By The Kansas City Star Editorial Board

A carbon tax would be the most effective way to change the behavior of industries that belch large amounts of greenhouse gases into America’s air.

The tax would cause coal-fired power plants and many other large polluters to invest in modern equipment that would reduce emissions. The tax would make it more expensive to produce power the old-fashioned way, which would encourage investment in cleaner and renewable energies such as wind and solar.

But there is, admittedly, a large problem with a carbon tax: Congress doesn’t have the spine to pass it, given the immense opposition from a wide variety of U.S. industries.

So President Barack Obama and many politicians, environmentalists and even some industry groups are coalescing around the next best idea.

It’s a cap and trade policy, which would allow the government to set a ceiling on total greenhouse gas emissions. Then, polluters would buy and sell permits as they attempt to meet the overall emissions goal.

If done properly, cap and trade would be a responsible compromise as the federal government attacks the problem of global warming.

As that occurs, the lobbyists’ lawyers on K Street in Washington will be all over the Capitol, trying to plug in special favors. Some industries will want to be exempt from parts of the policy. Others will want cut-rate prices in buying the permits to pollute. And some will simply try to make sure they can game the system in the future and continue their polluting ways.

Political compromises will be required to pass such a controversial and potentially expensive measure. Missouri Sen. Claire McCaskill is among those concerned about the financial burden that could be placed on residents of Missouri, Kansas and other states that largely depend on coal-fired electricity plants. The worry needs to be addressed in any final deal.

Still, some of the nation’s lowest electricity rates are found in Midwestern states. If coal-fired power becomes more expensive to produce with the goal of reducing pollution, many Americans could be compelled to trim their use of electricity and to conserve more energy. Both would be useful responses in the long run.

Obama and the Democratic leadership must stand firm during debate on the cap and trade policy. The final bill ought to contain strict, fair rules on who should pay to reduce greenhouse gases and how much it could cost.