Large hydro-electric dams continue to be planned and built in Africa, Asia and South America. In Western Europe and the US they're tearing them down. Peter Gibbs wants to know why.

These wonders of engineering are a symbol of our ability to harness nature to produce renewable energy. The trouble is that many dams radically alter the natural life of rivers and harm their ecosystems. The majority of rivers in Europe and the US have dams on them, many of which are aging and no longer serve any useful purpose. Gradually the conversation is changing and communities are realising that dams don't have to be forever. Now there's a growing movement to remove the worst offenders and restore rivers to their natural state.

France is currently embarking on the biggest dam removal in Europe. Two large hydro-electric dams will soon be demolished on the River Sélune in Normandy. Here a choice had to be made between energy production and biodiversity. Peter Gibbs meets the different groups involved in the project to find out how they are planning for the removals. Will the opening up of wild salmon migration routes and improvements in water quality make up for the loss of low-carbon energy?

Producer: Sophie Anton.

We've just endured a really tough winter but records suggest that Spring is on average beginning much earlier. Lindsey Chapman investigates how shifting seasons are affecting our wildlife.

Bumblebees in January, daffodils blooming early, 'thuggish-vegetation' thriving as a result of mild winters and damp summers: the seasons appear to be blurring and wildlife is becoming confused. The overall impact is 'quite staggering' according to Matthew Oates, butterfly expert from the National Trust.

In this week's Costing The Earth, Lindsey Chapman meets Matthew as he takes stock of our shifting seasons. He explains how early spring can throw several species out of kilter, creating a mismatch between wildlife and their prey. And what happens when- like this year- we get an icy snap in the middle of a mild spell?

Lindsey meets the scientists studying the mechanisms driving the UK's climate, phenologists who have been studying the link between seasons and species and the naturalists who are spotting new species turning up on our doorstep.

Producer: Martin Poyntz-Roberts.

Colombia is second only to Brazil in the extent of its rich biodiversity but armed conflict over a half century has limited exploration and charting of much of its land. Those researchers who braved it risked kidnap, injury or death. But in 2016 President Santos signed a peace treaty with the FARC guerrilla fighters which has opened the door for collaborations and exploration of previously occupied areas home to potentially thousands of new species of flora and fauna.

Costing the Earth follows teams from Kew Gardens, led by Colombian Mauricio Diazgranados, as they travel into uncharted territories and reveal what they see.

Presented by Tom Heap

It's a decade since Donald Trump began building his golf resort on the enormous mobile sand dunes of Balmedie in Aberdeenshire. Conservation organisations bitterly protested and the idea of building golf courses on sensitive dune habitats seemed tainted. Today, however, a new course is being proposed for Coul Links on the stunning coastline to the north of Inverness. Peter Gibbs investigates the impact of Trump's development and the increasingly bitter controversy over the new course.

Producer: Alasdair Cross.

Anything made from oil can now be made from trees, so is a new age of wood about to dawn? Tom Heap visits Finland which is pushing for a new industrial revolution based on trees and plants rather than oil and coal. He takes a glimpse into a future where cars, clothes, computers screens, and everything else we buy could begin its life in the forest. And he finds out how the UK is leading the way towards wooden skyscrapers.

Producer Sarah Swadling.

Around two thirds of fibres produced globally are synthetic material - many used in our clothing. It's emerged that plastic microfibres are being shed when we wear and wash these items - which ironically include fleeces and kit worn by 'outdoorsy types' like Tom Heap. With microplastics in the marine environment now high on the agenda, Tom hears how these tiny invisible strands can be a major contributor to the scale of plastics in the oceans. They also pollute land and freshwater and are being consumed by creatures in our rivers as well as the seas.

Tom takes his 'blue fleece of doom' to the experts - Professor Richard Thompson has been leading research on marine plastics for many years. He and Imogen Napper at the University of Plymouth have offered to wash his fleece to show how much it's shedding, where the fibres go and to discuss how much of a threat they might be to animals and humans.

Is Tom to purge the plastics and pursue a life of naturism...or natural fibres only?

Sophie Mather from Biov8tion hopes not. She says plastics have 'many beautiful benefits' and it's just a case of developing 'good' synthetic yarns. After being frustrated by the pace of microfibre research she crowdfunded to commission research form the University of Leeds to assess which factors affect breakage. Her years in textile innovation for some of the world's largest brands makes her believe fabrics can be designed to shed less and she is sharing the research with industry. Can she help save the synthetics and the fish?

Presented by Tom Heap

Our homes and their construction have a huge impact on the environment. The construction industry is estimated to contribute to 40% of worldwide energy use and in the UK alone the building sector uses more than 400 million tons of material a year, many of which have an adverse impact on the environment. Added to this is the impact on local air quality and green spaces and the energy used in heating, lighting and even furnishing new homes.

The government has set a target of 300,000 new homes a year to help solve the growing housing crisis but this figure is nearly double the current rate of building. So is there anyway we can solve the housing crisis without nearly doubling our emissions? Tom Heap sets out to find out where, what and how we could build affordable and green homes for all.

The rapid decline of the Great Barrier Reef is one of the environmental crises of the decade. But who is to blame?

Environmental activists have accused successive Australian governments of underestimating the threats to the reef from agriculture and the shipping industry but their focus is now on a coal mine.

India's Adani corporation has government support for the development of one of the world's largest new mines at Carmichael, inland from the Great Barrier Reef. Construction would increase shipping traffic around the reef but the real concern is the extra carbon dioxide that the burning of millions of tonnes of coal would send into the atmosphere. This could increase the speed of climate change and lead to yet warmer waters around Australia, potentially killing even more of the coral of the Great Barrier Reef.

Marine biologist and film-maker, Ellen Husain meets both sides of the debate to find out if new jobs from the mine could outweigh the damage to the reef and the jobs that reef tourism supports.

Producer: Alasdair Cross.

Marine biologist and film-maker, Ellen Husain studied the Great Barrier Reef for her Masters degree thirteen years ago. Today she's back to dive with her old supervisor. The picture is grim. So much of the life she remembers has gone, wiped out by the great coral bleaching events caused by rising sea temperatures.

Some who love the reef are in despair, others who once chose to ignore the signs are finally energised, determined to do what they can to slow or even reverse the decline. Ellen meets the people of the reef- tour operators, aboriginal Sea Rangers and coral scientists- to discover if one of the great natural wonders of the world really can be saved.

Producer: Alasdair Cross.

In the last General Election environmental issues barely merited a mention. Nine months on and the Prime Minister is making keynote speeches on recycling and Michael Gove is issuing a flurry of policy initiatives to get the green-minded voter on-side.

Tom Heap sets out to discover why this remarkable transformation has taken place. Is it the Attenborough Effect, the power of the newly-green Daily Mail or a blatant attempt to woo the youth vote? Perhaps senior politicians have actually come to accept the gravity of Earth's predicament.

Producer: Alasdair Cross.