Our Changing World

Summer is on its way, and this week we're exploring both the power and the peril of the sun. First, we visit the Ultrafast Laser Lab to learn about efforts to create better solar panels. Then, we hear about one professor's quest to teach kids about sun safety using an ultraviolet dosimeter you can wear on your wrist like a watch.

The sun, our closest star, is an incandescent ball of plasma powered by nuclear fusion, flinging energy off into space. As Earth's tilted orbit brings the southern hemisphere more into the sun's direct glare (summer is coming!), we bring you two stories about harnessing that energy and protecting ourselves from its harm.

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New solar power materials

A long bench wraps around a laser at the centre of the room. It's crammed full of lenses, mirrors and prisms - the tools of the trade for a scientist investigating the physics of materials, like Dr Michael Price.

Here at the Ultrafast Laser Lab at Victoria University of Wellington's Kelburn campus, Michael runs tests on different materials, as he tries to find the next breakthrough for better, cheaper and more efficient solar power.  

The quest to harness the sun's energy began in the mid-1880s with the discovery of the photovoltaic effect. Today, it has advanced to the large, crystalline silicon solar panels we see on roofs. But there's a limit to the efficiency of these silicon solar panels, and Michael wants to take it the next step. 

"If we could harvest more of the infrared, more of the ultraviolet, that would be one way that we could up that efficiency limit. And some of the materials we're looking at can help with that," he says.

In particular, Michael and his colleagues have been studying an organic molecule called Y6, which he thinks might be the key for that next breakthrough. 

Teaching sun safety

While we can harness the sun's rays to provide renewable energy, those same rays can be dangerous if they're directed at our skin instead of solar panels.

Exposure to the sun's ultraviolet (UV) rays can lead to skin cancer like melanoma. New Zealand's rates of melanoma are among the highest in the world and in 2020, Aotearoa had the highest death rate from melanoma out of any country. 

Already this year, UV level readings are higher than normal, possibly due to the Tongan volcanic eruption in January.

For a nation that loves to get outdoors and soak up the sun, we need to get smarter about our sun safety. …

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Behind the scenes at the Auckland War Memorial Museum, a "menagerie" of specimens is a treasure trove for curator Dr Matt Rayner, who is researching how the Hauraki Gulf's seabirds are faring using clues from very old feathers.

"A menagerie" is how curator Dr Matt Rayner describes the land vertebrate collection in the backrooms of the Auckland War Memorial Museum.

There's a horse's head, stuffed peacocks sitting on a workbench, and the back corridor is filled with large specimens - moa, emu, and ostrich as well as reindeer, caribou and rhinoceros heads and skeletons.

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We're most familiar with museum galleries: carefully curated spaces, designed to tell stories. Precise taxidermy allows animals to stand or perch as they would in real life.

But in most museums, these front-facing displays are only a tiny percentage of the collections they house. Behind the scenes, there's a lot more going on.

As a curator, Matt works on public displays - but he also has his own area of research: seabirds.

For a recent project, Matt wanted to know: what's happening to the seabird residents of Tīkapa Moana the Hauraki Gulf across time? It's a tricky question to answer given that seabirds haven't been particularly well studied over a long period of time.

"Many of our land birds have been counted for decades, whereas we're just catching up with seabirds," he says. So, in the absence of long-term data, Matt and his colleagues turned to the backroom specimens held at museums for clues.

Matt scoured the collections at Auckland Museum, Te Papa Tongarewa, and Canterbury Museum for five seabird species found in the Hauraki Gulf: kāruhiruhi / pied shag, pārekareka / spotted shag, kororā / little penguin, tara / white-fronted tern, and tarāpunga / red-billed gull.

He focused on specimens collected from the Gulf over the years, all the way back to the 1880s. Then, he sourced feathers from his chosen specimens.

Matt also collected feathers from contemporary live birds during fieldwork in the Gulf, assembling a timeline of seabird feathers stretching from the 1880s to now.

