Sustain Episode 12: What can we do about rising sea levels?

In this episode:

GUESTS:

Professor Karin Bryan, School of Environment, Faculty of Science, University of Auckland

Professor William Glamore, Professor and Principal Research Fellow at the Water Research Laboratory in the School of Civil and Environmental Engineering, University of New South Wales

Dr Richard Bulmer, marine ecologist and Director of Tidal Research

HOST: Ben Goldson, University of Auckland

Music: “What Goes Up” © Tim Page 2024
Production: Ben Goldson, Tim Page

Transcript of Episode 12
What can we do about rising sea levels?

Due to scheduling conflicts there were two separate interviews recorded separately and then edited together. 

Ben Goldson: Hello and welcome to Sustain, a podcast of the Ngā Ara Whetū – Centre for Climate, Biodiversity and Society, I’m Ben Goldson. Across the world, rising sea levels have become a pressing issue for coastal communities. Driven by our changing climate, sea level rise is already having a range of impacts, from increased flooding to the salinisation of freshwater resources. To discuss this growing threat, we have Professor Karin Bryan from the University of Auckland’s School of Environment, Professor William Glamore from the University of New South Wales’ School of Civil and Environmental Engineering, and Dr Richard Bulmer, the Director of private consultancy group Tidal Research.

Ben Goldson: So to begin with Professor Bryan, why does sea level rise occur and how serious of a problem is it?

Karin Bryan: Sea level rise occurs for two main reasons. The first reason is that our oceans are heating up and they’re expanding, just getting bigger. The other reason is that our ice is melting, and those are the two main reasons for sea level rising.

Ben Goldson: And I just saw from our co-director Jacqueline Beggs, there was a recent statement from the Australian Antarctic Research Conference, warning of a catastrophic sea level rise in Pacific nations due to the melting of Antarctic ice sheets.

Karin Bryan: The Pacific nations are particularly vulnerable, that could happen.

Ben Goldson: So how is this all measured?

Karin Bryan: Well, sea level rise is measured in a couple of ways. One of them is using satellite altimeters to measure the surface of the ocean. The other is using ground-based, water level sensors. We have a network of water level sensors around New Zealand that we can validate those measurements with.

Ben Goldson: And do those work with the university?

Karin Bryan: It’s not something that we do. The National Institute of Water and Atmospheric Research runs a number of sensors, ports and harbours run sensors. Also the regional councils have sensors. Those all together form our sea level rise network.

Ben Goldson: And so what sort of communities are most affected and in what ways?

Karin Bryan: Basically communities that live in and make use of low lying land. That can be farming communities, they can be communities that rely on that low lying land for other activities, like avocado farmers. It can be communities that rely on the intertidal regions for collecting shellfish. It can be communities that live at the coast for cultural reasons. The people that are particularly vulnerable to sea level rise are people that don’t have anywhere to move to, often poor communities.

Ben Goldson: Along with the slow creep of rising sea levels, what role do extreme weather events play in eroding coastlines?

Karin Bryan: That’s one of the misconceptions about sea level rise. If you look at the most realistic projections for the next 20 years, or till 2050, sea level rise is most likely to be around maybe 20 to 30 cm, something in that ballpark, which doesn’t seem like much. But the problem is not the elevation of the mean sea level. It’s the high tide and the storm surges and the storm events on top of those. Those storm events are becoming increasingly more frequent around New Zealand. We had a direct hit of a cyclone, Cyclone Gabrielle. That really brought home how vulnerable we are to these kinds of events.

Ben Goldson: And then also presumably the heating of the ocean plays a factor as well.

Karin Bryan: Well, the heating up of the ocean is incorporated into the sea level rise projections. But that heating is a source of energy for storms and cyclones as well. That’s one of the reasons that the storm events and cyclones are increasing.

Ben Goldson: Okay. Willliam Glamore, coming over to you. Looking specifically at wetlands and rivers, what role do they play in maintaining coastlines?

William Glamore: The really interesting bit is, if you think about a river as a hose, when we crank the hose up, the hose at the end flips around every which way. The river itself is like that, and that the river wants to go all across the floodplain. It wants to move around, particularly when the flows are up high, and the wetlands do a great job of trying to hold it in place. They say, no, right now we’re going to grow here, and the more we grow here, the more established we are, the more we’re going to keep that hose from flying each way and all around.

