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Environmental impacts of humans

There are several methods to measure or describe human impacts on Earth. They include the ecological footprint, ecological debt, carrying capacity, and sustainable yield. The idea of planetary boundaries is that there are limits to the carrying capacity of the Earth. It is important not to cross these thresholds to prevent irreversible harm to the Earth. These planetary boundaries involve several environmental issues. These include climate change and biodiversity loss. They also include types of pollution. These are biogeochemical (nitrogen and phosphorus), ocean acidification, land use, freshwater, ozone depletion, atmospheric aerosols, and chemical pollution. (Since 2015 some experts refer to biodiversity loss as change in biosphere integrity. They refer to chemical pollution as introduction of novel entities.)

The IPAT formula measures the environmental impact of humans. It emerged in the 1970s. It states this impact is proportional to human population, affluence and technology. This implies various ways to increase environmental sustainability. One would be human population control. Another would be to reduce consumption and affluence such as energy consumption. Another would be to develop innovative or green technologies such as renewable energy. In other words, there are two broad aims. The first would be to have fewer consumers. The second would be to have less environmental footprint per consumer.

The Millennium Ecosystem Assessment from 2005 measured 24 ecosystem services. It concluded that only four have improved over the last 50 years. It found 15 are in serious decline and five are in a precarious condition.