NZ’s next large Alpine Fault quake is likely coming sooner than we thought, study shows


NASA/JPL/NGA, CC BY-ND

Jamie Howarth, Te Herenga Waka — Victoria University of Wellington and Rupert Sutherland, Te Herenga Waka — Victoria University of Wellington

Graphic of Alpine Fault
The Alpine Fault marks the boundary between the Pacific and Australian plates in the South Island of New Zealand.
Author provided

The chances of New Zealand’s Alpine Fault rupturing in a damaging earthquake in the next 50 years are much higher than previously thought, according to our research, published today.

The 850km Alpine Fault runs along the mountainous spine of the South Island, marking the boundary where the Australian and Pacific tectonic plates meet and grind against each other, forcing up the Southern Alps. Over the past 4,000 years, it has ruptured more than 20 times, on average around every 250 years.

Alpine Fault earthquakes are recorded in lake sediment deposits.

The last major earthquake on the Alpine Fault was in 1717. It shunted land horizontally by eight metres and uplifted the mountains a couple of metres. Large earthquakes on the fault tend to propagate uninhibited for hundreds of kilometres.

Until now, scientists thought the risk of a major earthquake in the next 50 years was about 30%. But our analysis of data from 20 previous earthquakes along 350 kilometres of the fault shows the probability of that earthquake occurring before 2068 is about 75%. We also calculated an 82% chance the earthquake will be of magnitude 8 or higher.

Alpine Fault earthquakes in space and time

From space, the fault appears like a straight line on the western side of the Southern Alps. But there are variations in the fault’s geometry (its orientation and the angle it dips into Earth’s crust) and the rate at which the two plates slip past each other.

These differences separate the fault into different segments. We thought the boundaries between these segments might be important for stopping earthquake ruptures, but we didn’t appreciate how important until now.

Graphic of Alpine Fault
Differences in geometry and the rate of slip between the tectonic plates create sections along the Alpine Fault.
Author provided

We examined evidence from 20 previous Alpine Fault ruptures recorded in sediments in four lakes and two swamps on the west coast of the South Island over the past 4,000 years. From this evidence, we built one of the most complete earthquake records of its kind.

Once we analysed and dated the sediments from lakes near the Alpine Fault, we were able to see new patterns in the distribution of earthquakes along the fault. One of our findings is a curious “earthquake gate” at the boundary between the fault’s south western and central segments. It appears to determine how large an Alpine Fault earthquake gets.

Some ruptures stop at the gate and produce major earthquakes in the magnitude 7 range. Ruptures that pass through the gate grow into great earthquakes of magnitude 8 or more. This pattern of stopping or letting ruptures pass through tends to occur in sequences, producing phases of major or great earthquakes through time.




Read more:
New Zealand’s Alpine Fault reveals extreme underground heat and fluid pressure


Forecasting the next Alpine Fault earthquake

From the record of past earthquakes it is possible to forecast the likelihood of a future earthquake (i.e. a 75% chance the fault will rupture in the next 50 years). But from these data alone it is not possible to estimate the magnitude of the next event.

For this we used a physics-based model of how earthquakes behave and applied it to the Alpine Fault, testing it against data from earlier earthquake sequences. This is the first time we have been able to use past earthquake data that span multiple large earthquakes and are of sufficient quality to allow us to evaluate how such models could be used in forecasting.

The physics-based model simulated Alpine Fault earthquake behaviour when we included the variations in fault geometry that define the different fault segments. When the simulation is combined with our record of past behaviour it is possible to estimate the magnitude of the next earthquake.




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The Alpine Fault earthquake record shows the past three earthquakes ruptured through the earthquake gate and produced great (magnitude 8 or higher) earthquakes. Our simulations show that if three earthquakes passed through the gate, the next one is also likely to go through.

This means we’d expect the next earthquake to be similar to the last one in 1717, which ruptured along about 380km of the fault and had an estimated magnitude 8.1.

Our findings do not change the fact the Alpine Fault has always been and will continue to be hazardous. But now we can say the next earthquake will likely happen in the next 50 years.

We need to move beyond planning the immediate response to the next event, which has been done well through the Alpine Fault Magnitude 8 (AF8) programme, to thinking about how we make decisions about future investment to improve infrastructure and community preparedness.The Conversation

Jamie Howarth, Senior lecturer, Te Herenga Waka — Victoria University of Wellington and Rupert Sutherland, Professor of tectonics and geophysics, Te Herenga Waka — Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Many New Zealand species are already at risk because of predators and habitat loss. Climate change makes things worse


Education Images/Universal Images Group via Getty Images

Cate Macinnis-Ng, University of Auckland and Angus Mcintosh, University of CanterburyIslands are biodiversity hotspots. They are home to 20% of the world’s plants and animals yet cover only 5% of the global landmass. But island ecosystems are highly vulnerable, threatened by habitat fragmentation and introduced invasive weeds and predators.

Climate change adds to all these stresses. In our recent paper, we use Aotearoa New Zealand as a case study to show how climate change accelerates biodiversity decline on islands by exacerbating existing conservation threats.

Banded dotterel chick in a snad nest
Many native birds are threatened by introduced predators such as rats, possums and cats.
Shutterstock/Imogen Warren

Aotearoa is one of the world’s biodiversity hotspots, with 80% of vascular plants, 81% of arthropods and 60% of land vertebrate animals found nowhere else.

Its evolutionary history is dominated by birds. Before the arrival of people, the only native land mammals were bats. But now, introduced predators threaten the survival of many species.