William Glamore: They do a great job of locking the place in. That gives us all of the other services that come with that. If it’s locked in place, then we can live comfortably. We can establish our farms, we can live in our cities. That’s the beginning of the whole process. That’s the first step we need in order to actually have a landscape that we can then get the services that we want out of it.

Ben Goldson: How are they negatively affected by rising sea levels?

William Glamore: There’s a view of a river that the river itself is just the river channel. That pretty much anything above the river channel is no longer the river. But as the sea level comes up, or as the river comes up, this whole system gets bigger and bigger and bigger. Now, if sea levels come up really fast, they will push out the landscape and the ecosystems that are on the river side. If you’ve got saltmarsh or mangroves, as sea level rise comes up, it just eats away into that landscape and there’s no place for it to go, if we allow the river to naturally go into the floodplain next to it, then there’s some room for everything to move.

William Glamore: But if there is no space for it to retreat into with sea level rise, we have this thing called coastal squeeze, and it just squeezes it down until eventually there’s no wetland left there. It’s just a river going into a landscape where we live.

Ben Goldson: Presumably there’s something of a snowball effect where these natural features are degraded, leading to more sea level rise, which then further degrades them.

William Glamore: Our big fear is that if the sea level rise comes up faster than the ecosystems can adapt, eventually they’ll all be drowned out, and if all the ecosystem is drowned out, then they die and decay. As soon as they start decaying, then there’s nothing left, the whole system just drops away. Now the problem becomes much, much worse. We’ve got no ecosystem there to protect us, and you’ve gone from it just keeping up with sea level rise, to now it all being dead and washing away, so much bigger problems. It’s definitely a snowball effect

Ben Goldson: Are there any other negative impacts caused by humans on wetlands and rivers?

William Glamore: I tend to work in the systems that are tidal, so that’s down the very lowest part of the river system, where the tide goes in and out and. What we’ve done is over decades, and particularly in the 19th and 20th century, we’ve gone through and drained the landscape lower and lower and lower and lower, to eventually drain the lowest bits. The draining of those lowest bits has caused probably the worst problems. That’s where we’ve ended up with acid sulphate soils and blackwater.

William Glamore: We’ve had all these big issues happening because we’ve actually drained the lowest bit. The things that they were providing, like ameliorating floods or reducing carbon or providing fisheries, those are the things that we’ve chewed away at. Now we have a lot less fish in the river than we did before, and we produce a lot more carbon than we ever did before. The flood risk is a lot higher than we ever had before. By going through that process and developing well, we’ve actually made it a lot worse for ourselves.

Ben Goldson: Because wetlands have traditionally been seen as something that needs to be drained and rivers need to be controlled. Would you like to see a sort of a change in mentality towards these natural features?

William Glamore: Yeah, there’s definitely been this interesting approach where we’ve said, as I mentioned before, the river is no longer the entire river system. It’s just that little channel that it lives in. That’s what we think about when we think about rivers now, that thing it lives in, when it’s hardly flowing at all. Not the big thing when it bursts out of its banks and floods. We’ve broken that link between the river and the floodplain around it. As soon as we did that, we said, that’s the river down here, and we live over there.

William Glamore: We then justify that we should dump all our stuff in there. That meant we could dump all of our products that we put in there, all of our wastewater, all of our pollution, and most of our ways of legislating or planning for rivers was, how much can we dump in the river before we kill it all? That’s largely what we’ve done. That’s been death by a thousand cuts. I would love it if we actually said, instead of, what is the maximum amount we could do to a river before we kill it? Actually, what do we want from these river systems? How are we going to change that view so we can get the most out of it, not just the minimum amount?

Ben Goldson: So how do we restore wetlands and rivers to what they once were?

William Glamore: We’ve taken an approach that we don’t look backwards to what they once were. We look forward to what they can be. I’ve done a bunch of work with traditional owners of the land and traditional occupants of the area, and they view it as, when would we go back to? How far back will we look then?

