The 25-year-old Greater Dunedin candidate, who is completing her Masters degree in Science Communication at the University of Otago, believes there is broad support for finding local responses to international economic, climate and energy problems.
"This is a time in history for local authorities," Miss MacTavish said.
"In light of international failure in areas such as climate change negotiations, we need to find our own ways to respond."
Miss MacTavish grew up in Moeraki.
She is the granddaughter of dancer and choreographer Shona Dunlop-Mac-Tavish and the niece of actor and teacher Terry MacTavish.
The second youngest person ever elected as a Dunedin city councillor, Miss MacTavish said she believed people had voted for her because they wanted "fresh blood and new ideas" and because they supported her desire to "not just pay lip service to future challenges, but face them and do something about them".
"The big issues on my radar are climate change, declining global affordability of energy, particularly oil, and global economic instability," she said.
"At the moment we as a city are so dependent on these systems, which are starting to fail us.
"I think the council needs to look at how we can become more resilient as a city."
She did not believe her vision for a vibrant city fed by local food, linked by accessible sustainable transport options, powered by local, renewable energy and with a really robust, local economy was a "radical agenda".
Rather, it addressed "inevitable issues" that were becoming increasingly mainstream.
"I'm sure I'm challenging the status quo a bit. But out there, there is a lot of support."
The immediate challenge was to think of all the city councillors as one team, and then work with the community to clarify and work towards common goals.
"The more we as a council can work with the hundreds of community groups already beginning to address these issues, the better."
Being young was not a disadvantage, she said.
"In part it is irrelevant. What each person brings to the table is different irrespective of their age.
"What is relevant is that I can be a voice for youth.
"About a quarter of the city is under 25."
Miss MacTavish's parents still live in Moeraki.
She said they were active "building [a] resilient community".
Her grandmother was "very strong in what she believes" which was "an inspiration".
"I'm very lucky to have such a wonderful family to look up to".
Tomorrow, to avoid a conflict of interest, Miss MacTavish will resign her city council-paid position as the Enviroschools regional co-ordinator.
"I will really miss the job, the young people and the schools.
"I hope I will be able to support them in another capacity."
She would not be seeking other employment in the short term.
"I'm committed to being the best councillor I can be.
"If that means just being a councillor, that's what I'll do."