Complex interplay between many threats

Conservation efforts have rightly concentrated on the eradication of introduced predators, with world-leading success in the eradication of rats in particular.

Potential climate change impacts have been mostly ignored. Successive assessments by the Intergovernmental Panel on Climate Change (IPCC) highlight the lack of information for Aotearoa. This could be due to insufficient research, system complexity or a lack of impacts.

In the past, some researchers even dismissed climate change as an issue for biodiversity in Aotearoa. Our maritime climate is comparatively mild and already variable. As a result, organisms are expected to be well adapted to changing conditions.




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Palaeo-ecological records suggest few species extinctions despite abrupt environmental change during the Quaternary period (from 2.5 million years ago to present). But past climate change provides an incomplete picture of contemporary change because it did not include human-induced threats.

Habitat loss and fragmentation, land‐use change and complex interactions between native species and introduced predators or invasive weeds all contribute to these threats.

How climate change affects biodiversity

Species respond to climate change by evolving physiological adjustments, moving to new habitats or, in the worst cases, becoming extinct. These responses then change ecosystem processes, including species interactions and ecosystem functions (such as carbon uptake and storage).

Methods for identifying climate change impacts are either empirical and observational (field studies and manipulative experiments) or mechanistic (ecophysiological models). Mechanistic approaches allow predictions of impacts under future climate scenarios. But linking species and ecosystem change directly to climate can be challenging in a complex world where multiple stressors are at play.

Tuatara, a reptile found only in New Zealand.
Tuatara survive only on a few offshore islands and in sanctuaries.
Shutterstock/Ken Griffiths

There are several well-known examples of climate change impacts on species endemic to Aotearoa. First, warming of tuatara eggs changes the sex ratio of hatchlings. Hotter conditions produce more males, potentially threatening long-term survival of small, isolated populations.

Second, mast seeding (years of unusually high production of seed) is highly responsive to temperature and mast events are likely to increase under future climate change. During mast years, the seeds provide more food for invasive species like rats or mice, their populations explode in response to the abundant food and then, when the seed resource is used up, they turn to other food sources such as invertebrates and bird eggs. This has major impacts on native ecosystems.

How masting plants respond to climate change is complex and depends on the species. The full influence of climate is still emerging.

Looking up into the canopy of beech trees.
Every few years, beech trees produce significantly higher amounts of seed.
Shutterstock/sljones

Indirect effects of climate change

We identified a range of known and potential complex impacts of climate change in several ecosystems. The alpine zone is particularly vulnerable. Warming experiments showed rising temperatures extend the overlap between the flowering seasons of native alpine plants and invasive plants. This potentially increases competition for pollinators and could result in lower seed production.

Some large alpine birds, including the alpine parrot kea, will have fewer cool places to take refuge from invasive predators. This will cause
local extinctions in a process know as “thermal squeeze”.

Small alpine lakes, known as tarns, are not well understood but are also likely to suffer from thermal squeeze and increased drought periods. Warmer temperatures may also allow Australian brown tree frogs to invade further into these sensitive systems.

The alpine parrot kea
The alpine parrot kea lives in New Zealand’s mountain ranges.
Shutterstock/Peter Nordbaek Hansen

Climate change disproportionately affects Indigenous people worldwide. In Aotearoa, culturally significant species such as tītī (sooty shearwater) and harakeke (flax) will be influenced by climate change.

The breeding success of tītī, which are harvested traditionally, is strongly influenced by the El Niño Southern Oscillation (ENSO) cycle. As ENSO intensifies under climate change, numbers of young surviving are decreasing. For harakeke, future climate projections predict changes in plant distribution, potentially making weaving materials unavailable to some hapū (subtribes).




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Mātauranga, the Indigenous knowledge of Māori, provides insights on climate change that haven’t been captured in western science. For instance, the Māori calendar, maramataka, has been developed over centuries of observations.

Maramataka for each hāpu (subtribe) provide guidance for the timing of gathering mahinga kai (traditional food sources). This includes the gathering of fish and other seafood, planting of crops and harvesting food. Because this calendar is based on knowledge that has accrued over generations, some changes in timing and distributions due to environmental or climate change may be captured in these oral histories.

Climate change is here now

Future projections of climate change are complicated in Aotearoa — but it is clear the climate is already changing.

Last year was the seventh hottest on record for Aotearoa. Many parts of the country suffered severe summer drought. NASA captured images of browned landscapes across the country.

Satellite images of New Zealand, showing two years and the impact of drought.
These images show how the Hawke’s Bay dried out between the summer (December to February) periods of 2019 (left) and 2020 (right).
NASA, CC BY-SA

Much of the focus of climate change research has been in agricultural and other human landscapes but we need more effort to quantify the threat for our endemic systems.

On islands across the world, rising sea levels and more severe extreme weather events are threatening the survival of endemic species and ecosystems. We need to understand the complicated processes through which climate change interacts with other threats to ensure the success of conservation projects.

While we focused on terrestrial and freshwater systems, marine and near-shore ecosystems are also suffering because of ocean acidification, rising sea levels and marine heatwaves. These processes threaten marine productivity, fisheries and mahinga kai resources.

And for long-term conservation success, we need to consider both direct and indirect impacts of climate change on our unique species and ecosystems.The Conversation

Cate Macinnis-Ng, Associate Professor, University of Auckland and Angus Mcintosh, Professor of Freshwater Ecology, University of Canterbury

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When climate change and other emergencies threaten where we live, how will we manage our retreat?



