By Robert McLachlan 10/02/2020 6


James Renwick is Professor of Physical Geography at Victoria University of Wellington. He studied at Canterbury and the University of Washington and has worked on diverse aspects of climate science, including global atmospheric circulation and Antarctic sea ice. In December 2019 he was appointed to the New Zealand Climate Change Commission, which will recommend carbon budgets and mitigation strategies to the Government. An outspoken voice for climate action, he was awarded the Prime Minister’s Science Prize for Communication in 2018. He talked with Robert McLachlan on 3 February 2020.

Huge winds, giant currents, storms all over the place. And he’s not talking about summer in Wellington.

James Renwick, a.k.a. @CubaRaglanGuy

Robert McLachlan: I’d like to start with Antarctica, because the changes in Antarctica were one of the main things that fascinated me when I started learning about climate change. First, the grounded ice sheets.

James Renwick: The Doomsday Glacier!

RM: Exactly. The IPCC say that there’s a risk, somewhere between 1.5ºC and 2ºC of global warming, of destabilizing these ice sheets so that they start peeling off from the sea floor and accelerating towards the sea. Others say that they are already in retreat and the instability has been triggered.

JR: That’s correct. It’s still uncertain. My take on the science is that the vast majority of the glaciological community would say that we’re not past the threshold yet. There are some results just coming in now from a visit to the Thwaites Glacier. These are some of the first observations of what the ocean is actually doing under the ice, which is what controls all of this. Their preliminary results show that the grounding line retreat is slower than expected. That’s just one new result, but it supports the idea that we’re not yet at the tipping point. We must be getting close, it’s looking quite dangerous. The rates of ice loss from that area – the Pine Island Glacier, the Thwaites Glacier, all that region just to the west of the Antarctic Peninsula – have gone up hugely. Thwaites is about the size of the UK, and very thick, so the potential for sea level rise is there.

Schematic of the Marine Ice Sheet Instability (source). See antarcticaglaciers.org for more information.

RM: And this is where the uncertainty about the rate of sea level rise is coming from.

JR:  Yes. If all we had to think about was the thermal expansion of the ocean, and the melting of glaciers, we could be quite precise about sea level rise. We would expect half a metre or a bit more by the end of the century. But the rate of ice loss from Greenland and Antarctica has gone up rapidly in a few decades, and just how much more we get by 2100 and beyond is the big wildcard.

RM: Are they actually sending remote devices to the sea floor, right up to the grounding line?

JR: Yes, they drill a hole through the ice, which in itself is a pretty big effort, and send a drone down the hole. Once it’s down there it deploys its fins and swims around, measuring temperature and so on. There is similar work planned in the Ross Sea region, funded a year ago, to look under the Ross Ice Shelf with a remote operated vehicle.

The Icefin drone (source)

RM: The Ross Ice Shelf hasn’t shown much change yet, is that correct?

JR: The short answer is no. But we don’t know what the underside of the shelf is doing, whether it is getting thicker or thinner. It’s much bigger again, it’s the size of France! If it went, it would uncork an awful lot of ice. Not good. We know from the geological record that it’s come and gone many times. This is one of the great discoveries of the last decade or so: the Ross Ice Shelf is not stable at all.

RM: Like the grounded ice sheets, the floating shelves are also quite complicated physically. It’s a bit surprising: they’re hundreds of metres thick, the warming has melted a few metres mostly from below, and yet some of them have completely disintegrated.

JR: Like Larsen B, that’s right.

Collapse of Larsen B ice shelf in 2002. Image: NASA (source)

RM: It was spectacular, and not really expected, would that be right?

JR: Yes, that’s fair enough! You could say they were relatively small, thin shelves, but even so they are still large pieces of ice. As they disintegrated, the glaciers that flow off the Peninsula into the ocean have sped up dramatically. It’s hard to see through several hundred metres of ice what is going on. Most of the melting in Antarctica is happening from the bottom. Greenland is much further from the pole, so it’s exposed to much warmer air, so it’s mostly melting from the top down. Antarctica is melting from the bottom up. We can model it, but we have very few observations.

RM: What would you most like to know?

