban development analysis, and related transportation, energy and land use issues ; and urban metabolism analysis and characterization of its (local or distant) environmental impacts. The group potential on these fronts relies on its capacities to strongly improve existing integrated activity/land use/transportation models at the urban level on the one hand, and to build new and comprehensive decision-help tools for sustainability policies at the local and regional levels, in particular through the analysis of strategic social-environmental trade-offs between various policy options.

This theme is new at INRIA, but also for the researchers of STEEP who previously worked in other fields. Elise Arnaud, Emmanuel Prados and Peter Sturm worked on computer vision and Pierre-Yves Longaretti is a physicist. In particular Peter Sturm has joined STEEP only since May 2011. STEEP staff is still in the process of their own thematic transition and a significant part of their activity is not or only briefly mentioned in this document.

The work of STEEP follows four research directions, that are detailed in the following sections.