More or Less

If you spend much time on social media, and we don’t necessarily recommend it, then you’ve probably come across a strange fascination with water consumption.Mainly, this is people telling you that using AI is terrible for the planet because of how much water it uses. We’ve already made a couple of programmes about the numbers in those arguments and, long story short, they probably aren’t saying what you think they’re saying. But on platforms like X, BlueSky, and TikTok, an opportunity to keep an argument going is rarely missed And one of the numbers that’s been enlisted in that glorious cause concerns the water that’s used for a seemingly unrelated past-time - eating beef. Here’s an example from a user on X:“A kilogram of beef requires over 15,000 litres of water to produce,” they wrote. “A vegan who uses ChatGPT every day is living a more sustainable lifestyle than someone who regularly eats beef while boycotting AI.”Ignoring the AI part, is that true? Does it actually take 15,000 litres of water to produce a kilogram of beef? It turns out that the number isn’t wrong, but it probably isn’t saying what you think it’s saying.If you’ve seen a number you think we should take a look at, email the More or Less team: [email protected]: Mesfin Mekonnen, Assistant Professor at the University of Alabama Mark Mulligan, Professor of Physical and Environmental Geography at King's College London Tim Hess, Professor of Water and Food Systems at Cranfield University CREDITS: Presenter: Charlotte McDonald Producer: Mhairi MacKenzie Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Emma Harth Editor: Richard Vadon

Vaccine policy in the US is something of an ideological battleground. Health Secretary Robert F Kennedy Jr is a vaccine sceptic, and since taking office he has attempted to remake US vaccine policy. In March a judge blocked his proposal to cut the number of jabs that are recommended for kids. At the same time, last year saw the worst measles outbreak in the US in decades. There were more than 2000 cases last year, and three people died. There have been more than 1500 cases so far in 2026. There’s a lot going on, so it’s possible the public’s views on vaccination are shifting. A new poll published by online news site Politico added a big claim into the mix. According to the headline “more Americans doubt vaccine safety than trust it”. But is that what the survey actually found? Dr David Higgins, a paediatrician and public health assistant professor who writes a Substack called Community Immunity, explains why he believes the headline is misleading. If you've seen a number in the news you think we should take a look at, email [email protected] Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Neil Churchill Editor: Richard Vadon

US president Donald Trump is no fan of wind turbines, or windmills as he calls them.Not only does he think they ruin the view from a golf course he owns in Scotland, but they are also deadly to birds.“If you love birds, you’d never want to walk under a windmill,” he said in 2019. “It’s a very sad, sad sight. It’s like a cemetery. We put a little statue for the poor birds.”Earlier this year he posted on Truth Social saying that wind turbines were killing “millions” of birds.But is that true? We speak to Dr Hannah Ritchie, Deputy Editor at Our World in Data and senior researcher at the University of Oxford, who has dug into the numbers on bird mortality and wind turbines.Credits:Presenter: Charlotte McDonald Producer: Mhairi MacKenzie Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Sue Maillot Editor: Richard Vadon

Sometimes it is obvious to everyone when an idea is harmful, or a piece of advice is damaging. But not always. Occasionally bad ideas and terrible advice end up being accepted in society and supported by people in authority.In such circumstances, one of the most powerful tools for changing people's minds is evidence – scientific studies that show beyond doubt that the bad idea is, indeed, a bad idea.That's the subject of a new book by Helen Pearson, titled Beyond Belief: How Evidence Shows What Really Works.An editor at the scientific journal Nature in her day job, the book chronicles those determined individuals who shake up the status quo by gathering just the right kind of evidence.One story in that book stood out to us on More or Less as it shows just what happens when you don't have the evidence you need to challenge a dangerous way of doing things.It's the story of a piece of advice from childcare expert Dr Benjamin Spock.In a 1958 revision of his bestselling parenting guide Baby and Childcare he made a small change to his advice on sleeping position – advising parents to put their babies to sleep on their front.It eventually became clear that this sleeping position was associated with a significant increase in the risk of sudden infant death, or cot death.CREDITS:Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Rod Farquhar Editor: Richard Vadon

