Mr Radich told RNZ Dunedin had a "very low rate of sea-level rise, because the ocean’s quite cold".
Asked for clarification by the Otago Daily Times, he backtracked.
"No mayor wants to start his first day in the job with a mea culpa, but it’s fair to say that on this occasion I misspoke about the cold," Mr Radich said.
"Sea-level rise is very real, and rates are rising, so we need to make progress on these significant issues over the next three years."
Mr Radich said he was trying to get across that Dunedin was not experiencing the same level of sea-level rise as many other parts of New Zealand and the primary focus was on stormwater inundation, particularly in South Dunedin.
Data between 1901 and 2020 shows a rise relative to land in Auckland of 1.71mm a year, Wellington 2.04mm, Lyttelton 2.24mm and Dunedin 1.52mm.
Average coastal sea levels rose faster at all four sites between 1961 and 2020 than they did between 1901 and 1960.
The Dunedin City Council website says parts of the low-lying flat area of South Dunedin are likely to become more flood-prone over coming decades, because of climate change.
The area is home to about 12,000 people and 700 businesses.
University of Waikato coastal scientist Dr Rob Bell said Dunedin’s long-term rise in sea level since the early 1900s had been slower than other main ports, but it was catching up, as the rate of rise had more than doubled in the period from 1960 onwards, compared with the pre-1960 era.
The land mass along Otago’s coast was mostly stable, he said.
"Despite the stable landmass, St Clair Beach projections for future sea level are for accelerating rises in sea level, depending on how global emissions track out," Dr Bell said.
"It’s not how cold the waters are locally — it’s the relative change in any regional sea level over time from the change in warming of the oceans."
University of Otago senior environmental management adviser Associate Prof Mike Hilton said Dunedin had some of the most vulnerable urban areas.
"We may have slightly lower rates of sea-level rise but we’re close to the Great Southern Ocean and our coastlines are susceptible to winter storms."
