Ep78: Emily Shuckburgh 'Maths, Models And Melting Ice

In this episode of Cleaning Up, Michael Liebreich speaks to Emily Shuckburgh OBE, climate scientist and director of Cambridge Zero.

Michael and Emily begin by discussing Emily’s background in mathematics and how she became involved in climate modelling.

They then talk about Emily’s work in the Arctic and Antarctic and how climate change is affecting these regions.

Finally, Michael asks Emily about how women and girls can be encouraged into science-based careers.

This is an abridged transcript of the conversation, edited for clarity.


ML: You began your career not as an environmentalist but as a mathematician, is that right?


ES: That's absolutely right. I was an undergraduate studying mathematics. When I finished my undergraduate studies, I was wondering what to do afterwards. And I really wanted to see how I could use mathematics just to better understand the world. Mathematics can be a very theoretical subject. And actually the beauty of the theoretical aspect of it is very compelling. But I also wanted to see how that mathematics could be used to understand the world. And when I first started getting into the climate area it was just at the start of when it was  becoming a topic of political importance, it was just when the first IPCC report came out. So, really, my motivations weren't saving the world, they were more just a desire to understand the world more than anything else.


ML: So how did you get into climate modelling?


ES: Actually, the very first topic that I was applying mathematics to, was actually a slightly different environmental problem. It was actually more focused on ozone and ozone depletion. Because from a mathematical perspective, both the atmosphere and the oceans are fluids from a mathematical perspective, you need to understand how fluids move around. And for the ozone hole there is a really interesting interaction between the movement of the air in the atmosphere, and the chemistry of the atmosphere. The hole itself is primarily over Antarctica. What happens is that in the winter, in Antarctica in particular, you get these incredibly strong winds that circulate high up in the atmosphere in the stratosphere, around Antarctica and isolate the air. That's actually down to the physics because predominantly those winds are a result of the very strong temperature gradient that you have in winter between the pole and the equator. So, the air gets isolated, but it gets chemically isolated as well, because it's literally in this vortex. And that enables chemical reactions to occur that essentially take the chlorine out of the CFCs which originated from deodorant cans and refrigerators. But then to destroy the ozone, you have to have a photochemical reaction. So, it doesn't happen in winter, you just get the chemicals stored up in winter, and then the sunlight returns in spring. And those chemicals then destroy the ozone. So, it's a really fascinating interplay between different parts of the system. That's the aspect that I was originally looking at. And then from there, I started to move into looking at climate related problems. 


ML: How has your mathematics background helped you in developing climate models?


ES: I think that this is where it's really helpful to be coming from a more mathematical background. It's not one model, there's a hierarchy of different models. Many times the mathematical insight will be about extracting information from that has much less complexity to it, but potentially greater insight. Or it's about understanding which aspects of that incredibly complex system are highly uncertain, and which aspects are the really robust elements of the problem. It's almost a slightly different lens to look at the problem through. One of my current bits of research that we're focused on is how to take a slightly different approach. So traditionally, the modelling approaches in climate are very much out of weather forecasting. And the original models for the atmosphere came out of attempting to forecast the weather. And then slowly those climate models have developed, as we've added, for the purposes of modelling climate, more components of the system. So first of all, you started off with just the atmosphere-based models that were then simulations and more complicated oceans were added in, then some of the atmospheric chemistry, etc. And the models have become more and more complex, as we've been able to model more and more aspects of the climate system, both in terms of our understanding of the physics, but also the amount of compute power that we've been able to dedicate. Predominantly, the way that those climate models have been developed from those weather forecast models was by looking at how we could represent our understanding of the physics in terms of equations, and then those will get discretized and then simulated using the computer models. What we're trying to do now is blend that with more data driven approaches. And so, we're looking at how we can bring in AI machine learning approaches to augment those physics-based models with data driven models as well. And that's where the cutting edge of much of the model development is at the moment.


ML: You have spent time in Antarctica. What is the impact of climate change on Antarctica today?


ES: In total, I did five polar trips, three to the Arctic and two to the Antarctic. The first thing is that it's important to distinguish between two different types of ice because they sometimes get confused. There's the sea ice, which is floating ice on the sea that forms when the sea water freezes, and then there's the ice shelf and ice sheet so that the ice sheet off Antarctica that then goes down and creates an ice shelf. Those are distinct, physically different types of ice in terms of the ice sheets in Antarctica. The whole of Antarctica obviously is covered in ice, but the component of it that we are most concerned about is the western side of Antarctica. What we call the West Antarctic Ice Sheet. And the reason that we are particularly concerned about that is because we've seen significant loss of ice from that West Antarctic Ice Sheet. It's made up of glaciers. They're almost like the spine of the ice sheet itself. We believe that there's a number of the glaciers that are critical to the stability of the West Antarctic ice sheet, that are potentially already in irreversible retreat. To an extent, the ice sheet is melting from above as the air is warming, but Antarctica is so cold that that's not a particularly significant aspect. The key aspect is really that the oceans around Antarctica, the Southern Ocean, is warming up. And then that warmer ocean water is getting underneath the ice shelf and melting it from below. So that's the key mechanism. And so, another concern is that as those glaciers start to retreat, two things happen. They can accelerate as they start retreating and more ice actually comes from Antarctica into the ocean. But also, the whole system can eventually disintegrate. And there are key instabilities that can occur that accelerate that process. And there's a huge amount of ice, I mean, 60 metres or so locked up in the sea level equivalent, locked up in the Antarctic ice sheet altogether. The West Antarctic ice shelf could cause something like three metres of sea level rise.


ML: You are the Director of Cambridge Zero amongst all the other things that you do. Do you want to talk about what that is? 


ES: Cambridge Zero is an initiative which spans the entire university, and literally everything that the university does and stands for. It is essentially looking at how all of our resources and assets can be brought to bear to help support a response to climate change in a zero carbon sustainable future. And so, it's joining up all the research across the university. And that means all the science and technology, the social sciences, the legal and policy expertise, conservation and public health and so forth. It's also looking at our educational capacity, how we educate our own students in Cambridge, recognizing that we're essentially shaping the leaders of our future here in Cambridge. And then looking at our broader influence: how we communicate widely to everyone, whether it's policymakers about the findings of our research, or whether it's about engaging with industry about generating some of the solutions, or whether it's about inspiring innovation and entrepreneurship to translate the ideas that are developed in the university on lab benches into real world deployment and scale up across all sectors of the of the economy. And then it's about our own operations. And how do we decarbonize the university estate? How do we stop our academics flying around the world to conferences and producing carbon emissions? And how can we consider our own investments? What makes it distinctly different to what I think any other university is doing is that we've centred this right in the centre of the university spanning everything.


ML: If science is going to be more obviously focused on solving  big existential problems, like climate change, is that going to make it easier to get girls into science?


ES: First of all, if science is going to be addressing problems that address the whole of humanity, then we really ought to be having representatives of the whole of humanity being part of developing those solutions. Is it a topic that attracts more women to the topic? I don't know. There may be topics in which women are traditionally much more represented than others. I've been working through mathematics. I'm now based in a computer science department. These are not topics that traditionally have had a large number of men, I'm not sure that there's anything intrinsic about the topics themselves that make them unattractive to women. I think there's been lots of other barriers that have been in place, which I hope we are starting to break down. I can say from my own experience that they've been many times in my career where there's not been many women involved. For a long time women weren't even allowed to overwinter in Antarctica. But I like to think that we're slowly making progress, not least by having prominent women and creating an environment where it's not the subject that's not attractive, it's the environment that sometimes is not attractive for women to be working in and I hope we're starting to change that.