Rising sea levels

Impacts: Rising sea levels

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Summary

Sea levels change relative to the land for many reasons, see Tab 1. What causes sea levels to change?

The 2021 IPCC Sixth Assessment Report (AR6) projected that by 2100 global sea levels will rise at least 0.38m and as much as 0.88m relative to 1995-2014 levels (Tab 2|Fig. 2). But ‘a 2m sea-level rise by 2100 cannot be ruled out due to potential rapid ice-sheet instabilities’.

Many ice sheet scientists now believe that exceeding even 1.5°C will be sufficient to melt large parts of Greenland and West Antarctica, and potentially vulnerable portions of East Antarctica; generating inexorable sea-level rise that exceeds 10 meters in the coming centuries, even if air temperatures are later decreased. The pace of this long-term, unstoppable sea-level rise will pose major long-term persistent challenges for all coastal regions, and result in widespread loss and damage of critical infrastructure, agricultural land, and the livelihoods of all those who depend upon these at-risk regions. – State of the Cryosphere Report 2024

Global temperatures reached 1.5°C in 2024. A sea-level rise of multiple metres is now ‘locked in’ (Tab 3).
Once sea levels reach 20-30cm around Aotearoa, the effects of what was a 1-in-100 year coastal storm could happen every year.
The impacts will differ from coast to coast due to processes summarised in Tab 5: What are the effects of rising sea levels?

A common response to increasing climate risk is to “harden the coasts” to defend property from inundation. However, engineering solutions like seawalls, stopbanks, and levees only delay damage at best and might even be counterproductive, as it encourages intensification in hazardous locations. Responses to sea level rise insurance retreat should attempt to eliminate the underlying risk by moving homes out of harm’s way. – Storey et al 2020

Home > Climate wiki > Impacts > Rising sea levels

Summary

Sea levels change relative to the land for many reasons, see Tab 1. What causes sea levels to change?

The 2021 IPCC Sixth Assessment Report (AR6) projected that by 2100 global sea levels will rise at least 0.38m and as much as 0.88m relative to 1995-2014 levels (Tab 2|Fig. 2). But ‘a 2m sea-level rise by 2100 cannot be ruled out due to potential rapid ice-sheet instabilities’.

Global temperatures reached 1.5°C in 2024. A sea-level rise of multiple metres is now ‘locked in’ (Tab 3).
Once sea levels reach 20-30cm around Aotearoa the effects of what was a 1-in-100 year coastal storm could happen every year.
The impacts will differ from coast to coast due to processes summarised in Tab 5: What are the effects of rising sea levels?

Sea levels are constantly changing, and the effects are not the same everywhere

..actual sea-surface height is not just determined by the gravity and rotation of Earth, but also by, for example, ocean currents and large-scale circulation, winds, tides, seawater temperature and salinity. – Seeger & Minderhoud 2026

Sea level is generally referred to as ‘mean sea level’ or ‘MSL’ because the height of the ocean relative to the land is constantly changing for reasons summarised in Tab 1: What causes sea levels to change? Understanding vertical land movements (VLM) where the land is rising or falling relative to the ocean is a crucial factor for understanding how some coasts will be impacted sooner than others. This is refereed to as ‘relative sea-level rise’ (RSLR), that is, SLR+VLM. The NZ SeaRise tool (Tab 4) includes VLM to determine RSLR around Aoteaora. Earthquakes have also altered some coastlines in recent years. Understanding the variables of SLR is essential before making decisions about managing and living on coastal environments.

1: What causes sea levels to change?

1

Eustatic: the volume of the water in the ocean increases when the terrestrial cryosphere (ice caps, glaciers, and permafrost) melts. When the climate cools, the volume decreases because rain and snow that falls on the land builds up into glaciers instead of being carried by rivers into the ocean. Glaciers eventually merge to become ice sheets several kilometres thick.

Global

Months to millennia

2

Thermosteric*: the temperature of the ocean increases due to warming. Because warming water expands, it rises relative to the land. When the climate cools the ocean also cools and contracts so sea levels fall relative to the land.

Global

Months to millennia

3

Vertical land movement (VLM): land slowly rising or subsiding due to compression (including from buildings), slow earthquakes, water or oil extraction etc. SeaRise.nz has an option to use VLM when looking at the effects of sea level rise across Aotearoa.

NOTE:The new Christchurch City Council VLM figures supersede the SeaRise VLM figures for greater Ōtautahi Christchurch. See Tabs 4 & 5 below.

Regional or local rise & fall

Minutes to millennia

4

Vertical land movement (VLM) – isostacy: the lithosphere and sometimes the crust is compressed when a large load of ice is added to the land, or conversely when melting icecaps add water to the ocean. The llithosphere rebounds (rises) when the weight of ice (on the land) or water (in the ocean) decreases. The process is so slow that isostatic rebound or compression may continue for thousands of years after the weight has been removed or added. In some locations, land may still be ‘falling’ even though icecaps melted thousands of years earlier. See Tabs 4 & 5 below.

Regional rise & fall

Several millennia

5

Steric*: El Niño / La Niña Southern Oscillation (ENSO) and Southern Annular Mode (SAM)

Regional rise & fall

Months or longer

6

Steric: Interdecadal Pacific Oscillation (IPO) by altering trade winds and ocean temperatures (thermosteric)

Regional rise & fall

20-30 years

7

Thermosteric: local and regional seasonal temperature changes

Regional rise & fall

Seasonal

8

Halosteric: changes in volume of freshwater entering the ocean due to floods/melting ice and permafrost etc.

Local rise & fall

Seasonal

9

Chaotic interactions: seiche effect, where water flows back and forth in a confined space, just like tipping bathtub back and forth. This happens in Pegasus Bay where Ōtautahi Christchurch is located.

Local rise & fall

2-4 hours in Pegasus Bay

10

Atmospheric pressure: storms/cyclones. Low pressure allows water to rise higher as less ‘pressure’ is pushing down on it.

Regional rise & fall

Hours to days

11

Tides: lunar and solar. The episodic wobble of the Moon leads to higher than normal tides that can last for months.

Regional rise & fall

Episodic daily

12

Tsunami: tectonic & underwater landslides

Regional or local rise & fall

Hours to months, depending on the impacts

13

Tectonic: earthquakes, e.g. Christchurch and Kaikoura (see below Explainer: Effects of earthquakes). This may also change the rate of VLM over long periods.

Regional or local rise & fall

Seconds to minutes

14

Tectonic: volcanoes create new land (e.g. Surtsey island), extend coastal lands (e.g. Iceland & Hawaii), or destroy land (e.g. Hunga Tonga-Hunga Ha’apai; not including the impacts of tsunamis)

Regional rise & fall

Minutes to millennia

15

Changes in terrestrial water storage: non-cryospheric water held in rivers, lakes, dams, and aquifers.

Global rise or fall

Decades to millennia

16

Gravitational#: changes in local gravity due to mass changes in terrestrial ice-sheets. See the Explainer below. The impact is strong enough to affect Earth’s rotation.

Regional rise or fall

Centuries to millennia

17

Dynamic coastal processes – waves and swash: as the climate warms, wave heights may be reduced along the Canterbury coast## However more destructive storm waves may increase due to increasing storminess and cyclones tracking further south ###; see the NIWA coastal sensitivity index map.

Regional/local rise or fall

Hours to days

18

Dynamic coastal processes – currents & sediment budget: how much sediment enters or leaves a coastal area over time is called a sediment budget. More sediment = accretion (builds vertically) and possibly progradation (builds horizontally, that is, seaward). Less sediment = erosion. So much sediment was delivered by rivers to the coast that it created the Canterbury Plains. Following major earthquakes along the Alpine Fault, large pulses of sediment carried by rivers to the West Coast created dune fields while currents carried some sediment north, creating Farewell Spit. See Tab 5a below and Canterbury case studies: Kaitorete Spit.

