Image copyright iStock

A lot has gone wrong this year. We don't mean Brexit or the election of Donald Trump, both of which split opinion in Britain and the US.

We mean the thousands of migrants who died in the Med, the war in Syria, Zika virus, terror attacks all over the world, the hottest temperatures ever recorded. And, as if all that wasn't bad enough, David Bowie died.

So from the BBC World Service Inquiry programme here are four things that went right in 2016 from the perspective of four people who helped make them happen.

Four stories united by just one thing: the ambition to achieve the seemingly impossible.

Peace in Colombia

During the 50 years of war in Colombia, most people there have been touched by it in some way. But some more than others.

Twelve members of Teresita Gaviria's family were killed, including her father and two brothers. Then one day, her fifteen-year-old son was kidnapped on the way to school. She never saw him again.

"I went into the mountains shouting, 'Give me my son back,'" she says. "I wanted to die from the pain."

Image copyright Getty Images Image caption Teresita Gaviria with pictures of disappeared relatives in Medellin, Colombia in 2013

Teresita Gaviria started a weekly protest in front of a church. At first there were just five mothers who had lost children to the war.

Soon there were hundreds. And they did more than just protest. They went to prisons to speak to fighters, and lobbied the government to not only begin peace talks, but to include victims in the negotiations.

And they were successful. Teresita Gaviria and other victims were invited to Cuba where the negotiations were held.

There, they sat in front of members of the Farc and talked to them. Never before, in any other peace process anywhere in the world had this happened. "It was hugely important for us," she says. "The victims needed to confront the perpetrators."

This year, a peace deal was reached. It has been described as groundbreaking, partly because of the victims' contribution. Like most peace deals, it has its critics, but it is a beginning.

Media playback is unsupported on your device Media caption President Santos and Farc leader Londono were met with cheers of "Yes we could!"

Teresita Gaviria was there at the ceremony when it was signed. "It was a moment of sheer happiness," she says. "The bloodshed had finally come to an end. We were bursting out of our clothes with joy."

Gene editing

Professor Sophien Kamoun is a plant biologist from Tunisia. He has always been interested in plant diseases, particularly after seeing the devastating effects of pesticides in developing countries.

Every year, thousands die after using pesticides on diseased crops. What if you could create a type of plant that doesn't get diseases?

Image copyright Sophien Kamoun Image caption Professor Kamoun's Norwich lab aims to develop novel disease-resistant crops

That's what Sophien Kamoun has been experimenting with in his lab at Norwich University, using a new technique invented in the US that came of age this year - gene editing. It allows scientists to modify the genes of living things like plants.

Professor Kamoun experimented with editing the genes of a tomato plant so that it would no longer be susceptible to a particular disease.

First they isolated the gene that makes the tomato vulnerable to that disease. Then they removed the gene from the genome of the tomato. "And it became resilient to the fungal disease," he says.

Gene editing is an incredibly powerful tool. There are real concerns about how such a technology could be used, but regulate it properly, and you could change the way we feed the world.

"Every year we lose enough food to feed hundreds of millions of people to pathogens and parasites," he says. "If we could make some of our crops more resilient, then that would be an unique achievement."

Media playback is unsupported on your device Media caption Fergus Walsh explains how gene editing works

It is not only plant biologists who are experimenting with gene editing: doctors are using it to reverse the mutations that cause blindness, to stop cancer cells from multiplying and to make cells resistant to the virus that causes AIDS.

It is why some have called gene editing the invention of the century.

Malaria in Sri Lanka

In 2009, the Sri Lankan government decided to do something extraordinary: to try to eradicate malaria in less than five years.

Dr Hemantha Herath was one of those leading the campaign. He spent years going round the country treating people with malaria.

The lucky ones survived. The unlucky ones could fall into a coma and die. That is why the government wanted to get rid of malaria completely. They had tried to do it before, but when the civil war broke out in the 1980s, health workers couldn't get to the worst affected areas.

Image copyright Science Photo Library

When the war ended in 2009, the government saw an opportunity. They decided to track down every last case of malaria, including people who did not even know they had it. It was a bold strategy which no other country had tried.

They tested any patient who came to a hospital who had had a fever in the past. If they had malaria, not only would they be treated, but their family would be tested and their home sprayed with insecticide.

Then health workers went after the mosquitoes themselves. And to catch them, they offered themselves up as bait.

Those efforts paid off. This year it was made official: Sri Lanka is now malaria-free. For Dr Herath, it was a moment of great pride. "We showed to the world that malaria can be eliminated."

Solar plane circumnavigation

When Bertrand Piccard was little he was scared of heights. One day, he decided to cure himself by hangliding.

He didn't just conquer his fear of heights: he became obsessed and was soon leaping off 3,000m high mountains, doing hang glider acrobatics.

Image copyright Getty Images Image caption Bertrand Piccard was determined to fly around the world without using any fuel

Aged 40, he travelled non-stop around the world in a hot air balloon. He made history, but didn't like having to burn propane gas to keep the balloon airborne.

He made a promise: the next time he flew around the world it would be with no fuel. Concerned about rising carbon dioxide emissions, he wanted to show what clean technology could do.

And so the idea for a solar-powered plane was born.

Seventeen years later, after working on several prototypes, his plane was ready. On its outside were over 17,000 solar cells.

Early one Monday morning, Solar Impulse 2 took off from Abu Dhabi airport on the start of a 35,000 km journey round the world; a journey powered by nothing but the sun.

Bertrand Picard and co-pilot Andre Borschberg took turns to fly. By day they flew by the power of the sun.

"It's really a fantastic experience," he says. "You look at the sun, and on your left and your right you have the propellers turning, and you know you have no fuel.

"It's only the sun that makes you fly. You produce no pollution and you can fly theoretically forever."

Media playback is unsupported on your device Media caption Solar Impulse coming in to land in Abu Dhabi

By night they flew on the electricity stored up from the sun during the day. "You just hope you have enough to reach the next sunrise," he says.

One night they got down to the last 5% of battery life. "Those were the moments of my life where I felt the best," Piccard says. "This is the magic of adventure!"

On 26 July this year, Bertrand Piccard landed back in Abu Dhabi. After 17 years of planning, and 23 days of flight, he'd done it: flown the first solar-powered plane all round the world.

A few months later he created the World Alliance for Clean Technologies. The flight may have been over, but for Bertrand Piccard, a new project had begun.

The Inquiry is broadcast on the BBC World Service on Tuesdays. You can listen online or subscribe to the programme podcast.