Quakes help speed up sea-level rise in areas
The impact of sea-level rises could double in some areas as a result of sinking land levels, according to a Victoria University study.
While the findings had the potential to wipe thousands of dollars off the value of some seaside properties, for some it will be music to their ears, with shoreline uplift in other areas negating sea-level rises.
Study co-author Professor Tim Stern said this new information could be used by homeowners to decide land value, by the government to plan mitigation measures and the insurance industry to set premiums.
‘‘In parts of the North Island the actual surface of the land is going down 3 millimetres in relation to the centre of the Earth, you effectively double the global rate [of sea-level rise].’’
Insurance Council chief executive Tim Grafton said sealevel rise was on insurance companies’ radars, and was one of the risks insurers took into account.
‘‘Insurers draw on all available data points to inform themselves about risks.’’
Grafton had not seen the reports’ full findings, but said he would be interested in the projections.
Stern, from the School of Environment and Earth Sciences, said the global sealevel change due to global warming and the melting of polar icecaps was projected to be around 3mm a year.
‘‘The rate in New Zealand is being measured at about 1.5mm [a year] by tide gauges.’’
The study used 15 years of GPS data to predict land movements.
Kapiti Council previously included coastal hazard information in residents’ Land Information Memorandums (LIMS), but were forced to stop after residents litigated over lost property value.
Stern said banks and insurers would find the information invaluable.
‘‘If they have a better knowledge of what their particular area of the coastline is doing they will be in a much better shape to make good policy.’’
As the study continues and the data pool got larger, Stern said the margin of error became smaller.
The scope of the study is limited to areas with GPS stations.
A Victoria University image shows what could happen to sea-level in Wellington if average temperatures rise by 2 degrees Celsius this century compared with pre-industrial levels.