Matt analysed certain elements in the chemical makeup of the feathers using stable isotope analysis. Looking at the stable carbon and nitrogen isotope signatures from these feathers can give Matt general insights into what the birds were eating and where they were living when the feathers were grown. 

The nitrogen isotope analysis didn't indicate much change in the types of food these birds were eating (such as fish or crustaceans and squid)…

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How do you drill through 600m of thick Antarctic ice? Using hot water, of course. In this episode from the 2020 series Voices from Antarctica, Alison Ballance joins researchers hoping to solve the puzzle of why a giant river of ice has stalled.

It's a slow-moving stream of Antarctic ice across West Antarctica, that feeds the world's largest floating ice shelf.

So why has the Kamb Ice Stream been stalled for the past 170 years? 

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It's a puzzle researchers are trying to solve in this episode of Voices from Antarctica, produced by Alison Ballance. This is the last episode we're replaying from the award-winning 2020 series in this mini-rerun.

The ice stream goes through periods of flowing and stopping, but as climate change intensifies, it's important to figure out what this means for the ice - and us - in a warming world. 

To figure out what's happening, the team are using a hot water drill to access the liquid seawater and seafloor beneath the Ross Ice Shelf, which is 600m thick.

Listen to the full episode to dive beneath the ice.

Thank you to Liz Garton for help with this episode. 

Learn more: 

Read Alison's story from the original episode that first aired in 2020. 

Find all the Voices from Antarctica episodes here.

Go to this episode on rnz.co.nz for more details

Weddell seals have returned to breed near Scott Base in Antarctica after a decades-long absence. On land, they're blubbery lumps. But underwater, they're graceful dancers and ethereal singers. A team of scientists is finding out more about the under-ice lives and habits of Weddell seals. Alison Ballance joins them in this episode from the award-winning series Voices from Antarctica.

Dive beneath the sea ice in Antarctica and you might hear the ethereal echoes of Weddell seals - a symphony of space sounds and jungle noises that carries for kilometres in the cold dark water. 

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On ice, they're blubbery blobs. But underwater, Weddell seals are gloriously graceful swimmers. 

They are the southernmost breeding and living mammals in the world, and in this episode, Alison Ballance accompanies scientists as they study a small population near Scott Base. The seals have recently returned to the area to breed, after historic hunting to feed huskies drove them out of the vicinity of the base.

So how are the local seals faring? Is the recently established Ross Sea marine protected area benefitting Weddell seals? Where are they heading to find a feed? These are the questions the NIWA-led team are investigating using high-tech data loggers and video cameras.

Listen to the full episode to fully submerge yourself in the Weddell seals' world.

Thank you to Liz Garton for help with this episode. 

Learn more: 

Read Alison's story from the original episode that first aired in 2020. 

Find all the Voices from Antarctica episodes here.

Go to this episode on rnz.co.nz for more details

A team of NIWA scientists eagerly awaits the return of 19 emperor penguins carrying high-tech data loggers and video cameras. What will the data captured reveal about the penguins' secret lives at sea?

The emperor penguin mums and dads of Cape Crozier are returning from their fishing trips, bringing back full bellies - and some, treasure troves of scientific data.

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A team of NIWA scientists camped out at Cape Crozier equipped 19 penguins with data loggers, and five with video cameras, hoping to capture clues about where the penguins go to forage, and what they might be eating.

This week we're continuing our rerun of the award-winning 2020 series Voices from Antarctica, produced by Alison Ballance. In this episode, Alison sits down with penguin researcher Gitte McDonald to look at the data from a recently returned emperor penguin.

It turns out, each individual penguin travels out to quite different parts of the pack ice, swimming 250km from the colony, and making dives as deep as 400m over more than two weeks. During these trips, an adult bird can pack on up to 2kg in body weight.

Listen to the full episode to learn more about the secret lives of these remarkable ice-dwellers.

Thank you to Liz Garton for help with this episode. 

Learn more: 

Read Alison's story (and check out her photos!) from the original episode that first aired in 2020. 

Find all the Voices from Antarctica episodes here.

