"While this declaration does not carry any statutory or legal weight it provides a political framework for council's existing work stream on its climate change and adaptation strategy," Mr Gurunathan said.
"The declaration recognises our communities are facing an iceberg of significant costs now, and increasingly over the coming decades, from coastal erosion and floods."
These, he said, include:
Coastal erosion -
The 900m Paekākāriki seawall budgeted to cost about $17m.
The temporarily consented 170m Wharemauku block seawall has cost $600,000 with additional monitoring costs over the next seven years.
GWRC requires KCDC to secure a long-term solution which has been costed at $1.2m. There is a further 4km of beachfront properties south of the Wharemauku block seawall with a series of failing seawalls.
While the funding of a continuous seawall along this 4km has not been costed in detail, it is expected to be around $38m.
Along the 100m wide section stretching along Kāpiti's 42km coastline, there are an estimated 1800 properties potentially facing coastal erosion. These properties, with an estimated value of $1.6 billion, are also some of the district's highest ratepayers.
Inland floods -
More than 6000 inland properties are in flood-prone zones. Council has identified more than 300 stormwater projects over 60 years costing $250m.
The Niwa Climate Change Report for the Wellington Region August 2017 predicts climate change-related impacts on Kāpiti with a 15 per cent increase in winter rain delivered in short but very intense falls.
This coupled with Kāpiti's topography means increasing investment in pumping stations. Each cost about $4m with the Kena Kena project costing $7m.
