When was the last time Canada had a carbon emissions policy that made a big difference? One recent study in Science pins it at about 20 years ago.

The finding was made as part of a broader review of climate policy measures taken throughout the world from 1998 to 2022. Using data from the Organisation for Economic Co-operation and Development (OECD), the study authors looked at 1,500 climate policies in total, only to find that just 69 of these brought about “large emissions reductions” — that is, policies that had an effect larger than the model’s minimum threshold, a range of 4.5 to 13 per cent.