Local rise or fall

Hours to millennia

19

Dynamic coastal processes – wind/vegetation: high winds over soft (sandy/gravel) coastlines not vegetated with native plants are prone to erosion. Conversely, dunes with native plants accumulate sediment (accretion) or at least slow the rate of erosion. See Tab 5a.

Local rise or fall

Hours to years

20

Currents – global-scale circulation patterns: transferring heat, these impact regional and local weather and wave patterns that contribute to changes in sea levels. See currents.

Local rise or fall and global heat exchange

Ongoing

*Thermosteric (heat) and halosteric (salinity) are together referred to as ‘steric’ changes. Where ocean waters are warmer and/or saltier (more dense), sea levels are higher relative to regions of cooler and/or less saline water (less dense).

#There is a deep gravitational ‘hole’ over Antarctica and a part of the Indian Ocean. See the Explainer below: Gravity and sea levels.

##2022: Albuquerque et al; On the projected changes in New Zealand’s wave climate and its main drivers, New Zealand Journal of Marine and Freshwater Research

###2022: Shaw et al; Stormier Southern Hemisphere induced by topography and ocean circulation, PNAS 119 |5 (also see Shaw, Guest post: Why the southern hemisphere is stormier than the northern; Carbon Brief (open access plain English article on the above research).

Video 1: Sea level rise variations 1993 -2021 (Aviso CNES). This time lapse series shows the global variations in sea level height due to some of the factors outlined above. Note the large changes in sea levels across the central Pacific due to changes in ENSO (El Niño/La Niña).

2: How high could sea levels rise?

The relationship between the amount of CO₂ in the atmosphere, global average temperatures, and sea levels is well understood, well documented, and goes back many millions of years. During cold glacial epochs (colloquially called ‘ice ages’ ) the amount of CO₂ in the atmosphere was around 180ppm. During warm interglacial epochs CO₂ was around 280ppm. That extra 100ppm of CO₂ corresponded to a 6-8°C increase in temperature and 25-metre higher sea levels (Fig. 1).
In April 2026 CO₂ was 430ppm. That’s 150ppm more than it was 125,000 years ago when sea levels were 5-10m higher. It’s even more than it was 3 million years ago when sea levels were 20- 25m higher (Fig. 1). It takes time for temperatures and sea levels to catch up with the effects of so much CO₂ but the world is now committed to irreversible sea level rise for centuries to come.

Video 2: “The last time the world was 4°C warmer, the Ross Ice Shelf was gone, the West Antarctic Ice Sheet was gone. Sea level was about 20m higher than it is today.” – Prof.Tim Naish, Victoria University of Wellington and co-developer of the NZ SeaRise tool explained below.

Fig. 1: The relationship between atmospheric CO2, temperature, and sea levels for the past 55.9 million years. Terms: ‘CE’ = Common Era, ‘ka’ = thousand years ago, ‘Ma’ = Million years ago. Image: IPCC AR6 WGI (2021)

Fig. 2: Emissions pathways. Image: IPCC AR6 WGI (2021)

Figure 3 below shows a smooth rise in sea levels matching emissions pathways. The rate of sea level rise has more than doubled in the past three decades and is accelerating (Fig. 4). Recent observations of Greenland and Antarctic ice sheets (summarised in the 2025 State of the Cryosphere Report) adds to the growing body of evidence that melting ice sheets are reaching dangerous tipping points. That is, abrupt sea level rise may occur sooner than anticipated.

Fig. 3: Projected rise in sea levels under different emissions pathways. The ‘low likelihood’ pathway refers to ice-sheet instabilities in Greenland and Antarctica that are now being observed (image: IPCC AR6 WG1 p22).

Fig. 4: The rate that sea level is rising more than doubled between 1992 and 2024. Image: AVISO Satellite Altimetry

3. Could sea levels rise 2m within our lifetimes?

Following the end of the Last Glacial Maximum ~20,000 years ago, up to 16 sudden meltwater pulses (MWP) of freshwater poured into the ocean as ice sheets collapsed (see the MWP Explainer at the bottom of this web page).

E.g: between 14,700 – 13,500 years ago sea levels rose 16 – 25 metres. The average rate was 40–60 mm/year, however there were periods where it rose 4 metres/century for several centuries. (Video 3 & Fig. 5).

Video 3: “Around 13,000 year ago, for several centuries, sea level was rising about 4 metres per century.” – Prof. Eric Rignot University of California and Senior Research Scientist for NASA’s Jet Propulsion Laboratory

Fig. 5: MWP-1Ao: ~19,600 – 18,800 years ago sea levels rose at least 10 metres. | MWP-1A: ~14,700 – 13,500 years ago sea levels rose 16 – 25 metres. Much of this occurred over a 400–500 year period. MWP-1B: ~11,300 – 11,000 years ago sea levels rose 40 – 80 metres.

Over the last deglaciation, global sea level rose by ~120–130 m, 10–20 m of which was attributed to a singular, catastrophic event known as Meltwater Pulse 1A (MWP-1A) that spanned at most 500 years approximately 14.6 kyr ago... the sequence of ice sheet melting begins with the Laurentide contributing ~3 m (~14.6–14.2 kyr ago), followed by Eurasia and West Antarctica contributing ~7 m and ~5 m, respectively (~14.35–14.2 kyr ago). – Coonin et al 2025

While the Laurentide (North American) and the Eurasian ice sheets no longer exist, the Greenland ice sheet contains enough ice to raise sea levels by 7 metres and the West Antarctic ice sheet by 4-5 metres. Parts of the East Antarctic ice shelf also are showing signs of destabilising.

The glacier in Greenland’s largest drainage basin is thinning and its flow is accelerating. Updated simulations suggest that sea-level rise will be up to five-fold higher than previously expected. – Khan et al 2022

Mass loss from ice sheets in Greenland and Antarctica has quadrupled since the 1990s and now represents the dominant source of global mean sea-level rise from the cryosphere. – Stokes et al 2025

We show that in benchmark models of marine ice sheets typically found in Antarctica [the current calculations] leads to underestimates of 100-year sea-level rise contributions of between 21% and 35% depending on the climate forcing. – Martin et al 2026

Video 4: “The world needs to prepare for multiple metres of sea level rise… Geological evidence shows that at today’s level of [atmospheric] CO2, sea levels should be about 20m higher.” – Prof. Jason Box, November 2022

Video 4: “The Arctic is currently warming 3 to 4 times faster than the rest of the world. This is affecting the lives of billions of people, both in the Arctic and beyond.”

