Explain four 'basic, non-negotiable system conditions for global sustainability' as developed by Karl-Henrik Robert, founder of the environment organization. "The Natural Step".

In an attempt to address criticism of the vagueness in the definition of sustainable development, Karl-Henrik Robert, founder of the environment organization The Natural Step, along with a group of 50 scientists sought to obtain a consensus on sustainability and developed four 'basic, non-negotiable system conditions for global sustainability'. These include: No systematic increase of substances from the earth's crust in the ecosphere. This condition implies a drastic reduction in the use of minerals, fossils fuels and non-renewable resources. No systematic increase of substances produced by society in the ecosphere. This condition means that substances cannot be produced faster that they are broken down and degraded biologically. Therefore, the uses of non-biodegradable materials must be minimized. No systematic diminishing of the physical basis for productivity and diversity of nature. This condition requires preservation of biodiversity, non-environmentally damaging land use practices and use of renewable resources. Fair and efficient use of resources and social justice. This implies equitable access to an just distribution of resources.