Host: Shamini Bundell
Welcome back to the Nature Podcast. This week: a new, long-term record of tropical climate.
Host: Nick Petrić Howe
And the first pictures from the James Webb Space Telescope. I’m Nick Petrić Howe.
Host: Shamini Bundell
And I’m Shamini Bundell.
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Host: Shamini Bundell
First up on the show, to get an understanding of the history of the Earth’s climate, we often look to things like ice cores – layered histories of ice and snow. But for the tropics, long-term records like these have been markedly absent. Now, a team of researchers may have found an alternative way to see into the climatic past of the tropics. Anand Jagatia is here with more.
Interviewer: Anand Jagatia
The last ice age ended just under 12,000 years ago, a time when the climate was, obviously, much colder, and ice caps and glaciers covered a lot more of the globe’s surface. Earth has had at least five of these major planetary cold spells, called glacial periods, punctuated by warmer interglacial periods, when the ice retreats. We can reconstruct how the climate has cycled between these extremes using natural archives that capture information about their environment as they form. One example is ice cores – cylinders of ice extracted from places like Greenland or Antarctica. As layer after layer of water freezes in these areas, the physical properties of the ice down through the core can be used to work out ancient temperatures, going back hundreds of thousands of years. But that’s not the case with ice cores in the tropics.
Interviewee: Donald Rodbell
I think the longest one might go back about 20,000 years. And so, it’s not a deep, thick continuum of ice like we would get in Greenland or Antarctica.
Interviewer: Anand Jagatia
This is Donald Rodbell, a geoscientist at Union College in the US, who studies the history of glaciation in the Andes. In the absence of big enough ice cores, researchers like Donald could turn to another kind of record – material on the ocean floor. As sediment sinks and builds up on the bottom of the sea, its properties can be used to work out how much of the world’s water was locked up in ice at different points in time. But it turns out that that signal – known as global ice volume – is completely dominated by the ice in the Northern Hemisphere, where at least three quarters of all the ice on the planet has been found.
Interviewee: Donald Rodbell
We call it the global ice volume record, but it's really largely a Northern Hemisphere ice volume signal. So, we don't know what's happening in the tropics from the global ice volume record because the little glaciers in the tropics, as spectacular as they look, are tiny in their volume compared to the big ice sheets, and so they don't really matter.
Interviewer: Anand Jagatia
But now, scientists have found a record of the glaciation in the tropics that lets them look back further than ever before – sediment from the bottom of a lake in Peru. Before this, Donald says, the best record in the tropics was difficult to date accurately past around 125,000 years or so. But this one stretches back 700,000 years into the past, down through the mud beneath Lake Junín.
Interviewee: Donald Rodbell
This is a very unusual lake. It's sort of like a Goldilocks lake. It's not too far from the glaciers and not too close. And whenever there were glaciers in the mountains around the lake, they ground up rock, as glaciers do, like giant like giant belt sanders, tools of abrasion, and they produce a lot of rock flour. It literally looks like powder when it's dry and feels like flour. And it ends up in the streams of meltwater coming off the glaciers and it ends up dominating what is accumulating in the bottom of the lake. And in the interglacial periods, the glaciers pretty much disappeared, and the lake became dominated by a very different type of sediment. So, in that record then we could say, ‘Okay, we have an ice age. We have an interglacial period. We have another ice age.’ And we can kind of work our way down through a hundred metres of mud, documenting the presence or absence of ice.
Interviewer: Anand Jagatia
So, the presence of absence or this rock flour tells you whether glaciers were moving through the mountains around the lake, crushing the rock to dust as they went. It’s an incredibly useful record, but extracting a core from the hundred metres of sediment below a lake isn’t easy. In fact, it’s a huge undertaking.