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Christina Hanna, University of Waikato; Bruce Glavovic, Massey University, and Iain White, University of Waikato

Despite living in dynamic environments and facing an uncertain future due to climate change, New Zealanders generally expect their land and property rights will endure indefinitely.

But little stays the same. As last week’s offshore earthquakes and tsunami alerts reminded us, our coasts and the people who live near them are vulnerable to a range of hazards. Such risks will only increase as sea level rises due to climate change.

The government has announced that the Resource Management Act will be replaced by three new laws, including a Managed Retreat and Climate Change Adaptation Act. The writing is on the wall: planners and communities need to prepare for change.

For those living in highly exposed places, managed retreat may be necessary to save lives and secure public safety.

These “managed retreats” — from low-lying shorelines vulnerable to rising sea level, areas that flood regularly and unstable or exposed land — may be a bitter pill to swallow. Especially so in the midst of a national housing crisis and a global pandemic.

But the impacts of climate change are already being felt, and will compound natural hazard risks well into the future. Some existing developments are already proving untenable, exposing people and the things they cherish to severe harm.

So it’s imperative to include the option of managed retreat in adaptation planning for the most at-risk communities.

Empty and overgrown road and fields
Once a suburban hinterland, Christchurch’s earthquake ‘red zone’ now lies empty and abandoned.
Author provided

What are managed retreats?

Basically, managed retreats involve the strategic relocation of people, assets and activities to reduce risk.

For obvious reasons, retreats require difficult sacrifices for individuals, families and communities. The process can involve a range of mechanisms, including providing risk maps, official notices on land information memorandums (LIMs), development restrictions and financial incentives to relocate.

Planners and academics have been calling for a national managed retreat strategy, and the law change provides a unique opportunity.




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Aside from compulsory acquisition powers used to deliver public works, Aotearoa New Zealand may be the first country to develop specific legislation for managed retreats. The world will be watching with interest.

Managing retreats that are sensitive to the dislocation of people from their homes, livelihoods, landscapes and culture is challenging. Developing the new legislation will involve difficult decisions about why, when, how and where retreats take place — and at whose cost.

Putting people first

Just how these retreats will be managed, however, is yet to be determined. Our latest research examines who manages retreats and how. It’s a timely cue to examine the broad policy options and planning implications.

The proposed legislation presents an opportunity to transform land use patterns
in Aotearoa New Zealand. But as we have seen in Canterbury, Matatā and elsewhere, the way managed retreats are handled matters greatly to the people affected.

At present, local managed retreat interventions are risky – professionally, politically, financially, culturally and socially. The necessary planning frameworks and resources are seldom available to support effective and equitable outcomes.

Some communities exposed to hazards and climate perils also face the risk of maladaptation — paradoxically, their vulnerability is increased by inaction or misguided efforts.




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Who manages retreats and how?

Our research distinguishes three approaches to making policy for a spectrum of possible retreats. Broadly speaking, these are:

  1. government control: using legislation, standards, policies and regulations, central or local government may restrict certain developments or compulsorily acquire property to enforce retreat

  2. co-operative managed retreats: collaborative decision-making and negotiation between government agencies and affected parties, using instruments such as opt-in buyouts, relocation subsidies or land swaps

  3. unmanaged retreats: individual choices influenced by factors such as loss of insurance cover and other market changes, decisions not to invest more in a property or to sell it (potentially at a loss), or to remain in place and face the risk.

Using our framework, we consider the risks and implications of each form of retreat. We draw on decades of lessons from international practice in disaster resettlement and planned relocation.

Getting the law right

Fundamentally, we argue that facilitating co-operative managed retreats is preferable. This means people and communities are embedded in the retreat strategy design, decision-making and delivery.

Necessarily then, flexible, collaborative and fit-for-purpose policies and practices are important. To manage expectations around at-risk, transient and marginal land, regulation of new development or land use is also required (such as placing time limits on consents).




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Managed, co-operative and unmanaged retreats each have a role to play. But their associated practices and policy interventions must be strategically planned. To promote public safety, justice and equity, co-operation must be a central focus when managing the relocation of people.

Aotearoa New Zealand has an opportunity to foster long-term resilience in the face of climate change and many other land use challenges. Determining who manages retreats, how, and who pays is important work.

The shape of the new legislation — the processes and outcomes it encourages — will influence the lives and well-being of current and future generations.The Conversation

Christina Hanna, Lecturer, Environmental Planning, University of Waikato; Bruce Glavovic, Professor, Massey University, and Iain White, Professor of Environmental Planning, University of Waikato

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Ardern’s government and climate policy: despite a zero-carbon law, is New Zealand merely a follower rather than a leader?


David Hall, Auckland University of Technology

Back in pre-COVID times last year, when New Zealand passed the Zero Carbon Act, Prime Minister Jacinda Ardern insisted “New Zealand will not be a slow follower” on climate change.

It struck a clear contrast with the previous National government’s approach, which the then prime minister, John Key, often described as being “a fast follower, not a leader”.

He had lifted this language from the New Zealand Institute’s 2007 report, which argued against “lofty rhetoric about saving the planet or being a world leader”. Instead, it counselled New Zealand to respond without “investing unnecessarily in leading the way”.

Key was eventually accused of failing to live up to even this unambitious ideal — New Zealand came to be known as a climate laggard.

With her hand on the nation’s rudder since 2017, has Ardern done any better?
Is New Zealand a climate leader, and not merely a symbolic leader on the international speaking circuit but a substantive leader that sets examples for other countries to follow?

