Late on Friday, the ethylene plant run by ExxonMobil at Mossmorran in Fife suffered what the company called an “upset”. It was being shut down, resulting in the flaring of waste gas for 48 hours, the company explained.

This kind of pollution does not inspire confidence, particularly from one of Scotland’s highest carbon emitters. As we report today, ExxonMobil, alongside Ineos and Shell, have all belched rising levels of carbon dioxide into the air from their Scottish plants, helping to disrupt the climate.

It is not surprising that fossil fuel plants cause climate pollution. But what is unacceptable is that these companies seem to have been so ineffective at reducing their emissions in line with international agreements to combat climate change.

They all say they are working hard to improve their efficiency, though they seem to have differing attitudes to climate policy. Shell accepts it is happening and is promising to change, while Ineos talks about being “more able to compete in the global oil and fuels market”.

Now that Scotland’s coal-fired power stations have been closed down, the focus is on the big remaining industrial polluters. They have to drastically cut their carbon emissions to help avoid global climate chaos.

It’s no good relying on the failing European emissions trading scheme to guarantee reductions. If companies won’t voluntarily curb their pollution, it will be up to the Scottish Government to persuade them to change, either by persuasion or by legislation.