JR: I’d like a detailed profile of the thickness of the ice shelves around Antarctica, plus fifty years of annual records, please! But another thing I’d like to know, and this is more my area, is how thick is the sea ice around Antarctica? That’s completely unknown. It’s a feature of how the sea ice operates there. In the Arctic, the sea ice is right over the North Pole, in the coldest, driest place. The Antarctic sea ice is at lower latitudes, in the 60s, so it’s exposed to warmer air, and it gets a lot of snow falling on it. It’s very hard from a satellite to tell if you’re looking at ice or snow. If it’s snow, how deep is that snow? That controls how much of the ice is above sea level. You need to know that to know how thick the ice is. Sometimes there’s so much snow that the top of the ice is below sea level. You can get spot measurements from a plane, that’s happening now, but to get comprehensive, continuous measurements you need satellites, and so far they’re not up to the task.

RM: Also the weather patterns in the south are very different from the north.

JR: They are. Usually, there’s not much happening over the Arctic Ocean, whereas the Southern Ocean is one of the most dynamic, turbulent places on earth. Huge winds, giant currents, huge waves, storms all over the place.

RM: For many years the Antarctic sea ice was expanding, but for the last few years it’s been receding. Is this the start of a receding trend?

JR: That’s my supposition. But all the ups and downs of the sea ice over the past forty years have been to do with the winds. Antarctic sea ice is incredibly sensitive to what the winds are doing. Even El Niño explains a lot of the variation. But we have gone to a decreasing trend since 2014, and the atmosphere and the ocean are warming up. So there has to come a point where it’s hard for the ice to grow. If it hasn’t happened already, it’s bound to come along fairly soon.

Back to the Goldilocks zone

RM: Can changes in Antarctica affect New Zealand, or is it too far away?

JR: That’s a really good question… I’d give it a “maybe”. We know that if there’s a lot more sea ice, that will push the westerlies further north and that would affect the weather in New Zealand. But the changes so far have been quite small, a few percent, and it’s hard to find evidence that that affects New Zealand. Generally, it’s the other way around. The tropics hold most of the energy in the climate system, and New Zealand is more affected from the north than from the south. I’d love to find some evidence that sea ice variation can affect the weather in New Zealand, but I’ve been looking for twenty years and there’s nothing obvious there.

RM: There’s been a idea around that New Zealand is relatively protected from the effects of climate change.

JR: Things are happening more dramatically in the northern hemisphere, especially at the pole. Now we have the wavy jet stream. As the pole warms up, the north–south temperature difference decreases, and that’s what drives the strength of the winds. So you have a weaker jet stream, so it’s able to meander more. Even that is debated, it’s hard to say that those two things are connected but there’s a lot of other things going on. But New Zealand is – well, protected is the wrong word, but buffered by the ocean. The climate is already temperate, although variable. It’s usually fairly wet in most places. So you’ve got to change the climate quite a bit before it becomes really extreme. Whereas Australia was already extreme, so it doesn’t need much more change before you’re into what we’re seeing now with the fires and droughts.

RM: Speaking of the Australian fires – everyone was expecting change, but surely it’s come along more quickly and severely than people were expecting? And even New Zealand has had flash floods and bushfires.

JR: Yes, and even for New Zealand the projections are that the fire danger will double or triple in the east, but still not like Australia. The situation in Australia this summer has been quite shocking for everybody. Yet it’s what the climate projections have said for thirty odd years. It’s one thing to write a report saying, “Extreme fire danger in the 2000s, blah blah”, it’s another thing to see it happen. The reality is quite confronting for everyone.

RM: So many national parks burnt out in their entirety! Some ecologists say the ecology of the parks may be tipped over into a different state; the fire regime has changed and they’ve lost species.

JR: Even though they are fire adapted, I don’t know the ins and outs and how much more extreme the latest fires have been and how affected some species are. Even though they are fire adapted,  it could have been the death knell for some species.

Chicken and egg

RM: Yet it remains difficult for people to get the connection between mitigation and impacts. Even in New Zealand some argue that we should focus on adaptation instead of cutting emissions. I feel like we could be arguing this point until the end of the world.

JR: You’ve got to do both, obviously, because there are already impacts, obviously. They’re only going to get worse if we don’t cut emissions. The number one priority is to slow down the rate of change. These things can go together. You can improve your coastal defences by growing mangroves, and they also absorb carbon dioxide.

RM: You’ve been doing a lot of climate outreach, and recently you were involved in a public reading of the IPCC 1.5ºC report.

