"Sustainable development can be assessed using the Human Development Index (HDI) asan indicator of socio-economic development and Ecological Footprint as a measure of human demand on the biosphere. The United Nations considers an HDI of over 0.8 to be ‘high human development’. An Ecological Footprint less than 1.8 global hectares per person makes a country’s resource demands globally replicable. Despite growing adoption of sustainable development as an explicit policy goal, most countries do not meet both minimum requirements."
- Mathis_Wackernagel 
"What we want to achieve is development, meaning probably for most people who want to have development, to have great lives. There are different methods to measure that: United Nations uses the Human Development Index (HDI) which is probably limited, but still I don’t know anybody who wants to live on less than 0.8 HDI because that means shorter lives, little access to education and very minimal incomes. The HDI doesn’t cover everything but it’s a good first approximation of a minimal condition: an HDI 0.8 is a threshold for high human development according to the United Nations Development Programme (UNDP). And in addition, we need to ask: ‘how can we achieve this within the capacity of the planet, i.e. an ecological budget of 1.8 global hectares per person?’ That’s what we have available today, including the space for wild species. And it will be less per person as the human population grows." (https://www.researchgate.net/publication/234092351_An_overview_on_ecological_footprint_and_sustainable_development_A_chat_with_Mathis_Wackernagel [accessed Dec 27 2020].