Sea level rise in New Zealand
Sea level rise in New Zealand poses a significant threat to many communities, including New Zealand's larger population centres, and has major implications for infrastructure in coastal areas. In 2016, the
The results of studies from a programme called NZ Searise released in 2022, indicate that for some parts of New Zealand, the apparent sea level rise will be twice as fast as previously predicted. This is because of the combined effect of absolute rise in sea level with gradual subsidence of ground levels. [7] In some parts of Wellington, the land is subsiding by 3–4 mm per year, leading to an apparent 30 cm of sea-level rise in 18 years. By 2040, this is forecast to cause inundations every year that are equivalent to a 1-in-100 year event in 2020.[7]
Twentieth century
An analysis in 2004 of long term records from four New Zealand tide gauges indicated an average rate of
A 2008 study of cores from salt-marshes near Pounawea indicated that the rate of sea level rise in the 20th century, 2.8 ± 0.5 mm per year, had been greater than rate of change in earlier centuries (0.3 ± 0.3 mm per year from AD 1500 to AD 1900) and that the 20th century sea level rise was consistent with instrumental measurements recorded since 1924.[11]
Twenty-first century
Predictions about sea level rise vary considerably. In November 2014, Dr
In 2016, the Royal Society of New Zealand stated that a one-metre rise would cause coastal erosion and flooding, especially when combined with storm surges.[1][2] Climate scientist Jim Salinger commented that New Zealand will have to abandon some coastal areas when the weather gets uncontrollable.[3]
Associate Professor Nancy Bertler, of the Joint Antarctic Research Institute, at Victoria University of Wellington says: "New research suggests that sea level could rise as quickly as four metres per 100 years (or one metre per 25 years). Assuming even a modest global sea level increase of 50 cm by 2100 (IPCC scenario RCP 4.5), the frequency of coastal inundation in New Zealand is predicted to increase by a multiplier of 1000 times."[15]
Rising sea levels will further threaten coastal areas and erode and alter landscapes whilst also resulting in salt water intrusion into soils, reducing soil quality and limiting plant species growth.[16] The Ministry for the Environment says by 2050–2070, storms and high tides which produce extreme coastal water levels will occur on average at least once a year instead of once every 100 years. GNS climate scientist Tim Naish, says in the event of a two-metre rise in sea-level by the end of the century, one-in-100-year flooding event will become a daily event. Naish says: “We are a coastal nation so we are going to get whacked by sea-level rise. In many areas, we have to retreat "which comes with massive disruption and social and economic issues.”
Twelve of the fifteen largest towns and cities in New Zealand are coastal with 65% of communities and major infrastructure lying within five kilometres of the sea.[4] The value of local government infrastructure that is vulnerable to sea level rise has been estimated at $5 billion.[17] As flooding becomes more frequent, coastal homeowners will experience significant losses and displacement. Some may be forced to abandon their properties after a single, sudden disaster like a storm surge or flash flood or move away after a series of smaller flooding events that eventually become intolerable. Local and central government will face high costs from adaptive measures and continued provision of infrastructure when abandoning housing may be more efficient.[6]
In Auckland, the CBD, eastern bays, Onehunga, Māngere Bridge, Devonport and Helensville are the most vulnerable to inundation.[18]
NZ Searise study findings 2022
The results of studies from a programme called NZ Searise released in 2022, indicate that for some parts of New Zealand, the apparent sea level rise will be twice as fast as previously predicted. This is because of the combined effect of absolute rise in sea level with gradual subsidence of ground levels. [7] In some parts of Wellington, the land is subsiding by 3-4 mm per year, leading to an apparent 30 cm of sea-level rise in 18 years. By 2040, this is forecast to cause inundations every year that are equivalent to a 1-in-100 year event in 2020.[7]
