Greg Clark, of London, England, was commenting in an online presentation praising Dunedin's draft economic development strategy unveiled earlier this month.
He was commissioned to scrutinise the document after an approach by Dunedin City Council chief executive Paul Orders, formerly of Wales, who had previously worked with Mr Clark.
In the last decade, Mr Clark has advised about 100 cities on their economic development plans, working with local, regional and national governments, major corporations and inter-governmental organisations, among others.
He was also chairman of the OECD's development and investment forum, and boasts an impressive CV of other past and present roles.
Mr Clark said he was "very impressed" with the direction charted by Dunedin's new strategy, which was "exactly the right kind of document for Dunedin".
The age of globalisation meant travellers, workers and entrepreneurs were more mobile, as was money, including for investment, which created challenges and opportunities for cities like Dunedin.
Cities that successfully "set out their stall" could attract niche and specialist businesses, like Halifax, in Nova Scotia, Canada, which had been "incredibly effective" in building a medical and higher education cluster.
However, those that failed risked losing what they already had, as other cities tried to lure away businesses, he warned.
"It leaves cities with opportunities, but also with threats. Part of the question is how we deal with that."
In Dunedin, failure would mean fewer jobs and choices for those living in the city, and fewer reasons for companies to relocate to Dunedin.
That would also mean less rates income for the council and less resources available to improve the city's social and environmental spheres.
Instead, smaller cities like Dunedin needed to identify what they wanted their future to look like and how "proactive" to be in pursuing it.
They also needed to identify which niche opportunities to pursue, and promote the lifestyle and other qualities that made them a better option for specialists than bigger cities and their associated problems.
"Sometimes, small cities can be extremely attractive and extremely effective," he said.
That future could include the arrival of the oil and gas industry in Dunedin, if offshore extraction eventuated, but Mr Clark cautioned against relying on any boom indefinitely.
Instead, any period of prosperity should be used to invest in other opportunities to grow and diversify the city's economy, he argued.
Dunedin's strategy identified the potential to be found by targeting sectors including technology and engineering, higher education, and the creative and visitor economies, which were "hugely important" and growing all over the world, he said.
Globalisation meant more people in those sectors were looking for "a different kind of place" to base themselves, and Dunedin had "a great opportunity to position itself as that different kind of place".
The consultant was paid $10,000 for his work, but council economic development unit manager Peter Harris said his "huge" experience had been significant for the project.
Mr Clark helped shape the contents during online discussions with economist Stephen Knuckey, the strategy's author, as well as Dunedin city councillors, council staff and project partners the University of Otago, Otago Polytechnic, Otago Southland Employers' Association and Otago Chamber of Commerce.
"When you're in a small city ... you've got to be careful you're not just having conversations with yourself," Mr Harris said.
"To have somebody with that degree of international perspective is, I think, pretty exciting for the city."
Councillors last week voted to release the draft strategy for public consultation. Submissions may be made online at www.dunedineconomy.co.nz and are expected to close in mid-June.