JR: 1.5 Degrees Live! People volunteer to read for half an hour from the IPCC report. It’s a way of engaging with the science, engaging with the public. People come along and listen and ask questions. It took a whole week.

RM: The 1.5ºC report has caught the public imagination more than the others. It says we have to halve fossil fuel burning by 2030.

JR: Yes, the way that was packaged and messaged was very good. “Twelve years to halve emissions.” But that morphed into “Twelve years to save the planet”, “Twelve years till we’re all dead” – that’s not so helpful. Get across the urgency, sure, but people shouldn’t think there’s going to be some kind of armageddon in 2030. I would hate to think that that would demotivate people. It’s always going to be under our control, how much global warming we get.

RM: The message is out there, but there’s still a disconnect. People are still driving around in petrol cars and bringing in new ones all the time. There’s a gap between what people say they would like to be done about climate change and what they’re actually doing, or voting for.

JR: It’s a very complicated problem from a sociological, political, economic point of view. We have the society that we have because of the course of several hundred years of development and economic thinking. We’re all used to it. Most of us don’t think about the roots of our society and how it could be configured differently. It’s hard to imagine doing anything differently! So it’s not surprising to me that most people haven’t changed their lifestyles. And people still don’t get the urgency – the day to day weather is still the same, it’s just a bit hotter when it’s hot and a bit drier when it’s dry. They have plenty of other things to think about. That’s why this is very much a government-level problem. If it’s difficult or expensive to do the right thing, most people won’t go there.

RM: But the government can only do what they can get away with.

JR: Exactly! It’s a chicken and egg problem. One role of government is to persuade the population that there is an urgent problem to deal with. The protest marches help. That ball is rolling. Still, it’s hard for governments to get away from short-term thinking. Taking a political risk is literally a risk for a government. Our whole system is not set up to deal with a problem like climate change. The time scale is centuries and the consequences are beyond anything we’ve had to deal with before. We have to do a managed retreat from fossil fuels, like we’re envisioning a managed retreat from the coastline.

RM: Yet the fossil fuel industry isn’t talking about a managed retreat, they’re talking about exploring more, and also doing it.

JR: Yes, and they claim to be investing in clean energy but it’s 1% of their total budget. They’re still investing in disinformation campaigns and greenwashing, measures to slow down action on climate change. It’s a profitable industry and making money is attractive. It’s super frustrating. They’ve known the consequences for decades. To continue to push the extraction and use of fossil fuels, having that knowledge, seems…

RM: Wrong?

JR: I was thinking of stronger words that that! But, yes, wrong. I’m sure that if we’d started thirty or forty years ago we would be in a much better place now. The energy companies need to reimagine how they operate. This is part of the idea of a just transition: we don’t want to harm anybody’s livelihood, and I’d include the oil companies in that, but still we need to move away from fossil fuels.

RM: The steps that have been taken, like subsidising renewable energy, have been extremely effective.

JR: Yes they have. Incentivising the right behaviour, disincentivising the old behaviour. Put a price on carbon, subsidise electric vehicles, all kinds of measures. New Zealand is dabbling with these. But the fossil fuel industry is still subsidised here and around the world.

Time to stop dabbling

RM: And now you’re in the hot seat. Soon you’re going to be telling us what to do. Pretty exciting!

JR: It is! Being part of the Climate Change Commission is very exciting. Also daunting. And frightening. And in a year we’ll deliver our first carbon budget.

RM: We had a debate about the powers of the Commission and we’ve ended up with the British model of an advisory panel. But what I like about that is that they can be quite feisty and issue very stark advice to the government. And they seem to be respected.

JR: Yes, that’s a good model. I would like the Commission to have more regulatory power, but I accept it’s the way it is. It’s down to the government of the day to listen. It’s as good as we’re going to get.

RM: To do this on top of your job as a climate scientist and head of department, it’s a lot.

JR: It will need some juggling. We meet two full days a month, plus the background work. We’re also starting an engagement process, talking to sector groups. We have excellent people on the secretariat who have come from the Ministry for the Environment.

RM: Business is very important. I was disappointed by the Motor Industry Association, who represent the $6 billion new car industry, for their opposition to the proposed fuel efficiency standards. They asked the government to scrap it and start again. That’s not a way forward, industry needs to be onside.

JR: And argument is really not helpful; we don’t want to see one group offside of another. We need to find a way to all work together. It’s better to be on the crest of the wave! I think the debate will move forward quite quickly. Look at what’s happened in agriculture, where the climate focus has shifted rapidly from away from costs and towards benefits.

