Regarding the March 5 editorial “The wrong fight”:

The Keystone XL pipeline has galvanized climate activists not merely because it is a tangible symbol of the threat fossil fuels pose to the planet but also because it puts into clear perspective the ethics of participating in a scheme that offers a short-term, large private profit at long-term, larger public expense.

The Post argued that the Canadian oil company behind the pipeline will find another way to get its oil to world markets if the United States stands in its way, so we may as well let U.S. companies profit from building the pipeline. This is the moral equivalent of arguing that you may as well profit from stolen goods because the thieves will find a fence elsewhere if you don’t.

It’s time for the United States to show moral leadership on climate change, and rejecting this pipeline is a good place to start.

Ivy Main, McLean

The writer is vice chair of the Virginia Chapter of the Sierra Club.

We clearly need a price on carbon. The effects of carbon emissions threaten both economic and environmental sustainability. Price signals are what drive producer and consumer choices, and they are an efficient way to encourage lower emissions. At the same time, unemployment is our most critical economic problem. There are huge governmental, societal and personal costs to under- and unemployment.

Using carbon tax revenue to offset or reduce payroll taxes (our most regressive federal tax) would have two benefits: It would give working Americans more money, boosting the economy, and it would lower the cost of hiring workers, thus boosting employment. Over the long term, it would send a signal that hiring people will be less costly and that wasting energy will be more expensive. A carbon tax-payroll tax shift offers the prospect of real headway on the climate front while breaking the jobless recovery logjam.

Robert Wolcott, Silver Spring

The writer, a former deputy assistant administrator for policy at the Environmental Protection Agency, is an economic policy adviser to the group Get America Working.