In recent decades, the loss of native forest has slowed down. For example, in the first decade of the 21st century, we lost roughly 16,000 hectares of native forest, which translates to a loss of about 0.2% of the remaining total area covered in native forest (about 7.5 million hectares). The error associated with such estimates is considerable, though, because land cover is complex and highly fragmented.
According to Global Forest Watch, the drivers behind the more recent losses of native forests include exotic plantation forests, urban developments and wildfires. Indeed, the total land area dedicated to exotic plantation forests increased by about 200,000 hectares per decade between 1990 and 2017.
The project’s aim is to double the current planting rate and plant one billion trees between 2018 and 2028. The latest report shows about a quarter of this goal has been achieved in terms of the number of trees planted. In regards to forest area, 25,557 hectares have been reforested, about half of it with natives.
This is a remarkable achievement in light of the losses cited above and the short duration of the programme.
But peat bogs only store carbon if they remain wet. Once drained, they begin to emit carbon dioxide. Almost half of New Zealand’s peatlands are in the Waikato, but of a total of 89,000 hectares only 19,400 hectares remain in a natural state.
The Kopuatai bog itself is surrounded by dairy farms operating on drained peat. Collectively, the Waikato’s drained peatlands produce 10-33 tonnes of CO₂-equivalent emissions per hectare each year.
The draining of peatlands in the Waikato region did far more damage, in terms of carbon emissions, than a small loss of forest area.
But nevertheless, planting trees and increasing our forest area is an important and necessary contribution to climate mitigation, and often comes with a myriad of other benefits, far beyond carbon sequestration.
Sometimes it’s as easy as planting your own fruit trees around your house. They will capture carbon for years to come, and keep you from buying fruit that has been transported thousands of kilometres.
They might even motivate you to reduce food waste. Globally, about 25-30% of food goes to waste. If we reduced food waste, we could save agricultural land multiple times the size of New Zealand and plant trees there instead.
Like many endangered species, Aotearoa’s flightless and nocturnal kiwi survive only in small, fragmented and isolated populations. This leads to inbreeding and, eventually, inbreeding depression — reduced survival and fertility of offspring.
Mixing kiwi from different populations seems a good idea to prevent such a fate. But translocating kiwi in an effort to mate birds that are not closely related can come with the opposite risk of outbreeding. This happens when genetically distant birds breed but produce chicks with lower fitness than either parent.
Translocations have been part of the kiwi conservation effort for decades. We also have many genetic studies of the five species of kiwi in New Zealand.
But our research, which synthesised available genetic studies, shows we don’t yet have enough genetic information to predict translocation outcomes and manage genetic diversity to achieve safe and sustainable conservation practices.
Kiwi are cherished by all cultures in New Zealand as a symbol of a unique natural heritage. For Māori, kiwi are a taonga (treasure) and of vital importance to hapū (sub-tribal groups) and iwi (tribes) across Aotearoa.
Our research is the culmination of more than two decades of close collaboration and inclusion of mātauranga Māori (traditional knowledge) to improve conservation outcomes — for mana tangata (people with authority over land), for kiwi and for other species across the globe.
In the early 20th century, there were still millions of kiwi roaming the bush. But Pākehā settlers accelerated the destruction of New Zealand’s forests and introduced invasive predators, including stoats and ship rats, which are now a major threat, particularly to kiwi chicks.
Today there are fewer than 70,000 kiwi in the wild, and populations are declining in areas without predator control. The forests, wetlands and pastures where kiwi once lived have been milled, drained and ravaged by introduced browsers such as goats and deer.
Kiwi are also not immune to climate change, with worrying mortality events during recent severe droughts. In these new and changing conditions, kiwi face many challenges: new predators, new diseases, new seasonal events, new foods.
Genetic diversity provides a buffer against such challenges and better chances of survival for a species. One way to maintain genetic diversity is through mating between individuals that are not closely related.
But most kiwi live in groups of fewer than 100 birds. We have confined them to pockets of favourable habitat. As a result of well-meant conservation management to protect the birds from mammalian predators, we have moved them to safe havens on offshore islands or patches of remnant forests that effectively function as “mainland islands”, cut off from other habitat.
Call for more genetic research
One way to avoid inbreeding depression is to mix individuals from distant populations that have different genes and could provide the basis for genetic rescue. But some are opposed to such mixing because it raises the risk of outbreeding depression, which is particularly high if the parental populations differ in their adaptations to their respective environments.
Kiwi populations have evolved to adapt to local conditions on timescales of tens of thousands of years. This means one population of the same species may have adapted in different ways to another. For example, populations of North Island brown kiwi (Apteryx mantelli) are found from the warm lowlands of Te Tai Tokerau/Northland to the sub-apline volcanic plateau near Mount Ruapehu.
For decades the Department of Conservation (DOC) and community groups have been translocating kiwi all over Aotearoa. We need more gene sequencing research of such populations to investigate the effects of inbreeding and outbreeding.
Decision making in the absence of sufficient genetic information risks leading to management strategies that are inadequate or even harmful for future population sustainability.
Working with Māori
Māori, the Indigenous people of Aotearoa, are kaitiaki (guardians) of the kiwi. Whakapapa, a key concept of relatedness in te ao Māori (Māori world view), means Māori culture has a deep understanding of ideas described in western science as genetic diversity, inbreeding and hybridisation.
But hapū and iwi are not always consulted about conservation interventions, even though their role as co-managers of taonga species is well established in Te Tiriti o Waitangi.
In 2013, my research group teamed up with two hapū (Te Patukeha and Ngāti Kuta) to develop a management plan for the North Island brown kiwi in their area. A century of well-intentioned but somewhat random mixing of different North Island brown kiwi populations during translocations has effectively produced both “randomised experimental” and “control” groups.
We have also recruited support from other hapū and iwi in Tai Tokerau and have now started to analyse genetic information from several sites, using the latest techniques to investigate the genetic make-up of the birds. This research will shed new light on the effects of years of breeding in populations that started with kiwi from a single source versus those that started with mix-provenance birds.
We need to save North Island brown kiwi, but we need to do it properly. And when conservation efforts succeed, it would be far better if we knew why they worked. If we do this research right, the conservation management of other species will benefit, across Aotearoa and the world, at a time of an accelerating extinction crisis.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
Our research distinguishes three approaches to making policy for a spectrum of possible retreats. Broadly speaking, these are:
government control: using legislation, standards, policies and regulations, central or local government may restrict certain developments or compulsorily acquire property to enforce retreat
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
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).
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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.
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.
As the Earth continues to warm, we expect an even stronger human fingerprint on extreme glacier mass loss in the coming decades.
Research shows these record sea surface temperatures were almost certainly due to the influence of climate change.
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
We use several methods to track changes in New Zealand glaciers.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.