Hot on the tail of China’s heatwave comes the other side of the extreme coin – tragic flooding. Also, a coming global shortage of sulfur, while scientists produce useful oxygen on Mars in the MOXIE experiment.

Prof Chunzai Wang is the Director of the State Key Laboratory of Tropical Oceanography in Guangzhou, China. He tells Roland about the surprising nature of the extreme temperatures and droughts much of China has been experiencing, and how they are connected to so many of the record-breaking weather events around the northern hemisphere this summer, including the tragic flooding in Pakistan.

Some people of course saw this coming. Richard Betts of the UK Met Office talks of a paper by one of his predecessors published 50 years ago exactly that pretty much predicted the greenhouse gas-induced climate change more or less exactly.

Clearly, the world needs to cut carbon emissions, and oil and coal would be sensible places to start. But as Prof Mark Maslin points out, this will come with its own consequences in terms of pressure on the industrial supply of sulfur and sulfuric acid, essential to so many other devices and processes. Can a shortage be averted?

And scientists working on Nasa’s Mars Perseverance team report more results this week. Alongside all the sensitive instrumentation aboard, an experiment known as MOXIE was somehow squeezed in to demonstrate the principle of electrolyzing Martian carbon dioxide to produce usable oxygen gas. As Michael Hecht explains, the tech is scalable and would be more or less essential to any viable human trip to Mars in the future.

(Image: The Jialing River bed at the confluence with the Yangtze River is exposed due to drought in August 2022 in Chongqing, China. The water level of the Jialing River, one of the tributaries of the Yangtze River, has dropped due to high temperature and drought. Credit: Zhong Guilin/VCG via Getty Images)

Presenter: Roland Pease

The Jezero Crater on Mars was targeted by Nasa’s Perseverence rover because from orbit, there was strong evidence it had at some point contained a lake. When the Mars 2020 mission landed, it didn’t take long to spot rocks protruding from the bottom that looked for all the world like sedimentary rocks – implying they were laid down from the liquid water and maybe perhaps even contain signs of past life. This week, the science team have published some of their analysis from the first 9 months of the mission. And, as Principal Scientist Kenneth Farley of Caltech tells Science In Action, the geology is clearly more complex, as it turns out they are igneous, perhaps resulting from subsequent volcanic activity.

Back on earth, Shane Cronin of the University of Auckland has been digging into the legend of the Kuwea volcano in Vanuatu. Folk tales have long talked of an inhabited island that once disappeared beneath the sea. Over the years some have linked these and the submarine caldera with an eruption that occurred in 1452, yet the evidence has been debated. But the Hunga-Tonga eruption earlier this year has shifted Shane’s perception of the evidence. As he describes, he now suspects the 1452 eruption was as much as 5-7 times bigger in magnitude, and likely preceded by smaller eruptions that could fit with some of the legends surrounding the story.

This type of evidence, interpreted from the testimony of those who live there, is increasingly being employed in conservation studies. Heidi Ma of ZSL in London and colleagues this week declared in Royal Society Open Science, the Dugong – a relative of the manatee - is now functionally extinct in Chinese waters, but they reached this conclusion from interviewing hundreds of individuals in fishing communities along that coast. And very few of them had ever seen one.

When CrowdScience listener Eric spotted a few gnats flying around on a milder day in mid-winter, he was really surprised - as surely insects die off in the cold? It got him wondering where the gnats had come from and how they'd survived the previous cold snap. So he asked CrowdScience to do some bug investigation.

Presenter Marnie Chesterton takes up the challenge and heads out into the British countryside – currently teeming with buzzes and tiny beasties - to learn about the quite amazing array of tactics these small creatures use to survive the arduous days of cold.

She hears how some insects change their chemical structure to enhance their frost resistance whist others hunker down in warmer microclimates or rely on their community and food stocks to keep them warm. Marnie also asks how climate change might be affecting insect over-wintering behaviour - and its implications for the lives of these crucially important organisms.

(Image: Jezero Crater. Credit: Getty Images)

East Africa has endured more than two years on continuous drought. The latest predictions suggest the drought is not likely to end any time soon. We look at why climate change and weather patterns in the Pacific and Indian oceans are largely to blame.

Andrea Taschetto, chief investigator at the Centre on Climate Extremes at the University of New South Wales discusses the latest predictions Drought has also been an issue in Europe, comparable with events nearly 500 years ago.