William Glamore: Are we looking back a couple of hundred years ago, when European colonisers arrived? Are we looking a couple of thousand years ago, tens of thousands of years? That’s been a real eye-opener to me because it meant no, actually, we need to look forward as to what to do. If we’re restoring forward to how the landscape we’ve got can adapt, then we’re starting to think about, well, how does the system work? That’s where we’ve gone. In the last 25 years, I’ve restored thousands and thousands of hectares, and we started with a real basic understanding of how they work. Now we’ve moved to a better life cycle understanding, which is, if we can make a system that is good for all the different life cycles of the wetland, that wetland will thrive.

William Glamore: If we get it wrong for just one part of the life cycle, virtually the whole thing dies. We’ve got to work to understand how the system works, adapt to what’s coming, and then try to put all those things on the one side. That’s been really successful where we’ve been able to apply it.

Ben Goldson: Do these measures take place at the local level, or is it a top-down, state-led approach?

William Glamore: Look, the scale is really important. Traditionally, we’ve started at the local level. We run pilots at the local level and we get the one site right and show that we can do it well, and prove to the community that this is not a risk, this is a benefit. But to go from that pilot to a much bigger piece where we’re actually restoring lots of wetlands at scale, we definitely need to be thinking about urgent action that integrates policy and planning and finance and science. All those things have to be working together. If we’re going to do this in the time and space we’ve got available to us.

Ben Goldson: Do you ever encounter any pushback on this, either from communities or businesses?

William Glamore: The idea of change is challenging for some people. What we’re finding is the system is well set up now in most places for restoration within public lands, lands that are owned by the public, they’re the public good. They certainly are pretty open for restoration and to do this, and we’ve been doing that for a long, long time. Where we’re getting the biggest pushback is that we don’t have good mechanisms to do it on private land. You can’t just take private land that’s providing a good to the landholder away from them and say, no, this should be now restored. We’ve got to work out how it works for them and how do we change that so they get benefits as well?

Ben Goldson: Do you think there would be much benefit to pursuing a legislative approach to this, or do you think you need to more just get people onside

William Glamore: Right now, one of our biggest challenges is not the science of how to do it, but the legislative hurdle. For us to restore a site, a tidal wetland, a saltmarsh or mangrove system, we’ve got to go through the same legislative hurdles that we would have to go through if we were building a 7-Eleven on that same site. We’ve got to go through an EIS or an Environmental Impact Statement, a big assessment that costs millions of dollars, even though everyone knows what we’re doing is having a nature-positive outcome.

William Glamore: That’s because the way the legislation was set up was that everything you’re going to do is a risk. It was presumed everything was bad. If we could have supportive legislation for restoration, that would be a game changer. That would mean that yes, if you did these activities, you could get it through without the huge cost of all the legislation. That would be great.

Ben Goldson: So turning over to you, Richard, what form do the current efforts towards restoring coastal ecosystems take?

Richard Bulmer: There’s a range of different restorative actions occurring at the moment. There’s examples like mussel bed restoration in the Hauraki Gulf and Ohiwa Harbour. There’s seagrass restorations in Nelson estuaries and saltmarsh restoration in the Bay of plenty. But generally speaking, they’re fairly small scale, often community-led or heavily reliant on voluntary input.

Ben Goldson: So you’d say these are not really sufficient.

Richard Bulmer: Yeah. Not sufficient to turn around environmental degradation at the national scale. We need to do more to turn that around.

Ben Goldson: Would you like to see that come from a government-led approach, or do you think it can work from the bottom up?

Richard Bulmer: I think both ways are necessary. One of the limitations that we’ve had has been this focus on needing perfect information or predictions to address ecosystem decline. But I think we need to get out there and start doing some restoration and supporting the communities that are doing it and learning from them, and using that to inform a larger-scale restoration effort.

Ben Goldson: Just rewinding a bit, how do these efforts then help bolster the coastline against sea level rise?

Richard Bulmer: If we’re thinking about coastal blue carbon habitats, they themselves provide coastal protection. If we were to support restoration efforts that, say, restore saltmarsh in the Bay of Plenty, you’re not only going to have a benefit of coastal protection, but you’ll also have other ecosystem benefits from that, like water filtration benefits or biodiversity gains, and there’s also likely to be carbon gains as well.

Ben Goldson: Just to wrap up, would you like to share any final thoughts on this topic?