Finally a fast follower

On my analysis of Ardern’s government, New Zealand is now, finally, a fast follower.

The government’s climate policy is best evaluated from three perspectives: the domestic, international and moral.




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From a domestic perspective, where a government is judged against the governments that preceded it, Ardern is entitled to declare (as she did when the Zero Carbon Act was passed) that:

We have done more in 24 months than any government in New Zealand has ever done on climate action.

But at the international level, where New Zealand is judged against the actions of other countries and its international commitments, it is more a fast follower than a leader, defined by policy uptake and international advocacy rather than innovation.

At the moral level, where New Zealand is judged against objectives such as the 1.5°C carbon budget, its actions remain inadequate. A recent report by Oxfam notes New Zealand is off-track for its international obligations.

The nation’s record looks even worse when we factor in historical responsibilities. From this perspective, New Zealand, like other countries in the global north, is acting with an immoral lack of haste. It is for the next government to go from being merely transitional to truly transformational.

Turning in the right direction

The formation of the Ardern government in 2017 inaugurated a phase of rapid policy development, drawing especially from UK and EU examples. But the evidence of substantive climate leadership is much less clear.

The government’s most prominent achievement is the Zero Carbon Act, which passed through parliament with cross-party support in November 2019. This establishes a regulatory architecture to support the low-emissions transition through five-yearly carbon budgets and a Climate Change Commission that provides independent advice.

Its other major achievement, less heralded and more disputed, was the suspension of offshore oil and gas permits. This supply-side intervention is surely Ardern’s riskiest manoeuvre as prime minister, not only on climate but on any policy issue.

It stands as an exception to her careful, incremental style. It signalled that the Crown’s historical indulgence of the oil and gas sector was coming to an end.

But both policies involve followership. The Zero Carbon Act is closely modelled on the UK’s Climate Change Act 2008 and the leadership came from outside government. It was initially championed by the youth group Generation Zero. The independent Parliamentary Commissioner for the Environment then picked it up.

Similarly, the offshore oil and gas ban builds upon longstanding activism from Māori organisations and activists. In 2012, Petrobras withdrew prematurely from a five-year exploration permit after resistance from East Cape iwi (tribe) Te Whānau-ā-Apanui. New Zealand was also only following in the footsteps of more comprehensive moratoriums elsewhere, such as Costa Rica in 2011 and France in 2017.

Towards climate leadership

There are many other climate-related policies, including:

Only the last policy is a world first. Even then, private companies throughout the world are already adopting this approach without a mandate from government.




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In all likelihood, New Zealand’s greatest claim to pioneering policy is its decision to split targets for carbon dioxide and methane in the Zero Carbon Act, which means agricultural methane is treated separately. If the science behind this decision eventually informs the international accounting of greenhouse gases, it will have major ramifications for developing countries whose economies also rely heavily on agriculture.

Not all proposed policies made it through the political brambles of coalition government. Most conspicuously, commitments to an emissions-free government vehicle fleet, the introduction of fuel-efficiency standards, and feebates for light vehicles were all thwarted.

This is symptomatic of this government’s major weakness on climate. Its emphasis on institutional reforms rather than specific projects will yield long-term impacts, but not produce the immediate emissions reductions to achieve New Zealand’s 2030 international target under the Paris Agreement. This is where a future government can make the rhetoric of climate leadership a reality.


This article is adapted from an upcoming book – Pioneers, Leaders and Followers in Multilevel and Polycentric Climate Governance.The Conversation

David Hall, Senior Researcher in Politics, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Zealand invests in growing its domestic recycling industry to create jobs and dump less rubbish at landfills



Shutterstock/corners74

Jeff Seadon, Auckland University of Technology

New Zealand’s government recently put more than NZ$160 million towards developing a domestic recycling sector to create jobs as part of its economic recovery from the COVID-19 pandemic.

New Zealanders recycle 1.3 million tonnes of materials each year, but 70% is currently exported. A recent NZ$36.7 million funding boost to upgrade recycling plants throughout the country followed a NZ$124 million injection into recycling infrastructure to grow processing capacity onshore. The investment signals a focus on supporting services that create employment and increase efficiency or reduce waste.

The potential for expansion in onshore processing of recyclable waste is enormous – and it could lead to 3.1 million tonnes of waste being diverted from landfills. But it will only work if it is part of a strategy with clear and measurable targets.

COVID-19 impacts

During New Zealand’s level 4 lockdown between March and May, general rubbish collection was classed as an essential service and continued to operate. But recycling was sporadic.

Whether or not recycling services continued depended on storage space and the ability to separate recyclables under lockdown conditions. Facilities that relied on manual sorting could not meet those requirements and their recycling was sent to landfill. Only recycling plants with automated sorting could operate.

New Zealand’s reliance on international markets showed a lack of resilience in the waste management system. Any changes in international prices were duplicated in New Zealand and while exports could continue under tighter border controls, it was no longer economically viable to do so for certain recyclable materials.

International cardboard and paper markets collapsed and operators without sufficient storage space sent materials to landfill. Most plastics became uneconomic to recycle.

Recycling and rubbish bins
New Zealanders recycle 1.3 million tonnes each year.
Shutterstock/Josie Garner

In contrast, for materials processed in New Zealand — including glass, metals and some plastics — recycling remains viable. Many local authorities are now limiting their plastic collections to those types that have expanding onshore processing capacity.

Soft packaging plastics are also being collected again, but only in some places and in smaller quantities than at the height of the soft plastics recycling scheme, to be turned into fence posts and other farm materials.




