Opec believes oil demand could peak within 13 years if the Paris climate agreement’s targets are fully implemented, sounding a warning to its members just days after the accord to curb global warming came into force. The 14 members of the oil cartel are heavily reliant on energy revenues and have already been grappling with a prolonged downturn in prices, which has slashed budgets and pushed many producer countries into recession. Though not the first to argue oil demand could be nearing a peak as momentum for further action to reduce emissions builds, the forecast carries additional weight coming from a group that collectively pumps more than a third of world oil supplies. It will probably be welcomed by environmental campaigners as evidence that the energy industry itself recognises the threat posed by the Paris accord’s goal to spur government efforts to cut fossil fuel pollution.