IV. NEPA Observations and Questions Yet to Be Answered IV. NEPA Observations and Questions Yet to Be Answered

• Jurisdiction: United States

IV. NEPA Observations and Questions Yet to Be Answered

Though the judicial decisions addressing NEPA and climate change are few, they provide valuable case studies in how the judiciary may apply NEPA principles in the climate change context. Agencies, project proponents, and litigants can be assured courts will continue to apply long-standing NEPA principles, such as "reasonable foreseeability," even in the context of novel climate change arguments. Lessons learned from the cases include:

1. Disclose potential increases in GHG emissions when reasonably foreseeable as direct, indirect, or cumulative impacts.

2. Discuss how increases in GHG emissions may translate to climate change effects.

3. Consider whether insignificant increases in GHG emissions may become significant when added to other past, present, and reasonably foreseeable actions.

4. Different kinds of project will require different levels of climate change discussion. EISs for projects that emit carbon dioxide and other GHGs may be more closely scrutinized and should more carefully document possible emissions and climate change effects than projects that do not.

5. Consider using models to calculate potential emissions and effects to climate change.

6. Where information necessary to evaluate climate change effects is incomplete or unavailable, either collect the necessary information or discuss why the cost to obtain such information is exorbitant, how the missing information is relevant to the

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environmental analysis, and how the agency will evaluate impacts without the information.

The case law, though limited, demonstrates that courts are beginning to examine climate change issues more closely. Responding to cases like Border Power and Mid States Coalition, federal agencies have also begun to include discussion of potential climate change effects in NEPA documents, and the Environmental Protection Agency, which reviews EISs under CAA § 309, has begun to demand it.⁵⁴ However, many questions remain about various approaches to addressing climate change. Some of the most pressing questions are how to address climate change in cumulative impact analyses, whether agencies should be in the business of imposing mitigation measures to minimize climate impacts, and how to incorporate climate change in the need for the project and baseline environmental conditions.

A. Cumulative Impacts and Significance

Cumulative impacts are those that result "from the incremental impact of...