Human impact on the environment in the context of "Land use"

An urban area is a human settlement with a high population density and an infrastructure of built environment. Urban areas originate through urbanization, and researchers categorize them as cities, towns, conurbations or suburbs. In urbanism, the term "urban area" contrasts to rural areas such as villages and hamlets; in urban sociology or urban anthropology, it often contrasts with natural environment.

The development of earlier predecessors of modern urban areas during the urban revolution of the 4th millennium BCEled to the formation of human civilization and ultimately to modern urban planning, which along with other human activities such as exploitation of natural resources has led to a human impact on the environment.

Climate change and cities are deeply connected. Cities are one of the greatest contributors and likely best opportunities for addressing climate change. Cities are also one of the most vulnerable parts of the human society to the effects of climate change, and likely one of the most important solutions for reducing the environmental impact of humans. The UN projects that 68% of the world population will live in urban areas by 2050. In the year 2016, 31 mega-cities reported having at least 10 million in their population, 8 of which surpassed 20 million people. However, secondary cities - small to medium size cities (500,000 to 1 million) are rapidly increasing in number and are some of the fastest growing urbanizing areas in the world further contributing to climate change impacts. Cities have a significant influence on construction and transportation—two of the key contributors to global warming emissions. Moreover, because of processes that create climate conflict and climate refugees, city areas are expected to grow during the next several decades, stressing infrastructure and concentrating more impoverished peoples in cities.

High density and urban heat island effect are examples of weather changes that impact cities due to climate change. It also causes exacerbating existing problems such as air pollution, water scarcity, and heat illness in metropolitan areas. Moreover, because most cities have been built on rivers or coastal areas, cities are frequently vulnerable to the subsequent effects of sea level rise, which cause flooding and erosion; these effects are also connected with other urban environmental problems, such as subsidence and aquifer depletion.

The ecological footprint measures human demand on natural capital, i.e. the quantity of nature it takes to support people and their economies. It tracks human demand on nature through an ecological accounting system. The accounts contrast the biologically productive area people use to satisfy their consumption to the biologically productive area available within a region, nation, or the world (biocapacity). Biocapacity is the productive area that can regenerate what people demand from nature. Therefore, the metric is a measure of human impact on the environment. As Ecological Footprint accounts measure to what extent human activities operate within the means of our planet, they are a central metric for sustainability.

The metric is promoted by the Global Footprint Network which has developed standards to make results comparable. FoDaFo, supported by Global Footprint Network and York University are now providing the national assessments of Footprints and biocapacity.

Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.

Although environmental pollution can be caused by natural events, the word pollution generally implies that the contaminants have a human source, such as manufacturing, extractive industries, poor waste management, transportation or agriculture. Pollution is often classed as point source (coming from a highly concentrated specific site, such as a factory, mine, construction site), or nonpoint source pollution (coming from widespread distributed sources, such as microplastics or agricultural runoff).

In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them underpin biology as a whole. They affect a plethora of species, in all forms of environmental conditions, such as marine or terrestrial animals. Humans can make or change abiotic factors in a species' environment. For instance, fertilizers can affect a snail's habitat, or the greenhouse gases which humans utilize can change marine pH levels.

Abiotic components include physical conditions and non-living resources that affect living organisms in terms of growth, maintenance, and reproduction. Resources are distinguished as substances or objects in the environment required by one organism and consumed or otherwise made unavailable for use by other organisms. Component degradation of a substance occurs by chemical or physical processes, e.g. hydrolysis. All non-living components of an ecosystem, such as atmospheric conditions and water resources, are called abiotic components.

Animal welfare is the quality of life and overall well-being of animals. Formal standards of animal welfare vary between contexts, but are debated mostly by animal welfare groups, legislators, and academics. Animal welfare science uses measures such as longevity, disease, immunosuppression, behavior, physiology, and reproduction, although there is debate about which of these best indicate animal welfare.

Respect for animal welfare is often based on the belief that nonhuman animals are sentient and that consideration should be given to their well-being or suffering, especially when they are under the care of humans. These concerns can include how animals are slaughtered for food, how they are used in scientific research, how they are kept (as pets, in zoos, farms, circuses, etc.), and how human activities affect the welfare and survival of wild species.