The world is running out of water - can cloud-seeding save us?; Why some people get stuck in grief; Is our black hole actually a clump of dark matter?

0:00We're leaving today and entering a world of Mickey Mouse waving, Princess meeting and greeting. Lightsaber clashing. The Twilight Zone Tower of Terror dropping. Banshee flying. Space Mountain launching. Galaxy rewinding. What is the wonder of galaxy rewinding? Fireworks igniting. World of Other Worlds. For whatever you love. Infinite worlds await at the most magical place on Earth. Walt Disney World Resort. The world is running out of water. As we increasingly draw upon water that cannot be replaced, we're heading towards water bankruptcy. And amid this, countries are putting more and more faith in cloud seeding, a group of experimental techniques for encouraging rain or snowfall.

0:45And now there are some big claims of big results in the US. Also this week, we're looking at prolonged grief disorder, a psychiatric condition in which the sting of loss never fades. And it may affect as many as one in 20 people. A lot of people argue, how can we put an arbitrary timeline on what's a normal length of time to be grieving someone? And in the ongoing search for the universe's missing dark matter, we'll be asking if there is actually a clump of it at the centre of our galaxy. And the answer is, eh, maybe. A clump of dark matter, in theory, would match lots of observations just as well as a black hole.

1:22Maybe we've just been circling it all along.

1:29This is The World, The Universe and Us. I'm Dr Timothy Revel. And I'm Dr Penny Sarche. If you're looking for things to add to your list of what to worry about, I certainly always am, then water bankruptcy should be your newest concern. Three out of four people worldwide are living in countries that face water supply issues and increasingly we're having to dip into groundwater that would take thousands of years to replenish. So, can we tech our way out of this? Well, this week, there's news of a surprising cloud seeding technique that has brought a big boost to snowfall in the US. Reporter Alec Loon is here to tell us more.

2:03Alec, can we kick things off with this term water bankruptcy? It's not one I'm familiar with, and I've now added it to my list of worries. So what actually is it? So, yeah, the UN wanted to frame this in a new way. and bankruptcy can apply pretty well, actually, if you think about water in terms of we have the snow melt, rainfall, all these kind of seasonal influxes of water, that's like your checking account. So that's renewed each season. But then there's groundwater, which takes centuries, thousands of years, even tens of thousands of years for water to percolate down into those deep aquifers.

2:41So that's more like your savings account. And so we've known for a while that we're drawing more and more upon our checkings account and really using a lot of rainwater. It has to do with mainly agriculture and also urban centers, both expanding a lot, including in arid regions of the world. But then now we're starting to kind of dip more into the groundwater, where something like 70%, I think, of aquifers are declining around the world. So that's really worrying because that's not going to be replenished in any sort of human-relevant time frame. So that's where the water bankruptcy term comes from, and a lot of countries have been turning to cloud seeding to try and address this.

3:26And so cloud seeding is one of those ideas that's been around for a while. Can you remind us what it is? So it was developed in the 1940s, and actually Kurt Vonnegut's brother was one of the scientists who helped develop it. It was discovered when a refrigerator turned off in a lab, and a scientist put some dry ice into the refrigerator to try and cool it down quickly. And it immediately started raining. Well, it immediately started forming ice crystals in the air. And so he noticed that this dry ice was basically taking moisture out of the air and causing it to condense, crystallize. Then he ended up taking some dry ice up and dumping it out of a plane into a cloud in upstate New York.

4:06And it caused a lot of snowfall, or at least they thought it did. And so this idea has been kicking around for a long time, people using different kinds of materials to try and do this. You know, I used to be a foreign correspondent in Russia. And I remember it was always before the Victory Day parade or some sort of big event, there would always be like a lot of times there'd be cloudy weather and rainfall a couple days before or maybe a day before and and then you'd read in the news that they were cloud seeding to try and get the moisture out of the air before it rained on the parade wow and china has a huge program as well and has for for many years but now um as as water bankruptcy kicks in a lot of countries especially in places like the middle east the western united states are starting to to do their own programs.