Chantal Camenisch at the Institute of History at Bern University in Switzerland has been delving into European drought history and says despite the vast differences in living conditions there are many parallels with today. When a dinosaur killing asteroid hit the earth did it have company? A suspected impact crater discovered off the coast of West Africa may have been caused at around the same time . Heriot Watt University geostratigrapher Uisdean Nicholson and University of Texas geologist Sean Gulick have been investigating. And we have some of the answers to why T Rex had such small eyes for the size of its skull, Stephan Lautenschlager at the University of Birmingham has the gruesome answer.

Also, Have you ever wondered why waterfalls appear white when still water is transparent? Why clouds, or snow, appear white when they too are essentially just water molecules in different states? What makes something white, opaque or transparent? These are the questions CrowdScience listener Gerardo has been pondering ever since taking in the beauty of fallen water on a hiking trail in his home of Cantabria, Northern Spain. Presenter Marnie, sets off on a quest to find out the answers to all of those questions and more. What even is white? Is it a colour, the absence of colour or all the colours of the rainbow combined? Is black really the opposite of white? And what colours do we mix to make white or black paint?

Image: Woman carrying water in drought, Kenya Credit: Getty Images

We talk to volcano scientist Ed Marshall in Iceland about working at the volcano which has burst into life spectacularly again after a year of quiet.

Also in the programme, we'll be following migrating moths across Europe in light aircraft to discover the remarkable secrets of their powers of navigation, and hearing how synthetic biology promises to create smarter and more adaptable genetically engineered crops.

Imagine waking up to the smell of freshly baked bread. Doesn’t it make your mouth water? Now imagine the smell of a fish market on a warm day… still feeling hungry? CrowdScience listener Thanh from Vietnam is intrigued by the effects of smell on our appetite, and wants to know whether certain aromas can make us feel more full than others. Never averse to a food-based challenge, presenter Anand Jagatia takes us on a journey from the nose to the brain, where we find out what exactly happens when we get a whiff of various foods. He discovers how the digestive system prepares for a meal and the extent to which our stomach has a say in whether or not we want to eat, based on how appetizing the smells are around us. Anand also explores our cultural differences. In some parts of the world a stinky Limburger cheese is considered a delicacy, while in other places it could make people lose their lunch. We’ll find out why some of us get triggered in different ways than others.

(Image: Lava spews from the volcano in Fagradalsfjall. Credit: Getty Images)

This week two research groups announced that they have made synthetic mouse embryos that developed brains and beating hearts in the test tube, starting only with embryonic stem cells. No sperm and eggs were involved. Previously, embryos created this way have never got beyond the stage of being a tiny ball of cells. These embryos grew and developed organs through 8 days – more than a third of the way through the gestation period for a mouse. Roland Pease talks to the leader of one of the teams, developmental biologist Magdalena Zernicka-Goetz of Cambridge University and Caltech about how and why they did this, and the ethical issues around this research.

Also in the programme: the latest research on how we spread the SARS-CoV-2 virus when we breathe. Infectious disease researcher Kristen Coleman of the University of Maryland tells us about her experiments that have measured the amounts of virus in the tiny aerosol particles emanating from the airways of recently infected people. The results underscore the value of mask-wearing and effective ventilation in buildings.

We also hear about new approaches to vaccines against the virus – Kevin Ng of the Crick Institute in London talks about the possibility of a universal coronavirus vaccine based on his research, and immunologist Akiko Iwasaki of Yale University extolls the advantages of nasal vaccines against SARS-CoV-2.

From dumping raw sewage into rivers to littering the streets with our trash, humans don’t have a great track record when it comes to dealing with our waste. It’s something that CrowdScience listener and civil engineer Marc has noticed: he wonders if humans are particularly prone to messing up our surroundings, while other species are instinctively more hygienic and well-organised.

Are we, by nature, really less clean and tidy than other animals? Farming and technology have allowed us to live more densely and generate more rubbish - maybe our cleaning instincts just aren’t up to the vast quantities of waste we spew out? CrowdScience digs into the past to see if early human rubbish heaps can turn up any answers. We follow a sewer down to the River Thames to hear about The Great Stink of Victorian London; turn to ants for housekeeping inspiration; and find out how to raise hygiene standards by tapping into our feelings of disgust and our desire to follow rules.

(Image: Stem cell built mouse embryo at 8 days. Credit: Zernicka-Goetz Lab)

In the last week, teams of astronomers have rushed to report ever deeper views of the universe thanks to the James Webb Space Telescope. These are galaxies of stars more than 13.5 billion light years from us and we see them as they were when the universe was in its infancy, less than 300 million years after the Big Bang. As University of Texas astronomer Steve Finkelstein tell us, there are some real surprises in these glimpses of the cosmic dawn. The super-distant galaxy that Steve's group has identified is named after his daughter Maisie.

