The Wellington region must work collaboratively to cope with climate change, as nature does not respect political boundaries, Greater Wellington Regional Council says.
Chairwoman Fran Wilde's comments follow a major report from the Intergovernmental Panel on Climate Change, which urged adaptation to more intense rainfall and sea level rises.
Wilde said the council wanted a regional climate change policy, but failed to get other councils to agree to it four years ago.
"It was a great disappointment. All of the officials agreed but we couldn't get it before their councils."
The Government had to take a more active role in adaptation planning, setting bottom lines for what had to be done, she said.
"Political boundaries are not respected by nature, and it's important we plan this as a whole."
Iain Dawe, the regional council's senior policy adviser for natural hazards and coasts, said work on identifying areas at risk from climate change continued.
Wellington was more vulnerable to rising sea levels, as the lower North Island is subsiding up to 4mm a year while the seas rose 1.8mm, placing pressure on coastal roads.
A lot of work had also gone into identifying places at risk of flood in a climate with more intense rain.
"We probably are not going to get more flood events, but the intensity will increase," Dawe said. "What we previously classified as a one-in-50 or a one-in-100 [year event] will occur every five to 10 years."
If necessary, stop banks and other flood defences had to be upgraded. If the defences failed, the consequences could be severe.
Wilde said the regional council did not want to have to build more flood banks to protect new development, and planning should change to reflect this.
"We've had a big debate with councils about building in flood zones. Hutt Valley is one gigantic flood plain. If it was today, you would not build a city there."
Ratepayers were paying for bad planning decisions made decades ago. "We put tens of millions a year into flood protection that's already there."
Spending on defences would continue but development had to be restricted, she said.
- The Dominion Post
What do you make of New World's Little Shop toys?Related story: Shopping giveaway 'harming children'