For most of human history, pumping carbon dioxide into the air has come free of charge. Burning fossil fuels powered the industrial revolution and powers most industries to this day.

But all that carbon stays up in the atmosphere and dealing with the consequences won’t be free. The cost of climate change stretches beyond the lives lost in natural disasters. There will be a huge economic cost - to pay for sea defences, put out forest fires and care for millions of climate refugees.

Around the world, governments and businesses are finding different ways of putting a price on the carbon that industries pump out. They’re trying to change how the global economy operates, by making industry pay for the harm their carbon emissions cause.

(Photo Caption: A cloud and money / Photo Credit: Getty Images)

In the US most people who are charged with a crime can’t afford expensive lawyers and investigators to prepare their case. The public defenders who represent them usually have heavy workloads and limited resources. Family and friends would often like to help but don’t know how.

So a group in California is trying to make things fairer by teaching them how the legal system works and explaining what they can do. It shows them how to dissect police reports, put together a social biography for the defendant and get crucial evidence for their lawyer.

Started in San Jose, California, the model is now being used across the US and beyond.

We hear from people whose lives have been transformed by this approach.

(Photo Credit: Silicon Valley De-Bug)

It’s estimated that more than 100 million girls under the age of 18 will be married in the next decade.

(Photo Credit: BBC)

Each year, mental health practitioners from around the world visit Trieste in Italy to see what they can learn from the city’s approach to mental illness.

In 1978, Trieste led a ‘revolution’ in Italian mental health care by closing its asylums and ending the restraint of patients. Today the city is designated as a ‘collaboration centre’ by the World Health Organization in recognition of its pioneering work.

Reporter Ammar Ebrahim visits Trieste to see how the system works - from the informal community centres where people can drop in and stay as long as they need, to the businesses that offer career opportunities for those who have been through the system.

We hear about the city’s policy of ‘no locked doors’, and ask how Trieste deals with patients other societies may deem ‘dangerous’.

Presenter: Tom Colls

(Photo Caption: “Freedom is therapeutic” written on a wall in Trieste / Photo Credit: BBC)

On average, one in eight children in the UK has a mental health disorder – that’s about three children in every classroom. Yet there are just 4.5 psychiatrists for every 100,000 young people - that’s fewer than most other European countries. With the UK’s mental health provision for children so stretched, help often ends up coming from families and schools.

Today’s programme features some of the children that have benefited from these ideas – but can other schools replicate them?

Reporter: William Kremer

(Photo Credit: BBC)

Neighbours in the US are using cameras that read car number plates to record vehicles driving down their streets.

Presenter: Tom Colls

(Photo Credit: BBC)

More than five billion people around the world don’t have access to safe, affordable surgical care. It has been a big problem in Ethiopia where most specialist doctors are concentrated in the cities, contributing to high rates of maternal mortality.

(Picture credit: BBC)

In the 1990s Portugal had a major heroin problem, and when it came to people injecting drugs it had one of the highest rates of HIV infection in the EU. It took a radical approach and decriminalised all personal drug use.

The law introduced in 2001 means people carrying drugs for personal consumption aren’t prosecuted - instead they are referred to health and social services to receive treatment, and the focus is on harm reduction.

And the strategy worked. The number of people using drugs fell dramatically, new HIV and Hepatitis C infections dropped and drug-related crime became much less of a problem.

So why haven’t more countries followed their lead and adopted this model?

Produced by Hannah McNeish for BBC World Service

(Photo Credit: Getty Images)

To prevent the worst effects of climate change, we need to massively cut how much carbon we pump into the atmosphere. But those carbon cuts might not happen in time, so another approach may be needed.

Around the world, scientists, engineers and entrepreneurs are working on ways to give us more time to change our way of life. They’re developing technologies and techniques that effectively do climate change in reverse. Instead of pumping carbon dioxide into the atmosphere, they suck it in and store it.

These projects range from using rock dust for “enhanced weathering” to trap carbon in farmers’ fields, to the power station attempting to capture it on its way up the chimney.

We go on a tour of these projects to see if they offer hope for the future.

Producer and reporter: Tom Colls

Photo Caption: Carbon dioxide illustration / Photo Credit: Getty Images

People diagnosed with bipolar disorder are commonly treated with a variety of drugs. They aren’t always effective and can come with a range of side effects.

For several decades, an Italian psychiatrist has been pioneering a different approach. By asking his patients to stay awake for 36 hours three times over the course of a week – and combining the counterintuitive idea with bright light therapy and lithium – he has found that some of them demonstrate a remarkable improvement in mood, which can last indefinitely.

The therapy has caught the attention of researchers across the world, and new trials are being carried out, but the idea is not without its critics.

Sam Judah spends a week with a cohort of patients as they undergo sleep deprivation treatment at the San Raffaele hospital in Milan, and tries to find out if it is effective.

Producer: Sam Judah

(Photo caption: Francesco Benedetti / Photo credit: BBC)