William Glamore: For me, the big issue is that, even if we stopped all of our emissions today now, and we produced no more carbon into the atmosphere, sea level rise is going to continue. It’s baked in, the oceans are going to kick up and we’re going to have the lowest lying lands impacted the soonest. The lower you are on the landscape, the more you’re going to be impacted by sea level rise.

William Glamore: If you think about that hockey stick of sea level rise, people know that sort of goes along and then it kicks right up. It’ll come faster than we think. A lot of the work we’re doing shows that that low lying land, the bits that are causing us all our problems are the bits we can restore really quickly, but we need solutions that are going to be urgent, that are going to be scalable. Right now, those things for me are market-based solutions. If I use the market to do something, I know I can do it at scale and fast. My final thoughts are that we need to create markets for the public sector and for the private sector that will encourage change and make it happen. We need to incentivise it and stop trying to use the stick over and over again, and start using the carrot as something to incentivise change, because that will happen quickly.

Richard Bulmer: I’ve kind of covered it a little bit there, but my observation is that we’ve got a problem with the marine environment degrading, and we really need to do more. Coastal restoration is an opportunity to turn that around. We need to utilise the knowledge that we’ve been developing for things like the Sustainable Seas Challenge, and as part of other research projects where we can leverage those sorts of approaches to inform our decision-making and make decisions in these uncertain, or complicated systems.

Richard Bulmer: But still actually move forward, because that’s my area of focus, one way that you can help understand the value of a coastal restoration action. But that’s not the only thing that’s of importance. There’s many other ecosystem benefits that are provided by these systems. It’s important that we better understand and communicate their benefits to inform restoration action, and restoration in response to impacts like sea level rise.

Ben Goldson: Just getting back to that, so what are some of the challenges in communicating these benefits?

Richard Bulmer: We don’t have perfect data necessarily to inform exactly what these habitats are doing and where, but we can provide a pretty good assessment of their value. Literally just communicating things, like how a saltmarsh has benefits not only from a carbon gain, but also coastal protection, water filtration and biodiversity perspectives are valuable for informing these restoration actions. It also can enhance the amount of potential financing that you can get for a restoration as well. We know that agencies like the Nature Conservancy and Conservation International are interested in supporting restorative action in the coastal blue carbon space.

Richard Bulmer: We know that if we can better communicate those other values of these systems, it’s more likely to result in increased financial support for this restoration action, because we know that it’s not necessarily cheap as well.

Ben Goldson: And speaking of data, that sounds like a good time for you, Professor Bryan. Final thoughts?

Karin Bryan: My final thoughts are that a healthy, adaptable coastal area actually requires space. Around Aotearoa New Zealand, we’re facing what everyone calls a squeeze. The sea level’s coming up in the front, and we’ve often got stopbanks and buildings and houses in the back. In order to restore and protect and move us forward into the future, we actually need space. Some of the communities that are having most struggles, and will have most struggles, are because they’ve got no space to move, they’ve got no space to build a new wetland and to let that wetland migrate landwards

Karin Bryan: Facing that, we need to figure out clever ways of bringing us into this future where sea level rise and storm surges are going to be much more common. We need to think of really clever ways of how we can do that in a very limited space that’s getting increasingly squeezed.

Ben Goldson: Are there any of these clever ideas coming through the pipeline right now?

Karin Bryan: I hope so. We’re working on that at the moment, we’re developing new ways of mapping the coast. Ones that use different kinds of signals, for example, the different colours of our coast, using hyperspectral imagery. We’re using InSAR data, which is the satellite-based surface level, we can track changes in the level.

Karin Bryan: We’re looking at using drone-based technologies to look at emissions and costing that up. At the moment, it’s fairly expensive. Totally new for New Zealand, but if we can get that off the ground, I think that would be a real added benefit. We’ve also got colleagues from the School of Computer Science that are looking at novel AI techniques to ingest that information at much greater speed.

Ben Goldson: Maybe we can get you on in about a year’s time to talk about some of these. All right, well, that’s pretty much all the time we have for today. Thank you for joining us on Sustain.

The ideas expressed in this podcast reflect the speaker’s views and are not necessarily the views of Ngā Ara Whetū.

Music: “What Goes Up” © Tim Page 2024; Production: Ben Goldson, Tim Page.