People, Pipelines, and Probabilities: Clarifying Significance and Uncertainty in Environmental Impact Assessments

Area of Science:

• Environmental Science
• Risk Assessment
• Environmental Policy

Background:

• Significance determinations are crucial for prioritizing environmental impacts in assessments.
• Impact predictions inherently involve uncertainty, yet this is often inadequately addressed.
• Fossil fuel pipeline proposals exemplify issues arising from the casual treatment of uncertainty.

Purpose of the Study:

• To highlight common ways uncertainty is neglected in determining environmental impact significance.
• To propose improvements for handling uncertainty in environmental impact assessments.
• To enhance the quality of decision-making in environmental assessments.

Main Methods:

• Analysis of environmental assessments for recent North American fossil fuel pipeline proposals.
• Identification of five key areas where uncertainty is overlooked in significance determinations.
• Review of existing methods and proposal of new guidelines and oversight mechanisms.

Main Results:

• Environmental impact assessments frequently underestimate or ignore the role of uncertainty.
• Neglecting uncertainty leads to uninformed stakeholders, industry frustration, and inconsistent public decisions.
• Specific examples from pipeline assessments illustrate the consequences of inadequate uncertainty treatment.

Conclusions:

• Current practices for determining impact significance often fail to adequately incorporate uncertainty.
• A combination of established methods, updated guidelines, and effective oversight can significantly improve current practices.
• Addressing uncertainty is vital for robust environmental impact assessment and informed decision-making.