"I heard somewhere in Auckland they charge for plastic bags in supermarkets," the 17-year-old Kaikorai Valley High School pupil said.
And if he became mayor, the bags would no longer be available.
Joel had the opportunity to consider the matter when he spent a day with Mayor Peter Chin yesterday, after winning the opportunity at last month's Dunedin City Council expo.
He met Mr Chin for lunch, before trying on the mayoral robes at the municipal chambers.
Council business support manager Narelle Barbour said Joel won two competitions at the expo, the second one from getting every question right in a quiz that followed visits to the expo stalls.
It was his interest in the environment, and his suggestion in his competition entry the council-funded Enviroschools initiative should be available in every primary school, that won the day.
And for someone who wants to be a marine biologist, a visit to the Tahuna sewage treatment plant may have provided some useful knowledge as his day wrapped up.