In 2022, the State of the Cryosphere report concluded that under our current high emissions scenario:

WAIS [West Antarctic Ice Sheet] collapse would be inevitable and potentially rapid, with sea-level rise of 2 meters possible by 2100, and up to 5 meters by 2150; 10 meters sea-level rise from all sources is likely by 2300. Sea-level rise will continue for many centuries even with temperature stabilization and slow decline, with the eventual complete loss of the Greenland ice sheet. Such a rapid rise in atmospheric CO2 concentrations and temperature has no counterpart in Earth’s geologic record, but Antarctica is known to have had essentially ice-free conditions at +6°C above today’s level. Restoration of the polar ice sheets would only begin with temperatures well below pre-industrial (i.e., substantial global cooling). – p7

The subsequent 2023 IPCC Synthesis Report states:

Due to deep uncertainty linked to ice-sheet processes, global mean sea level rise above the likely range – approaching 2m by 2100 and in excess of 15m by 2300 under the very high GHG emissions scenario (SSP5-8.5) (low confidence) cannot be excluded. – pp19-20

The terms ‘limited evidence ‘and ‘low confidence’ should not be read as ‘probably won’t happen’:

Because these effects are so consequential, the possible triggering of these tipping points and their effects must be acknowledged and considered when managing risk, despite the uncertainty. This is acknowledged in IPCC Sixth Assessment Report through ‘low likelihood, high impact’ outcomes. However, given deep uncertainties we propose that the term ‘poorly understood likelihood, high impact’ outcomes is perhaps more inclusive and appropriate. – p17 CSIRO 2024

These warnings are reflected in Aotearoa’s Coastal Hazards and Climate Change Guidance 2024, which recommends using the ‘worst case’ SSP5-8.5H+ scenarios (Tab 4. NZ SeaRise tool):

This guidance takes a risk-based approach to the use of projections and/or increments of RSLR (relative sea levels). In this respect, the upper-range SSP5-8.5 H+ should continue to be used in screening and detailed hazard and risk assessments to identify coastal areas potentially affected (Policy 24, NZCPS, DOC, 2010) and high-end stress testing of adaptation options and pathways (step 6) . – p53

4: Using the online SeaRise NZ mapping tool
4a: Sea level rise with VLM (vertical land movement)

The NZ SeaRise projections will be periodically updated to incorporate new information that has been robustly assessed, peer-reviewed and published, in order to provide the latest and best information for coastal risk assessments. [Caveat: updates may depend on funding as the current National-led Government has cut back on overall climate research funding.]

IMPORTANT NOTE: WHEN USING THIS TOOL to assess the greater Ōtautahi Christchurch area (from the south bank of the Waimakariri River and around Banks Peninsula to Taumutu) DO NOT USE THE SeaRise figures for VLM. Instead use the post-earthquake 2025 VLM figures here (PDF) and shown in Tab 5. See also on this website: Case Study: Ōtautahi Christchurch

Fig. 6: Composite of four screen grabs on the NZ SeaRise tool taken 25 April 2026. This shows four possible sea level rise scenarios for an area of north of Christchurch along the Waimakariri coast at site number #4299 including the effects of VLM. When using the tool online, the years are displayed individually.The blue coloured dots on the map indicate a trend of land dropping (-VLM). Click on the map to be go to the website.

Figure 6 is a composite of four possible sea level rise (SLR) scenarios at a site #4299 north of Ōtautahi Christchurch. The tool projects (not predicts) SLR to 2300 based on different SSP scenarios. The Coastal Hazards and Climate Change Guidance 2024 recommends using SSP5-9.5M(p50) and the ‘worst case’ SSP5-8.5H+ (p83) scenarios. Before using the tool read the disclaimer! Note: this tool provides a ‘bathtub’ estimate of SLR. It does not factor in the compounding effects of coastal geomorphological processes (erosion, deposition, cliff collapse) coastal and river/rain flooding (Tab 6), or engineered structures (sea walls, groins) etc.

There are multiple options for choosing different future climate scenarios. In the Figure 6 example, the ‘Projection to 2300’ was selected with VLM (vertical land movement). The ‘low confidence’ to 2300 is because the point at which ice sheets will collapse is uncertain. The blue coloured dots on the map indicate a trend of land dropping (-VLM). The term ‘p50’ is the mid-point estimate of a rise in sea levels. ‘p17’ is the lower end of the estimate while ‘p83’ is the upper ‘worst case’ scenario. For example, by 2050 sea levels might rise as little as 0.12m (p17) or as much as 0.57m (p83) above the 1995-2014 baseline. Currently 0.32m (p50) is the mid-range scenario.

The developers of the NZ SeaRise tool discuss this in Video 5 and also Tab 3 |Video 4.

Video 6: What’s happening in Antarctica and what it means for sea levels around Aotearoa. The keynote presenters developed the NZ SeaRise tool.
4b: Post-earthquake VLM Ōtautahi Christchurch

IMPORTANT NOTE: When using the NZ SeaRise tool to assess the greater Ōtautahi Christchurch area, use the following VLM figures (See also the 2025 GNS paper: Co-seismic and post-seismic rates of vertical land movement in the Canterbury Region).

5: What are the effects of sea level rise?
5a: Erosion

NIWA’s ‘coastal sensitivity index’ (Fig. 7) takes multiple factors into consideration to assess the vulnerability of coastlines to erosion.

The impacts of erosion will be compounded in areas where parts of the coastal area is sinking, such as areas around
Christchurch and North Canterbury (see Tab 4 above).

Overall, erosion will happen faster along beaches that have bigger waves and where the land is dropping (-VLM) as rising seas will reach further inland, faster.

Modelling in 2022 indicates that the southern and western parts of the country will be affected by higher waves, whereas wave heights along the eastern coasts may be reduced. However, the overall number and scale of storms is predicted to increase as the climate warms, and it’s the storm waves that do the most damage.

Figure 8 is a generic illustration of coastal dunes that have a coastal wetland, lagoon, behind them. Dunes with native plants have adapted to the prevailing wave climate. They commonly respond to rising sea levels by migrating inland by overtopping low lying wetlands and coastal lagoons behind them. If there is sufficient space, these wetlands and lagoons and entire ecosystems of all types, will also migrate inland. Efforts to prevent this migration in order to defend private property or infrastructure may buy time but will ultimately be futile. See also Coastal Dunes and Wetlands (this website).

Fig. 7: Image: NIWA

Fig. 8 (A): Healthy coastal dune systems are complex and dynamic, adapting and responding to waves and storms, protecting the land behind. Native grasses like pingoa and spinifex bind loose grains of sand, creating low-profile dunes that sap much of the energy from storm waves. The shape of shrubs and small native trees helps the wind lift up and over the dunes, dropping more sand and holding it in place. Wetlands and estuaries behind the dunes are filled with native plants, many salt-tolerant, creating peaty soils that capture and sequester carbon dioxide while supporting native fish and invertebrates such as mussels and clams. Together these species clean nitrates and other pollutants from streams and rivers that flow into them. Behind the wetlands, native shrubs and forests capture and store more carbon and provide habitat for native species. (B): Degraded coastal dune system. Wetlands and estuaries may have been filled in and converted to agriculture or covered in buildings and roads. Radiata pine plantations create artificially steep dunes. Storm waves slam up against these steep dunes, tearing out their bases and undercutting them. The waves carry the eroded sand away. Currents may carry some to nearby beaches, however some sand may be permanently lost if it’s carried into deep water. (Image: S. Whitelaw)

While rocky beaches won’t erode much in our lifetimes, low-lying rock platforms will be inundated (drowned) by rising seas. Where volcanoes created cliffed coasts, for example Banks Peninsula, Dunedin, and the headland at Moeraki, some of the ‘rock’ is in fact volcanic ejecta (ash and scoria rather than hard lava). This material might seem solid because its been compressed over several million years, but it’s easily eroded. Cliffs made of this volcanic material are particularly susceptible to being undercut by waves (Fig. 9D), and risk collapsing with little to no warning.

Fig. 9: Four ways in which cliffed coastlines respond to rising sea levels. This is based on the cliffs being made of reasonably solid rock, not unconsolidated ejecta from ancient volcanoes that has compressed over time. Image: Dickson and Thompson

Unless an earthquake lifts an entire coastline evenly, rising sea levels will still impact the area. For example, the Papatea Fault at Kaikoura did not lift the coast perpendicular to the ocean. Rather, it lifted parts of the seabed at an angle to the coast, so rising seas will still reach the beaches. (See Explainer: effects of earthquakes at the end of this page). However, the newly uplifted areas may help reduce some of the impact of wave erosion, and may act as groins.

