Thirty years ago, world leaders met at the United Nations Earth Summit in Rio and appeared to commit to action to tackle two of the world's greatest environmental threats. The Earth Summit launched the UN Climate Change Convention and the Convention on Biological Diversity. Science in Action assesses their success by talking to atmospheric scientist Sir Bob Watson, a former chair of the International Panel of Climate Change, and to Tom Oliver, professor of applied ecology at the University of Reading. Arctic zoologist Kristin Laidre tells us about the identification of an unique population of polar bears in Southeast Greenland. The bears’ unusual habitat and means of survival may make them more resilient to the loss of sea ice as the Arctic region continues to warm. Finally, archaeo-geneticist Maria Spyrou talks about her team’s detective work which points to an area of Kyrgyzstan in Central Asia as the likely source of the 14th Century Black Death pandemic. What is a quantum computer? Every year, new computers are being developed that are faster and smarter than ever before. But if you really want to take things to the next level, you have got to go quantum. CrowdScience listener Atikah in Hungary likes the sound of a quantum computer but wants to know what exactly is it, what can it do that a normal computer cannot, and how soon can he get hold of one? The digital devices in our everyday lives - from laptop computers to smartphones - are all based on 0s and 1s: so-called ‘bits’. But quantum computers are based on ‘qubits’ - the quantum 0s and 1s that are altogether stranger, but also more powerful. CrowdScience presenter Alex Lathbridge picks the brains of quantum scientists to find out how these ‘qubits’ allow computers to perform calculations millions of times faster than normal - and discovers how much of the theory is being used in reality. While quantum computers do exist, they are not yet big enough or stable enough to be really useful. Alex visits a working quantum computer to understand what they can do right now, and why it’s so incredibly difficult to scale them up. He hears from the engineers racing to overcome the obstacles and unlock the potential of these mega-powerful systems. But once the engineering problems are solved, what then? What should we do when the first really powerful quantum computer comes online? We explore the exciting range of possible applications - from helping create new drugs, to making electric batteries much more efficient and maybe even helping farmers fertilize their crops for a fraction of the price. Presenters: Roland Pease and Alex Lathbridge Producers: Andrew Luck-Baker and Cathy Edwards (Photo: Earth Summit In Rio De Janeiro, Brazil, 2 June, 1992 Credit: Antonio Ribeiro/Gamma-Rapho/Getty Images)

Researchers have developed a medical imaging technique which reveals where in the body HIV lies hidden, even when people have their infection well controlled by antiviral drugs. The team at the University of California, San Francisco hope this will lead to better treatments and even cures for HIV. As Timothy Henrich told us, they are also going to use the technique to investigate the notion that Long Covid is caused by the coronavirus persisting deep in the body's tissues. Also in the programme, Roland Pease reports from the vast particle accelerator in Switzerland where the famous Higgs particle was discovered ten years ago. The scientists there are preparing to begin experiments with an upgraded Large Hadron Collider to learn more about the particle and the fundamental nature of the Universe. Roland also talks to Frank Close, physicist and author of 'Elusive' - a new biography of Peter Higgs, a scientist as elusive as the particle named after him. Finally an international team of archaeologists have revised the ancient history of the chicken, with a new programme of radiocarbon dating and analysis of buried bird bones. Humanity's relationship with the bird began much more recently than some researchers have suggested. Naomi Sykes of Exeter University and Greger Larson of Oxford University tell Roland when, where and how the domestication began and how the birds spread from Southeast Asia to the rest of the world. And, Humans can walk for miles, solve problems and form complex relationships on the energy provided by three meals a day. That's a lot of output for a fairly modest input. Listener Charlotte from the UK wants to know: how are we so efficient? And how does human efficiency compare to that of machines? CrowdScience presenter Marnie Chesterton pits her energetic wits against everything from cars to wheelchairs to find out how she shapes up. Cars can travel many hundreds of kilometres a day if you give them a couple of tanks of fuel. But the only fuel Marnie needs to walk to work is a cup of coffee. She gets experts to help her work out who does the most efficient job. Marnie also explores whether humans are born equal when it comes to fuel efficiency. Does the energy from one banana get converted into the same amount of movement from person to person? And how does she compare to an Olympic athlete? Marnie gets put through her paces to find out how efficient she really is. Image: VRCPET body scan reveals HIV's hideouts Credit: Timothy Henrich / University of California, San Francisco

