State of the Environment 2011 (SoE 2011)
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to
the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
1 Approach
3.5 Risk
What are the key impacts of current and emerging pressures? When we take into account management interventions and resilience, how likely and potentially severe are these impacts?
In assessing risk, the focus shifts from historical trends and current status to projections about what the future may hold. The assessment uses information from the preceding assessments to examine the likely environmental impacts of pressures that are unmitigated by management responses and resilience. It also examines new impacts that may be emerging due to changing pressures and drivers. The impacts may be either chronic in nature, such as ‘health disorders due to poor air quality’, or sporadic one-off events, such as ‘sudden reduction in vegetation cover due to mega-fires’.
The risk associated with an impact is a combination of two factors:
- the likelihood of an event, action or activity occurring that will create an impact
- the extent and severity of the consequences of that impact on environmental values if it does arise.
For a particular potential issue, risk is assessed qualitatively; grades of risk are assigned by selecting the most appropriate descriptor from a scale of five categories for each of the two factors (Box 1.4). The sections on risks provide a snapshot of current and emerging risks that relate to the values featured in each chapter.
Box 1.4 Assessing risk
The following approach, definitions and grading scales for risk assessments were adapted from the principles and guidelines outlined by Standards Australia,9 and interpreted for each reporting theme according to the nature of the values, impacts and management responses that are dealt with in the theme chapter.
The overall risk of an impact on environmental values is determined by examining both the likelihood that the impact will take place and the severity of anticipated consequences if it does occur. The following definitions are used as a national-scale framework for risk assessments across the theme chapters.
Risk = likelihood x consequence
Likelihood is the probability (expected frequency) of an impact due to a pressure. Frequency refers to the time period in which the impacts are expected to be manifest. The likelihood of an impact is assessed on a scale of five levels of frequency, adapted from those used by the Intergovernmental Panel on Climate Change.10 The chapters cover a very wide range of environments, so the time periods between impacts are equally diverse and are adapted to be theme specific.
| Likelihood | Frequency |
|---|---|
| Almost certain | Expected to occur almost continuously throughout the year; or expected to occur at any time in the near future |
| Likely | Not expected to be continuous, but will probably occur at least once each year; or could occur at any time in the near future |
| Possible | Expected to occur two to three times within a 10-year period |
| Unlikely | Not expected to occur regularly within a 10-year period, but can be expected to occur one to three times within a 100-year period |
| Rare | Not expected to occur within the next 100 years |
Consequence is the extent and severity of impacts. Consequence is assessed on a scale of five levels of severity and extent. The nature of consequences at local and regional levels is considered, but the analyses in the theme chapters represent the results of a national-scale assessment.
| Consequence | Severity and extent of expected impacts |
|---|---|
| Catastrophic | Impact will seriously affect environmental values, disrupting major environmental structures or functions. Potentially irreversible |
| Major | Impact will seriously affect environmental values, disrupting many environmental structures or functions. Long periods of recovery |
| Moderate | Impact will affect environmental values, disrupting some aspects of environmental structures or functions, but recovery periods are relatively short |
| Minor | Impact will be limited and affect only minor environmental values. Recovery periods are relatively short |
| Insignificant | Impact will be very limited and have no discernable effect on environmental values, including sensitive populations, communities and assets |
Results of the risk assessment are presented in a likelihood–consequence matrix that provides a visual snapshot of the significance of the risks. Impacts that were assessed as rare and/or of insignificant consequence are not included in the matrix or given further attention in the SoE report, but the categories are included in the matrix for reasons of completeness.
The assessments do not extend into discussions about risk management but instead highlight the key challenges, many of which are then examined further in the final section of each theme chapter—Outlook.
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