In his Aug. 27 opinion piece, Stephen Snyder describes the Keystone XL pipeline as the “best option in a no-win scenario.” It is best, he thinks, because we must use either trains or pipeline to transport the oil that is extracted from the Athabasca shale — also known as the “tar-sands — and pipeline beats train. It is a no-win scenario, he thinks, because either method of transport poses risks to relevant local environments.

This assessment ignores the most important reason why we should not build the pipeline, and why we all should actively oppose the pipeline.

The latest Intergovernmental Panel on Climate Change reports emphasize that we can avoid the catastrophic consequences that would accompany an average global temperature increase of more than two degrees Celsius only if we transition rapidly to green energy. Approving the pipeline ensures that we will not transition rapidly to green energy. So, approving the pipeline ensures catastrophe.

Why does approving the pipeline ensure that we will not transition rapidly to green energy?

Not all oil is equal. How much any given fuel contributes to climate change is a function of two factors. One factor is the greenhouse gases the fuel releases into the atmosphere when burnt. Here, all oil is roughly equal. The other factor is the greenhouses gases that are released into the atmosphere while bringing the fuel to market. Here, some oils are far worse than others.

The proposed Keystone XLipeline would carry oil that comes from the Athabasca shale, which is among the very worst oils for two reasons. First, extracting and refining the materials that become the oil is especially resource intensive. Second, extracting those materials requires cutting down boreal forest, thereby releasing the carbon stored in the forest’s plants. So, burning a gallon of oil from the Athabasca shale contributes more to climate change than burning a gallon of oil from a traditional oil well does.

Given that the oil from the Athabasca shale is especially bad, continuing to extract it makes sense only if we plan to burn through much of the better oil that can be brought to market. But if we do so, we will far exceed the average global temperature increase of two degrees Celsius.

Crucially, oil and gas industry executives and Wall Street investors know all of this. So, approving the pipeline would send them a clear signal: “Don’t invest in green energy anytime soon because we plan to continue relaying mostly on oil for decades, and thus, the return on investment in green energy is far, far away.” If energy companies and investors get that signal now, then we cannot rapidly transition to green energy.

Approving the pipeline, then, ensures catastrophe. This is why leading climate scientist and Iowa’s own James Hansen is correct to say that approval of the pipeline would be “game over” for all of us. This is why we should all oppose the pipeline.