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The investment in onshore processing facilities is part of a move towards a circular economy. The government provided the capital for plants to recycle PET plastics, used to make most drink bottles and food trays. PET plastics can be reprocessed several times.

This means items such as meat trays previously made from polystyrene, which is not recyclable from households, could be made from fully recyclable PET. Some of the most recent funding goes towards providing automatic optical sorters to allow recycling plants to keep operating under lockdown conditions.

Regulation changes

The government also announced an expansion of the landfill levy to cover more types of landfills and for those that accept household wastea progressive increase from NZ$10 to NZ$60 per tonne of waste.

This will provide more money for the Waste Minimisation Fund, which in turn funds projects that lead to more onshore processing and jobs.

Last year’s ban on single-use plastic bags took more than a billion bags out of circulation, which represents about 180 tonnes of plastic that is not landfilled. But this is a small portion of the 3.7 million tonnes of waste that go to landfill each year.

More substantial diversion schemes include mandatory product stewardship schemes currently being implemented for tyres, electrical and electronic products, agrichemicals and their containers, refrigerants and other synthetic greenhouse gases, farm plastics and packaging.

An example of the potential gains for product stewardship schemes is e-waste. Currently New Zealand produces about 80,000 tonnes of e-waste per year, but recycles only about 2% (1,600 tonnes), most of which goes offshore for processing. Under the scheme, e-waste will be brought to collection depots and more will be processed onshore.

Landfilling New Zealand’s total annual e-waste provides about 50 jobs. Recycling it could create 200 jobs and reusing it is estimated to provide work for 6,400 people.




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But all these initiatives are not enough. We need a coordinated strategy with clear targets.

The current Waste Strategy has only two goals: to reduce the harmful effects of waste and improve resource use efficiency. Such vague goals have resulted in a 37% increase in waste disposal to landfill in the last decade.

An earlier 2002 strategy achieved significantly better progress. The challenge is clear. A government strategy with measurable targets for waste diversion from landfill can lead us to better resource use and more jobs.The Conversation

Jeff Seadon, Senior Lecturer, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How climate change made the melting of New Zealand’s glaciers 10 times more likely



Dave Allen, Author provided

Lauren Vargo, Te Herenga Waka — Victoria University of Wellington

Glaciers around the world are melting — and for the first time, we can now directly attribute annual ice loss to climate change.

We analysed two years in which glaciers in New Zealand melted the most in at least four decades: 2011 and 2018. Both years were characterised by warmer than average temperatures of the air and the surface of the ocean, especially during summer.

Our research, published today, shows climate change made the glacial melt that happened during the summer of 2018 at least ten times more likely.

A person taking an image of a glacier
Scientists have been monitoring glaciers in New Zealand for more than 40 years.
Dave Allen, Author provided

As the Earth continues to warm, we expect an even stronger human fingerprint on extreme glacier mass loss in the coming decades.




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A bird’s eye view of New Zealand’s changing glaciers


Extreme glacier melt

During the 2018 summer, the Tasman Sea marine heatwave resulted in the warmest sea surface temperatures around New Zealand on record — up to 2℃ above average.

Research shows these record sea surface temperatures were almost certainly due to the influence of climate change.

map of sea surface temperatures
Summer sea surface temperature anomalies (in °C, relative to mean temperatures between 1979 and 2009) for December 2010 to February 2011 (left) and December 2017 to February 2018 (right),
Author provided

The results of our work show climate change made the high melt in 2011 at least six times more likely, and in 2018, it was at least ten times more likely.

These likelihoods are changing because global average temperatures, including in New Zealand, are now about 1°C above pre-industrial levels, confirming a connection between greenhouse gas emissions and high annual ice loss.

Changing New Zealand glaciers

Glaciers in New Zealand's mountains
New Zealand’s glaciers lost more ice in 2011 and 2018 than in any other year in the last four decades.
Dave Allen, Author provided

We use several methods to track changes in New Zealand glaciers.

First, the end-of-summer snowline survey began in 1977. It involves taking photographs of over 50 glaciers in the Southern Alps every March.

From these images, we calculate the snowline elevation (the lowest elevation of snow on the glacier) to determine the glacier’s health. The less snow there is left on a glacier at the end of summer, the more ice the glacier has lost.

The second method is our annual measurement of a glacier’s mass balance — the total gain or loss of ice from a glacier over a year. These measurements require trips to the glacier each year to measure snow accumulation, and snow and ice melt. Mass balance is measured for only two glaciers in the Southern Alps, Brewster Glacier (since 2005) and Rolleston Glacier (since 2010).

Both methods show New Zealand glaciers lost more ice in 2011 and 2018 than during earlier years since the start of the snowline surveys in 1977.

Images taken during the end-of-summer snowline survey show how the amount of white snow at high elevations on Brewster Glacier decreases over time, compared to darker, bluer ice at lower elevations.




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Attributing extreme melt

Earlier research has quantified the human influence on extreme climate events such as heatwaves, extreme rainfall and droughts. We combined the established method of calculating the impact of climate change on extreme events with models of glacier mass balance. In this way, we could determine whether or not climate change has influenced extreme glacier melt.

This is the first study to attribute annual glacier melt to climate change, and only the second to directly link glacier melt to climate change. With multiple studies in agreement, we can be more confident there is a link between human activity and glacier melt.

Franz Josef is another iconic New Zealand glacier. This timelapse video shows it has retreated by 900 metres since 2012. Credit: Brian Anderson.

