Author: BBC World Service

Removing carbon dioxide from our atmosphere - and stopping it getting up there in the first place - is becoming increasingly urgent if we want to prevent catastrophic climate change. There are some seriously high tech machines being developed to try and tackle this problem, but could an equally powerful solution be found in the dirt under our feet? Prompted by New Zealand farmer and CrowdScience listener Kem, we dig deep to see how effectively plants and soils soak up CO2 from the air; and what that means for how we should farm the land around the world. And we visit a Scottish forest to find out how the ancient art of making charcoal is staging a comeback in the fight against climate change.

Presenter: Marnie Chesterton Producer: Cathy Edwards for BBC World Service

(Photo: A young plant in soil, in the morning light. Credit: Getty Images)

We may take our ability to smell for granted but it’s a far more complex sense than many people realise. Listener Annabel wants Crowdscience to investigate why perfume makes her queasy, so Anand Jagatia sets out to discover why we can’t all agree when we follow our noses. He gets a whiff of the world’s stinkiest flower - and finds some people enjoy it – then asks what’s happening in the brain when we love or hate a scent. But could our different perceptions about this under-appreciated sense actually come down to a lack of words to describe it? He hears about one culture which has developed its own language for smell. Presenter: Anand Jagatia Producer: Marijke Peters

(Image: A woman smelling roses. Credit: Getty Images)

Communicating quickly, accurately and, ideally, in a way that's well-received is no easy feat, wherever you live in the world. For this week's listener, who lives and works in several different countries as a member of the armed forces, good communication can be a matter of life or death. And this doesn’t just affect military life – anyone who flies on aeroplanes may be interested to hear how clear use of language is crucial for airline safety.

But what do we mean by an efficient language – it is the fastest and most accurate speech, or most widely understood in multiple countries? Maybe there’s even some technology – a machine out there that can do the communicating more efficiently than we can? Presenter Marnie Chesterton attempts to apply science and evidence to the art of speech, in a quest to discover what language is the most efficient on Earth.

Produced by Jen Whyntie

(Image: A group of people holding up speech bubbles sitting on a bench. Credit: Getty Images)

From IVF to premature babies we explore what science we would need to make a baby outside the body in a pursuit to answer a question from Nigerian listener, Aminu asking: Can we make an artificial womb?

To find out, presenter Nastaran Tavakoli-Far gets very close to a uterus transplant operation, peers at the earliest cells of a placenta, and sees a disembodied womb being kept alive in a box full of artificial blood. She asks how close current reproductive medicine brings us to gestating babies in a lab.

Producer: Rory Galloway

(Photo: A human fetus. Credit: Getty Images)

How should we tackle the biggest clean-up job in history? Listener Michelle from Ireland sends CrowdScience to investigate what to do with years’ worth of spent nuclear fuel. Most of the highly toxic waste is a by-product from nuclear power production and the stockpiles across the world continue to grow. “Could we blast it into the sun? Dilute it across the continent? Or should we bury it?” Michelle asks.

We travel deep into the Finnish bedrock to visit what could be its final resting place and speak to the scientists who are securing the facility many ice-ages into the future. The nastiest stuff in the waste soup needs to stay put for thousands of years before it becomes safe. No man-made structure has ever before lasted so long. The Finnish solution is not easy to replicate in other countries as communities oppose nuclear waste being permanently buried in their backyard.

Presenter Marnie Chesterton discovers that scientists have come up with solutions that could let us recycle the spent fuel more effectively, but it costs more than the industry is willing to spend. The clean-up job of the century comes down to dollars and not science.

Presenter: Marnie Chesterton Producer: Louisa Field

(Photo: a man in protective workwear in waste factory. Credit: Getty Images)

Mohammed is from India and he’s blind. He emailed CrowdScience because he wanted to know more about new technologies that could help him see again. Specifically, he was interested in artificial vision - what is it and what does it look like?

Bobbie Lakhera travels to Germany to find out. There, she meets a blind patient called Manuel. He’s about to have a major operation. A computer chip will be implanted into his eye and his surgeon, Florian Gekeler, believes that it will restore some of Manuel’s sight. But what happens if you have no eyes for a chip like this to be inserted into? Bobbie speaks to Dr Nader Pouratian about his brain prosthesis. Because the implant is attached directly to the visual cortex of the brain, it means you could have no eyes or no optic nerve and you could still see with this type of therapy. Whilst both these technologies are limited to black and white vision, Bobbie asks whether one day we may be able to develop systems that give those living with blindness 20/20 vision.

Presenter: Bobbie Lakhera Producer: Graihagh Jackson

(Photo: A female iris, bionic eye concept. Credit: Getty Images)

When it comes to speed, humans have got nothing on cheetahs - or greyhounds, kangaroos or zebras for that matter. It’s over long distances we really come into our own: when running for hours or even days, our body structure and excellent sweating skills make us able to outpace much faster mammals.

But what are the limits of human endurance? Can we run ever further and faster, and what’s the best diet to fuel such ambitions? This week’s questions come from two CrowdScience listeners in Japan who already know a fair bit about stamina, having run several marathons and long-distance triathlons between them. We head to Greece, legendary birthplace of the marathon, to witness an even more arduous challenge: hundreds of athletes following in the footsteps of the ancient Greek messenger Pheidippides, to run an astonishing 246km across the country. The ever-so-slightly less fit CrowdScience team do our best to keep up, and try to discover the secrets of these runners’ incredible endurance.

Presenter: Marnie Chesterton Producer: Cathy Edwards

(Photo: a runner in the Spartathlon ultramarathon, with kind permission from the International Spartathlon Association)

Would you willingly break a mirror, walk under a ladder or cut up an image of someone you love - or might you be worried about tempting fate – even if you don’t believe in supernatural forces? Anand Jagatia enters the world of magical thinking on behalf of CrowdScience listeners to explore why - even in this era of scientific rationalism – superstition, magic and belief in concepts like the evil eye and luck appear deeply entrenched in our cultures and psyche. Meeting historians and psychologists, Anand sets out to reveal the enduring lure of superstition and explore the biological factors that can influence us, like how our brains have evolved to look for connections and find patterns in seemingly random events. Is it possible that some people are ‘lucky’ and can we enhance our own ‘luck’? Experimental evidence is thin on the ground but finger’s crossed, CrowdScience can find some. Presenter: Anand Jagatia Producer: Melanie Brown

(Image: A handmade Voodoo Doll with pins. Getty Images)