Sustainability in the context of "Global Sustainability Assessment System"

A city is a human settlement of a substantial size. The term "city" has different meanings around the world and in some places the settlement can be very small. Even where the term is limited to larger settlements, there is no universally agreed definition of the lower boundary for their size. In a narrower sense, a city can be defined as a permanent and densely populated place with administratively defined boundaries whose members work primarily on non-agricultural tasks. Cities generally have extensive systems for housing, transportation, sanitation, utilities, land use, production of goods, and communication. Their density facilitates interaction between people, government organizations, and businesses, sometimes benefiting different parties in the process, such as improving the efficiency of goods and service distribution.

Historically, city dwellers have been a small proportion of humanity overall, but following two centuries of unprecedented and rapid urbanization, more than half of the world population now lives in cities, which has had profound consequences for global sustainability. Present-day cities usually form the core of larger metropolitan areas and urban areas—creating numerous commuters traveling toward city centres for employment, entertainment, and education. However, in a world of intensifying globalization, all cities are to varying degrees also connected globally beyond these regions. This increased influence means that cities also have significant influences on global issues, such as sustainable development, climate change, and global health. Because of these major influences on global issues, the international community has prioritized investment in sustainable cities through Sustainable Development Goal 11. Due to the efficiency of transportation and the smaller land consumption, dense cities hold the potential to have a smaller ecological footprint per inhabitant than more sparsely populated areas. Therefore, compact cities are often referred to as a crucial element in fighting climate change. However, this concentration can also have some significant harmful effects, such as forming urban heat islands, concentrating pollution, and stressing water supplies and other resources.

Urban density is a concept used in urban planning, urban studies, and related fields to describe the intensity of people, jobs, housing units, total floor area of buildings, or some other measure of human occupation, activity, and development across a defined unit of area. In general terms, urban density describes the degree of concentration or compactness of people or development in a city. As such it is to be distinguished from other measures of population density. Urban density is considered an important factor in understanding how cities function. Research related to urban density occurs across diverse areas, including economics, health, innovation, psychology and geography as well as sustainability.

A 2019 meta-analysis of 180 studies on a vast number of economic outcomes of urban density concluded that urban density had net positive effects. However, there may be some regressive distributional effects.

Sustainable development is an approach to growth and human development that aims to meet the needs of the present without compromising the ability of future generations to meet their own needs. The aim is to have a society where living conditions and resources meet human needs without undermining planetary integrity. Sustainable development aims to balance the needs of the economy, environment, and society. The Brundtland Report in 1987 helped to make the concept of sustainable development better known.

Sustainable development overlaps with the idea of sustainability which is a normative concept. UNESCO formulated a distinction between the two concepts as follows: "Sustainability is often thought of as a long-term goal (i.e. a more sustainable world), while sustainable development refers to the many processes and pathways to achieve it."

A sustainable city, eco-city, or green city is a city designed with consideration for the social, economic, and environmental impact (commonly referred to as the triple bottom line), as well as a resilient habitat for existing populations. The UN Sustainable Development Goal 11 defines as one that is dedicated to achieving green, social, and economic sustainability, facilitating opportunities that prioritize inclusivity as well as maintaining a sustainable economic growth. Furthermore, the objective is to minimize the inputs of energy, water, and food, and to drastically reduce waste, as well as the outputs of heat, air pollution (including CO2, methane, and water pollution).

The UN Environment Programme calls out that most cities today are struggling with environmental degradation, traffic congestion, inadequate urban infrastructure, in addition to a lack of basic services, such as water supply, sanitation, and waste management. A sustainable city should promote economic growth and meet the basic needs of its inhabitants, while creating sustainable living conditions for all. Ideally, a sustainable city is one that creates an enduring way of life across the four domains of ecology, economics, politics, and culture. The European Investment Bank is assisting cities in the development of long-term strategies in fields including renewable transportation, energy efficiency, sustainable housing, education, and health care. The European Investment Bank has spent more than €150 billion in bettering cities over the last eight years.