Figure 10 is an online mapping tool that charts the rate at which coastlines changed between 1938-2023. It hasn’t mapped the entire coast, but is instead focused on ‘soft’ coastlines: sand, sediment, and gravel. The red dots indicates erosion. Blue dots indicate accretion. Not all coasts have been modelled, and the Goct. cut back funding so

Note: The term ‘accretion’ may be misleading as it is not the same as ‘progradation’, which means to extend seaward. The dunes in Figure 8A for example are not as tall as dunes in Figure 8B, which may have been accreting for 20-30 years due to the pines. But native-vegetated dunes are far less susceptible to erosion as sea level rise accelerates.

In many coastal areas such as the Waimakariri, by 1938 native plants on dune systems had been destroyed by grazing and were undergoing rapid erosion. What appears to be ‘accretion’ and ‘progradation’ between 1938-2023 is in fact recovery.

Some coastal areas are experiencing erosion as well as accretion and progradation due to the movement of sediment along the coastline. Examples include the South Canterbury Bight/ Kaitorete Spit and Moeraki.

Fig. 10: Image: Coastal Change NZ. the red dots
5b: Saltwater intrusion

As the seas rise, saltwater reaches further upstream into rivers, hāpua, and aquifers. For example the Kaiapoi River:

Saline intrusion is sensitive to high tide level, indicating that sea level rise is expected to increase the frequency of saline intrusion. We used the relationship between Waimakariri river flow, high tide level and saline intrusion to investigate the sensitivity of saline intrusion to sea level rise for a range of river flows, finding that even small amounts of sea level rise are associated with notable increases in the frequency of saline intrusion. Under current sea levels a flow of 72 m3/s prevents intrusion on 90% of tides, but with 0.1 m of sea level rise a flow of 77 m3/s is needed, and with 0.5 m of sea level rise a flow of 97 m3/s is needed. – Measures & Dudley, 2025 p29

In low elevation areas where coastal aquifers are not sealed, saltwater intrusion may lead to rising groundwater and turn freshwater into saline water. The result can be an increase in surface flooding, particularly during high tide or storm surges. The salty water can also corrodes foundations and kill grass, trees, and agricultural crops.

The effect of rising groundwater will also compound the risk of flooding from rain and rivers.
5c: Coastal Flooding | NIWA flood mapping tool

Sea level rise does not look like the ocean coming at us… It looks like the groundwater coming up. – Tada, 2020

Small sea-level rise increments of 10–40cm predicted to happen around parts of the coast in the next 20–30 years may not seem like much. But:

Once sea levels reach 20-30cm, a 1-in-100 year coastal storm could happen every year – MfE & Stats NZ 2025

Flooding may be temporary due to poor drainage and rising groundwater. Low-pressure systems raise sea levels, storm waves are bigger than normal waves and reach further inland (Fig. 11), and the water from rain-filled rivers and rain-drenched land can’t drain away. Together, this can result in widespread inland flooding inland as well as along coastlines, leading to more intense coastal erosion.

Fig. 11: The compounding effects of storm tides, storm surge, and wave run up on sea levels. As sea levels rise, the effect of extreme events will reach higher and further inland, reaching locations that have never before experiences the effects of waves and flooding, them even more vulnerable. (Image: Environment Canterbury)

According to NIWA, in 2018 exposure to coastal flooding across New Zealand was several billion dollars (Fig. 12). Ultimately, areas prone to flooding will become permanently inundated.

Fig. 12: Based on modelling that predates the current estimates of sea level rise (Image: NIWA; 2018)

Coastal flood mapping tool

Before using this tool, the effects of VLM was checked using the SeaRise tool (Tab 4a). VLM along this coastline was assessed at being -1.7mm/yr. This figure was inserted into the calculator shown on the right of Figure 13A under ‘Choose vertical land motion’. The ‘worst case’ sea level rise scenario (SSP5-8/5H highest percentile) by the year 2075 was also selected. This shows that under these circumstances, sea levels could be 90cm higher than they were in 2005, in the event of a AEP1% storm tide flood, the yellow area indicates what could be inundated based on the current ‘bathtub’ topography.The term ‘AEP1%’ is often called a ‘1-in-100-year’ event. In a changing climate, these events are becoming more frequent.

Figure 13B uses a different tool to show the effects of a AEP1% rainfall flood event in today’s climate. See ‘floods‘ for more details. It’s included here to illustrate the potential for compounding events that should be taken into consideration.

NOTE: Using the SeaRise tool before using this tool shows the effect of VLM across the length of this coast varies from -1.3mm/yr (Marshlands) to -0.3mm/yr (Saltwater Creek), with the area around Kaiapoi/Pines Beach being the worst (-1.7mm/yr.). Selecting the ‘worst’ value is essential because water flows through the lowest, not highest points. This illustrates the range of variables that should be considered when using these tools.

Fig. 13A: screen shot of the NIWA flood layers tool enables users to visualise the effect of a 1% annual exceedance probability (AEP1%) extreme sea level flooding under current climatic sea conditions PLUS the effects as sea levels rise above present-day mean sea level.

Fig. 13B: Screen shot of the flood layers tool taken 02 May 2026 enables users to visualise the effect of a 1% annual exceedance probability (AEP1%) flood event from rainfall. This is NOT the same as a combined flood event from rising sea levels + a storm tide in Fig. 13A. It uses ‘bathtub’ modelling based on present day temperatures, not future climate scenarios.
5d: Inundation

Inundation maps are based on topography. They’re useful where a coastline is solid rock, but they do not factor in how dynamic coastal processes (wind and waves, especially storm waves) change the shape of sandy and gravel beaches, estuaries, bays, harbours, or hāpua.

Consequently ‘inundation maps’ are not a true picture of what will happen.

The SeaRise online mapping tool (Tab 4) of the Waimakariri District Pegasus coastal area indicates that the worst case scenario for this area would be a rise of 1.89m by the year 2100. Figure 14 is an inundation map showing what this would look like (rounded up to 2m).

However, this coastline is a sandy dune system exactly as per Tab 5a | Figure 8. As sea levels rise and reach further inland, waves will undercut the front of the dunes. Once destablised, some sediment is likely to be driven inland, overtopping the lagoons and raising their height, with new lagoons reforming further inland as groundwater rises. The timing and sequence of events is unclear as a single storm or flooding from the Waimakariri River can carry away sediment into deep ocean water. So an inundation map based entirely on the existing height of the land is of limited value.

Fig. 14: 2m sea level rise inundation map of (Image: floodmap.net)
5e: Changing and migrating coastal ecosystems

In the ocean, marine plants and animals including entire communities have shifted their distributions poleward at an average speed of 59km per decade due to increasing water temperatures. Ocean acidification and decreasing oxygen in the water also play a part. Together all three processes have caused a reorganisation of biodiversity over the past 50 years, especially at the ocean surface. Those species that cannot adjust or move fast enough are at high risk of becoming extinct. – IPCC AR6 WGII 2022

What’s in a name?

In 2023, the Environmental Defence Society (EDS) published several papers discussing policy frameworks for ‘Managed Relocation’ from the coast, suggesting that the word relocate was more appropriate and empowering than managed retreat. Retreat implies defeat and with it, a desire to protect, even retaliate through inappropriate, unsustainable maladaptive behaviours.
Similarly, marine transgression is the geological term for sea level rise forcing the shoreline to move to higher ground. This causes flooding (Tab 5c), saltwater intrusion into freshwater systems via tidal and groundwater systems (Tab 5b), and ultimately, permanent oceanic inundation by ‘transgressing’ coastal areas.

