Oceans, physics and virtual audiences: Helen Czerski's Royal Institution Christmas Lecture

The Royal Institution Christmas Lectures were started by Michael Faraday in 1825. They are now broadcast on national television every year, bringing scientists to our screens over three nights of the festive season.

The series of lectures has always been held in London, but this year, of course, is going to be slightly different.

The 2020 Christmas Lectures, titled Planet Earth: A User's Guide, are hosted by Professor Chris Jackson, Dr Helen Czerski and Dr Tara Shine.

Lecture two airs tonight, 29 December, at 8pm on BBC Four. Watch lecture one on BBC iPlayer.

In lecture two, physicist and oceanographer Helen Czerski will talk about the part our oceans play in the climate crisis. We spoke to Helen for an episode of the Science Focus Podcast, which you can listen to in full at the bottom of this page. Here's what Helen told us about being a 2020 Christmas Lecturer.

Chris Jackson, Helen Czerski and Tara Shine on the Christmas Lectures 2020 © Paul Wilkinson — From left to right: Helen Czerski, Chris Jackson and Tara Shine, the Christmas Lecturers for 2020 © Paul Wilkinson

What's in the ocean for a physicist?

Mostly energy, in the form of heat, but there is also kinetic energy.

We know that it takes a lot of energy to boil the kettle – we don't necessarily see it because you just hit a switch, the light comes on, and sometime later there's tea. But if you monitor the energy use in your house, the two biggest spikes are the kettle and the tumble dryer.

What that tells us is that you don't have to heat up the ocean very much to store a lot of energy. Even though it doesn't heat up the ocean very much, once that energy goes to other places it can have quite large effects. So, the ocean is basically a battery for Earth.

It helps make our planet a lot nicer, because it means that if, say, it's cloudy for a few days, the temperature doesn't drop by 50 degrees, for example. It only goes down a little bit and we all complain about it.Actually, the oceans are keeping us warm and during the very hot summer days, they're actually keeping us cool.

The ocean is that store of energy for the Earth. It's something that the Earth's system can store up when there's plenty of energy and then extract it back when there's not as much energy available.

You can imagine Earth borrowing energy from the Universe: it comes in, the energy hangs around in the Earth's system a bit and eventually it flows away into space. We're just holding on to a bit of it, using it – sort of getting in the way of its journey out on into the Universe.

Read more about the ocean:

But to do so, we need a store. The ocean is critical for all that and it also moves energy around the planet. You know, the poles would be much, much colder in the depths of the Arctic winter if there wasn't an ocean. Actually, you can see that in the surface temperature in the Arctic, in the Antarctic during the polar night.

We look at the ocean and we just see blue and it's sort of flattish and there's lots of it. But, actually there's loads of stuff happening underneath the surface as it shifts that energy around.

Because of its nature, as a battery for energy on Earth, does it mean it's one of the best sources of renewable energy?

No, interestingly. So, there are ways you can extract energy from ocean temperature, but only works in a small number of places.

When we talk about energy and really, if you're being picky, when it comes to renewable energy, it's not energy we're short of at all. What we're short of is useful energy. And what you need, in order to have useful energy, is a difference.

Let's imagine you are a bird soaring through the atmosphere. If you're travelling at the same speed as the wind, you don't experience the wind because you're moving and the wind is moving but relative to each other, there's no movement. There's no doubt that you've got kinetic energy and the wind has kinetic energy, but because there's no difference between those two positions, you can't you can't get anything useful out of that.

From the point of view of renewable energy, the ocean is very low-grade energy for humans. Not for the ocean, because it runs the system. But it's very low-grade because it's kind-of-a-bit warm, there's not a big energy difference. You can't extract energy from a small temperature difference.

That's the reason that sunlight is useful: you have a dark day and then you have bright sunlight – that's a huge difference. You can definitely take usable energy out of that. There's a fundamental physics point here, which is that it's this useful energy that really matters.

The ocean doesn't provide us with 'useful energy' in the same way that the Sun and wind can © Getty Images

So, although the ocean battery is really important, it is quite hard to extract energy from it. There are a couple of exceptions: heat pumps which use the difference at the tropics between the very warm water at the surface and the very cold water at depth.

There's an energy plant in Hawaii that I visited where they basically do that – they kind of have a hot tub and a cold tub for the ocean. They have, very entertainingly, coloured them red and blue. But it was built as a demonstration plant, and even in Hawaii, they can only just get enough energy out of that to make it workable.

Actually being on land, we can use the energy that tends to come with stationary things like a wind turbine, you know, when the weather is right. The warmth of the ocean might help drive that weather, and then the weather pushes the wind turbine round.

