Limits to the Natural Environment

• Using resources faster than they can be restored

• Releasing pollutants and wastes faster than they can be absorbed

Sustainability depends on balancing feedback loops. If they are not balanced, rapid growth can occur. An imbalance leads to unsustainable overshoots. A delay in the response or a lack of pressure can worsen the unsustainable overshoot.

Positive feedback loops drive the problem. Negative feedback loops act to reduce the problem, balancing the issue.

Population:

Development leads to a reduction in poverty, reducing fertility and births per year, and could lead to a sustainable population.

Industrial capital and cultivated land:

Feedback loops are linked; e.g. cultivated land impacts food per person which impacts mortality, and industrial capital causes outputs which affect cultivated land and causes pollution, which can also increase mortality. The link between the feedback loops can help to achieve development without exceeding environmental limits.

Rapid population growth leads to an overshoot of environmental limits, and if there is a delay in the response, collapse and irreversible change in the environment are risked.

What we need to do

• Extend the planning horizon

• Improve the signals

• Speed up response times

• Minimise the use of finite resources

• Prevent erosion of renewable resources

• Use resources with maximum efficiency

• Slow/stop the exponential growth of population and physical capital

Sustainability requires an understanding of environmental, ecological and resource limits. Engineering should be seen as part of the bigger picture, and an ‘all round’ approach should be taken. Governance at all levels to keep a balance of feedback loops.

Precautionary principles, where the response is proactive and not reactive, will reduce the delays and prevent irreversible change. We need to act now to change patterns of growth.

Actions should be based on evidence, but also include public values.