Also in the programme: a 550 million year old fossil which is much the oldest representative of a large group of animals still with us today. The early jellyfish relative lived at a time known as the Ediacaran period when all other known complex organisms were weird, alien-looking lifeforms with no surviving descendants. Roland Pease talks palaeontologist Frankie Dunn at the University of Oxford who's led the study of Auroralumina attenboroughii.

Did the cultural invention of romantic kissing five thousand years ago lead to the spread of today's dominant strain of the cold sore virus (Herpes simplex 1) across Europe and Asia? That's the hypothesis of a team of virologists and ancient DNA experts who've been studying viral DNA remnants extracted from four very old teeth. Cambridge University's Charlotte Houldcroft explains the reasoning.

And, if a tree falls in a forest and no-one is there to hear it, does it make a sound? This is an age-old debate that listener Richard and his family have been arguing about for years. Can CrowdScience settle it once and for all?

Caroline Steel speaks to experts in hearing, biology, philosophy, physics and sound design, which takes her to some unexpected places.

Professor Stefan Bleek is an expert in psychoacoustics who says that sounds only exist in our heads.

Things get truly weird as we delve into the strange implications of quantum physics. If there is such a thing as reality, doesn’t it change when we’re there to observe it? Does the tree even fall if we aren’t there?

Image: Maisie's Galaxy aka CEERSJ141946.35-525632.8.

The extreme heat wave in western Europe over the last couple of weeks is just one of many in the Northern Hemisphere in 2022. How is global warming changing the atmosphere to make heat waves more frequent and more intense? We talk to climatologists Hannah Cloke, Friederike Otto and Efi Rousi.

If we want to stabilise global warming to two degrees by the end of the century, how are we going to do that? One novel idea is to harness the world's vast railway infrastructure and equip freight and passenger trains with an additional special wagon or two. These extra cars would be designed to suck carbon dioxide out of the air, liquify it and transport it to sequestration sites. Critically all the energy to capture the carbon dioxide comes free from regenerative braking on the trains. University of Toronto chemist Geoff Ozin and Eric Bachman, founder of the start-up CO2 Rail, explain the vision.

On the 40th anniversary of the International Whaling Commissions announcing an end to commercial whaling, we hear from Greenpeace co-founder Rex Weyler about the high seas campaign in the 1970s that helped prevent the extinction of the great whales. He talks about the contribution to the cause made by the discovery of whale song, and the release of humpback whale recordings as a commercial disc.

And, you have probably experienced an ‘earworm’ - a catchy bit of music that plays round and round in your head and won’t go away – at least for a short while. But why did it pop up in the first place and how did it get stuck?

CrowdScience listener Ryota in Japan wants us to dig into earworms, so presenter Datshiane Navanayagam bravely puts on her headphones to immerse herself in the world of sounds that stick. She meets with a composer of children’s songs as well as music psychologists to find out if there is a special formula to creating catchy songs and probes if this musical brain quirk serves any useful purpose. Datshiane then explores whether some people are more prone to catching earworms than others. Finally, for those who find this phenomenon disturbing - she asks is there a good way of getting rid of them?

Come join us down the audio wormhole - disclaimer - the BBC is not responsible for any annoying earworms caused by this broadcast.

(Image: Firefighter trucks burning during a wildfire on the Mont d'Arrees, outside Brasparts, western France, 19 July 2022. Credit: LOIC VENANCE/ AFP via Getty Images)

Roland Pease talks to two astronomers who began working on the James Webb Space Telescope more than two decades ago and have now seen the first spectacular results of their labours. Marcia Rieke of the University of Arizona and JWST's senior project scientist John Mather discuss the highlights of the first four images.

Also in the programme, geologists discover precisely where on the Red Planet the most ancient Martian meteorite came from - we speak to Anthony Lagain whose detective work identified the crater from which the rock was ejected into space. And what causes vast areas of the Indian Ocean to glow with strange light - a rare and mysterious phenomenon known as 'milky seas'? The world is a step closer to understanding this centuries' old maritime enigma thanks to the crew of a yacht sailing south of Java, atmospheric scientist Steven Miller and marine microbiologist Kenneth Nealson.

We are running out of ammunition against certain infections, as bacteria increasingly evade the antibiotics we’ve relied on for nearly a century. Could bacteriophages – viruses that hunt and kill bacteria – be part of the solution?