4:53Yeah, sort of on the surface level, it feels like, oh, this is fairly straightforward. You need a bit more rain. So you do something to get a bit more rain. But it's quite controversial an idea, right? Yeah, it's been in the news a lot recently because people have been starting to blame it for some of this extreme precipitation that we've been getting. So Dubai flooded in 2024. That's pretty unusual. A dry place like Dubai having this really, really catastrophic flooding. And so a lot of people then were blaming this on the cloud seeding program that Dubai has been doing for a couple decades now, which scientists debunk.

5:26They say that there's no way that cloud seeding could have caused anywhere near that much rain to cause that flooding. But nonetheless, people kind of latch on to this. Same thing happened when there were the deadly floods in Texas last year. People were blaming that on cloud seeding, although that's also not surely not the case. And then most recently in Iran, with this big popular unrest in Iran, one of the contributing factors was water scarcity. And so Iran, to try and address this, has started a cloud seeding program as well. Am I right in thinking that water on this planet is a zero-sum game?

6:01So if you're seeding rain, you're either taking it from a time you would have had it anyway or you're taking it from somewhere else. Yeah, I mean, it's called the water cycle for a reason, right? So it's just this constant cycle. And what people who are doing cloud seeding would tell you is just that, oh, yeah, we're just kind of speeding up this cycle, this natural process. We're causing it to maybe the water vapor, a little bit of the water vapor to rain out a little bit earlier than it would have. Maybe it rains out over land rather than over the ocean. But there are, of course, a lot of fears about water stealing and whether, you know, one area doing cloud seeding and getting some rain for themselves might mean that that rain then doesn't fall over another adjacent neighboring country or state, let's say.

6:47So that's part of the whole controversy. And it's surprisingly hard to tell if it can work or not, because really clouds are actually pretty complex things. What you have is water vapor condensing into tiny, tiny droplets. Some of those droplets are falling. Some of them are rising with the updraft of air. And as they're doing that, they're colliding. And sometimes when they collide, they bounce off. Sometimes when they collide, they stick together. and when the droplets get big enough, then they rain out as rain. And so cloud seeding, there's many different types that target different kinds of clouds, but the basic premise is that you're trying to help that condensation process, help more droplets form, help bigger droplets form so that then more rain falls.

7:36And so then now there are claims that a new technique for doing this has increased precipitation over a mountain range in Utah in January. So what's new? What's the new method? So this is a cloud ionization technique. It's been extremely dry in Utah. They've had the lowest, the driest winter on record in Utah. So it's pretty stunning for these guys to come along and say that they've increased snowfall by 20%. That's a big deal if that's true in the American West where the Colorado River has been drying up. And there's a lot of, yeah, there's a long-term problem with water bankruptcy. So what they do is they basically have a coiled wire that's between two pylons just out on a ranch somewhere, essentially.

8:24And they're running 10 ,000 volts of electricity through this wire. It's kind of like when you sometimes you can drag your feet on a carpet, let's say, and then you touch a door handle and you get that spark, that little shock. What you've done is you've basically picked up an electrical charge from the carpet and passed it to the doorknob. And so this is a similar idea where they're providing the electrical charge. The wind is carrying small particles, aerosols, stuff like dust, salt, small pollutants through the air. And as it passes this array, those aerosols are picking up electrical charge.

9:01They're basically picking up electrons, becoming charged. And then the wind, when it carries them up into the cloud, that charge helps them to form droplets. because we know from previous science that charged particles attract each other. Even if they're all the same charge, they will actually polarize. So they'll have a charged side and a negative charged side and positively charged side. And then the different particles, you know, negative side of one particle, positive side of the other, they attract each other. And so the idea is these droplets that are forming around the charged aerosols are attracting each other better, forming bigger droplets and falling out as rain.