Interviewee: Donald Rodbell
We needed a platform the size of a tennis court and we needed hydraulics and heavy equipment. But first, we needed access to the lake. The marshlands around the lake make it impossible to access the lake, so we literally had to dig a little canal to get some of the early craft out into the lake. Then we needed to get a platform. We rented a modular system from Houston, Texas and shipped it to Lima, and this is sort of like really large Lego pieces. We had to get a crane delivered to the lake edge also from Lima, and it's about an 8- or 10-hour drive through a very treacherous canyon. And so, first we got the crane, and then the trucks started to arrive, and the crane would offload these Lego pieces and they were assembled in in the canal.
Interviewer: Anand Jagatia
Once the platform was assembled and taken out into the deepest point of the lake, the crew could get to work on drilling and extraction.
Interviewee: Donald Rodbell
So, you can imagine a 3-metre-long straw, 3-4 inches in diameter, being pushed down into the mud. And then it would be extracted, brought up to the platform at the surface, and the science crew would extrude it and describe it quickly, and ship it back to our nearby lab for some more analysis and eventually shipped home. The coring would continue down at 3 metres at a time until we hit something we couldn't get through. And we were coring for about 6 weeks, 24 hours a day. We had a night crew and a day crew, and each crew would go for 12 hours, but in the end, it worked out remarkably well.
Interviewer: Anand Jagatia
After this mammoth operation had been completed, the team began analysing the cores. Using radiocarbon dating and other techniques, they were able to work out the age of the different layers of sediment. Then looking for the presence of glacial rock flour, they started piecing together a chronology of the ice ages in this region.
Interviewee: Donald Rodbell
Overall, there is a remarkable similarity between the timing of the ice ages in the tropical Andes and global ice volume, again, primarily a northern hemisphere signal. And so, that was really the first time we can say that over 700,000 years that the timing is really locked in. But then there were also some differences. So, we sort of compared the magnitude of glaciation and found that there were intervals where the tropical glacial cycles were bigger relatively than you would expect them to be compared to the globalised volume signal. And this, we believe, is maybe due to enhanced precipitation, snowfall, in the Andes that would make a larger glaciers than you might otherwise expect.
Interviewer: Anand Jagatia
But for the most part, this new core reveals that largely the climate was in lockstep the world over. So, what might explain why the ice age record is so tightly correlated around the world?
Interviewee: Donald Rodbell
This particular paper provides substantial new data to further that hypothesis that it was greenhouse gases that dragged the other regions of the globe that are not the Northern Hemisphere, high-latitude regions, dragged them to march in sync with the Northern Hemisphere. And that's about the only mechanism that we know of that could tie the globe together so tightly.
Interviewer: Anand Jagatia
So, as well as telling us about what was happening in the tropics during the ice ages, the record also tells us that Earth’s climate has been connected across different regions and hemispheres for many millennia. Each time, it seems greenhouse gases were pushing the climate across the globe in new directions, and Donald says that that can offer us some perspective on the state of the climate today.
Interviewee: Donald Rodbell
When you study these things that happened in deep time and you see the profound effect that they had on the landscapes, under what were relatively modest, natural changes in greenhouse gases, and then you look at what humans are doing, it does more than give you pause. It sort of makes you stay up at night. And I think these perspectives are really important to get out to policymakers to really kind of understand the magnitude of what we're beginning to see in climate records and modern climate today.
Host: Shamini Bundell
That was Donald Rodbell from Union College in the US. To find out more about this research, check out the show notes for a link to the paper.
Host: Nick Petrić Howe
Coming up, we chat to one of Nature's resident astronomy buffs, Alex Witze, about the first pictures that have come from the James Webb Space Telescope. Right now, though, it's time for the Research Highlights, read this week by Noah Baker.
