Look at a map of Louisiana — not the surface of it, but underneath. One will find one of the more complex nexuses of pipelines in the world.

Pipelines are big and difficult projects that are essential to distribution of energy in America from the Gulf Coast, particularly Louisiana.

Maybe familiarity breeds content, in this case, but we find it difficult to understand the harsh criticisms that have blocked the proposed Keystone XL pipeline. It is to be built to bring oil from tar sands in Alberta, Canada, to American refineries and then on to American markets.

Construction is a major job creator, and there seems little doubt that adding jobs in America today is a good idea. Critics in the environmental community dispute them, but environmental impact studies suggest it can be built without undue harm.

What is perhaps more of a motivator to the opposition is twofold. First, there is a prejudice against the old-fashioned energy sources compared with sexy new ideas such as solar or other renewables. Even as steadfast a backer of the oil companies as U.S. Sen. David Vitter, R-La., calls for an energy policy of “all of the above.” We, too, want renewables to be a bigger part of America’s energy future, but that happy day is a way off.

Second, there is opposition from those concerned about global warming. Tar sands oil is heavy oil, more expensive to produce and more difficult to refine. It is a source of energy that, like other hydrocarbons, is a contributor to greenhouse gases in the atmosphere.

Again, unfortunately, we can’t do away with greenhouse gas production in America’s economy anytime soon. To block the pipeline is a one-sided score in a game that doesn’t calculate benefits and losses to the environment and society as a whole.

We’re just not as easily scared by the word “pipeline” in Louisiana. Unless there is a more compelling argument than so far heard, the government of the United States should not stand in the way of this project.