Go to this episode on rnz.co.nz for more details

Revisit the frozen continent with us in this mini rerun of the Voices from Antarctica series. This week, Alison visits Cape Crozier to meet a colony of emperor penguins and the team of scientists studying them.

Emperor penguins spend part of the year huddled together on the ice, keeping eggs and then chicks warm. But where do they go once breeding season is over? 

Follow Our Changing World on Apple Podcasts, Spotify, Stitcher, iHeartRADIO, Google Podcasts, RadioPublic or wherever you listen to your podcasts.

This week we're starting a mini rerun of Alison Ballance's award-winning 2020 series Voices from Antarctica. We're starting with episode four: after travelling south to the frozen continent in a Hercules aircraft and visiting Scott Base, Alison is now at Cape Crozier in Antarctica to meet the resident emperor penguins - and the scientists studying them.

Here, a team of NIWA researchers is hoping to unravel the emperors' secret lives at sea using data loggers.

Thank you to Liz Garton for editing help.

Learn more:

Read Alison's story (and check out her photos!) from the original episode that first aired in 2020.

Find all the Voices from Antarctica episodes here

Go to this episode on rnz.co.nz for more details

It's spectacularly spiky and delivers a painful or even deadly sting. Why are a team of conservationists growing and planting up Orokonui Ecosanctuary near Dunedin with more and more native tree nettle, ongaonga? It's all because of a pretty little pollinator called the kahukura, or red admiral butterfly, and its prickly preferences. Claire Concannon visits Orokonui to learn more about the ongaonga-kahukura relationship, as well as new research investigating whether these native butterflies are the victims of a sneaky ecological 'trap'.

With stems and leaves covered in sharp, needle-like spines, it's a native plant that screams 'don't touch me'.

And rightly so. If you do touch the native tree nettle ongaonga, the consequences can be painful - and even deadly.

Listen here

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Walking down the Butterfly Track at Orokonui Ecosanctuary just north of Ōtepoti Dunedin, you'll come across plentiful ongaonga, purposefully planted.

Why would we want more of this 'ferocious' plant that can deliver an unpleasant sting?

Part of the ecosanctuary's mission is to provide as many native species as possible with habitats and ecosystems, says botanist and educator Taylor Davies-Colley.

"A lot of  species require very specific host species for their caterpillars to live on," he tells Our Changing World.

Native butterflies like the kahukura / red admiral rely on the sharp barbs of ongaonga (aka Urtica ferox), which provide a safe haven for their precious eggs and larvae.

As the caterpillar grows, it folds the spiky leaves around itself as a protective tent during the day.

University of Otago Master's student Greer Sanger has been researching how the kahukura's preferences may be leading the butterfly species into an 'ecological trap' - a situation where an animal inadvertently opts for a less-than-ideal habitat.

Dragonflies attracted by the shiny surfaces of black headstones because they resemble the surface of water are an example of this.

In the case of kahukura, could introduced nettles be swindling butterflies with the offer of inferior habitat?

To test this idea out, Sanger caught some kahukura from around Ōtepoti and placed them in special cages with either ongaonga, a Chatham Islands hybrid nettle, or the introduced dwarf nettle. She then watched to see where the butterflies chose to lay their eggs.

"They definitely had a preference for the native  over the introduced ," Sanger says. "None of them chose to lay on the introduced nettle." …

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We're saying farewell to the Stratospheric Observatory for Infrared Astronomy (aka SOFIA) this month. The mission, which was partially based in Christchurch, wraps up after a decade of observing comets, stars, planets, and the moon. In July 2017, Alison Ballance boarded the Boeing 747 with a flying telescope for one of its research flights.

Last month, the SOFIA telescope left Ōtautahi Christchurch for the final time, heading for retirement in California. The Stratospheric Observatory for Infrared Astronomy (SOFIA) isn't your usual telescope: it's installed on a Boeing 747 jet plane with a hole cut in its side.

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Since 2013, the SOFIA telescope took off from Christchurch to cruise the clear southern skies and capture observations of comets, stars, and planetary atmospheres. Data collected by SOFIA contributed to the October 2020 finding of water on the surface of the moon.