9:37That's the technique. That's the claim. You know, there's a little bit of scientific evidence. There was a really interesting study that looked at, for instance, nuclear weapons testing during the Cold War. And they looked back at weather records and they found that nuclear weapons testing actually can ionize air, can put charge into air because of the radioactive elements that it's releasing into the winds and the atmosphere. And so they found that in the days after nuclear testing in 1960 through 1962, rainfall increased over the Shetland Islands, which they attributed in this study to the ionizing effect of the nuclear bombs.

10:16So this is kind of a similar idea. And they've done a trial in Oman previously, this company, Rain Enhancement Technologies, where they claimed that it increased rainfall by 10 to 15 percent. but this is all very, very early days and not a lot of proof out there for it. But it has the promise of being a much cheaper and less controversial way to do cloud seeding. Yeah, because a lot of the other ways of doing cloud seeding, you're spraying stuff into the atmosphere, and that's been real fodder for conspiracy theories, right? Yeah, so the chemtrails conspiracy theory has been also kicking around for many, many years.

10:57And I saw one survey that found that worldwide something like 17 % of people believe in the chemtrails conspiracy theory, which, of course, is that the contrails you see behind airplanes are not actually condensed water vapor, but some sort of nefarious substance that the government is using for mind control or changing the climate or what have you. So cloud seeding is kind of dovetailed with this really well where a lot of people kind of tend to go down this conspiratorial path when they hear about cloud seeding. You know, why is the government doing this? You know, the image of the government flying planes that are spraying chemicals just kind of conjures up all sorts of fears in the general population, it seems like.

11:42It's not raining more. They're just convincing us it's raining more. That's what's happening. And there's also the bit with the water stealing, as I mentioned. But that seems legitimate, right? That's not just conspiracy. Potentially, if this works. So that's an interesting question. So where I've seen it come up is with China, which has a very, very large cloud seeding program where they're basically trying to create a giant transfer of water from the Tibetan Plateau east into northern China. That's a very dry area. And so they're just doing it on a massive scale, not just aircraft, but also firing rockets with silver iodide.

12:18One of the traditional techniques is to put salt particles into the cloud to condense that water. So firing rockets, even having these kind of like chimneys that are just belching this pollution basically into the clouds to try and form water. So just doing it on a massive scale. And, you know, people were saying, well, won't that mean that India, let's say, gets less water if China is taking, is kind of encouraging more of it to fall out of the air? And, you know, that may be a concern if it gets to a really, really big level. But, you know, most scientists say that the effects of cloud seeding, they tend to be pretty small.

12:57They tend to be pretty underwhelming. They tend to be pretty localized. Most scientists would not say that this is happening right now, that regions are water stealing from other regions. You'd have to have a much bigger scale. I think that's one of the things I find so fascinating about it, because it's like this idea that we can manipulate the weather, which on the line is like that's super exciting. And there's this huge investment of time and energy already going into it. But yet scientists seem to think it's not having a big effect. Even if it is, it's quite marginal. What do we make of these new claims from rain enhancement technologies that it's improving rain or snow in this case by a fifth?

13:32Is there any reason to believe that's true? It's really hard to say because it's basically impossible to do a controlled experiment. The weather changes all the time. You know, you're dealing with a hypothetical. You cannot have, you know, the weather pass through and you do cloud seeding and then have the same weather pass through and you don't do cloud seeding. It just doesn't happen in real life. So there's no way to have a control on the experiment. So that's why it's always really fraught. And, you know, so people, a lot of times they'll, so what rain enhancement technologies did, for instance, was they did this cloud ionization technique in one range of mountains in Utah, and then they had another range of mountains in Utah, and they looked at the precipitation levels in five previous dry years in those two mountain ranges, and they established a relationship.

14:19When this mountain range gets this much precipitation, this one tends to get this much. And then they use that to say, okay, well, this year we did cloud seeding here and we exceeded the expected amount based on what happened to the other mountain range by 20%. So that's what they're doing basically. So it's not a perfect control. It's not a perfect comparison. And so there's a lot of questions about it. The World Meteorological organization. Well, it has said that traditional cloud seedings are spraying salt into clouds. There is some evidence, there is a mechanism that's been proven that that can increase rainfall.