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Noah Baker
Snapping shrimp, although tiny, can generate shock waves that travel through water at supersonic speeds, and researchers have now shown that the crustaceans protect their brains from the blasts with special ‘helmets’ – the first known biological armour against shock waves. Bigclaw snapping shrimp make mighty snaps with their claws, forming bubbles that then collapse, creating shock waves which stun their prey and rivals. And now, a group of researchers in the States have tested whether a helmet-like extension on the shrimps’ carapace, called the orbital hood, could protect it from its own shock waves, as well as those of its rivals. After being exposed to a peer snapping its claw, shrimps that had had their orbital hoods removed seem disoriented and had trouble coordinating their movements. And seeing as the shock waves that shrimps experience from their own snaps are similar to those felt by their targets, orbital hoods might also protect them from their own punches. The researchers found that orbital hoods can halve the magnitude of the shock waves, probably by trapping water and then expelling it – a process that might redirect some of the waves’ energy. You can read more about that study in Current Biology.
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Noah Baker
Did you know that storing white wine in clear glass bottles can damage its quality, and it's all down to light? Some wavelengths can degrade wine’s smell, creating odours described as ‘wet dog’ or ‘boiled cabbage’. Manufacturers are increasingly selling wine in clear glass bottles to show off its colour, but those bottles also let in the damaging light. To understand just how light alters a wine’s chemistry, a group of researchers set up an experiment using over 1,000 bottles of white wine, some colourless and others green, placed under simulated supermarket-like conditions. Using various techniques to analyse the wine’s volatile compounds, they found that the wines in clear bottles had more than 70 molecules degraded by light. After only 7 days, the concentration of some of these molecules, which are associated with positive aromas, fell by as much as 70%. But wine stored in green bottles were protected from the changes even after 50 days. So were control wines kept in darkness. What's more, losing compounds associated with positive smells doesn't only degrade the wine’s bouquet directly. It also reduces the compounds’ ability to mask less pleasant aromas. You can sniff out that research in the Proceedings of the National Academy of Sciences USA.
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Interviewer: Nick Petrić Howe
Next up on the show, after more than two decades of development, billions of dollars, many delays and some pretty tense moments, the first images from the James Webb Space Telescope have arrived here on Earth. To get a grasp of what these images mean for science, Nature’s Alex Witze is joining me here. Hi, Alex, how’s it going?
Interviewee: Alex Witze
Good. How are you, Nick?
Interviewer: Nick Petrić Howe
I am good, and I'm excited to talk about these images. I was waiting with bated breath for them to come and waiting and waiting and waiting, but they did eventually get here. But I was only waiting for a few hours. You've been reporting on this for, I want to say, since the very beginning of James Webb. How does it feel to finally see these images?
Interviewee: Alex Witze
It has been a very long time. It's been in the works for a very long time. It's been through a lot of delays. There have been so many times it didn't seem like it would launch or something would go wrong. Who knew if this thing would work? Obviously, the big deal here is this is the most sophisticated space telescope that anybody's ever sent up. It has an enormous mirror. It's incredibly complicated. The design and engineering is unlike anything anyone's ever done. So, getting it built and getting it launched and getting it to work in space were just a series of extraordinary events that, yeah, if you'd asked me 10-15 years ago, we would not have imagined.
Interviewer: Nick Petrić Howe
And so, the first image was released on Monday. And, well, this is an audio medium, so I'll do my best to try and describe it. It kind of looked like some kind of high-definition stars to me. But I've heard it described as sort of the deepest astronomical image yet. What can you tell me about this first image?
Interviewee: Alex Witze
Yeah, it is the deepest image ever taken, and what that just means is the telescope stared at a patch of sky for a little over 12 hours and like sort of put together this amazing image. So, the image is full of galaxies. Think about a starry sky but not just individual stars. These things are galaxies. All of them are amalgams of other worlds, other stars. Everything you're seeing in there is something like our Milky Way galaxy, and they are so, so much farther away. If you look at the image, things are distorted, kind of strung out, kind of it looks like they're smeary. A lot of them are red and smeary. And that's because there's this massive cluster of galaxies between us and what we're looking at, and it's distorting the light. It's kind of working like a magnifying lens. So, when you look at this first image, you see lots of light, you see lots of smeary things, you see lots of red things, and that's because you're looking at the distant Universe being magnified through this magnifying lens. And things are red because the Universe has been expanding and light has been shifting towards the red over the history of the Universe. To me, it looks like you're just diving into a swimming pool of galaxies.