Should we worry about the most recent Omicron subvariants, BA 4 and BA5? They are the subtypes of the Covid-19 virus now dominant in southern Africa and spreading elsewhere. New research suggests that they are better at evading our antibody defences than other forms of the virus. Columbia University virologist David Ho explains the findings and what they means for us. Also, reducing air pollution makes agricultural crops grow better, how large wildfires warm the upper atmosphere, and the dolphins in the Red Sea which use secretions from corals and sponges as preventative medicines. This week’s CrowdScience is dedicated to bodily fluids – and why humans spend so much time spraying them all over the place. From snot and vomit to sweat and sneezes, listeners have been positively drenching our inbox with queries. Now presenter Marnie Chesterton and a panel of unsqueamish expert guests prepare themselves to wade through… One listener has found that as he ages, bright light seems to make him sneeze more and more – with his current record sitting at 14 sneezes in a row. He’d like to know if light has the same effect on other people and why? Sticking with nasal fluids, another listener wants to know why she’s always reaching for a tissue to blow her endlessly dripping nose and yet her family seem to produce hardly any snot at all. Could it be because she moved from a hotter climate to a colder one? CrowdScience reveals the answers to these and other sticky questions… if you can find the stomach to listen. Image Description: Coronavirus COVID-19 virus Credit: Getty Images

This week Science in Action comes from a vast gathering of earth scientists in Vienna, at the general assembly of the European Geosciences Union. Roland Pease hears the latest insights into the cataclysmic eruption of Hunga Tonga in the Pacific ocean from volcanologist Shane Cronin of the University of Auckland. He also talks to NASA's Michael Way about how the planet Venus might have acquired its hellish super-greenhouse atmosphere, and how the same thing could happen to planet Earth. There’s intriguing research from geologist John Tarduno of the University of Rochester that hints of a link between the ups and downs of the Earth’s magnetic field and the evolutionary history of animals. Fraser Lott of the UK's Hadley Centre explains his ideas for calculating an individual person's responsibility for climate change-driven extreme weather events. And ... On Crowd Science, why can't I find gold in my back yard? If you go outside with a spade and start digging, the chances are you won't find any gold. You might get lucky or just happen to live in a place where people have been finding gold for centuries. But for the most part, there'll be none. But why is that? Why do metals and minerals show up in some places and not others? It's a question that's been bothering CrowdScience listener Martijn in the Netherlands, who has noticed the physical effects of mining in various different places while on his travels. It’s also a really important question for the future – specific elements are crucial to modern technology and renewable energy, and we need to find them somewhere. Marnie Chesterton heads off on a hunt for answers, starting in a Scottish river where gold can sometimes be found. But why is it there, and how did it get there? Marnie goes on a journey through the inner workings of Earth's geology and the upheaval that happens beneath our feet to produce a deposit that’s worth mining. On the way she discovers shimmering pools of lithium amongst the arid beauty of the Atacama Desert, meets researchers who are blasting rocks with lasers and melting them with a flame that’s hotter than the surface of the sun, and heads to the bottom of the ocean to encounter strange potato-sized lumps containing every single element on Earth. And maybe, just maybe, she’ll also find gold. Image: Multi-beam sonar map of Hunga Tonga volcano post-eruption Credit: Shane Cronin/Uni of Auckland/Tonga Geological Services Presented by Roland Pease and Marnie Chesterton Report by Jane Chambers Produced by Andrew Luck-Baker and Ben Motley

Tree mortality in tropical moist forests in Australia has been increasing since the mid 1980s. The death rate of trees appears to have doubled over that time period. According to an international team of researchers, the primary cause is drier air in these forests, the consequence of human-induced climate change. According to ecologist David Bauman, a similar process is likely underway in tropical forests on other continents. Also in the programme: the outbreaks of monkeypox in Europe and North America… Could SARS-CoV-2 infection lingering in the gut be a cause of Long Covid? News of a vaccine against Epstein Barr virus, the cause of mononucleosis, various cancers and multiple sclerosis. Digging and excavating are bywords for archaeology. But why does history end up deep under our feet? This question struck CrowdScience listener Sunil in an underground car park. Archaeological remains found during the car park’s construction were displayed in the subterranean stairwells, getting progressively older the deeper he went. How had these treasures become covered in so much soil over the centuries? CrowdScience visits Lisbon, the capital of Portugal – and home to the above-mentioned multi-storey car park. The city has evidence of human habitation stretching back into prehistory, with remnants of successive civilisations embedded and jumbled up below today’s street level. Why did it all end up like this? Human behaviour is one factor, but natural processes are at work too. Over at Butser Ancient Farm, an experimental archaeology site in the UK, we explore the myriad forces of nature that cover up – or expose - ancient buildings and artefacts over time. Image: Credit: Getty Images