The European Union wants to slash greenhouse-gas emissions to 80% below 1990 levels by 2050. It is on course to cut just half that amount. To get back on track, on February 15th, 2017 the European Parliament voted for a plan to raise the cost for firms to produce carbon. It has prompted growing calls for the bloc to tax the carbon emissions embodied in the EU’s imports. At best, such a levy will barely curb emissions. At worst, it could cause a trade war.

The EU’s latest reforms try to put up the price of carbon by cutting the emissions allowances firms are granted. They include the EU’s first border tax on carbon, levied on cement imports.

Under the EU’s reforms, steelmakers in Europe would pay up to €30 ($32) to emit a tonne of carbon, but foreign producers selling in the EU would not have to pay a cent. Putting an equivalent tax on these imports is a neat solution to this problem. “It’s wonderful in theory,” says Jean Chateau, an economist at the OECD, a club of rich countries. But “in reality it’s very problematic.”

One big problem is how to calculate the carbon in imports. This is not easy even for simple steel sheets; for items made of several bits of metal from different sources, it is hellishly complex. Some countries might even refuse to provide the information. And any method brought in for foreign firms, if not applied to local ones, could fall foul of WTO rules,..

A global carbon price would produce far greater economic benefits than border taxes, but would require closer international co-operation. A trade war is not the way to get there.

Excerpts from Steely defences: Carbon tariffs and the EU’s steel industry, Economist,  Feb. 18, at 62