sustainability above is that a system is not sustainable unless it can operate indefinitely into the future. For a system to do so inevitably requires optimization over time and space—goals that are central to much of computer science.
The report SMART 2020: Enabling the Low Carbon Economy in the Information Age5 usefully groups opportunities for applying IT to sustainability into three broad areas: (1) built infrastructure and systems, (2) ecosystems services and the environment, and (3) sociotechnical systems. The following describes each of these areas and outlines applications of IT and opportunities for computer science research:
• Built infrastructure and systems. This area includes buildings, transportation systems (personal, public, and commercial), and consumed goods (commodities, utilities, and foodstuffs). IT contributes to sustainable solutions in built infrastructure in numerous ways, from improved sensor technologies (e.g., in embedded sensors in smart buildings) and improved system models, to improved control and optimization (e.g., of logistics and smart electric grids), to improved communications and human-computer interfaces (enabling people to make more effective decisions).
• Ecosystems and the environment. This area encompasses assessing, understanding, and positively affecting (or not affecting) the environment and particular ecosystems—these efforts represent crosscutting challenges for many sustainability efforts. The scale and scope of efforts in this area range from local and regional efforts examining species habitats, to watershed management, to understanding the impacts of global climate change. The range of challenges itself poses a problem: how best to assess the relative importance of various sustainability activities with an eye toward significant impact. Additionally, computational techniques will be valuable for developing scientific knowledge and engineering technologies, including improved methods for data-driven science, modeling, and simulation to improve the degree of scientific understanding in ecology.
• Sociotechnical systems. Sociotechnical systems encompass society, organizations, and individuals, and their behavior as well as the technological infrastructure that they use. Large and long-lived impacts on sustainability will require enabling, encouraging, and sustaining changes in behavior—on the part of individuals, organizations, and nation-states over the long term. IT, and in particular real-time information and tools, can better equip individuals and organizations to make daily, ongo-