This confidence is especially important for Intergovernmental Panel on Climate Change (IPCC) reports, which use findings like ours to inform policymakers.

Recent research shows New Zealand glaciers will lose about 80% of area and volume between 2015 and the end of the century if greenhouse gas emissions continue to rise at current rates. Glaciers in New Zealand are important for tourism, alpine sports and as a water resource.

Glacial retreat is accelerating globally, especially in the past decade.
Research shows by 2090, the water runoff from glaciers will decrease by up to 10% in regions including central Asia and the Andes, raising major concerns over the sustainability of water resources where they are already limited.

The next step in our work is to calculate the influence of climate change on extreme melt for glaciers around the world. Ultimately, we hope this will contribute to evidence-based decisions on climate policy and convince people to take stronger action to curb climate change.The Conversation

Lauren Vargo, Research Fellow in the Antarctic Research Centre, Te Herenga Waka — Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Sharks are thriving at the Kermadec Islands, but not the rest of New Zealand, amid global decline




Adam Smith, Massey University

A recent global assessment of shark populations at 371 coral reefs in 58 countries found no sharks at almost 20% of reefs and alarmingly low numbers at many others.

The study, which involved over 100 scientists under the Global FinPrint project, gave New Zealand a good score card. But because it focused on coral reefs, it included only one region — Rangitāhua (Kermadec Islands), a pristine subtropical archipelago surrounded by New Zealand’s largest marine reserve.

It is a different story around the main islands of New Zealand. Many coastal shark species may be in decline, and less than half a percent of territorial waters is protected by marine reserves.

The first global survey of reef sharks shows they are virtually absent in many areas.



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Sharks in Aotearoa

In New Zealand, there are more than a hundred species of sharks, rays and chimaeras. They belong to a group of fishes called chondrichthyans, which have skeletons of cartilage instead of bone.

Some 55% of New Zealand’s chondrichthyan species are listed as “not threatened” by the International Union for Conservation of Nature (IUCN). Not so encouraging is the 32% of species listed as “data deficient”, meaning we don’t know the status of their populations. Most species (77%) live in waters deeper than 200 metres.

Seven species are fully protected under the Wildlife Act 1953. They are mostly large, migratory species such as the giant manta ray. Some are threatened with extinction according to the IUCN, including great white sharks, basking sharks, whale sharks and oceanic white tip sharks.

Basking shark and snorkellers
Basking sharks were once common in some coastal areas in New Zealand.
Martin Prochazkacz/Shutterstock

Historically, basking sharks were caught as bycatch in New Zealand fisheries, and seen in their hundreds in some inshore areas. Sightings of these giant plankton-feeders suddenly dried up over a decade ago. We don’t know why.

Commercial shark fisheries

Eleven chondrichthyan species are fished commercially in New Zealand under the quota management system. Commercial fisheries for school shark, rig and elephant fish took off from the 1970s and now catch around 8,000 tonnes per year in total.

Finning of sharks has been illegal throughout New Zealand since 2014.

Most of New Zealand’s shark fisheries are considered sustainable. But a sustainable fishery can mean sustained at low levels, and we must tread carefully. School shark was recently added to the critically endangered list after the collapse of fisheries in Australia and elsewhere, and there’s a lot we don’t know about the New Zealand population.

We do know sharks were much more abundant in pre-European times. In Tīkapa Moana (Hauraki Gulf), sharks have since declined by an estimated 86%. An ongoing planning process provides some hope for the ecosystems of the gulf.

Protecting sharks

Not surprisingly, the global assessment found a ban on shark fishing to be the most effective intervention to protect sharks. Several countries have recently established large shark sanctuaries, sometimes covering entire exclusive economic zones.

These countries tend to have ecotourism industries that provide economic incentives for protection — live sharks can be more valuable than dead ones.

Other effective interventions are restrictions on fishing gear, such as longlines and set nets.

Waters within 12 nautical miles of the Kermadec Islands have been protected by a marine reserve since 1990. In 2015, the Kermadec Ocean Sanctuary was announced but progress has stalled. The sanctuary would extend the boundaries to the exclusive economic zone, some 200 nautical miles offshore, and increase the protected area 83-fold.

A large population of Galapagos sharks, which prefer isolated islands surrounded by deep ocean, thrive around the Kermadec Islands but are found nowhere else in New Zealand. Great white sharks also visit en route to the tropics. Many other species are found only at the Kermadecs, including three sharks and a sex-changing giant limpet as big as a saucer.

Galapagos sharks
Galapagos sharks were recorded around Raoul Island in the Kermadec archipelago.
Author provided



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New technologies are revealing sharks’ secrets

What makes the Global FinPrint project so valuable is that it uses a standard survey method, allowing data to be compared across the globe. The method uses a video camera pointed at a canister of bait. This contraption is put on the seafloor for an hour, then we watch the videos and count the sharks.

Grey reef, silver tip and hammerhead sharks circle a baited camera station set up near Walpole Island in the Southwest Pacific.

Baited cameras have been used in a few places in New Zealand but there are no systematic surveys at a national scale. We lack fundamental knowledge about the distribution and abundance of sharks in our coastal waters, and how they compare to the rest of the world.

Satellite tags are another technological boon for shark research. It is difficult to protect sharks without knowing where they go and what habitats they use. Electronic tags that transmit positional data via satellite can be attached to live sharks, revealing the details of their movements. Some have crossed oceans.

Sharks have patrolled the seas for more than 400 million years. In a few decades, demand for shark meat and fins has reduced their numbers by around 90%.