Interviewer: Nick Petrić Howe
And that's just the first image that came out, then yesterday there were four more images. What can you tell me about these?
Interviewee: Alex Witze
They are designed to show off the strength of the Webb Telescope. So, we're all familiar with the Hubble Space Telescope, which has done amazing pictures over the years. You see beautiful pillars of dust, galaxies whirling around in space. So, we're used to these gorgeous Hubble images. So, unlike Hubble, Webb works in infrared wavelengths, and the first set of images that came out this week are meant to demonstrate what we can see in infrared light that we can't with something like Hubble, which barely goes there. So, for instance, there's a set of galaxies called Stephan's Quintet, and there's five galaxies and they're all mushed together doing weird things. With infrared light, you can see how they're interacting with each other really well, so you see these knots of star formation, these big, bright bubbles of light where these galaxies are kind of coming together. And those are popping up because we're looking with infrared eyes.
Interviewer: Nick Petrić Howe
And so, I guess they look super striking. They're very beautiful images. And you've talked a little bit there about us being able to see things we weren't able to see before. What did these images mean for astronomers? And what are we able to sort of determine from them?
Interviewee: Alex Witze
So, there's a lot of big questions that Webb is trying to answer that we haven't been able to do before in astronomy – questions about how stars are born and how stars die. Those are things that happen in dusty regions that you can only see with infrared light. How galaxies have evolved throughout the Universe, I mean Webb was built essentially as a time machine to be able to look as far into the distant Universe as possible, which gets you closer and closer back to the Big Bang that created the Universe. So, we'll be able to see farther. And what are these galaxies, essentially, at the dawn of time? What do they look like? We haven't seen those before because we haven't had a ginormous machine with infrared light. And then lastly, and this was not a really good picture from this week because it's a spectrum, so it's a squiggly line, but one of the astonishing things about Webb is it will be able to tell us about the atmospheres of other worlds so, exoplanets, they're called, right. 5,000 or more worlds that we know of around stars other than the Sun beyond the Solar System. And this is a field that didn't even exist when Webb was being dreamed up. We hadn't even discovered the first exoplanets. But it turns out that Webb, with its infrared eyes, is really great at looking at the light passing through the atmospheres of these planets. And so, spectra sound boring, but it tells you what's there. Is there water in that atmosphere? Is there methane? Is there carbon dioxide? And then you start to get a sense of, wow, if there's a rocky world that has methane and water in its atmosphere and there's clouds, hey, could that be like Earth? And we haven’t had that before, and just like something like a quarter of the time of Webb is devoted to looking at exoplanets’ spectra. Again, sounds boring, but it is what are other worlds? What are they like?
Interviewer: Nick Petrić Howe
Oh, that sounds very tantalising. And what has been the reaction from astronomers? Everyone was sort of waiting with bated breath, I know. But now it's here, what is the reaction?
Interviewee: Alex Witze
Well, the internet lost its mind. Astro Twitter went out of control. Their minds are boggled, right? I called a couple of astronomers fishing for quotes and like, three different people said, ‘I'm amazed.’ I'm like, I can't have three astronomers saying, ‘I'm amazed.’ Please use another word. But they are. They're completely amazed. So, for instance, that deep field image, the distant galaxies with all the smeared galaxies we talked about, they're downloading the high res of that, which is like 182 megabytes, and they're panning it and they're looking around and they're trying to get a sense of what this distant realm is like. Yeah, astro Twitter lost its mind this week, for sure.
Interviewer: Nick Petrić Howe
And one thing I wanted to touch on as well, like they've obviously been delays, and it's taken a long time to get here. One of the things with the James Webb as well is there has been this push to rename the telescope. James Webb was very influential at NASA and was very important for keeping science very prominent there, which is why the telescope was named after him. But in his other roles in government, it seems he may have been complicit in the persecution of LGBT people. Now the images are here, have there been any sort of renewed calls to rename the telescope.
