• Environmental assets may have critical thresholds Changes to some renewable environmental assets beyond unknown thresholds may cause non-linear and irreversible changes to occur. These thresholds mark the boundary between alternate stable states. If these critical thresholds are breached, the asset may no longer be able to continue providing services or may no longer be adequately replenished, leading to eventual depletion of the asset.
Ecosystems are often subject to these thresholds, including ‘source limits’ such as fish stocks and top soil (where breaching this threshold will lead to a change or collapse in the ecosystem) and ‘sink’ limits, such as limits to the degree that water and soil can absorb chemical outputs from production, and where breaching this limit can cause temporary or permanent disruption to ecological functioning61. However, there is a great deal of scientific uncertainty around if and where critical thresholds might exist. In the absence of robust evidence, the precautionary principle would suggest preventing degradation or depletion well before these thresholds are reached.