The debate over the development of oil sands in Alberta, Canada, is inflaming tensions in and between Canada and the United States.

In April, US President Barack Obama deferred a decision on the fate of the proposed Keystone XL oil pipeline, despite escalating pressure to approve it from Canadian Prime Minister Stephen Harper. The contentious pipeline would transport 830,000 barrels per day of partially refined bitumen from Alberta’s oil sands, through the US Midwest, to Gulf Coast refineries. Harper is also facing a controversial domestic battle over his approval on 17 June of the Enbridge Northern Gateway pipeline, to connect Alberta with a port on British Columbia’s remote Pacific coast.

But drama over the pipelines obscures a larger problem — a broken policy process. Both Canada and the United States treat oil-sands production, transportation, climate and environmental policies as separate issues, assessing each new proposal in isolation. A more coherent approach, one that evaluates all oil-sands projects in the context of broader, integrated energy and climate strategies, is sorely needed.

Although Keystone XL and Northern Gateway are among the first major North American projects to highlight flaws in oil-sands policies, more than a dozen other projects are on the drawing board. Meanwhile, the US government is considering its first oil-sands leases on federal lands, as bitumen mining expands on state land in Utah’s Uinta Basin.

As scientists spanning diverse disciplines, we urge North American leaders to take a step back: no new oil-sands projects should move forward unless developments are consistent with national and international commitments to reducing carbon pollution. Anything less demonstrates flawed policies and failed leadership. With such high stakes, our nations and the world cannot afford a series of ad hoc, fragmented decisions.