Canada's national energy regulator says it will for the first time consider the impact of upstream and downstream emissions from potential increased consumption of oil at hearings into the Energy East Pipeline.
The National Energy Board says the decision is based in part on 820 public submissions it received since last spring.
It says it will also for the first time consider the effect of meeting government greenhouse gas emission targets on the financial viability and need for the pipeline.
Alberta's energy minister says she's disappointed in the National Energy Board's decision to widen the scope of its review of the pipeline.
Margaret McCuaig-Boyd said her office will continue to review the board's decision.
She said an initial analysis indicates that the NEB is at risk of committing a "historic overreach."
Ecojustice lawyer Charles Hatt said in a statement the NEB's decision is "both lawful and sensible."
"Surely it is now self-evident that a pipeline review must consider all potential greenhouse gas emissions and the risk that the pipeline will become a stranded asset in tomorrow's economy," he said.
In a statement, the Canadian Energy Pipeline Association said it does not support the decision.
"CEPA firmly believes that broad public policy issues, such as climate change, should be addressed at the political level, and not through pipeline project reviews," it read.
"While it is appropriate to address the direct GHG impact of a pipeline project through the NEB process, upstream and downstream impacts are appropriately dealt with in the context of the Pan Canadian Framework on Clean Growth and Climate Change.
"The NEB's quasi-judicial process, which requires a balance of socio-economic, safety and environmental matters, is not the appropriate venue to address broader public policy issues."
Previously, the NEB only considered GHG emissions directly associated with construction and operation of the pipeline.
The NEB will now invite public comment on the completeness of TransCanada's applications before issuing a hearing schedule.
The board invited public input last spring on topics that should be considered during upcoming hearings, including the issue of greenhouse gas emissions related to increased consumption of oil from completion of the 4,500-kilometre conduit.