RM: There’s a call for a Citizen’s Climate Forum, which has been tried in Ireland. Is that something the Commission could be involved with?

JR: Possibly. I support the idea. I’m not sure if the Commission would be active in it, but it would look on with interest.

RM: It could capture media and public attention.

JR: That’s right. It’s a good way of getting ideas about how to reduce emissions out there and focusing on solutions. But in Ireland they had strong support from the government from the start, which helped.

RM: Ireland is quite similar to New Zealand. They had been dragging their heels for a long time, good talk but no action, and now seem to have changed. They also have a lot of cows. They’re planning to offset their agricultural emissions with trees, which is what Simon Upton recommended here, but which we’ve decided not to do.

JR: There’s lots of moving parts, aren’t there. There is the billion tree programme.

RM: I’m becoming skeptical of the whole idea of planting trees. It’s a risky delaying tactic.

JR: It is a delaying tactic, but you’ve got to use that time you’ve gained to actually reduce emissions. Globally, there isn’t enough land anyway. In New Zealand, although we hear a lot about agriculture, the biggest growth areas have been transport and industry. Those are easier targets. We know how they work and what the alternatives are. For agriculture, the solutions, as laid out by the IPCC last year, involve people and agriculture moving from animals to plants. Fewer cows, more beans. Yes, it’s a change. I grew up in Canterbury; when I was a kid it was very different, it was dry country, sheep and grain. So I know that farmers are very adaptable and flexible. There are alternatives to betting on dairy.

RM: Have you met people from the School Strike 4 Climate?

JR: Yes, and I’ve spoken at a couple of the strikes. I’m really impressed with the whole movement.

RM: It’s so exciting, and so dramatic how it’s grown so quickly. But people could get frustrated. They need to know what the next step is and how they can be involved.

JR: Yes, although there is power in persistence. Greta Thunberg is now in week 76 of her climate strike. School strikers, keep it up! Getting your voice heard politically is really important for everybody. If anyone wants to get involved in climate action, send your MP an email! That’s the minimum effort.

The university formerly (and still) known as Victoria

RM: You work at Victoria University, which has set a goal of Net Zero by 2030, and they have a bold plan to get there. Is everyone on board with that?

JR: I think so, I think they’re pleased to be part of it. It does involve planting trees, but it’s done in a smart way. The university is buying some land and using it as an outdoor laboratory. We’re also phasing out gas boilers and moving to heat pumps and solar panels.

RM: Can you see academics flying less to international conferences?

JR: You do see some academics flying less. And there is offsetting. The Antarctic Research Centre is offsetting all their flights with Ekos. But science is a global enterprise. Colleagues and conferences are all over the world.

RM: It’s the rate of increase of flying which is a concern. Even a little thing like asking at every invitation if you can present remotely will make a difference.

JR: I have done remote presentations in New Zealand, but not at an international conference yet. But there are conferences where you can register to present remotely, and the whole thing is livestreamed. It’s possible. You miss out on the informal interactions. Maybe the way forward is a purely online conference with a fluid timetable… let’s get creative. But even flying less is better than doing nothing at all. I do have a trip coming up, to the IPCC which is preparing the 6th assessment report, due in April 2021.

RM: One of the criticisms of the IPCC process is that it’s a bit slow.

JR: Yes, I’ve thought for several years that it should be overhauled. But apparently governments are very keen on the IPCC as it is now. And it has seen some changes towards faster turnaround and rolling reporting. The 6th assessment began last year in 2018 with the 1.5ºC report, then the oceans and cryosphere report, then the land report.

RM: There’s also the UN’s parallel policy process, with their annual COP meetings. Everyone was very disappointed with the most recent COP, in Madrid, and yet for all that, 2019 did see a lot of renewed climate action from many countries.

JR: It’s a hard problem. Emissions are still going up.

RM: It’s a pity that in New Zealand there isn’t some community that is more progressive and is showing us the way to get out of fossil fuels.

JR: I don’t suppose there is. That’s what I’ve said at Victoria University, perhaps we can be the role model for other universities. And perhaps Wellington can be a role model for New Zealand. It’s a race that I would love to see everyone competing in! That’s how the Paris Agreement is supposed to work, and this year countries are supposed to upgrade their pledges. Let’s see what happens.