So, sadly, although it may be the case that we're accumulating heat energy on Earth, it's not very useful for running our society with.

What current initiatives give you hope for the future?

It's easy to feel that things are changing really slowly. But the thing is, we're not starting from the beginning of the running track here.

My mum, recently, sent me a picture of me standing next to her 25 years ago campaigning for Friends of the Earth on the streets of the town that I lived. These are not new problems and people have been thinking about them for a long time.

I think that the reason that's important now is that people are really starting to talk about them a lot more, which is brilliant, but a lot of the ideas have been turning around for decades so they've now got to the stage where they're ready for use.

Read more climate change initiatives:

It does feel frustrating sometimes, it feels like nothing's changing immediately. Actually, on the time scales of human civilisations, on the human lifetime, things are changing really quickly. The conversation is really important, but also all of this work has already happened to come up with good ideas. They already exist. And, there might be more of them and they might be better but we're also building on a foundation.

We're not starting from square one. And I think what's really important when it comes to the the scale of the task is realising that actually we're already quite a long way along this road.

How will this year's broadcast differ from previous lectures?

Well, obviously, we have a virtual audience and not a real audience. A lot of the filming will be very similar. In the sense that, normally if you're making a TV documentary, you'd stop and start and you do everything in bits, and this will be filmed pretty much as a lecture. Even though we'll be talking to cameras rather than to physical people who are there in the room.

The thing that is hardest for us is that the fundamental unit of human civilisation is a human talking to another human. It's a very powerful thing. People are interested in other people fundamentally, and we get a lot of cues from talking to other humans. So, in a live situation, that's there.

The wonderful thing about the Royal Institution as a place to talk normally, is that you are right in the middle of it. What you see on TV are these very steep seats that curl around and you as the lecturer, on whatever lecture you're giving, are right in the middle. It's like a Greek democracy, you're in the middle of all the people and you have to defend yourself to the surround-sound audience.

Obviously, when you speak to the audience, you are connecting with them. You hear them breathe, you can hear if they're not interested, actually, they go very quiet. Even if they think they're being quiet, you can feel the response in the room.

As a human, you're used to judging that in real time. Right, you can change this sentence based on what happened with that sentence. We won't be able to do that. So I think it'll be interesting managing the emotional journey. I guess my biggest concern is, even though I won't have any way of judging, that I might be misjudging the way the audience is reacting at home. Although we do have a virtual audience, it'll be a little bit different.

Interviews with previous Christmas Lecturers:

But, I have every confidence in the Royal Institution demonstrations team. It has to be said that the most impressive thing about all of this is the amount of effort that the Royal Institution and others put in behind the scenes to make these demonstrations work.

Although we have the ideas and we help, we're not the ones who are adjusting the height of the glass tube 14 times in the afternoon to try to make it work. So we have to acknowledge the teamwork that goes on behind the scenes.

Actually, one of the things that I’m excited about for my lecture is there are ocean demonstrations that we academics don’t have time to build. We can't spend an entire afternoon, adjusting a test tube 14 times to make a demonstration work. There will be demos that I think are useful from probably all of our lectures for teaching. Because you don't normally have the opportunity to set them up. Once you've done it and you filmed it, then they become useful to everyone forever. So that's a great thing.

There is actually a benefit here to the online world. So, although these will be broadcast on TV, all the other lectures are available online. And what that does is it removes a barrier.

In the past, if you did not come to this quite posh Mayfair venue and if you weren't on the invitation list, then you didn't get to see [the Christmas Lectures]. I think one of the things that all of us came in caring about a lot at the start is that the audience are not just the people who always get to come. It's other people who get to be part of the virtual audience, as much as we've been able to manage.

There are hopefully some things that will come out of having virtual audiences and online things which might stay [after the pandemic] because they open the door to more people. I think that is really important. Yes, there's all this tradition and this is the way it's always been done. And that's all brilliant. But there's no harm in the tradition opening its doors and sharing it.

If you've got a good thing, why not share it as widely as possible and why not use it to to share views that come from as many places as possible? All of that matters quite a lot. And I think this year is a really good opportunity to really push forward on that.

What do you hope the 2021 Lecturers will take from your experience?

Next year's lectures... hopefully there will be a live audience again. But I think some good things will have come out of doing it this way.

It's really important that it doesn't just go back to exactly how it was before. There are probably things that can be done this way [virtually] that couldn't have been done in the other [live] way. And it's important to incorporate those. So I would say, don't look at us as the weird ones that did a thing that will never be done ever again. Something out of this will be good enough that it gets done every year in the future. It would be great if they looked to find that.

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