Interviewee: Alex Witze
With the launch, there's been certainly renewed attention on that. The group that led the petition to rename the telescope has resurfaced that this week. There's a new documentary that came out from a group called JustSpace Alliance a couple of days ago that sort of looks at Webb's history and kind of his role in government during this period. So, there's definitely been resurfacing. A number of folks say that their excitement about the new images has been tempered by their concerns. So, it's definitely a conversation that's going on.
Interviewer: Nick Petrić Howe
And I'm sure it's a conversation we'll be monitoring here at Nature. But thinking about the telescope itself, what is sort of next for it? And what would you like to see? What would be your favourite picture to be able to see from the telescope now it's sending back images?
Interviewee: Alex Witze
I want to see more of these like deep Universe things because I just love those. Again, it feels like you're falling into a swimming pool of galaxies, the distant Universe, like the edge of time almost, right? The edge of space and time it feels like you're falling into. So, I want to see more of those smeary blobs from the edge. To me, it just seems incredible to be travelling through time with these images. We just haven't had that before. The Hubble will take pictures of one distant galaxy and we know a little bit about it. But Webb is really going to reveal that in all its detail. I would love to see also images of exoplanets. That's going to happen sort of a bit later in Webb's tenure. Right now, it's getting all these spectra, which are those wiggly lines, but it will be doing some direct imaging, and I can't wait to see some of that as well, too. So, there is lots coming.
Interviewer: Nick Petrić Howe
There certainly is, and I'm looking forward to changing my desktop background at least five more times in the next few weeks. But I think that's all we've got time for. So, thank you so much for joining me.
Interviewee: Alex Witze
Thanks for having me, Nick.
Interviewer: Nick Petrić Howe
Nature's Alex Witze there. For more on this story, and for some image-based insights, make sure you check out a new story written by Alex in the show notes.
Host: Shamini Bundell
Finally on the show, it’s time for the Briefing chat, where we discuss some of the stories found in the Nature Briefing. So, I’m slightly cheating today because I would like to tell you about a very cool paper that I’ve actually made a film on. So, usually, I leave the film plugs until the end, but this time, the whole Briefing chat is just going to be a sort of secret film plug. But I’m going to tell you all about the very cool research as well.
Host: Nick Petrić Howe
I’m not sure it counts as a secret film plug if you tell me it’s a secret film plug, but I am very intrigued. Tell me about the video. I guess, to start off, what’s it about?
Host: Shamini Bundell
So, it is about crystals made of starfish embryos.
Host: Nick Petrić Howe
What?
Host: Shamini Bundell
Well, yeah, exactly. That's what we thought when we first heard about this paper, so we had to go and find out what on Earth that was about. And this led me to the field of active matter physics, which is not something that I knew much about before making this film. But it's very important context as to why the researchers in this film were looking at starfish embryos and making crystals out of them.
Host: Nick Petrić Howe
So, this field of active matter, this is just about starfish embryos, that's what I'm getting from this?
Host: Shamini Bundell
No, so starfish embryos are the particular organism being studied in this lab, in this paper, but active matter is really broad actually. So, active matter is a term that physicists use when they are looking at systems and almost sort of materials that are based on components – sort of the individual entities that are active. And what they mean by that is that they are consuming energy and moving under their own power. So, starfish embryos being alive, being living organisms, are one such thing. But there are lots of other things, in particular living organisms, that do fall into this category of active matter. And one of the easiest examples to grasp is birds in a flock in the sky, a murmuration of starlings, say, as we see in this country, and each of those starlings is obviously moving independently, it's active, it's using energy to create its own movement. And it's also following simple rules, like stay aligned with the bird next to you. But when you look at the whole flock, you see emergent properties, shapes, sort of waves and strange patterns that form, and active matter physicists look at that whole sort of system and say, okay, what are the rules at the individual level that are leading to these strange properties, such as the sort of shimmering of a flock of birds that you see at the larger scale?