Sharks are generally more vulnerable to exploitation than other fishes. While a young bony fish can release tens of millions of eggs in a day, mature sharks lay a few eggs or give birth to a few live young. Females take many years to reach sexual maturity and, in some species, only reproduce once every two or three years.

These biological characteristics mean their populations are quick to collapse and slow to rebuild. They need careful management informed by science. It’s time New Zealand put more resources into understanding our oldest and most vulnerable fishes, and the far-flung subtropical waters in which they rule.The Conversation

Adam Smith, Senior Lecturer in Statistics, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Zealand wants to build a 100% renewable electricity grid, but massive infrastructure is not the best option



Juergen_Wallstabe/Shutterstock

Janet Stephenson, University of Otago

A proposed multibillion-dollar project to build a pumped hydro storage plant could make New Zealand’s electricity grid 100% renewable, but expensive new infrastructure may not be the best way to achieve this.

New Zealand’s electricity generation is already around 80% renewable, with just over half of that provided by hydro power. The government is now putting NZ$30 million towards investigating pumped hydro storage, which uses cheap electricity to pump river or lake water into an artificial reservoir so that it can be released to generate electricity when needed, especially during dry years when hydro lakes are low.

The response to the announcement was mostly enthusiastic – not least because of the potential for local jobs. But whether it is the best solution needs careful evaluation.

There are many realisable changes to electricity demand, and New Zealand should consider other, potentially cheaper options that deliver more efficient use of electricity.




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Promise of a purely renewable grid

Electricity is mooted to play a major role in achieving New Zealand’s target of net zero carbon emissions by 2050. To support the government’s plan to accelerate the electrification of the transport and industrial heating sectors, generation will need to grow by around 70% by 2050, all from renewable sources.

Worldwide, pumped hydro energy storage is seen as a promising option to support cheap and secure 100% renewable electricity grids.

New Zealand’s analysis will mainly focus on one particular lake, Lake Onslow. If it stacks up, it would be the biggest infrastructure project since the “think big” era of the 1980s. But at an estimated NZ$4 billion, the cost would also be massive and the project would likely face opposition on ecological grounds.

Such a scheme would be a step towards the government’s target of 100% renewable electricity generation by 2035 and fit with the overall goal of New Zealand achieving net zero carbon emissions by 2050. It would also solve the problem conventional hydropower plants face during dry years, when water storage runs low and fossil-fuelled power stations have to kick in to fill the gap.

But the possible closure of the Tiwai Point aluminium smelter would free up around 13% of renewable electricity supply for flexible use. This alone raises the question whether a pumped storage development on this scale is necessary.




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Changing supply and demand

Getting to 100% renewables and achieving a 70% increase in supply in the next 30 years will mainly come from new wind and solar generation (both now the cheapest options for electricity generation) as well as some new geothermal. Major new hydro dams are unlikely because of their significant environmental impacts.

As a result, electricity supplies will become increasingly variable, dependent on the vagaries of sun, wind and river flows. This creates a growing challenge for matching supply with demand, especially if hydro lakes are low.

Last year, the Interim Climate Change Commission concluded New Zealand could get to 93% renewable generation by 2035 under current market conditions. But it warned the final few per cent would require significant overbuilding of renewable generation that would rarely be used.

It suggested the most cost-effective solution would be to retain some fossil-fuelled generation as a backup for the few occasions when demand overshoots supply. At the same time it recommended a detailed investigation into pumped storage as a potential solution for dry years.

A hydropower lake in New Zealand
New Zealand already has more than 100 conventional hydropower stations supplying renewable electricity.
Dmitry Pichugin/Shutterstock

Electricity demand — the collective consumption of all businesses, organisations and households — is also changing.

Households and businesses are switching to electric vehicles. Farm irrigation is becoming widespread and creates new demand peaks in rural areas. Heat pumps are increasingly used for both heating and cooling. These all create new patterns of demand.

And households aren’t just consuming power. More and more people are installing solar generation and feeding surplus back into the grid or storage batteries. Local community energy initiatives are starting to emerge.

New markets are developing where businesses can be paid to temporarily reduce their demand at times when supply is not keeping up. It is only a matter of time before such demand response mechanisms become commonplace for households, too. In the near future, housing collectives could become virtual power plants, and electric vehicles could feed into the grid when supply is stressed.

Cheaper options with added health benefits

So with more reliance on sun, wind and water, electricity supply will become more variable. At the same time, patterns of demand will become more complex, but will have more potential to be adjusted quickly to match supply, on time scales of minutes, hours or days.

The big problem lies with winter peaks when demand is at its highest, and dry years when supply is at its lowest – especially when these coincide. At these times the potential mismatch between demand and supply can last for weeks.

The current solutions being mooted are to increase the security of supply, either with fossil-powered generation or pumped hydro storage. But there are options on the demand side New Zealand should consider.

New Zealand houses are typically cold because they are poorly insulated and waste a lot of heat. Despite relatively new insulation standards for new houses and subsidies for retrofitting older houses, our standards fall well below most developed countries.




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We can take inspiration from Europe where new buildings and retrofits are required to meet near-zero energy building standards. By investing in upgrading the national housing stock to something closer to European standards, we could achieve a significant drop in peak demand as well as additional benefits of lower household heating costs and better health.

Efficient lighting is another under-explored solution, with recent research suggesting a gradual uptake of energy-efficient lighting could reduce the winter evening peak demand (6pm to 8pm) by at least 9% by 2029, with the bonus of lower power bills for households.