In the English language, the word transgression means ‘an act that goes against a law, rule, or code of conduct; an offence or sin’. Thus, the term marine transgression positions the ocean as the transgressor, rather than the ocean responding to the anthropogenic transgressions causing climate change. For this reason, the term marine migration is more useful frame of reference to acknowledge the corresponding forced migration of entire marine and coastal ecosystems.

Even if greenhouse gas emissions are reduced to zero, sea levels will continue to rise for hundreds of years until they reach equilibrium with global temperatures, which are still increasing. Both coastal and marine ecosystems will be in a continuous state of migration for generations to come. Some species will be lost. Some marine species will try to migrate south to cooler waters, or land species will migrate inland away from the salt. Welcoming these climate refugees rather than treating them them as invaders, will ensure a better transition for all. For example, saltwater marshes or mangrove forests may replace seagrasses, and freshwater lakes may become estuaries and hāpua. Removing structures on coasts that may contain pollutants and toxins will be an essential component of any adaptation strategy.
5f: Insurance retreat

The inability to insure private property and infrastructure on coastal areas will become increasingly difficult. Notably, banks require mortgaged properties to be insured.

My fear is that this will turn into an insurance crisis, then a banking crisis into a government debt crisis. – Massey University banking and insurance expert Dr Micheal Naylor, 2024

Fig. 15: Approximate timing of insurance retreat from coastal areas. This will vary across different parts of each city according to their location. Many coastal areas could lose their housing insurance within 25 years. Graphic created by Mark Garrison with data from Storey et al.

6. Adapting to rising sea levels & Govt. recommendations
The Greenland Ice Sheet is only one of more than 20 recognised tipping elements in the Earth system, including ocean currents, forest biomes, permafrost and monsoons. Several features differentiate tipping points from the climate change we are accustomed to managing, transforming the basic grammar of governance.

Conventional climate governance assumes continuity. It relies on temperature targets, carbon budgets and sea-level projections—tools suited to gradual, predictable, reversible change. The Paris Agreement’s 1.5°C goal, for instance, presumes a stable relationship between emissions and impacts; national adaptation plans proceed as if change will remain incremental along one of the IPCC’s scenarios. But tipping processes violate that logic. They are moments of commitment to irrevocable systemic shifts. When thresholds are crossed, Earth systems do not simply deteriorate—they become something new. An unfamiliar territory for social organisation and human development. Governance can no longer aim only to optimise within a stable baseline; it must anticipate disruption, prioritise prevention and learn to navigate complexity. – p14 Global Catastrophic Risks 2026

In February 2024 the Ministry for the Environment published ‘Coastal hazards and climate change guidance‘ [emphasis theirs]:

This [MfE] guidance takes a risk-based approach to the use of projections and/or increments of RSLR. In this respect, the upper-range SSP5-8.5 H+ should continue to be used in screening and detailed hazard and risk assessments to identify coastal areas potentially affected (Policy 24, NZCPS, DOC, 2010) and high-end stress testing of adaptation options and pathways (step 6). Furthermore, using the RSLR projection based on SSP5-8.5 M allows RSLR to be linked to the other climate drivers (e.g., rainfall) if a multi-hazard and risk assessment is being done.

If the risk is underestimated, the consequences will be severe with lasting social, cultural and economic effects. If the risk is overestimated for a specific timeframe, using relative sea-level rise projections based on higher emission scenarios, this will be temporary (decade to multi-decadal timescales). This is because sea level will continue to rise, even as emissions are reduced, and it is only a matter of time before the adaptation threshold is reached for those exposed to the risk. While overestimation places costs today, the observed and increasing climate change impacts mean both current and future generations are, and will be, paying the costs. It is also important to consider how the costs and risks experienced by future generations may be affected by decisions taken today…Temporary adaptation options like seawalls, filling land or raising buildings above flood levels may buy time if they can be implemented quickly, but they can entrench development and limit access to communities, making it harder to transition to options like managed retreat, while also increasing ongoing adjustment costs. – Coastal hazards and climate change guidance, MfE, 2024.
See also:

2nd National Climate Change Risk Assessment (2026)
NIWA’s online game Future Coasts Aotearoa (either as single player or up to 5 players) to learn about the risks
and impacts and how you and your community can develop resiliency—or not.

The National Coastal Change database; the National-led Government scaled back the project, putting communities at risk

‘Response: retreating from coasts and rivers‘ (this website)

Community-led retreat and adaptation funding: Issues and options (August 2023)
Adaptation Plan for New Zealand (August 2022)

More information

Explainer: Effect of earthquakes on sea levels

Earthquakes can abruptly lift or drop coastal lands relative to the ocean. The 2010-2011 Canterbury earthquake sequence caused complex changes to the previous pattern and rate of vertical land movement (VLM) across Ōtautahi Christchurch. in 2025 the Christchurch City Council (CCC) commissioned GNS to calculate the current VLM. If you use the SeaRise tool to asses how rising sea levels could affect your area, use the CCC data for VLM, not the SeaRise VLM data.

In Kaikoura, much of the coastal area was experiencing long term subsidence (-VLM) when the earthquake struck in 2016. Parts of the coastal area lifted by as much as 3m, exposing reefs. This abrupt uplift did not protect the coast from rising sea levels as the land did not rise evenly everywhere. Indeed, some of the land lifted was at an angle to the coast (Video). Moreover:

The data show that the subsidence we observed before the Kaikoura earthquake resumed within a year after the earthquake (in fact subsidence/sinking rates are much higher). So, while the land generally went up fast during the earthquake, it has since resumed subsiding. The earthquake reset the coastline datum (instantaneously), but the pattern of long term subsidence continues. – SeaRise FAQs

Video 7: In less than 2 minutes the Papatea Fault, part of the 2016 Kaikoura earthquake sequence, raised the seabed up to 3m in places. However, rising sea levels will still affect areas of the coast as only parts of the shoreline were uplifted and the sea can still reach inland behind the raised reefs (Geonet NZ).

Explainer: Why does a warming ocean raise sea levels?

The oceans cover 70% of Earth and the deepest areas are almost 4,000m; that’s a huge area to store heat.

Additionally the ocean is dark, so it has a very low albedo (see the tab below) meaning that it can absorb much more heat than the land. As water gets warmer, it expands. As it can only expand upwards, relative the to land, it rises. However, the ocean doesn’t absorb heat evenly. Local factors such as ocean currents and weather systems like El Nino and La Nina also have an impact.

Recent research reveals that the oceans are heating 40% faster than predicted in the IPCC 2013 Fifth Assessment Report. The figures for rising sea levels in that report are still commonly used by regional and district councils. Water around New Zealand has also been warming faster (Fig. 17).

Fig. 16: The oceans cover 70% of Earth and the deepest areas are almost 4,000m; that’s a huge area to store heat.

Fig. 17: Changes in ocean temperatures around New Zealand 2010 – 2019 (Image: NIWA)

Explainer: How does gravity affect sea levels around the planet?

As the Greenland and Antarctic ice caps melt into the ocean, they lose mass. Less mass means that the pull of
gravity is reduced, so not as much ocean water is pulled towards them. It may seem perverse, but the result is a relative drop in sea levels around them. See Table 1#16 above. Gravitational changes are also one of several ways that help ‘fingerprint’ where Meltwater Pulses (tab below) originated.

Gravity is not the same everywhere on the planet. The deepest gravitational ‘hole’ is over Antarctic (Fig. 18). Another is over the Indian Ocean (Video 8).

Fig. 18: Glišović & Forte:Cenozoic evolution of earth’s strongest geoid low illuminates mantle dynamics beneath Antarctica, Nature Scientific Reports 15 | 45749, 2025 (Open access – click the image to go to the website)

Video 8: the Gravity ‘hole’ over the Indian Ocean.

