Europe Needs to Save Its Carbon-Market Marriage: Editorial

When the UK left the European Union, it created a rift in the global fight against climate change: Suddenly, the EU’s ambitious carbon cap-and-trade system — designed to reduce harmful emissions of greenhouse gases throughout Europe — had to be split in two.

Now the UK and EU say they want to get their carbon markets back together, as part of a broader “reset” in relations. It’s a great opportunity to demonstrate that, despite Brexit, common sense in climate and trade policy can prevail.

Launched in 2005, the EU’s emissions trading system stands out as the world’s largest and most ...