An ancient Babylonian text, Hammurabi’s Code of Laws, forbids the cutting down of street trees without permission. Nearly 4000 years later, threats to our urban trees still arouse the strongest passions. Coventry residents organised a record-breaking mass tree hug in November to save 26 trees marked for the chainsaws and the battle to save thousands of Sheffield's street trees from the council's contractors inspired folk songs and expensive legal battles.

As so many of us bring a tree home for Christmas, Tom Heap and Helen Czerski consider our feelings about street trees, the sweet hit of nature that provides year round shade and wildlife habitat in the least promising of city circumstances.

They're joined by Jon Stokes of the Tree Council, landscape historian Sonia Dümpelmann and Paul Powlesland, barrister and founder of Lawyers for Nature.

Producer: Alasdair Cross

Assistant Producers: Ellie Richold and Toby Field

Rare Earth is produced in association with the Open University

With fans travelling halfway across the country, stars expecting first class flights and venues serving up beefburgers and drinks in plastic cups the worlds of professional sport and live music share a pretty poor reputation for environmental impact. Add in the wasteful habits of high end film and TV productions and it starts to look as though anything that's fun has a disproportionate impact on the planet.

In Liverpool, they're hoping to change all that. The United Nations has asked the city to use its reputation as a hotbed of culture to devise ways to cut the carbon cost of live events and film production. To launch the project the city is hosting a conference and a series of high profile gigs with Massive Attack, Idles and Chic to showcase best practice and spread the word that fun doesn't need to cost the planet.

Helen Czerski and Tom Heap host a panel from the worlds of sports, entertainment and science to discuss a green future for fun, in front of an audience at Liverpool's Exhibition Centre.

Producer: Alasdair Cross

Assistant Producer: Toby Field

Rare Earth is produced in association with the Open University

It's been a hard year for the Amazon rainforest. The toughest drought on record has helped spread fires that have been the worst in two decades. That combination has hit the local people. “If these fires continue, we indigenous people will die,” says Raimundinha Rodrigues Da Sousa who runs the voluntary fire service for the Caititu indigenous community in the Brazilian Amazon. Her land is supposed to be protected but outsiders come in and set fires so that they can clear the land for agriculture.

For Rare Earth, Tom Heap and Helen Czerski take a look at the state of the Amazon rainforest, analyse its role in the global climate and consider the political battle over its future. They're joined by BBC South America correspondent, Ione Wells and by Angela Maldonado who has worked for 25 years in the Amazon, protecting night monkeys that are stolen and traded for medical research. Based on the Colombia-Peru-Brazil border, Angela has a unique perspective on the long-running war between development and conservation in the region.

Patricia Medici explains her work to conserve the extraordinary tapir, South America's largest land mammal and Niki Mardas reveals the latest results from Global Canopy's Forest 500 campaign which examines the involvement of 500 major companies in the supply chains which hasten the destruction of the Amazon rainforest.

Producer: Alasdair Cross

Assistant Producer: Ellie Richold

Rare Earth is produced in association with the Open University

Some of the wealthiest tech entrepreneurs share a vision of life beyond the horizon. They see a future for humankind that abandons our tired, dirty planet and creates new colonies of health and creativity on the Moon, on Mars or even further into deep space. Is this a wise precaution for all our futures or an insurance policy for the super-wealthy as they continue to trash our home planet? Tom Heap and Helen Czerski are joined by British astronaut, Tim Peake to consider the big moral questions of space colonisation and the practical problems of devising ways to make the best of the extraordinary possibilities of space without increasing the pressure on Earth’s resources. If we do colonise another planet how do we avoid making the same mistakes again? How do we grow food and find or produce freshwater? How can we travel to, from and around these planets without burning more fossil fuels? Could the answers help us all live a better life right here, right now? Joining Helen, Tom and Tim in studio are Eloise Marais, who leads the Atmospheric Composition and Air Quality research group at University College London and co-chair of the Environmental Task Force at Space Scotland, Andrew Fournet, and Tom pays a visit to a company in Bletchley who are developing nuclear fusion propulsion.

