Fast forward over twenty years and he is now a professor of physical geography at Victoria University and last year he received the Prime Minister's Science Prize for Communication for his work spreading information about climate science.
Renwick is a fan of Greta Thunberg, the Swedish high school student started a climate change movement that has ricocheted around the globe.
"I absolutely take my hat off to her. If anyone ever doubted the power of the individual, you've only got to look at her."
He believed many corporations and governments were threatened by the 16-year-old girl and the movement she had led.
"There's a lot of money tied up in the status quo, such as drilling for oil, big business manufacturing or the energy industry."
He said the effects of climate change in New Zealand were not obvious yet and people's gaze had to be thrown further afield around the globe to get the bigger picture.
"You can get the wrong impression by looking at what's in your back yard. You really have to look more broadly than that.
"We have a pretty pleasant climate and it's not especially extreme at the moment. Climate change might not seem like that much of a threat here yet, compared to Alaska or somewhere like the Pacific Islands."
While climate change has been an issue lurking in the minds of people for many years, it was only recently that it had been urgently thrust into the public consciousness.
"It was always sort of on the radar but most people thought it was a distant problem that might affect the grandchildren. Now people are like, 'hey, the climate has changed and we're already facing these issues'."
Renwick believed this is a natural for some people to look away from the issue.
"We're all pretty conservative and humans by nature want to continue doing what they've done in the past.
"The catch is that if we collectively do that then the problem is only going to get worse and worse, and there'll be serious consequences."
He urged people to talk to their family, neighbours and workmates about climate change.
"Just get it out and normalise the conversation around climate change.
"We are fighting against the status quo here. We need to change the way the economy operates which is a big ask and a hard job.
"Everybody can at least add to the conversation on that and that doesn't cost anything."
Professor Renwick will be speaking at the Tauranga Arts Festival event, Getting Louder.
Tauranga Arts Fesitval - Getting Louder
November 3, 2.30 pm - 90min running time
Carrus Crystal Palace
Go to Ticketek to book tickets
A panel headed by Scott Campbell with climate scientist Dr James Renwick, winner of the 2019 PM's Science Communication Prize; Green MP Chlöe Swarbrick; longtime business journalist Rod Oram; BOP Regional Council's GM of Strategy & Science Namouta Poutasi; and Rachel Stewart, environmental campaigner and former farmer.
