SOME ENVIRONMENTALISTS hoped that Virginia Gov. Terry McAuliffe (D) would try to block a large natural gas pipeline proposed for North Carolina, Virginia and West Virginia. The project would encourage fracking, they warn, when the state needs to encourage renewable sources of electricity. Instead, Mr. McAuliffe has rightly sided with reality and backed the pipeline’s construction.

The 550-mile natural gas conduit would cost a partnership of energy companies about $5 billion to build, and it would be able to transport 1.5 billion cubic feet of gas to markets in North Carolina and Virginia every day. The line would connect the Mid-Atlantic directly to some of the richest gas deposits in the world, contained in shale rock formations in Ohio, Pennsylvania, West Virginia and elsewhere.

Backers claim that the project would mean thousands of temporary construction jobs. But the long-term economic benefits are more important. The ease and abundance of the gas supply would keep energy prices in check, discouraging spikes during supply disruptions, periods of high demand or both. Existing households and businesses would benefit from that. Mr. McAuliffe reasonably bets that manufacturers would also move into the state, seeking low production costs and energy reliability.

The opposition is focused on environmental concerns. Much of the gas that would be transported would probably come from drillers employing fracking — a process in which a combination of water and drilling liquids is pumped underground at high pressure. Aside from the worries some have raised about water contamination, a major concern is the mixture of gases that escapes from wells, storage facilities and transportation infrastructure, which can worsen the ambient air and raise a climate-change problem. Though natural gas produces half the carbon dioxide than its equivalent in coal when burned, its main component, methane, is a potent greenhouse gas when released uncombusted. At the very least, environmentalists say, the federal government needs to have tighter rules in place to prevent this sort of leakage before permitting another natural gas pipeline.

We disagree. This pipeline won’t be in service for at least four years, and the new infrastructure will be relatively leak-free. By then, the Bureau of Land Management and the Environmental Protection Agency will have sorted out the air-pollution standards they will apply to the fracking wells feeding the pipeline. Which brings us to two crucial points about natural gas. First, environmental concerns can be addressed through relatively inexpensive regulation rather than shutting down the industry and forgoing the economic benefits. Second, switching out coal for natural gas has significant environmental benefits that activists should not dismiss.

Though mere fuel switching will not cut greenhouse-gas emissions enough in the long term, it is an inexpensive way to make medium-term progress and avoid potentially catastrophic high-emissions scenarios. Virginia should embrace that promise.