Host: Nick Petrić Howe
Ah, right, got you. So, I'm guessing then, in this particular case, the starfish embryos have some sort of emergent property. They're doing something together that physicists are sort of interested in.
Host: Shamini Bundell
Yeah, and they’re not quite as complex as starlings or other birds. In fact, they look remarkably simple. They do not, you'll be disappointed to learn, look like tiny starfish with cute little legs. They are just, in fact, round at this stage. And they don't do much, but one of the things that they do is that they spin in the water. So, they'll come up to wherever the sort of surface of the water is, if you have them in like a little dish, say, and they will just rotate and they tend to all rotate in the same direction. And what the physicists noticed was, if you get a bunch of them in a dish – now you can see this in the video but it's all sped up footage because they're quite slow, so this is over a long period of time – as more of them come together and spin, they start to sort of line up. It forms a very sort of regular arrangement. So, imagine sort of rows and columns, almost like a grid, a lattice of these little round starfish embryos. And one of the things that particularly interested the physicists is that this sort of regular lattice arrangement is very much like what we would call a crystal. If it was made of atoms, that material would be a crystalline material. So, this is a crystal that's made up for the first time of living multicellular organisms.
Host: Nick Petrić Howe
Oh, wow. So, this is the first time that such a thing has been observed.
Host: Shamini Bundell
As far as the researchers know, yeah, and they were very interested to see this. And they published this paper in Nature basically looking at, as I mentioned, sort of what are some of the rules behind how this is happening? And also, what are some of the properties of this big crystalline structure?
Host: Nick Petrić Howe
And have they been able to answer some of these questions? Do they know what the rules are that the starfish embryos are playing by?
Host: Shamini Bundell
Well, like I said, it is a very basic movement that they're doing. What each individual embryo is doing is just spinning. But you can see, and they had to use a microscope for this because these are very, very small, when they are coming together, they're all spinning in the same direction, and the forces between them in the water that they're in is causing this alignment. And by kind of studying those forces and figuring out what's going on, there's the potential to be able to maybe even like recreate something like that with manmade creations, manmade entities.
Host: Nick Petrić Howe
And what would be the sort of aim in recreating a weird starfish crystal, I guess?
Host: Shamini Bundell
Well, yeah, that's a long way off. This is not a paper that intends to provide an application. But in the field of active matter physics, some of the ideas are, if these sorts of cool things are happening in nature in many examples, the idea is could you recreate some sort of weird material, where you're providing energy to the individual entities to sort of recreate some of the effects? It's not necessarily the case that sort of spinning and forming a crystal is necessarily going to be useful, but this is exactly the kind of thing that active matter physicists are interested in.
Host: Nick Petrić Howe
Well, this sounds super interesting. It's almost like the sort of thing I would want to see, like where might I be able to see it, Shamini?
Host: Shamini Bundell
It is cool to watch. So, yeah, it's there on our YouTube channel, so that youtube.com/naturevideochannel. There'll be a link in the show notes. And they've got some cool microscope footage that the lead author sent me of the little starfish embryos. You can see them spinning and you can see them coming together and forming these sorts of big rafts of sort of floating crystals in the water.
Host: Nick Petrić Howe
Wow, that was super cool. I did not think I was going to be talking about starfish embryos when I got in this morning, but it sounds absolutely fascinating. Thanks for that, Shamini. And listeners, if you want more stories like this one, while you're in the show notes checking out the video, make sure you check out the link there where you can sign up to the Nature Briefing.
Host: Shamini Bundell
That’s all for this week. As always, you can reach out to us on Twitter – we’re @NaturePodcast. Or you can send us an email to podcast@nature.com. I’m Shamini Bundell.
Host: Nick Petrić Howe
And I’m Nick Petrić Howe. Thanks for listening.