RM: We’re in a better position in New Zealand than some other countries. Even though we haven’t started cutting emissions yet, we are at least well placed to start.

JR: There’s a good amount of political goodwill there.

RM: James Renwick, thank you for your time.

Our conversation is over. It’s midmorning and the chain café has filled up with retirees meeting for coffee. Outside, SUVs prowl around the enormous shopping mall car park which merges into big box stores. Further away lies new suburban development and the new motorway, presently being extended another 30 km further north. It’s a scene repeated dozens of times across New Zealand, all supported by countless interlocking agreements and habits. If anything, we are still accelerating down a path we chose fifty years ago. But we’re not yet out of control, not quite. As James Renwick has said, it’s up to us to decide how much warming we get.


6 Responses to “Climate Commission is cleared for takeoff: James Renwick talks ice, snow, and climate action”

  • Hi Robert,

    The IPCC does not disclose evidence that human emissions cause dangerous surface warming. Neither does the Royal Society, the Royal Society of NZ, or the Ministry for the Environment. I know this because I have asked each of them. If you don’t believe me, ask these organisations for yourself—if you haven’t already asked them.

    Do you agree that, as this climate crisis, as it’s now called, represents the greatest challenge of the age, that will cost even New Zealand trillions of dollars over a few decades (for no detectable reduction in GMST), yet no evidence has been shown that we’re influencing the weather, much less dangerously, we ought to see some evidence? That, with nobody, including James Renwick—no matter how relaxed he affects to be in front of an audience, no matter how confident he seems—able to prove that we’re endangering the planet with our emissions, it’s a bit strange the IPCC and the Royal Society, etc., will not tell us the evidence?

    Even Sciblogs have no evidence. If you do, I challenge you to tell me what it is.

    I challenge you to ask this simple question of James, the RSNZ, the MfE, James Shaw, or any earth scientist here or overseas: “What is the evidence that human emissions cause dangerous warming?” Also a piece of advice: if anyone—anyone—tells you in response to read the IPCC reports, ask them for a page number.

    One more thing. This is a scandal that is not going away.

    Best regards,
    Richard Treadgold.

  • I see JR has caught Algorism disease. Right after he said “But we have gone to a decreasing trend since 2014, and the atmosphere and the ocean are warming up. So there has to come a point where it’s hard for the ice to grow. If it hasn’t happened already, it’s bound to come along fairly soon.” Antarctic sea ice has recovered and it is back to 1981-2010 mean.
    http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

  • It sure has recovered, Chris. (Remember to click “Antarctic” after clicking the link.) You must be impressed with how JR knows the future so precisely: “it’s bound to come along fairly soon.” Amazing.

  • Robert,

    Your concluding remark is ironic in the extreme:

    As James Renwick has said, it’s up to us to decide how much warming we get.

    I have to wonder at your distance from reality. Since the scientists don’t know how much warming carbon dioxide causes (or won’t tell us), the question of future warming is the very area of deepest uncertainty. Of course, we don’t know how it works, either. I mean, how does man-made CO2 increase the GMST? It’s quite impossible for us to choose the warming without better guidance! If the scientists knew how much warming to expect, they would have told us a million times and we would know it by heart, but we don’t. The magical output of climate models is shrouded in nothing more thickly than doubt. Ask James what he means, since he appears to consider it important, but we don’t understand it.

  • I am gratified to note that James Renwick acknowledges how little is known about Antarctic ice, both on land, and on sea. It is remarkable how many projections/predictions have been made about the future state of the ice based on so little factual information.

  • @Gary Kerkin – There are several factors at work here. In the past, Antarctica was relatively little studied, for obvious reasons. The Marine Ice Sheet Instability was proposed only in 1978 and although widely reported (I remember reading about it in Scientific American soon after that), it was not followed up rapidly, in part due to the difficulty of getting direct observations. The hypothesized grounding line retreat in response to global warming was first observed in the late 1990s. It is still the case that more observations would help. Second, there is rapid change over a large area. Third, the situation is intrinsically difficult to predict due to the complexity of the situation: the ice is sticking, slipping, fracturing, and under internal stress. This is one reason why forecasts of sea level rise out to 2100, 2200 and beyond include such wide ranges. Having said that, there is now a great deal of factual information involving the rate of grounding line retreat and the acceleration of mass loss from multiple independent lines of evidence.