Te Rūnanga o Ōtākou representative Rachel Wesley, of Dunedin, said past under-investment in marae areas had put the iwi on the back foot.
Because Ngāi Tahu were a coastal people, their communities were likely to be directly impacted by climate change, Ms Wesley said.
"We’re seeing increasing erosion, and rising sea levels affect our traditional burial sites and food-gathering places," she said.
"Our Ōtākou marae is not at direct risk ... but the wider area is, being on the peninsula.
"We need to allow space for hapu and runaka to be able to have some agency over decision-making at a policy level when it comes to the future of our marae and our villages.
"That will require working closely with central and local government."
Ms Wesley said there had been historic under-investment at a local and national level in marae infrastructure, including public transport, roading and Three Waters.
"Having our infrastructure enabled would better help our whānau and marae communities respond to a lot of the intangibles of climate change.
"There are ways that Ngāi Tahu can address it, but it requires further support from council and central government.
"It’s both a local issue and a global issue."
Ms Wesley’s comments come on the back of Ngai Tahu’s recent climate change symposium, in Christchurch, held to mark the 25th anniversary of the iwi’s Crown Settlement.
There were updates on sustainability initiatives and progress towards targets set out in Te Kounga Paparangi, the Ngāi Tahu climate action plan.
A statement from the iwi said in 1998, Ngāi Tahu received an apology from the Crown, cultural and tribal redress, and $170 million compensation.
"It was the culmination of a quest for justice over seven generations."
Since then, the iwi said it had built a "solid asset base" and invested more than $930 million in tribal development including education grants, environmental initiatives, language revitalisation, marae projects, and other schemes that advanced the wellbeing of the iwi.
At the symposium, kaiwhakahaere (chief executive) Lisa Tumahai told the iwi that 16 of their 18 Ngāi Tahu marae were at risk of climate change impacts, being in low-lying coastal areas and exposed to rising sea levels and flooding.
"We have just topped 80,000 registered iwi members.
"We have built a thriving business, which is investing in our people and generating stronger education, health, and cultural outcomes for our whānau.
"We are allowed to be a bit proud.
"At the same time, we are in the middle of the challenge of our lifetime — climate change."
Ms Tumahai told the Ngāi Tahu governance board it needed to start having conversations quickly in order to work out mitigation strategies and potential solutions.
It would involve discussions about whether buildings can be relocated and what managed retreat might look like.
Ms Wesley said the symposium was a great opportunity to hear from community leaders about the upcoming impacts of climate change, particularly from its younger members.
"They spoke about climate anxiety, and challenged those of us in charge to work harder to address it," she said.
Ms Wesley said it was time to have a national conversation about the effects of insurance retreat, as insurers pull back from insuring properties facing increasing exposure and vulnerability to escalating hazards.
"It’s going to affect us all, but it is going to have a significant impact on those communities where there has been an under-investment in infrastructure," she said.
— Additional reporting RNZ