Explainer: Abrupt sea level rise (Meltwater Pulse events)

At the end of the last glacial (not the end of the ice age: we still are in the Pleistocene Ice Age) the ice sheets that covered much of the planet began to melt. While some meltwater flowed into the ocean, gradually raising sea levels, there were several periods where huge volumes of meltwater also pooled into vast lakes dammed by the natural shape of the land, the walls of the retreating glaciers, and/or ice shelves along coasts. As the Earth continued to warm, the lakes kept filling until they eventually collapsed and burst open, and the meltwater rushed into the ocean Video 9:

Northeast of Lake Missoula, around 12,800 years ago thousands of cubic kilometres of icy water and icebergs from Lake Agassiz abruptly poured into the North Atlantic and Arctic Oceans (Fig. 19). This effectively switched off the North Atlantic’s circulation system, chilling the Northern Hemisphere. Winter temperatures in northern Europe plummeted by as much as 22°C until ~11,500 years ago, after which the global warming trend continued. This highlights some of the complex feedback effects of abrupt warming.

Fig. 19: Image: Sheffield University

Explainer: What is the Albedo Effect?

Clean ice and snow have a very high albedo, that is, they reflect up to 90% of solar radiation back into space. The ocean is much darker, so it has a very low albedo, reflecting only about 6% of the incoming solar radiation and absorbing the other 94%, warming it much faster than the snow and ice (Fig. 20).

As more ice forms, the water is cooler, leading to more ice forming, and so on, in a feedback effect.

Fig. 20: The albedo effect (image – Nathan Kurtz / NASA)

Recent global temperature surge intensified by record-low planetary albedo – Science, 05 Dec. 2024

Fig. 21: Albedo decline 2003-2024

Fig. 22: The planetary cooling effect of sea ice loss has reduced by 14% since the 1980s (Image: Duspayev et al 2024)

Explainer: What do the RCP and SSP climate scenarios mean?

RCP or Representative Concentration Pathway, is a way of showing the path our climate would take based on the concentration of greenhouse gases in the atmosphere. Four credible pathways, RCP2.6, RCP4.5, RCP6, and RCP8.5 represent four possible ranges of radiative forcing values: 2.6, 4.5, 6, and 8.5 Watts/m², respectively. The numbers refer to the effect of heat retained in the atmosphere due to actual concentrations of greenhouse gases, not the amount of emissions that put them there, because the natural carbon cycle absorbs a percentage of carbon emissions.

The term RCP was adopted by the IPCC for climate modeling and research for the fifth assessment report in 2014.

The researchers who developed the RCP 8.5 scenario describe the pathway in detail here.

The IPCC sixth assessment report (2021) used instead the term Shared Socioeconomic Pathways (SSPs). These are scenarios of projected socio-economic global changes up to 2100. That is, how different policies around greenhouse gas emissions will result in different outcomes. The following explanation is from the 2019: FINAL DRAFT Chapter 1 Supplementary Material IPCC SR Ocean and Cryosphere, Chapter 1: Framing and Context of the Report Supplementary Material (page 7):

Five SSP narratives describe alternative pathways for future society (Figure SM1.1). Each SSP looks at how the different RCPs could be achieved within the context of the underlying socioeconomic characteristics and shared policy assumptions of that world. The SSPs five alternative socio-economic futures compromise: sustainable development (SSP1), middle-of-the-road development (SSP2), regional rivalry (SSP3), inequality (SSP4), and fossil-fuelled development (SSP5) (Kriegler et al., 2016; Riahi et al., 2017). Across these five SSP narratives there are a total of 23 ‘Marker’ SSP scenarios. Appendix 1.A, Figure 2 shows some specific SSP Markers compared with the RCPs, according to (O’Neill et al., 2016). SSP5-8.5 represents the high end of the range of future pathways, corresponding to RCP8.5. SSP3-7.0 lies between RCP6.0 and RCP8.5, and represents the medium to high end of the range of future forcing pathways. SSP4-6.0 corresponds to RCP6.0, fills in the range of medium forcing pathways. SSP2-4.5 represents the medium part of the range of future forcing pathways and updates RCP4.5. SSP5-3.4 (Overshoot) fills a gap in existing climate simulations by investigating the implications of a substantial 21st century overshoot in radiative forcing relative to a longer-term target. SSP4-3.4 fills in the range of low forcing pathways, and there is substantial mitigation policy interest in this scenario that reaches 3.4 W m–2 by \] 2100. SSP1-2.6 is similar to RCP2.6. It is anticipated that it will produce a multi-model mean of less than 2°C warming by 2100. –

SSP1: Sustainability: The world shifts gradually but consitently toward a more sustainable path, with net zero emissions by 2050
SSP2: Low emissions: Emissions decline to net zero by 2050
SSP3: Regional rivalry: resurgent nationalism, conflicts, less investment in education and technological development, consumption is material-intensive, and inequalities persist or worsen over time. Emission stay at current levels and fail to reach net zero by 2100
SSP4: Inequality: increasing conflict and decreasing global co-operation. Social cohesion degrades and conflict and unrest become increasingly common. Investments in both carbon-intensive fuels like coal and unconventional oil, but also low-carbon energy sources. Environmental policies focus on local issues around middle and high income areas. ie, the wealthy are protected. Emissions double by 2100
SSP5: Fossil-Fueled Development: increasing faith technological ‘fixes’ to manage social and ecological systems, including by geo-engineering if necessary. Emissions triple by 2075.

Both SSP 1 and 2 are unlikely. Our current emissions pathway (2026) is between SSP3-7.0 and SSP5-8.5. This may change over time.

Explainer: Why did the Paris Accord overlook melting ice sheets?

The IPCC didn’t include melting ice caps in their models for rising sea levels until 2018 and 2019. In the 2019 State of the Cryosphere report, the IPCC acknowledged that Greenland was most likely responsible for much of the 4 metre rise/century in sea levels ~125,000 years ago during the Eemian Epoch. But by then, the 2015 Paris Agreement, which is based on the much earlier IPCC 2013 report, had been signed.

In effect, countries including New Zealand were working to keep warming under 1.5°C based on information that’s woefully out of date because these older models that don’t include the single largest concern around rising sea levels: the rapidly melting Greenland and Antarctica. Aotearoa’s First National Climate Change Risk Assessment (NCCRA) has made updated recommendations that take into account the possibility of abrupt sea level rise.

It’s worth noting that 125,000 years ago temperatures were 1-2°C warmer that pre-Industrial levels and CO₂ in the atmosphere was 280ppm. As of April 2026 temperatures are hovering around 1.5°C, and with 430ppm already in the atmosphere, temperatures will rise rapidly.

Explainer: What is 'Infrastructure'?
The term ‘critical infrastructure’ is used to describe built structures. Defined by the National Emergency Management Agency it includes:

Power (electricity, fuel, gas)

Transport (roads, rail, bridges, airports)

Communications (cell towers etc.)

Three waters (supply of safe freshwater, wastewater treatment, and stormwater removal)
Health service

The term is mechanistic insofar as all parts are interlocking, interdependent, and can be rationally explained. However, this refers to critical built infrastructure, which supports modern society but not human existence. Ecosystem services are also mechanistic, providing

When natural critical infrastructure is damaged or destroyed, it disables or removes the capability of built infrastructure. Hence, natural critical infrastructure is a first order essential that supersedes and underpins built critical infrastructure.

In the real world, critical natural infrastructure is a higher order priority because it provides the life-supporting services we need to exist. This includes:

clean healthy water

oxygen to breath

nutrient recycling

food to eat

carbon capture and storage

stable climate

In short, the entire toolkit of essential infrastructure services without which humans cannot exist.