When you’re listening to the news, you will often hear words that are meant to communicate the probability of something happening.   A terrorist attack is “a realistic possibility”, the spread of a certain strain of virus is “highly likely", the relegation of your favourite football team is “possible”.But when you hear these terms, do you really know what kind of probabilities they’re trying to convey? Do you know how likely “likely” is? Or what probability “probable” is meant to get across?In some cases, it seems you probably don't.Professor Adam Kucharski, author of Proof, the Uncertain Science of Certainty, designed a quiz to work out the actual probabilities of the language we use to convey risks.The data he got back shows how sometimes these words mean very different things to different people.If you want to try the quiz for yourself, head over to https://probability.kucharski.io/Email the More or Less team: [email protected] CREDITS:Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Gareth Jones Editor: Richard Vadon

As Artificial Intelligence continues to expand rapidly, some people have raised concerns about its potential environmental impact - in particular its use of water, which is used to cool both data centres and the power generators that supply them with electricity.One recent book on AI contained the alarming prediction that AI could consume between 4 and 6 trillion litres a year by 2027. Could this eye-popping figure be right? If not, what is the correct figure, and is it a big number?The devil, as ever, is in the detail, and with the help of expert Alex de Vries-Gao, the More or Loss team has taken a deep dive to get to the truth about AI and water consumption.If you’ve seen a number in the news and you think More or Less should take a look, email the team on [email protected]: Charlotte McDonald Producer / Reporter: Nathan Gower Series Producer: Tom Colls Programme Coordinator: Brenda Brown Sound Mix: Dave O’Neil Editor: Richard Vadon

Paul Ehrlich’s bestselling book The Population Bomb opens with an apocalyptic paragraph. “The battle to feed all of humanity is over,” it states. “In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate.”Professor Ehrlich, who died last week, made a simple argument. The global population was outrunning our capacity to produce enough food to feed everyone. Famine, disease and nuclear Armageddon would follow if the population was not controlled.The book made him a celebrity, and he regularly spoke in public, warning of the imminent threat to humanity. Sometimes his warnings were quite vague in terms of the timescale, but other times not - he was reported as saying in 1968 that if current trends continued, by the year 2000, the UK would be a “small group of impoverished islands, inhabited by some 70 million hungry people". "If I were a gambler," he was quoted as saying, "I would take even money that England will not exist in the year 2000".But the UK did not collapse, the global death rate did not increase, and we have more food per person now than when he wrote the book. So, what went wrong with Paul Ehrlich's predictions of a population apocalypse?If you’ve seen a number or claim that you think More or Less should look at, email [email protected] CONTRIBUTORSVincent Geloso, Assistant Professor of economics at George Mason UniversityDarrell Bricker, global CEO of Ipsos Public Affairs and co-author of Empty Planet, the Shock of Global Population DeclinePeter Alexander, Professor of Global Food Systems at the University of EdinburghCREDITS:Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neil Editor: Richard Vadon

In most sports, men compete against men and women compete against women. That is generally considered fair, because men are faster, more powerful and have greater endurance.But there is an ongoing controversy about transgender women - people who were born male and now identify as women. Is it fair for them to compete in the women’s sport category or do they have an advantage?A study in the British Journal of Sports Medicine recently added to the debate with an analysis that found the strength and fitness of transgender women is “comparable” with that of women.More or Less looks into the research to explain what it does, and does not, say.Contributors:Professor Alun Williams, Manchester Metropolitan UniversityCredits:Presenter: Charlotte McDonald Reporter: Tom Colls Production co-ordinator: Brenda Brown Sound Mix: Gareth Jones Editor: Richard Vadon

On Saturday 28th February, the US and Israel launched a military attack on Iran, targeting the country's missile infrastructure, military sites and leadership.In response, Iran launched a wave of strikes across the region, including on Israel and the Gulf states.Iran has a stockpile of ballistic missiles, which it’s firing at neighbouring countries. These countries in turn are using interceptor missiles to try and shoot them down.But is it clear who will run out of missiles first?Contributor:Kelly Grieco, senior fellow at the Stimson CenterCredits:Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound Mix: Tom Brignell Editor: Richard Vadon

Have a million new species just been discovered?That’s the claim made by Dr Oliver Vince, co-founder of a company called Basecamp Research, who are collecting genetic data to train AI systems. The hope is that they’ll be able to use this to discover new medicines.But is this number a good one? Rob Finn, from the European Bioinformatics Institute, explains what is being counted and how you go about counting them.Credits: Presenter and producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neill Editor: Richard Vadon