14:56New techniques like cloud ionization are lacking scientific proof still. So that's where the, that's the state of the science. And, you know, even though, even if we say that traditional cloud seeding works, then the question becomes, well, it works, but how much? How much does it That's where my next question for you is we kind of open this talking about water bankruptcy. How much does it work? Does it work enough to be a potential technique to counteract water bankruptcy or not? So, you know, any even so even rain enhancement technologies, they're claiming to do at the most 20 percent increase.

15:29And so that would be somewhere like the UK, probably not a lot, not really worth it. But but somewhere like the Western US where they're desperate for water, 20 percent could be could be a lot. So then it kind of, I think, comes down to price. You know, if you're flying tons of aircraft targeting certain clouds, you have, you know, it's a full scale. You know, you have to have lots of scientists, lots of aircraft, all sorts of logistics. You have to hit the clouds at the right time when they have lots of moisture in them to condense. And so it just becomes this huge operation that's very expensive.

16:05And then if you're only getting 5 % extra rainfall, maybe it's not worth it. But that's where this technique is interesting because it is kind of a cheap and dirty way to do this where you don't need aircraft. You don't need chemicals. All you need is just a source of electricity essentially. So that's what's kind of interesting here is if this works, maybe it could change the calculus on cloud seeding for a lot of places because it is cheaper. When you want your spring break to feel like. And your kid's pool day to feel like. And your hotel bed to feel like... Ooh, and room service to feel like...

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17:03Part of the human condition is the sting of loss and the heartache of grief. But for one in 20 of us, the sadness felt after the death of a loved one is something that can persist for beyond the usual time frame of mourning. And this has a name. It's called prolonged grief disorder. And we are now starting to get a better sense of really what it actually is. Alexandra Thompson is here to tell us more about it. So, Alex, what do we actually know about this condition? So prolonged grief disorder occurs when a person's natural response to losing someone doesn't dissipate over time, which is what we typically expect to happen.

17:38So for some people, which is about 5%, pretty significant chunk of people, they experience really intense and distressing symptoms that persist for a long time and it interferes with their daily life. So has this been recognised as a sort of distinct condition then? Yes. In 2022, the American Psychiatric Association included it in its diagnostic manual. And this was controversial because a lot of people argue, they argued at the time, they still do, We shouldn't really pathologise someone's grief. And how can we put an arbitrary timeline on what's a normal length of time to be grieving someone?

18:14It's an interesting question. What is a sort of normal frame of time for that fading of grief and to slightly return to normal life? The association says it's at least six months. And beyond that, maybe somebody is tipping over into having prolonged grief disorder. But it's not just the timeline. They also, to get a diagnosis, have to meet at least three of a fairly long list of symptoms. And a lot of those are pretty similar to what people experience when they have shorter term grief. So it's things like disbelief at their loss, either intense emotional pain or numbness. They might struggle to go back to work, socialise, do hobbies.

18:52They might feel that life is meaningless without them. So these are sort of the typical symptoms we see with grief anyway. But with prolonged grief disorder, what really differentiates it is the timeline. these people just feel stuck in it. That makes a lot of sense. I mean, I think six months feels so short, but then if you're still experiencing the same heightened acute level of grief, then then that's maybe where you're in this position. But we're talking about it this week. Why? What's new? Because there's been a review of several studies that have monitored the brain activity of people with prolonged grief disorder and people who are recently bereaved but don't have the disorder.

19:26And they've also looked at the brain activity of people with conditions like depression, anxiety and PTSD which can also occur after you've lost somebody. So the trials have varied in their design but a couple of them had their brain activity monitored while they were asked to think about their loved one or even to look at their photograph. Yeah so what have they found? Well perhaps unsurprisingly there are overlaps in brain activity between prolonged grief disorder and things like depression but the disorder also has some quite distinct features as well So for example more pronounced changes in a larger number of reward related brain circuits.