When natural critical infrastructure is damaged or destroyed, it disables or removes the capability of built infrastructure. Hence, natural critical infrastructure is a first order essential that supersedes and underpins built critical infrastructure.

Reference: Wagner: Formally designate blue-green infrastructure for climate adaptation, Nature article 26 July, 2022

Explainer: What are 'net emissions'?

Net emissions means gross (total) greenhouse gas emissions from all industrial activities, burning fossil fuels for energy, and agriculture, minus carbon saved and stored underground permanently via natural terrestrial and oceanic ecosystems.

While every country also includes plantation forestry (in New Zealand, mostly radiata pine) as part of their carbon savings to offset gross emission, in reality, this is a very short term saving as there are huge carbon costs and risks associated with plantation forestry that are not fully accounted for.

Most negative emissions technology to remove carbon from the atmosphere (Carbon Capture and Storage – see this website) also are included in the carbon ‘savings’ calculations for tax purposes. However the vast bulk of this engineering recycles carbon back into the atmosphere rather than permanently sequester carbon underground.

‘Net emissions’ is thus an accounting term that countries use for reporting purposes, to calculate the balance of their emissions based on what they choose to include in those calculations. What’s left out of these equations still goes into the atmosphere.

Global emissions continue to increase each year in spite of Covid-19 and dangerous tipping points are being breached, which means natural carbon sinks are now becoming sources of methane and carbon dioxide.

References and further reading
2026: 2nd National Climate Change Risk Assessment, Aotearoa Climate Change Commission
2026: Lentz et al, Challenges and Opportunities for National-Scale Projections of Future Coastal Landscape Change AGU Earth’s Future 31 March (open access)

Plain English article: How to Study Coastal Evolution EOS

2026: Martin et al; Rates of Sea-Level Rise Are Highly Sensitive to Ice Viscosity Parameters in Model Benchmarks, AGU Advances 04 March

Plain English article: Glaciers May Flow into the Ocean More Quickly Than We Think

2026: Boucharel et al; Climate mode interactions amplify coastal flood risks and their seasonal predictability, Nature Geoscience 19 pp317-324

2025: Measures & Dudley; Causes of saline intrusion in the Kaiapoi River Analysis of monitoring data Prepared for Environment Canterbury, Earth Sciences NZ

2025: Glišović & Forte:Cenozoic evolution of earth’s strongest geoid low illuminates mantle dynamics beneath Antarctica, Nature Scientific Reports 15 | 45749 (Open access)

Plain English: EOS Scientists Remap Earth’s Gravity: An uncommon way of looking at the world reveals the evolution of a deep gravity hole beneath Antarctica.

2025: Christchurch City Council: Coastal Hazards Adaptation Plan Planning for sea-level rise in Whakaraupō Lyttelton Harbour and Koukourarata Port Levy (PDF)

2025: Our Marine Environment 2025 Tō Tātou Taiao Moana, MfE & Stats NZ

2025: Nauels et al; Multi-century global and regional sea-level rise commitments from cumulative greenhouse gas emissions in the coming decades, Nature Climate Change 15 pp1198-1204 (open access)

2025: Coonin et al; Meltwater Pulse 1A sea-level-rise patterns explained by global cascade of ice loss, Nature Geoscience 18 pp254-259

2025: Sadai et al; Estimating the sea level rise responsibility of industrial carbon producers, Environmental Research Letters 20 | 4 (Open access)

2025: Cox et al; Empirical Models of Shallow Groundwater and Multi-Hazard Flood Forecasts as Sea-Levels Rise AGU/Earth’s Future 08 February (Open access)

Plain English: Flooding from Below: The Unseen Risks of Sea Level Rise

2025: Stokes et al; Warming of +1.5 °C is too high for polar ice sheets, Nature Communications & Environment Article 6 | 351 (open access)

2025: ICCI; State of the Cryosphere International Cryosphere Climate Initiative (ICCI), Stockholm, Sweden

2025: Storey et al, Insurance retreat in residential properties from future sea level rise in Aotearoa New Zealand, Springer/Climate Change 177 | 44

2024: Duspayev et al; Earth’s Sea Ice Radiative Effect from 1980 to 2023, Geophysical Research Letters 51 | 14 (Open access)

2024: Hamlington et al; The rate of sea level rise has doubled during the past three decades, Nature Communications Earth & Environment 5 |601 (Open access)

2024: ICCI: State of the Cryosphere, Lost Ice, Global Damage, International Cryosphere Climate Initiative (ICCI), Stockholm, Sweden

2024: MfE; Coastal hazards and climate change guidance. Ministry for the Environment

2024: Walker et al; Recent global temperature surge intensified by record-low planetary albedo – Science, 05 Dec. 2024

2024: UN Technical Brief; Surging Seas in a Warming World

2024: Bradley & Hewitt; Tipping point in ice-sheet grounding-zone melting due to ocean water intrusion, Nature Geoscience 25 June (Open access)

2024: Rignot et al; Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica, PNAS 121 (22) (Open access)

2024: Bett et al; Coupled ice–ocean interactions during future retreat of West Antarctic ice streams in the Amundsen Sea sector, EGU 18|6

2024: Lowry et al; Ocean cavity regime shift reversed West Antarctic grounding line retreat in the late Holocene, Nature Communications 15 | 3176, 23 April

2024: Gibney; Climate change has slowed Earth’s rotation — and could affect how we keep time, Nature News 27 March

2023: Levy et al; Melting ice and rising seas – connecting projected change in Antarctica’s ice sheets to communities in Aotearoa New Zealand, Journal of the Royal Society of New Zealand 54 | 4

2023: ICCI; State of the Cryosphere – Two Degrees is Too High. International Cryosphere Climate Initiative (ICCI), Stockholm, Sweden (PDF)

2023: Paulik et al; National Assessment of extreme sea-level driven inundation under rising sea levels, Frontiers in Environmental Science (Open access)

2023: Naughton et al; Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century. Nature Climate Change (Open access)

Plain English article (this website under ‘News’)

2023: Community-led retreat and adaptation funding: Issues and options (MfE August 2023)

2023: Park et al; Future sea-level projections with a coupled atmosphere-ocean-ice-sheet model, Nature Communications 14 | 636 (open access)

2023: Hague et al; The Global Drivers of Chronic Coastal Flood Hazards Under Sea-Level Rise. Earths Future 11 | AGU research article (Open access)

2023: Cabana et al; Enabling Climate Change Adaptation in Coastal Systems: A Systematic Literature Review. Earths Future 11 | AGU research article (Open access)

2023: Batchelor et al; Rapid, buoyancy-driven ice-sheet retreat of hundreds of metres per day, Nature article April 2023

Guardian article explanation in plain English: Ice sheets can collapse at 600 metres a day, far faster than feared, study finds (open access).