As a send-off for SOFIA, which officially wraps up its mission on 30 September, we're replaying an episode from September 2017. Alison Ballance reports from aboard one of SOFIA's research flights.

See Alison's original story from September 2017

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In a future that is free of fossil fuels, where will we source all the products that we get from the petroleum industry? Scientists at the forest research institute Scion think that trees might provide the solutions we need.

Fossil fuels aren't just used for transport and energy - they're also used to make everyday products. As we move away from fossil fuels, where else can we find these materials? For the team at the forest research institute Scion, the answers can be found in our forests. 

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"We need to strike the word waste from our vocabulary," says Dr Stefan Hill, the portfolio leader of high-value biorefineries at Scion. His team are responsible for figuring out what useful compounds can be extracted out of waste biomass - for example, the bark that is stripped from pine trees before they get shipped overseas as timber. 

Bark is essentially the skin of the tree, key for its protection and defence. So the team are interested to see if they can extract antimicrobial and water repellent compounds for use in health and clothing applications. 

Some of the work is at early stages, but one idea that has progressed to proof-of-concept stage is the extraction and use of vegetable tannins. 

Chemist Dr Hilary Corkran works on the tannin extraction from pine bark in the lab. Working with Callaghan Innovation to upscale their extraction process, and in partnership with the leather and shoe research association (LASRA), they've been able to show that these tannins can be used to create a soft, good-quality leather product. In fact, with McKinlays footwear in Dunedin, they've produced the only pair of New Zealand-sourced tannin leather boots. Currently all tannins used in creating leather in Aotearoa are imported and the current most common method uses the heavy metal chromium. The team hope that their work will provide a locally sourced vegetable tannin product to change this. 

Of course, biorefineries will only work if it is technically and economically feasible to extract the materials. That is where the work of Dr Marie-Joo Le Guen comes in. She collaborates with industry partners to essentially find a 'home' for the materials and compounds, and work on the upscaling of the extractions to make them worthwhile.    …

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In a room in the Manaaki Whenua building in Auckland are rows and rows of shelves, with cardboard boxes containing an array of weird and wonderful dried fungi. Claire Concannon visits to learn how and why these specimens are kept, and finds out about its sister culture collection, which is helping in the defense against invading plant pathogens.

The New Zealand Fungarium has a library feel - a quiet and calm room, with just the hum of air conditioning as a backing track. On display in a glass fronted cabinet is a small group of mummified caterpillars on a stick, like weird larval lollipops.

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Ingesting a spore of a particular native fungus causes the caterpillar to change its behaviour, explains Dr Mahajabeen Padamsee, curator of the New Zealand Fungarium. "It goes and buries itself with its head pointing up, and the fungus grows from the top of the head," she says.

These 'vegetable caterpillars' are part of more than 100,000 specimens that make up this collection, a store of dried fungi housed in the Manaaki Whenua - Landcare Research building in the suburb of St Johns in Auckland. 

A large climate-controlled room hosts row upon row of shelves, stacked with large cardboard boxes, themselves filled with envelopes containing dried fungi wrapped in tissue. Some of the specimens are just too large for envelopes, and rest instead in larger boxes or are wrapped in plastic bags to trap their spores. 

Adrienne Stanton, the collection manager, is responsible for keeping the specimens safe and in good condition, as well as facilitating specimen loans to researchers. Alongside a huge number of native New Zealand fungi, the collection also contains many specimens from across the Pacific.  

The New Zealand Fungarium is used for two main functions - investigating fungal biodiversity and helping biosecurity efforts. It grows each year by about 2,000 specimens. Some are given to the collection by researchers, but many are gathered during the annual Fungal Foray - a multi-day fungi treasure hunt, held in a new area each year with the Fungal Network of New Zealand.

An important part of the collection consists of 'type' specimens - individual specimens chosen to serve as exemplars, the physical basis for naming and describing a species.

Down the corridor from the Fungarium, there's a restricted access room filled with large, stainless-steel tanks. …

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