In 2019, CrowdScience travelled to Georgia where bacteriophages, also known as phages, have been used for nearly a hundred years to treat illnesses ranging from a sore throat to cholera. Here we met the scientists who have kept rare phages safe for decades, and are constantly on the look-out for new ones. Phages are fussy eaters: a specific phage will happily chew on one bacteria but ignore another, so hunting down the right one for each infection is vital.

Since then, we’ve lived through a pandemic, the medical landscape has been transformed, and interest in bacteriophages as a treatment option is growing throughout the world. We turn to microbiologist Professor Martha Clokie for updates, including the answer to listener Garry’s question: could phages help in the fight against Covid-19?

Following a bout of Covid-19, a significant number of people suffer with weeks or months of 'brain fog' - poor concentration, forgetfulness, and confusion. This is one of the manifestations of Long Covid. A team of scientists in the United States has now discovered that infection in the lung can trigger an inflammatory response which then causes patterns of abnormal brain cell activity. It’s the kind of brain cell dysregulation also seen in people who experience cognitive problems following chemotherapy for cancer.

Also in the programme, the latest discoveries about the asteroid Bennu from the Osiris Rex mission, how Malayasian farmers led US researchers to a botanical discovery, and a new explanation for why dinosaurs took over the world 200 million years ago.

Artists can conjure up people, cities, landscapes and entire worlds using just a pencil or a paintbrush. But some of us struggle to draw simple stick figures or a circle that’s actually round. CrowdScience listener Myck is a fine artist from Malawi, and he’s been wondering if there’s something special about his brain that has turned him into an artist. It’s a craft that combines visionary ideas with extraordinary technical skill, but where does that all come from? Do artists have different brains from non-artists? What is it that makes someone a creative person, while others are not? And is artistic ability innate, or is it something you can learn? Presenter Marnie Chesterton goes on a colourful journey into the mind to find out how artistic people see the world differently.

(Image: System of neurons with glowing connections. Credit: Getty Images)

Audio for this episode was updated on 8th July.

A new analysis of deaths in cities across Latin America suggests rising global temperatures could lead to large numbers of deaths in the region and elsewhere in the world. Even a 1-degree rise in extreme heat can add 6% to the risk of dying. Lead researcher Josiah Kephart at Drexel University tells Roland Pease the lessons from Latin America should apply to cities across the global south.

Brazilian ecologist Andreas Meyer talks about the troubling prospects for the health of ecosystems, particularly in tropical regions, if the world does not cut its fossil fuel emissions hard and fast in the next few years.

In the USA, a team of engineers and neurosurgeons are developing a radical new approach for targeted pain relief – in the first instance, for patients recovering from surgery. It’s a flexible implant that wraps around a nerve and cools it to prevent it from transmitting pain signals. What’s more, says bioengineer John Rogers, the implant is made of a material designed to have dissolved safely into the body by the time its pain-killing work is done.

Geologist Bob Hazen has spent more than a decade producing a new classification system for the 5,700 minerals known to exist on the Earth. It improves on the pre-existing scheme by taking into account the myriad ways that many minerals have come into being. He tells Roland that this new way of categorising minerals lays bare a 4.5 billion-year history of remarkable chemical and biological creativity.

And, Hair is an important part of our identities – straight, frizzy, long, not there at all – and our efforts to keep it styled and clean have created an $80 billion hair care industry. Many products offer to improve the life of the stuff on our heads, but isn't it all just dead protein?

CrowdScience listener Toria wants to know what 'healthy' hair really means. To untangle the science behind hair, we zoom in to see how hair grows from the follicles in our scalp and explore how the hair growth process will change over our lifetimes.

Changes in our hair and disorders affecting the scalp can often have emotional impacts on our lives, as presenter Marnie Chesterton learns from a dermatologist who specialises in hair issues.

Having been on a journey with her own hair in recent years following chemotherapy, Marnie is ready for a new 'do and ventures to the hair salon to find out about the health of her own hair.

Meanwhile, another CrowdScience listener, Lucy, wonders why humans lost hair (or fur) on most of our bodies when most other mammals are covered in the stuff. A biological anthropologist who studies not only why hair became concentrated on our heads, but also why there's so much diversity in hair types across humans, unpacks the evolutionary benefits.

Does different hair need different care? And when it comes to shampoo, conditioner, washing, blowdrying and dyeing, what should we be doing to keep our hair structure sound?

As we learn about this strange, non-living feature of our bodies, Marnie finds a new appreciation for the "dead strands of protein sticking out of our skin". And with listener Toria's help and advice, she also finds a new shade for her chemo-curled locks.

(Image: Rio de Janeiro City. Credit: Pintai Suchachaisri/Getty Images)