This summer, many parts of the world have seen devastating flooding, from New Orleans and New York, to the UK, Germany and Belgium. More than 300 people lost their lives in floods in central China, including a number who were trapped in a subway train in the city of Zhengzhou. Professor Hannah Cloke of the University of Reading is a natural hazards researcher and hydrologist, who spends her time trying to prevent these terrible losses. She models where flooding is likely to happen and advises governments.

Hannah Cloke talks to Jim al-Khalili about how her fascination with the water on the earth goes back to her childhood – her memories of holidays for instance all revolve around swimming or building dams on the beach. She is now passionate about finding new ways of telling the public about the dangers of flooding, which includes writing poetry.

How many of you have sleep problems? Maybe it’s waking up in the middle of the night and then not being able to get back to sleep, or waking up too early, or nodding off all too often in front of the TV… or, more embarrassingly, during work meetings? One thing’s for sure: our modern world means that we are not sleeping in the way we used to. Derk-Jan Dijk, Distinguished Professor of Sleep and Physiology at the University of Surrey and Director of the Surrey Sleep Centre, says: we are the only species to extend our day using artificial light, and that has consequences.

Jim Al-Khalili talks to Derk-Jan Dijk about the many aspects of sleep that he has studied over the last thirty years – such as how circadian rhythms interact with our sleep cycles, and how sleep changes in people with dementia.

When did you last really think about the amount of electricity your household uses? Are all your appliances A rated? Have you switched to LED lights? And what about the Energy Performance Certificate of your home? Is there room for improvement there?

For decades now, Brenda Boardman has been thinking about how to reduce the amount of energy we use in our homes. We have Brenda to thank for the rainbow-coloured energy efficiency labels with their A- G ratings that appear on new fridges, freezers, TVs, dishwashers, and washing machines. As a result of these labels and subsequent legislation, it’s no longer possible to buy an energy inefficient fridge or incandescent light bulbs. And there’s a strong incentive for manufacturers to make appliances ever more energy efficient. But the introduction of the Energy Performance Certificate for homes has been less successful.

So, is achieving carbon net zero in our homes a realistic proposition?

Brenda tells Jim Al-Khalili how much she learnt travelling the world, having just missed out on a place at university. And why in her thirties she decided to study part-time for a degree. Working and bringing up children at the same time, it took a while to complete a degree and then a PhD. But, aged 48, Brenda began her academic career working at the Environmental Change Institute in Oxford and has no regrets about the time she spent getting to know who she was an what the world was like.

Producer: Anna Buckley

Literature student turned neuroscientist, Prof David Eagleman, tells Jim Al-Khalili about his research on human perception and the wristband he created that enables deaf people to hear through their skin. Everything we see, taste, smell, touch and hear is created by a set of electro-chemical impulses in the dark recesses of our brain. Our brains look for patterns in these signals and attach meaning to them. So in future perhaps we could learn to ‘feel’ fluctuations in the stock market, see in infra-red or echo-locate like bats? Each brain creates its own unique truth and David believes, there are no real limits to what we humans can perceive.

‘I didn’t know I wanted to be a mathematician until I was one’ says Hannah Fry, now a Professor in the Mathematics of Cities at University College London. Her mother pushed her hard at school, coming down on her like a tonne of bricks when she got a C for effort in mathematics. Never mind that she was top of the class. By the time she’d finished a PhD in fluid dynamics, she had realised that she probably wasn’t going to be a hairdresser and pursued her other passion, Formula One. Sadly F1 wasn’t the dream job she’d imagined: all the interesting equations were wrapped up in computer simulations and no further maths was needed.

Keen to continue doing mathematics, she joined the Centre for Advanced Spatial Analysis at University College London just as people were starting to use data to understand human behaviour. (Yes. If you zoom out enough and use some mathematical tools, there are parallels between the airflows around racing cars and the way humans behave.) She has studied everything from the mathematics of love to civil unrest, and has advised governments and Deep Mind, the artificial intelligence research lab owned by Google.

At a public lecture in Berlin in 2018, she learnt the hard way that it’s a mistake to detach data from its context. Never again will she forget to ask, what do these numbers represent? How else could my algorithms be used? Is this something we, as a society, want?

Data and algorithms help humans to solve problems. Big, difficult problems like climate change and Covid-19. Mathematics can help us to police a riot or find love. But the idea that maths and numbers are value-neutral is deeply flawed, Hannah says. The artificial intelligence we create is a reflection of who we are. It can discriminate horribly. But, applied wisely, it could help us to start to overcome our unconscious biases and prejudice.

We humans are not perfect. Neither is AI. If we scrutinise the algorithms that now make so many decisions for us and make sure that their priorities are our priorities, then perhaps we can get the best of both. In the Age of the Algorithm, humans have never been more important

Hannah Fry tells Jim Al-Khalili about her life as a mathematician and why her attitude to risk and statistics changed dramatically earlier this year.

