The world’s largest global forum for young leaders will open on Tuesday, as more than 2,000 young people from across the world converge on London.

One Young World’s 10th annual summit will welcome young delegates from more than 190 countries as well as political and humanitarian leaders, including the former UN secretary general Ban Ki-moon, the former president of Ireland Mary Robinson, Sir Richard Branson, Sir John Major and the Canadian prime minister, Justin Trudeau.

“Our young delegates are founders, activists and entrepreneurs in their own right, united by a common goal to resolve some of the world’s most pressing challenges – from climate change and violent extremism to sexual violence and poverty,” said Kate Robertson, a cofounder of the UK-based not-for-profit organisation.

In a world where the most recognisable climate activist is a 16-year-old girl from Sweden, Robertson said: “At the heart of every global threat is a failure of leadership. This new generation is the most informed, most educated, most connected generation in human history.”

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The organisation estimates that almost 21 million young people have been impacted by its ongoing programme of mentoring across the world.

The Duchess of Sussex, the singer Ellie Goulding, the supermodel Leomie Anderson and Edward Enninful, Vogue’s editor-in-chief, will also attend the annual four-day summit, which will be London’s largest and most international event since the 2012 Olympic and Paralympic Games.

The summit will also feature speeches from 30 global chief executives, including Alan Jope of Unilever, James Quincey of Coca Cola, Bram Schot of Audi, and Feike Sijbesma from DSM.

They will be speaking to some would-be leaders of the future, among them:

Madhav Datt

Datt founded Green the Gene as a small environmental club in his school when he was eight years old. The organisation is now one of the world’s largest youth-run environmental non-profits. It has projects in 62 countries and has mobilised more than 7,000 young people, all under 24, to build tangible solutions for communities facing acute climate crisis.

Now 23, Datt has created a number of technology and data projects to address specific problems, including low-cost water filtration units, providing safe water to more than 40,000 people in rural Tanzania, recycling 3,000,000+ litres of swimming pool water annually in Haryana in India and planting more than 1,500,000 trees in Gambia and 600,000 in India.

As a software engineering intern at Google, Datt developed machine-learning algorithms for Nest thermostat energy demand response programs, to reduce energy used by home heating/cooling systems during peak demand times.

I learned about the climate crisis at firsthand: the water level in our local dam had fallen by 2ft, which meant our water and electricity was severely rationed. There was nothing abstract about the issue for me. Starting the environmental club, planting trees and talking to local shopkeepers about plastic bags were things I couldn’t not do.

One of the biggest things that being young gave me was the power to go up against huge issues because I simply didn’t appreciate that they were widely regarded as impossible problems.

Bella Burgemeister

Burgemeister was 10 when she decided to write a book to help school-aged children understand the climate crisis. The book, now in its second edition, is in every school in her community in the south-west of Western Australia. In the past three years, Burgemeister has spoken to 5,000 children and 8,000 adults in schools, conferences and meetings. She is a climate activist and organiser.

It was tough, aged just 10, to get my head around things like economic growth and responsible consumption but it’s important that children understand these issues because for most of my life, the major political parties have done as little as they can get away with when it comes to climate change.

Young people like me are the ones who will live with the consequences of inaction on climate. That was a huge motivator for me.

Some politicians and local councillors said I was too young but I didn’t care: I knew what I was doing was right.

Edgar Edmund

Edmund founded Green Venture Recycles, a company that turns plastic waste into affordable building products, when he was 14. The Tanzanian company has already turned more than 20m plastic bags into 20,000 bricks.

I was 12 when I became aware that climate change was causing the floods that regularly destroyed my community. The flood waters were always full of plastic waste.

When I was 15, I had a lightbulb moment: I realised that plastic was harder after being heated, which meant I could use the plastic waste to rebuild my community’s homes strong enough to withstand the floods. It was one solution to two problems.

I asked myself whether I was too young to deal with this but I realised that if I had to wait for someone else to solve the problem, it would be too late.

I designed my first machine using $20 of savings. It took me a year of hard work but after I’d finished, I took it to a science fair and won $100. I used that money to make a more efficient machine which was nominated for a prize in South Africa.

I won $15,000 in that competition and used it to create an electric machine. Then I was invited to Sweden and won $7,000 and met investors who helped me get the machine into production.

Brighton Kaoma

Growing up in the Zambian city of Kitwe, 12 -year-old Kaoma saw the impact of climate breakdown firsthand: as floods and droughts began to destroy his community, he found he was having to walk an extra mile to fetch water and suffered repeated respiratory infections because of the toxic emissions from nearby copper mines.

When he was 14, Kaoma asked a local radio station if he could present a show on the environment. Environmental Watch became one of the station’s most popular programmes, educating listeners about the problems affecting them – from global heating and deforestation to pollution – and how they could help.

Now 25, Kaoma has founded Agents of Change Foundation, training young people to be agents of change in their community. It has trained 260 children so far, many taking up leadership positions in their own communities.

I mobilised my community, we planted trees, I organised marches, opened conservation clubs in schools across the area. By the time I approached the radio station, they had already heard about me and my work.

Being so young meant I was free-spirited: I wasn’t afraid on my programme to call a spade a spade. I called to task multinationals and government.

People said I was too young. They threatened me by saying my life would be affected by getting on the nerves of everyone from government to local business.

But I was fearless. I was too scared of my future, living in a world with no resources other than those that had been polluted, to let them scare me.

Noga Levy-Rapoport

Levy-Rapoport, 17, is a core UK Student Climate Network organiser and spokeswoman for Labour for a Green New Deal. She led her first London climate strike at 16.

I have aways been aware of climate change but we all grew up being told that if we recycled more and switched off the lights, we would save the planet.

I realised as I got older that that’s wrong. I realised that I couldn’t plan my future 20 to 30 years ahead because the world was going to hit a brick wall: it would descend into chaos.

Young people have so much power because we’re so angry. We’re growing up in climate change and amid political disasters.

There’s always a risk that adults will think that we will sort this out but we’re really clear: we don’t have time for us to grow up before a solution is found. We’re very clear that it’s your mess and you must clear it up.

Kehkashan Basu

Winner of the 2016 International Children’s Peace Prize, Kehkashan Basu has been campaigning on behalf of children’s rights, gender quality and climate change since she was 8 years old.

When I was 8, I planted my first tree and began talking to the children and grown ups around me about environmental issues. I realised that the children were so much more responsive and enthusiastic than the adults I was speaking to, so I determined to work with children instead, informing them about environmental issues and what they could do about it.

Young activists have an advantage over adults because we have an uninhibited view of the world. We’re not affected by cynicism or by awareness of how big problems are. We are determined to solve problems and are truly open to new solutions. The world needs more of that attitude.

This article is part of a series on possible solutions to some of the world’s most stubborn problems. What else should we cover? Email us at theupside@theguardian.com