20:01These people also show a bias towards reminders of the deceased. It's almost like they're choosing to sit down and think about them. Whereas people with say PTSD or anxiety they tend to show neural activity that promotes avoidance behaviours. So they might try and distract themselves or they choose to suppress those emotions. they're also when these people view images of their loved one or even just a death related picture like a graveyard they have heightened activation of the amygdala and the right hippocampus which are involved in emotion processing the memory whereas when they see like a cute animal or a serene landscape they have deactivation in these regions so that really suggests that there's disrupted emotional regulation and a diminished capacity to experience positive emotions.

20:47So this review then lends weight to this being a distinct psychiatric condition which you know is still quite a new idea and relatively controversial. Grief is a horrible thing to have to live with. Do we know if this condition also affects a person's physical condition because often there's a link between your mental state and physical illness? Yes we know that intensely grieving somebody can raise our blood pressure. It's also been linked to reduced longevity and And that might be because of the strain it puts on the body or it might be sort of lifestyle changes. If you feel that way, you might drink more alcohol and you might be less motivated to exercise.

21:24So it could be a combination or either of those things. So, of course, we can't stick everyone who experiences loss into a brain scanner to see if they've got or they're going to get this disorder. But are there any practical uses for this work? Yeah, we can't stick everyone in a brain scanner. And I'm not sure how useful a one-off scan would be anyway with a condition like this. But we do know there are some people who are particularly susceptible to prolonged grief disorder. So, for example, people who have the history of depression, if they have little social support, if the death was violent or unexpected.

21:57There's even evidence that if the death takes place in intensive care as compared to a home, that can raise the risk. So now we sort of know who's particularly susceptible. perhaps we could scan their brains and see how it's matching up and then they could be offered extra support. So is that how you go about treating this? It's about support. Is there anything else that we can do? There are grief-specific psychotherapies which there's evidence that can help. So that helps people to accept their loss and to find a way to work towards their goals and have an improved quality of life without that person.

22:34there are bereavement support and peer groups where people share their experiences so they don't feel so alone in what they're going through and because there is such an overlap and prolonged grief disorder can occur alongside depression in those instances antidepressants might help and finally this week the small matter of whether the black hole at the center of our galaxy may actually be made of dark matter the elusive substance that we just can't find A small matter of is it dark matter? Reporter Lea Crane is here to talk us through this. Lea, what is this? So the question is, is our galaxy's black hole, Sagittarius A star, made of dark matter?

23:15And the answer is maybe. It's possible. It's maybe not, you know, super likely, but it is possible. This group of researchers calculated that a clump of dark matter, in theory, would match lots of observations just as well as a black hole. The observations they used are mostly about the rotation of our galaxy and the orbits of stuff really close to galactic center. And it would have to be a particular kind of light dark matter particle called fermionic dark matter, which isn't exactly a front runner right now, but it's also not ruled out. So this clump of dark matter would look pretty much identical to the supermassive black hole that we've always thought was there, but it wouldn't be a black hole.

23:59So they've done a calculation and they basically said, hey, what if instead of a black hole, it was dark matter? Yes, that would fit everything that we've observed or looked at. Yep, that is exactly what they did. Yeah. And you say, you know, would it fit everything? There are some folks questioning whether it fits everything. They didn't obviously compare it to every single piece of data that exists, but it does fit a lot of things. So the kind of argument of it, it looks like dark matter, it might well be dark matter. Yeah, well, it looks like dark matter in that dark matter is invisible. Yeah, well, quite.

24:36So like dark matter is this weird stuff that's meant to like permeate the universe, it like makes up most of it, but also we've not seen any of it yet. I mean, what is going on with it there? Yeah, so we know that dark matter should exist because of its gravity. We know that there's more gravity than there should be if only visible matter is what there is. But other than gravity, dark matter doesn't interact with normal matter or light. So that makes it, as you can imagine, super hard to look for. So we haven't seen it directly. We don't know what it could be made of. So is this sort of a new idea that maybe black holes are actually dark matter or made of dark matter?