Just how bad will it get if the world fails to get to grips with climate change?

On day two of the UN Climate Action Summit in New York, Justin Rowlatt speaks to David Wallace-Wells, author of the apocalyptic book Uninhabitable Earth, which lays out the dire predictions of climatologists for the coming decades if humanity continues to put ever more carbon dioxide into the atmosphere unabated.

Yet despite the potentially terrifying outlook, it remains very difficult to motivate politicians and the public to take meaningful action to cut emissions. Why is that, and how might that change? Kelly Fielding is a social psychologist at the University of Queensland in Australia, and has some of the answers.

Producer: Laurence Knight

(Picture: Dead bumblebee from the cover of Uninhabitable Earth by David Wallace-Wells; Credit: FXseydlbast/Getty Images)

The Swedish teenage activist Greta Thunberg explains how she aims to get the world's governments gathered for the UN Climate Action Summit in New York to take meaningful action on global warming.

Justin Rowlatt speaks to her about her ambitions for her transatlantic trip, and whether one person can really make that much of a difference.

In order for her mission to succeed, it will mean rebuilding the global economy from the ground up, including the phasing out of most of the oil and gas industry. John Hofmeister, the former president of Shell's US subsidiary, claims the big oil companies are ready and willing to do their part, if the politicians will only give them the green light.

Producer: Laurence Knight

(Picture: Greta Thunberg testifies at the US Congress in Washington DC; Credit: Alex Wong/Getty Images)

What next for the social media giant? Jane Wakefield speaks to one former mentor of Mark Zuckerberg, and a British member of parliament about what changes Facebook needs to make after data scandals and concerns over its power.

(Photo: Facebook logo, Credit: Getty Images)

What robots driving cars can tell us about artificial intelligence. Ed Butler speaks to Bryn Balcombe, chief strategy officer of the autonomous vehicle project Roborace. Gary Marcus, professor of psychology at New York University, explains why he thinks AI development is fundamentally limited. Yoshua Bengio, professor of computer science at the University of Montreal in Canada, gives a defence.

Producer: Laurence Knight

(Photo: A Roborace robot-driven car in action on the track, Credit: Getty Images)

How economies spring up in extreme places from refugee camps to prisons. Ed Butler speaks to economist Richard Davies, author of a new book called Extreme Economies, who describes the economic activity in extreme places, from a Syrian refugee camp in Jordan to one of the toughest prisons in the world, in the United States. Former US prisoner Lester Young fill us in on how to trade behind bars.

(Photo: A prison in Louisiana State Penitentiary, Credit: Getty Images)

Should shareholders come first? Or should companies also serve their employees, customers, and society in general?

Ed Butler explores the growing backlash against "shareholder primacy" - the idea espoused in the 1970s by economist Milton Friedman that businesses should only care about maximising the bottom line for the benefit of their investors, and that other stakeholders' interests should not be their prerogative.

He speaks to Lenore Palladino, economics professor at the University of Massachusetts Amherst, who has a list of changes she wants to see in the way that American companies are governed, plus Ken Bertsch of the Council of Institutional Investors, who says that the real problem is not the role of investors like the ones he represents, but too much focus on short-termism.

Meanwhile Chris Turner thinks he has the solution - he works for the non-profit organisation B Lab, which provides an objective assessment to hundreds of corporations of whether they are having a positive impact on society.

(Picture: An American flag is displayed on a trading screen at the New York Stock Exchange; Credit: Bryan R. Smith/AFP/Getty Images)

Will the roll out of online lending stimulate economic boom or just a credit binge in Africa?

Ed Butler speaks to many of the businesspeople providing the continent with much needed banking services via mobile phones. They are optimistic that financial inclusion for small businesses, farmers and rural consumers could stimulate much faster economic growth. But is there a dark side to the sudden availability of east loans?