These revised projections cut in half the time that was thought to be available to plan and implement risk management strategies for these vulnerable areas. The current forecast for global sea level rise is for 0.5 m by 2100, but in some parts of New Zealand, the effective rise in sea level could be twice as great by that time, because of the combined effect of gradual land subsidence.[7] Many different parts of the country are affected by the change in forecast sea level rise. For example, because of the effects of gradual land subsidence, Akaroa on Banks Peninsula in Canterbury can expect 30 cm of sea level rise by the year 2040, instead of 2060. The Wairarapa coastline, around the south-east of the North Island, is forecast to experience the largest increases in sea level.[20]
Vulnerable areas
Nelson airport
The NZ SeaRise programme identified Nelson airport as one area of particular vulnerability, with a projected subsidence of 5 millimetres (0.20 in) per year.[21] In February 2018, the approach road to the airport was flooded when the adjoining Jenkins Creek burst its banks during a storm that brought king tides and strong winds. The airport was closed for about one hour.[22] The airport's Chief Executive said that the proposed runway extension would be planned around the latest sea level rise forecast, and that the airport was "here to stay", despite the concerns over the threats posed by sea level rise.[21]
Adaptation plan
In August 2022, the Ministry for the Environment published Aotearoa New Zealand's first National Adaptation Plan, covering the years 2022–2028. The plan includes a range of adaptation options: Avoid, Protect, Accommodate and Retreat.[23]
See also
References
- ^ ISBN 978-1-877317-16-3. Archived from the original on 23 June 2016.)
{{cite book}}
: CS1 maint: unfit URL (link - ^ a b Morton, Jamie (19 April 2016). "Six reasons why you should worry about climate change". New Zealand Herald.
- ^ a b New Zealand will need to abandon some coastal areas – climate change expert, Newshub 9 February 2018
- ^ a b Warne, Kennedy (November–December 2015). "Three feet high and rising". New Zealand Geographic (136). Retrieved 3 May 2022.
- ^ "Maps made available to show extent of flooding threats". RNZ. 25 May 2023. Retrieved 25 May 2023.
- ^ a b Insurance, Housing & Climate Adaptation: Current Knowledge & Future Research, Motu Economic and Public Policy Research,
- ^ a b c d e Cardwell, Hamish (1 May 2022). "Sea levels rising twice as fast as thought in New Zealand". RNZ. Retrieved 1 May 2022.
- S2CID 53465696. Archived from the originalon 11 May 2011. Retrieved 25 January 2010.
- S2CID 129887186.
- S2CID 128387917.
- .
- ^ Changing climate and rising seas: Understanding the science Archived 26 January 2022 at the Wayback Machine, November 2014
- ^ Sea levels and sea-level rise, NIWA
- ^ Climate change doomsday scenario could start by 2050 if we don't act, report warns, Stuff 6 June 2019
- ^ Sea level rise to impact on New Zealanders – report, Science Media Centre, 27 November 2014
- ^ "Overview of likely climate change impacts in New Zealand". www.mfe.govt.nz. Ministry for the Environment. Archived from the original on 27 February 2018. Retrieved 28 May 2018.
- ^ Coughlan, Thomas (2 May 2022). "NZ can't build its way out of billion-dollar infrastructure hole - Robertson". NZ Herald. Retrieved 2 May 2022.
- ^ 2050 climate: Wellington becomes Auckland, Auckland becomes Sydney, NZ Herald, 14 July 2019
- ^ Higher sea-level calculations push more of Wellington under water, Stuff 2 August 2019
- ^ Law, Tina (1 May 2022). "Sinking coastlines mean parts of Christchurch will feel impact of sea-level rise earlier than expected". Stuff. Retrieved 1 May 2022.
- ^ a b Bradnock, Erin (19 May 2022). "Nelson Airport 'reassessing' future with new sea-level rise data". RNZ. Retrieved 19 May 2022.
- ^ Jones, Katy (8 February 2018). "Airport plans unchanged after terminal shut due to storm surge". Stuff. Retrieved 19 May 2022.
- ^ "Aotearoa New Zealand's first national adaptation plan". Ministry for the Environment. 3 August 2022. Retrieved 4 August 2022.