Producer: Alasdair Cross

Produced in association with the Open University

Our love affair with plastic has grown beyond all expectations since we were first introduced to the substance in the mid 20th century, and the rate at which we're using it shows no sign of slowing. But the tidal wave of plastic pollution we've unleashed is causing serious environmental problems. In this programme, Helen Czerski and Tom Heap hear how some of our plastic waste is burnt in incinerators or sent overseas, causing pollution far from our shores. In their search for solutions, they visit the Plastic Waste Innovation Hub at University College London, where Professor Mark Miodownik shows them how science is trying to keep up with the proliferation of plastic pollution. Back in the studio, they're joined by Professor Steve Fletcher from the University of Portsmouth, Sally Beken from Innovate UK, and environmental journalist Leana Hosea from Watershed Investigations, to talk about how we got here and how we can change our relationship with plastic. In the 2000s the amount of plastic waste generated rose more in a single decade than it had in the previous forty years. It's in everything - from our clothes, cars and cosmetics, to the 2.5 billion disposable drinks cups now discarded every year in the UK. It seems we can't live without it. So Helen and Tom ask: who's in charge now - us or plastic?

Producer: Emma Campbell

Produced in association with the Open University

Nothing beats the sight of a top predator as it hunts. In the British Isles that means looking up. Our birds of prey are bouncing back after decades of shooting, poisoning and habitat loss. Buzzard numbers are up by 80% since 1995 and Red Kite by 2000%. Peregrine Falcon are thriving in London and Marsh Harriers have returned to our wetlands.

Helen gets up close to Black Kites and an Eagle Owl at the Owl and Raptor Centre in Kent and travel writer Antonia Bolingbroke-Kent describes the extraordinary migration of tens of thousands of birds of prey through the Batumi Gap on the border of Georgia and Turkey.

The RSPB's Mark Thomas and Robert Benson of the Moorland Association discuss the threat that birds of prey still face on some of Britain's shooting estates and Jennifer Ackerman, author of 'What An Owl Knows' joins Tom and Helen to explore the science behind the night-hunting skills of so many owls.

Producer: Alasdair Cross

Assistant Producer: Toby Field

Rare Earth is produced in association with the Open University

How can we build new green infrastructure without wrecking the countryside? Helen Czerski and Tom Heap debate the issue with a panel of experts, and ask what the measures outlined in last week's budget will mean for planning decisions and the environment. On the panel this week: Emma Pinchbeck, new CEO of the Climate Change Committee; Roger Mortlock, chief executive of the CPRE - the Countryside Charity; and Professor Matthew Kelly, modern historian from Northumbria University.

Producer: Emma Campbell

It's four metres long, the weight of two grizzly bears and dangerously delicious. The Bluefin Tuna is back in British waters so Tom Heap and Helen Czerski are here to celebrate the role of the tuna in food, culture and nature.

Unseen since the 1960s, these enormous fish have surprised surfers and anglers by leaping clear out of the waters of South-West England. Rare Earth takes a deep dive with the tuna to examine their unusual biology and their cultural importance to people all around the world. They can live up to 60 years, dive up to 1km below the ocean surface and swim as fast as 40 km per hour. Unfortunately for the bluefin, they’re particularly tasty, prized for their meaty sashimi, with some fish reaching prices close to £2m in the ceremonial new year auction at Tokyo’s fish market.

Tom explores the intense Japanese relationship with tuna while Helen makes a plea to give this fish the respect it deserves- we should celebrate its extraordinary biology rather than stuffing it in a tiny can with a ‘dolphin-friendly’ stamp on the label.

Producer: Alasdair Cross

Assistant Producer: Toby Field

Rare Earth is a BBC Audio Wales and West production in conjunction with the Open University

US elections always have an outsized impact on the planet. As the world's second largest polluter and one of the primary sources of green technology and finance, America's lead on environmental issues is a vital part of our battle against climate change.

Tom Heap and Helen Czerski analyse the efforts of the Biden regime and examine the rival policies of Harris and Trump. Joe Biden's Inflation Reduction Act is said to have helped channel half a trillion dollars into clean technology and renewable energy. Has all that money brought down emissions or funded fresh answers to the planet's biggest challenge? Trump talks tough on the environment, supporting oil, gas and coal companies but did his presidential term really accelerate global warming?

Tom and Helen are joined by Professor Leah Stokes from the University of California, Santa Barbara, Trisha Curtis, CEO of PetroNerds and presenter of the PetroNerds podcast and by Pilita Clark, Associate Editor and environment and business columnist for the Financial Times.

Producer: Alasdair Cross

Assistant Producer: Toby Field

Rare Earth is a BBC Audio Wales and West production in conjunction with the Open University

The environment and wildlife show returns with a celebration of the humble microbe. Tom Heap and Helen Czerski are joined by a ‘microbe explorer’ who travels to some of the Earth’s most hostile environments in search of microbes with a huge appetite for carbon dioxide. They also be visit the crop trial field station of Imperial College London where researchers are studying changes to bacteria in soil that could help agriculture and the environment.

Producer: Emma Campbell

Assistant Producer: Toby Field

Rare Earth is made by BBC Audio Wales and West in association with the Open University.