The programme includes interviews with Matthew Davie, chief strategy officer at the US micro-lending fin-tech Kiva; Omotade Odunowo, chief executive of the Nigerian digital wallet service Fets; Joshua Oigara, chief executive of Kenya's biggest commercial bank KCB; and Kevin Njiraini, regional director for southern Africa and Nigeria at the International Finance Corporation.

(Picture: Young African woman using a mobile phone; Credit: wilpunt/Getty Images)

Why it's time to start paying attention to the global remittances industry. Ed Butler speaks to Monica, a nurse from the Philippines working in the UK - one of millions of people around the world who regularly send money back to their families abroad. Dilip Ratha from the World Bank describes the scale of the money flows, and the persistently high costs of international money transfers. Ralph Chami from the IMF highlights the challenges such big inflows of cash can have on developing countries. And Elena Novokreshchenova from the company Remitly explains how technology can help reduce costs.

(Photo: A bank teller counts bills in Manila, Philippines, Credit: Getty Images)

The cannabis extract CBD or cannabidiol is legal in many countries, and now it's finding its way into everything from soaps to cosmetics. But is it just a fad, and are its health claims bogus?

Manuela Saragosa asks Harry Sumnall, professor in substance use at Liverpool John Moores University, whether it is true that CBD is not a psychoactive substance - unlike the more infamous cannabis extract THC. And is it true that it can be used to treat the symptoms of Alzheimer's, anxiety and cancer amongst others?

Meanwhile Katie Prescott explores the booming market for CBD products. She speaks to Jim McCormick, president of cannabis brand Ignite International; Eveline van Keymeulen, head of life sciences regulations at law firm Allen & Overy; Alex Brooks of financial services firm Canaccord Genuity; and Chris Tovey of GW Pharmaceuticals.

(Picture: Cannabis leaf; Credit: digihelion/Getty Images)

The attorneys general of 48 out of the 50 US states have come together to challenge the control of the search giant over what we buy or view online.

Manuela Saragosa speaks to the BBC's technology correspondent Rory Cellan-Jones about why the US anti-trust authorities have decided to join their EU counterparts in taking on Google.

Jonathan Tepper, author of the new book The Myth of Capitalism: Monopolies and the Death of Competition, takes us through the history and significance of anti-trust legislation. But are anti-monopoly laws equipped to deal with the tech giants of today? And can these companies even be called monopolies? We'll also hear from Sally Hubbard of the Open Markets Institute, and Alex Moazed, co-author of the 2016 book Modern Monopolies.

(Picture: The Google logo displayed through a magnifying glass; Credit: Chesnot/Getty Images)

Sperm counts worldwide have been in steady decline for decades, and a group of tech start-ups are finally giving the problem attention.

Manuela Saragosa speaks to the heads of two such companies: Tom Smith of Dadi Inc, which provides home kits for freezing sperm, and Mohamed Taha of Mojo Diagnostics, which is using artificial intelligence to make male fertility testing more reliable. Plus Mylene Yao of Univfy Inc, which focuses on female fertility, says she has noticed a generational shift in her clients' attitudes, with much more focus now on the joint responsibility of men in achieving a pregnancy.

But why is there such a crisis in male fertility in the first place, and what can men do to improve their chances of having a child? Manuela asks Professor Richard Sharpe of the Centre for Reproductive Health at Edinburgh University.

(Picture: Human sperm and egg cell; Credit: koya79/Getty Images)

The global construction boom is fuelling an illegal trade in sand used to make concrete, causing environmental degradation and spawning sand mafias in parts of the world. Manuela Saragosa speaks to Prem Mahadevan of the Global Initiative Against Transnational Organised Crime, on what is becoming a global phenomenon. Campaigner Sumaira Abdulali, founder of the Awaaz Foundation NGO in India, recounts how she confronted illegal sand miners who were destroying a stretch of beach she owns south of Mumbai, and John Orr, Cambridge University lecturer in concrete structures, on how we could use less sand in construction.

Producer: Laurence Knight

(Photo: Illegal sand mining in Senegal, Credit: Getty Images)