Such solutions to the supply-demand mismatch could be much cheaper than a single think-big project, and they come with added benefits for health. Alongside the NZ$30 million being put into investigating pumped hydro storage, I suggest it is time to develop a business case for demand-side solutions.The Conversation

Janet Stephenson, Associate Professor and Director, Centre for Sustainability, University of Otago

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Zealand’s White Island is likely to erupt violently again, but a new alert system could give hours of warning and save lives



Jorge Silva/Reuters

David Dempsey and Shane Cronin

Tourists visiting Whakaari/White Island on December 9 last year had no warning of its imminent violent eruption. The explosion of acidic steam and gases killed 21 people, and most survivors suffered critical injuries and severe burns.

The tragedy prompted us to develop an early alert system. Our research shows patterns of seismic activity before an eruption that make advance warning possible. Had our system been in place, it would have raised the alert 16 hours before the volcano’s deadly eruption.

Ash covers the ground after Mt Tongariro erupted overnight on August 7 2012.
NZ Police

We were also motivated by the fact that several other New Zealand volcanoes pose similar threats. Explosions and surges at the popular visitor destination Waimangu geothermal area killed three people in 1903, an eruption at Raoul Island in 2006 killed one person, ballistics at Mt Ruapehu in 2007 caused serious injuries and tourists narrowly escaped two eruptions on a popular day walk in the Tongariro national park in 2012.

Our automated warning system provides real-time hazard information and a much greater level of safety to protect tourists and help operators determine when it is safe to visit volcanoes.




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Why White Island erupted and why there was no warning


This image of the 2019 eruption of Whakaari White Island eruption was taken by a visitor.
Michael Schade/AAP

A history of eruptions

New Zealand has a network of monitoring instruments that measure even the smallest earth movements continuously. This GeoNet network delivers high-rate data from volcanoes, including Whakaari, but it is not currently used as a real-time warning system for volcanic eruptions.

Although aligned with international best practice, GeoNet’s current Volcano Alert Level (VAL) system is updated too slowly, because it relies mainly on expert judgement and consensus. Nor does it estimate the probability of a future eruption — instead, it gives a backward view of the state of the volcano. All past eruptions at Whakaari occurred at alert levels 1 or 2 (unrest), and the level was then raised only after the event.

Our study uses machine learning algorithms and the past decade of continuous monitoring data. During this time there were five recorded eruptions at Whakaari, many similar to the 2019 event. Since 1826, there have been more than 30 eruptions at Whakaari. Not all were as violent as 2019, but because there is hot water and steam trapped in a hydrothermal area above a shallow layer of magma, we can expect destructive explosions every one to three years.

A memorial in Whakatane, following the White Island eruption in 2019.
Jorge Silva/Reuters

Last year’s eruption was preceded by 17 hours of seismic warning. This began with a strong four-hour burst of seismic activity, which we think was fresh magmatic fluid rising up to add pressure to the gas and water trapped in the rock above.

This led to its eventual bursting, like a pressure cooker lid being blasted off. A similar signal was recorded 30 hours before an eruption in August 2013, and it was present (although less obvious) in two other eruptions in 2012.

Building an early warning system

We used sophisticated machine-learning algorithms to analyse the seismic data for undiscovered patterns in the lead-up to eruptions. The four-hour energy burst proved a signal that often heralded an imminent eruption.

We then used these pre-eruption patterns to teach a computer model to raise an alert and tested whether it could anticipate other eruptions it had not learned from. This model will continue to “learn by experience”. Each successive event we use to teach it improves its ability to forecast the future.

We have also studied how best to optimise when alerts are issued to make the most effective warning system. The main trade-off is between a system that is highly sensitive and raises lots of alerts versus one that sets the bar quite high, but also misses some eruptions.

We settled on a threshold that generates an alert each time the likelihood of an eruption exceeds 8.5%. This means that when an alert is raised – each lasting about five days – there is about a 1-in-12 chance an eruption will happen.

This system would have raised an alert for four of the last five major eruptions at Whakaari. It would have provided a 16-hour warning for the 2019 eruption. But these evaluations have been made with the benefit of hindsight: forecasting systems can only prove their worth on future data.

We think there is a good chance eruptions like the 2019 event or larger will be detected. The trade-off is that the alerts, if acted upon, would keep the island off-limits to visitors for about one month each year.




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Where to from here

We have been operating the system for five months now, on a 24/7 basis, and are working with GNS Science on how best to integrate this to strengthen their existing protocols and provide more timely warnings at New Zealand volcanoes.

The Tongariro crossing is one of New Zealand’s most popular day walks and receives thousands of visitors each year.
EPA

We plan to develop the system for New Zealand’s other active volcanoes, including Mt Tongariro and Mt Ruapehu, which receive tens of thousands of visitors each year. Eventually, this could be valuable for other volcanoes around the world, such as Mt Ontake in Japan, where a 2014 eruption killed 63 people.

Because of the immense public value of these kinds of early warning systems, we have made all our data and software available open-source.

Although most eruptions at Whakaari appear to be predictable, there are likely to be future events that defy warning. In 2016 there was an eruption that had no obvious seismic precursor and this would not have been anticipated by our warning system.

Eruptions at other volcanoes may be predictable using similar methods if there is enough data to train models. In any case, human operators, whether assisted or not by early warning systems, will continue to play an important role in safeguarding those living near or visiting volcanoes.The Conversation

David Dempsey, Senior Lecturer in Engineering Science and Shane Cronin, Professor of Earth Sciences

This article is republished from The Conversation under a Creative Commons license. Read the original article.