The viability of New Zealand’s public insurer, the Earthquake Commission (EQC), is at risk from climate change, new research shows.

The EQC should be planning for a 7 to 8% rise in future payouts for weather-related damage over the next two decades as a result of extreme rain events, a study by academics at the Motu Economic and Public Policy Research Trust found.

“The expectation that the frequency and intensity of extreme weather will be amplified by climate change ultimately implies additional liability for the EQC, and potentially poses a risk to the long-term sustainability of New Zealand's public insurance scheme,” the paper says.

By 2080 and beyond, EQC costs could jump by a quarter, it says.

Floods and storms and landslides cost the EQC NZ$450 million ($429.69 million) during 2000-2017.

“Extreme weather events resulting from climate change will increase the EQC’s liabilities. Whether this increase necessitates a policy change, for example in the amount of premiums the EQC collects annually, or in the types of risks it insures, are questions for future research,” the Moto paper says.

The findings were achieved by combining past insurance claims with future climate and greenhouse gas projections to forecast losses caused by extreme weather. It analysed more than 8000 claims.

Last year, insured losses from New Zealand’s severe weather events totalled more than $NZ118 million ($113.18 million).