Producer: Anna Buckley

Certainty is comforting. Certainty is quick. But science is uncertain. And this is particularly true for people who are trying to understand climate change.

Climate scientist, Tamsin Edwards tackles this uncertainty head on. She quantifies the uncertainty inherent in all climate change predictions to try and understand which of many possible storylines about the future of our planet are most likely to come true. How likely is it that the ice cliffs in Antarctica will collapse into the sea causing a terrifying amount of sea level rise?

Even the best supercomputers in the world aren’t fast enough to do all the calculations we need to understand what might be going on, so Tamsin uses statistical tools to fill in the gaps.

She joined the International Panel on Climate Change (IPCC) in 2018 and is currently working on the 6th Assessment Report which will inform the 2021 United Nations Climate Change Conference, COP26.

She tells Jim Al-Khalili about her life and work and why she wishes more people would have the humility (and confidence) to consider the possibility that they might be wrong.

Producer: Anna Buckley

As the craze for cold water swimming continues, Jim Al Khalili talks to triathlete and Professor of Extreme Physiology, Mike Tipton. Is it as good for our mental and physical health as many enthusiasts claim? And do the benefits go beyond a rush of adrenaline causing feel good endorphins to be released in our brains?

Mike studies why people drown. He wants to understand the precise physiological changes that occur when we expose ourselves to extreme environments and to use that information to help save lives. (Shivering and sweating will only get you so far when it comes to temperature control).

Most deaths at sea are caused by the initial cold water shock response, not hypothermia. People gasp for air and swallow lethal quantities of water.

What does the scientific evidence say about the idea that repeated cold water immersion can boost our immunity and have an anti-inflammatory effect?

Mike tells Jim how he came to specialise in this area of science and why he believes we should all be challenging our bodies more.

Producer: Anna Buckley

When does a crowd of people become unsafe? How well will Aston Villa do next season? When is it cost-effective to replace a kitchen?

The answers may seem arbitrary but, to Nira Chamberlain, they lie in mathematics. You can use maths to model virtually anything.

Dr Nira Chamberlain is President of the Institute of Mathematics and its Applications, and Principal Mathematical Modeller for the multinational engineering company SNC-Lavalin Atkins.

He specialises in complex engineering and industrial problems, creating mathematical models to describe a particular feature or process, and then running simulations to better understand it, and predict its behaviour.

Nira is one of just a handful of esteemed mathematicians, and the first black mathematician. to be featured in ‘Who’s Who’, Britain’s book of prominent people.

Since 2018, he’s made the Black Power List, which celebrates the UK’s top 100 most influential people of African or African-Caribbean heritage, ranking higher than Stormzy and Lewis Hamilton when he was first listed. Proof, he says, that maths really is for everyone.

PRODUCER: Beth Eastwood

Luminescent bone-eating worms, giant squid and a sea cucumber commonly known as the headless chicken monster: some extraordinary creatures live at the bottom of the sea. For a long time almost everyone agreed the pressure was too intense for any life to exist. Now, it seems, the more we look the more new species we find. But, many fear, marine life would be threatened if plans to extract precious metals from the potato-sized metallic nodules that grow on the seabed are allowed to go ahead.

Metals such as copper, manganese and cobalt are in high demand in the manufacture of mobile phones and renewable energy technologies, such as batteries for electric cars, wind turbines and solar panels. Deep sea mining companies argue that we will need these metals to create a carbon Net Zero economy. Meantime, the World Wildlife Fund is pushing for a moratorium on deep sea mining. And several companies agree: including Google, BMW, Volvo and Samsung. Do we need to choose between green and blue? Or is there a third way that protects both the planet and all the riches in our oceans?

Marine biologist, Helen Scales talks to Jim Al-Khalili about her life and work: fish watching off an atoll in the South China Sea to assess the extinction risks to the Humphead Wrasse and a research expedition to explore the brilliant abyss. And she warns of the environmental devastation that could be caused if plans to mine the metals on the bottom of the ocean were to be allowed to go ahead.

Producer: Anna Buckley

Throbbing head, nausea, dizziness, disturbed vision – just some of the disabling symptoms that can strike during a migraine attack. This neurological condition is far more common than you might think, affecting more people than diabetes, epilepsy and asthma combined.

While medications, to help relieve the symptoms of migraine, have been around for some time, they haven’t worked for everyone. And what happens in the brain during a migraine attack was, until recently, poorly understood.

Peter Goadsby is Professor of Neurology at King's College London’s Institute of Psychiatry, Psychology & Neuroscience and is a true pioneer in the field of migraine.

Over the course of his career, he has unravelled what happens in the brain during a migraine attack and his insights are already benefiting patients - in the form of new medications that can not only treat a migraine, but also prevent it from occurring.

Peter shares this year’s Brain Prize, the world's largest prize for brain research, with three other internationally renowned scientists in the field.

Producer: Beth Eastwood