The 2030 Agenda for Sustainable Development, adopted by all United Nations (UN) members in 2015, created 17 world Sustainable Development Goals (abbr. SDGs). The aim of these global goals is "peace and prosperity for people and the planet" – while tackling climate change and working to preserve oceans and forests. The SDGs highlight the connections between the environmental, social and economic aspects of sustainable development. Sustainability is at the center of the SDGs, as the term sustainable development implies.

These goals are ambitious, and the reports and outcomes to date indicate a challenging path. Most, if not all, of the goals are unlikely to be met by 2030. Rising inequalities, climate change, and biodiversity loss are topics of concern threatening progress. The COVID-19 pandemic from 2020 to 2023 made these challenges worse, and some regions, such as Asia, have experienced significant setbacks during that time.

Full employment is an economic situation in which there is no cyclical or deficient-demand unemployment. Full employment does not entail the disappearance of all unemployment, as other kinds of unemployment, namely structural and frictional, may remain. Full employment does not entail 100% employment-to-population ratio. For instance, workers who are "between jobs" for short periods of time as they search for better employment are not counted against full employment, as such unemployment is frictional rather than cyclical. An economy with full employment might also have unemployment or underemployment where part-time workers cannot find jobs appropriate to their skill level, as such unemployment is considered structural rather than cyclical. Full employment marks the point past which expansionary fiscal and/or monetary policy cannot reduce unemployment any further without causing inflation.

Some economists define full employment somewhat differently, as the unemployment rate at which inflation does not continuously increase. Advocacy of avoiding accelerating inflation is based on a theory centered on the concept of the Non-Accelerating Inflation Rate of Unemployment (NAIRU) and those who hold it usually mean NAIRU when speaking of full employment. The NAIRU has also been described by Milton Friedman, among others, as the "natural" rate of unemployment. Such views tend to emphasize sustainability, noting that a government cannot sustain unemployment rates below the NAIRU forever: inflation will continue to grow so long as unemployment lies below the NAIRU.

Sustainable architecture is architecture that seeks to minimize the negative environmental impact of buildings through improved efficiency and moderation in the use of materials, energy, development space and the ecosystem at large. Sometimes, sustainable architecture will also focus on the social aspect of sustainability as well. Sustainable architecture uses a conscious approach to energy and ecological conservation in the design of the built environment.

The concept of sustainability, or ecological design, ensures that the use of current resources does not adversely affect future society's well-being or render it impossible to obtain resources for other uses in the long term.

Land management is the process of managing the use and development of land resources. Those resources are used for a variety of purposes for example agriculture, forestry, water resource management, human settlements and tourism. One aim of land management is to prevent or reverse land degradation. Another aim is to ensure water security by increasing soil moisture availability, decreasing surface runoff, and decreasing soil erosion. Unsustainable land managements leads to land being over- or misused which in turn degrades the land, reduces productivity and disrupts natural equilibriums.

Sustainable land management (SLM) is the set of practices and technologies that aim to integrate the management of land, water, and other environmental resources to meet human needs while ensuring long-term sustainability, ecosystem services, biodiversity, and livelihoods. Sustainable forest management is a sub-category of sustainable land management.

Weak and strong sustainability are terms that have emerged from the field of environmental economics and describe different approaches to sustainability, specifically in relation to natural resource management and economic development. Weak sustainability is applicable when certain natural and human capital assets are assessed as interchangeable, meaning that the use or loss of, for example, a reduction in natural capital can be considered sustainable if the simultaneous change in human capital meets or exceeds the value of the change in natural capital. It assumes that different types of capital can be measured and given value in the same way. Strong sustainability is applicable when a specific capital asset, typically a natural capital asset, is assessed as incommensurable or so valuable that it should be maintained or enhanced independently of changes in other, typically human-made, capitals. It particularly considers that certain natural assets have critical ecological functions that cannot be substituted by human-made alternatives.

For example, according to weak sustainability, replacing a natural forest with a park or agricultural land can be considered sustainable if the recreational or economic value equal the value of the biodiversity lost and further environmental impact caused. According to strong sustainability, cutting down trees in a natural forest and planting new trees elsewhere might not be considered sustainable, when the value of biodiversity loss and wider ecological implications cannot be measured or offset.