2023: Gómez-Valdivia et al; Projected West Antarctic Ocean Warming Caused by an Expansion of the Ross Gyre, Geophysical Research Letters, 50 |6

2023: Vernimmen & Hooijer, New LiDAR-Based Elevation Model Shows Greatest Increase in Global Coastal Exposure to Flooding to Be Caused by Early-Stage Sea-Level Rise, AGU 11 | 1

2022: Albuquerque et al; On the projected changes in New Zealand’s wave climate and its main drivers, New Zealand Journal of Marine and Freshwater Research

2022: Urlich & Hodder-Swain: Untangling
the Gordian knot: estuary survival under sea-level rise and catchment
pollution requires a new policy and governance approach, New Zealand Journal of Freshwater Research 56|3

2022: Rullens et al; Understanding the consequences of sea level rise: the ecological implications of losing intertidal habitat New Zealand Journal of Freshwater Research 56|3

2022: Shaw et al; Stormier Southern Hemisphere induced by topography and ocean circulation, PNAS 119 |5

Shaw, Guest post in Carbon Brief : Why the southern hemisphere is stormier than the northern (open access plain English article on the above research)

2022: Khan et al; Extensive inland thinning and speed-up of Northeast Greenland Ice Stream, Nature (open access)

2022: National adaptation plan; Ministry for the Environment

2022: Interim guidance on the use of new sea-level rise projections; Ministry for the Environment

For the latest research and impacts on New Zealand, see GNS/NIWA/Victoria University of Wellington: SeaRise

For real-time and forecast marine heatwaves, see Marine Heat Waves

For information and research on flood impacts and risks: NIWA: Increasing flood resilience across Aotearoa

New Zealand Climate Change Commission

2022: Box et al; Greenland ice sheet climate disequilibrium and committed sea-level rise, Nature Climate Change article [open access]

2022: Hubbard; What’s going on with the Greenland ice sheet? It’s losing ice faster thanforecast and now irreversibly committed to at least 10 inches of sea level rise, The Conversation (plain English explanation of the above research paper)

2022: Wagner, Formally designate blue-green infrastructure for climate adaptation, Nature article 26 July

2022: Braddock et al; Relative sea-level data preclude major late Holocene ice-mass change in Pine Island Bay, Nature Geoscience 15 pp568-572

2021: Tonkin+Taylor; Coastal Hazard Assessment for the Christchurch Ōtautahi District [Technical Report]

2021: Ijzendoorn et al; Sea level rise outpaced by vertical dune toe translation on prograding coasts, Nature Scientific Reports 11 | 12792

2021: Thompson et al; Rapid increases and extreme months in projections of United States high-tide flooding, Nature Climate Change 11 pp584–590

2021: Edwards et al; Projected land ice contributions to twenty-first-century sea level rise, Nature 593 pp74–82

2021: Lanard; The Future Shape of Water, Water And Atmosphere, NIWA

2020: Kool et al; Preparing for Sea-Level Rise through Adaptive Managed Retreat of a New Zealand Stormwater and Wastewater Network Infrastructures 5(11) p92

Stuff article explaining the above research paper

2020: Tian et al; Deglacial–Holocene Svalbard paleoceanography and evidence of meltwater pulse 1B. Quaternary Science Reviews, 233

2020: The University of Hong Kong. “Paleontologists discover solid evidence of formerly elusive abrupt sea-level jump.” ScienceDaily, 10 March 2020

2020: Storey et al; Insurance Retreat – Sea level rise and the withdrawal of residential insurance in Aotearoa New Zealand, Report for the Deep South National Science Challenge, December 2020.

2020: Dickson & Thompson; Coastal cliff erosion in Aotearoa New Zealand and the potential impacts of sea level rise, pp39-44 in Coastal Systems and Sea Level Rise: What to look for in the future, Special Publication 4, December, New Zealand Coastal Society

Resilient Shorelines (Canterbury & Marlborough research projects)

Deep South Science Challenge (NZ): Will your property become uninsurable?

Deep South Science Challenge (NZ): Planning for coastal adaptation

Deep South Science Challenge (NZ): How should the risks be shared?

NIWA: Coastal Erosion and Sediment Systems

2020: Voosen, Seas are rising faster than ever, Science article

2020: Frederikse et al; The causes of sea-level rise since 1900 Nature 584, pp393–397

2020: Stephens et al; Spatial and temporal analysis of extreme storm-tide and skew-surge events around the coastline of New Zealand Natural Hazards Earth Systems Science 20 pp783–796

2020: Ortiz et al; Ancient ice-sheet collapse, Nature Geoscience 13 pp328–329

2020: Tada; The Rising Tide Underfoot, Hakai magazine

2019: Kopp et al: Usable Science for Managing the Risks of Sea‐Level Rise AGU: Earth’s Future 7 (12) pp1235–1269

2019 NIWA: Coastal Flooding Exposure Under Future Sea-level Rise for New Zealand; prepared for Deep South Challenge

2019: McDonald; What to do about the constant threat – and reality – of flooded homes in coastal communities, Stuff, Sept. 19.

2019: Turney et al; Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica PNAS 117 (8) pp 3996-4006

2019: (IPCC) Intergovernmental Panel on Climate Change’s special report on the oceans and cryosphere

In-depth Q&A: The IPCC’s special report on the ocean and cryosphere (Carbon Brief)

2019: Hicks (NIWA): Rising sea-level impacts on braided river mouths (hapua). Braided Rivers 2019 Seminar

2019: Sutherland et al; Direct observations of submarine melt and subsurface geometry at a tidewater glacier; Science 365 /6451, pp369-374

2019: Dangendorf et al; Persistent acceleration in global sea-level rise since the 1960s; Nature Climate Change 9, pp705–710

2019: Milillo et al; Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica; Science Advances 2019 Jan; 5(1): eaau3433

2019: Mouginot et al; Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018; PNAS May 7, 2019 116 (19) 9239-9244

2018: Nerem et al; Climate-change–driven accelerated sea-level rise detected in the altimeter era, PNAS February 27, 2018 115 (9) 2022-2025

2018: Ivanovic et al; Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt Geophysical Research Letters (open access)

2018: (IPCC) Church et al; Sea Level Change. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

2017: Ministry for the Environment: Preparing for coastal change: summary of coastal hazards and climate change guidance for local government

National Geographic: Ancient DNA reveals complex migrations of the first Americans

2016: Hansen et al; Ice melt, sea-level rise and superstorms: evidence from paleoclimate data, climate modelling, and modern observations that 2◦C global warming could be dangerous. Atmos. Chem. Phys., 16, 3761–3812, 2016

2016: DeConto et al; Contribution of Antarctica to past and future sea-level rise, Nature 531, pp591–597

2015: Whitelaw; Where will estuaries be allowed to go?

2015: Parliamentary Commissioner for the Environment: preparing New Zealand for rising seas

2014: Kopp et al; Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites. AGU (full access article)

2014 IPCC Climate Change (AR5): Impacts, Adaptation, and Vulnerability

2013 IPCC Climate Change (AR5): The Physical Science Basis

2012: Gregoire et al; Deglacial rapid sea level rises caused by ice sheet saddle collapses, Nature 487, pp219–222

2012: Deschamps et al; Ice-sheet collapse and sea-level rise at the Bølling warming 14,600 years ago; Nature 483, pp559–564

2012: Hume et al; Coastal stability in the South Taranaki Bight – Phase 1, NIWA Client Report No: HAM2012-083

2011: Schmidt et al; Abrupt Climate Change During the Last Ice Age. Nature Education Knowledge 3 |10:11

2011: Whitelaw; The Vulnerability of Tuhaitara Coastal Park to Rising Sea-levels
2010: Goring & Henry, Short period (1–4 h) sea level fluctuations on the Canterbury coast, New Zealand Journal of Marine and Freshwater Research 32 | 1 pp119-134

2010: Murton et al; Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean Nature 464, pp740–743

2010: New Zealand Coastal Policy Statement

2010: Church et al (eds); Understanding Sea-Level Rise and Variability, Wiley-Blackwell, UK

2007; Wells & Goff; Coastal dunes in Westland, New Zealand, provide a record of paleoseismic activity on the Alpine fault, Geology 35 | 8

2007: Alley; Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change Annual Review of Earth and Planetary Sciences 35 pp241-272

2005: Alley et al; Ice-sheet and sea-level changes, Science 310| 5747 pp456-60

Impacts