Image source, EPA

That wraps up our coverage of the wave of climate protests that began in Australia this morning before spreading across nearly every corner of the globe to the US West Coast.

Millions of young people marched on Friday, from handfuls of demonstrators on Pacific islands to mass rallies in cities like Melbourne, Mumbai, Berlin and New York.

The Swedish teenage activist Greta Thunberg, who inspired the protests, called it the biggest climate strike in history.

Here's Greta Thunberg speaking to the BBC earlier today about how flabbergasted she was by the scale of the protests.

Dikembe Wilkins
BBC News, Washington DC

Climate protesters have also marched across Washington DC to the US Capitol building.

Image source, EPA

One of them was Michael Pion, who was wearing a Trump 'Make America Great Again' hat. He told the BBC: "I thought it would be funny to see how people would react to the MAGA hat and to be honest with you ultimately it wasn’t that exciting."

He thinks it's important to pay attention to climate change so "we can avoid the ‘Mad Max’ scenario that will unfold if we don’t take some kind of action about it relatively soon".

Another protester, Jane Mahon (below left), said: "I’m here today because I’m scared."

Her friend, Leah Woods (right), said: "I think people should be here just to simply fight for our humanity."

Rosie Blunt
BBC News

Image source, Reuters

Greta Thunberg continued her speech by talking about the UN climate action summit, which takes place in New York next week. Leaders from around the world will be attending the event.

"The eyes of the world will be on them," she said. "We will make them hear us."

"We are doing this to wake the leaders up. We are doing this to get them to act. We deserve a safe future and we demand a safe future. Is that really too much to ask?

"Right now we are the ones who are making a difference. If no one else will take action then we will.

"It should not be that way. We should not be the ones who are fighting for the future. And yet, here we are."

She finished her speech on a powerful and optimistic note.

"Together and united we are unstoppable.

"This is what people power looks like. We will rise to the challenge. We will hold those most responsible for this crisis accountable and we will make the world leaders act.

"We can and we will.

"And if you belong to that small group of people who feel threatened by us then we have some very bad news for you.

"Because this is only the beginning. Change is coming, whether they like it or not."

Rosie Blunt
BBC News

Image source, Reuters

Greta Thunberg's speech continues... here are some of the highlights:

"We are striking today in over 150 countries on all continents, including Antarctica.

"We are not in school today and this time we are not alone - we have some adults who are not at work today either. And why? Because this is an emergency. Our house is on fire. And it's not just the young people's house. We all live here, it affects all of us. We will not just stand aside and watch.

"We are united behind the science and we will do everything in our power to stop this crisis from getting worse, even if that means skipping school or work, because this is more important.

"Why should we study for a future that is being taken away from us? That is being stolen for profit?

"Some people are saying we should study to become climate scientists and politicians, but by then it will be too late. We need to do this now.

"Pay attention to the facts.

"Nowhere have I found anyone in power who wants to tell it like it is. They leave that burden to us - us teenagers, us children."

Luiza Vianna de Mello Franco
BBC News, Sao Paulo

Image source, Reuters

The young climate protesters who gathered in Avenida Paulista, in São Paulo, on Friday night had a common target: President Jair Bolsonaro.

Almost everyone who went on stage criticised the president’s environmental policies. Some kids talked about what individuals can do to reduce their footprint on the environment.

Vinicius Guimarães, who is 18, held a sign in English saying, "Sorry for our president".

He told the BBC he has no links to political parties and that his motivation to show up today was the survival of his generation.

“We have to fight now because we’re the ones who will have to deal with the consequences," he said.

Here was President Bolsonaro's recent comments on the Amazon fires, which UN officials have described as extremely concerning for the planet’s natural life support systems,

Rosie Blunt
BBC News

Greta Thunberg arrived to cheers from the audience in lower Manhattan and was introduced as "the nicest, kindest most humble person".

"Around the world today about four million have been striking and we are still counting," she said.

"This is the biggest climate strike ever in history and we all should be so proud of ourselves because we have done this together."

She read out the numbers of people at each protest, including:

Australia 350,000 people

London 100,000

Berlin 270,000

Dublin 25,000

A medic was sent to help someone in the audience, which has put her speech on hold for now.

Image source, Reuters

Ashitha Nagesh
BBC News, London

Image source, AFP

Hundreds of thousands of people - and counting - have been taking to the streets today to call for action on the climate crisis.

The catalyst for this huge movement has been Greta Thunberg - the Swedish teenager who inspired a global climate movement with her solitary protests last year. She is expected to address the crowds in New York imminently.

Now she's arguably the most famous climate activist in the world, with a nomination for the Nobel Peace Prize and a gig addressing the UN's climate summit next week.

Her sharp words to US Congress on Thursday also helped cement her icon status. "Sorry, you're not trying hard enough" - a message echoed by many frustrated teenagers, and adults, around the world.

Now, after a day of international demonstrations, she's getting ready to address a rally outside the UN's headquarters.

• Who is Greta Thunberg?
• Why are young climate activists facing so much hate?

Image source, AFP

You might be tempted to ask, like the student protesters above, where are the grown-ups in the room? Why haven’t any of our world leaders sorted this out?

Well… some of them have been trying, but it hasn’t always gone smoothly.

One recent milestone was the 2015 Paris climate deal, which united all the world’s nations in a single agreement on tackling climate change.

Image source, AFP

President Donald Trump announced two years later that he would withdraw from the deal - making the US the only country in the world to reject it.

Nonetheless, the deal is still considered historic, with signatories committing to keeping temperatures below 2.0C (3.6F) above pre-industrial times.You can read more about what it covers here.

Ashitha Nagesh
BBC News, London

Employees at Amazon headquarters in Seattle are joining today's climate strike, protesting against a crisis they say their employer has contributed to.

Ahead of the global protests, the company's CEO – Jeff Bezos – outlined a climate pledge that would see Amazon become carbon neutral by 2040.

But the strikers, from the group Amazon Employees for Climate Justice (AECJ), say this isn't enough.

The group says Mr Bezos' plan to offset Amazon's carbon emissions by 2040 stops far short of its demand that the company stop using fossil fuels entirely within the next decade.

Image source, AFP

AECJ also called for Mr Bezos to stop donating to politicians and lobbying groups that deny the existence or the extent of the climate crisis, and to stop working with oil and gas companies on the exploration of fossil fuel reserves.

The Amazon CEO has not agreed to these two demands.

Rebecca Sheppard is a senior product manager at Amazon and a member of AECJ.

She told BBC Newsday earlier today: "It’s absolutely a victory, but it’s not everything that we asked for. We actually don't want to be carbon neutral, we want to be zero emissions. We don't want to rely on carbon offsets."

You can listen to Rebecca's radio interview here.

Shrai Popat
BBC News, New York City

A rallying chant spread through the crowd: "What do we want? Climate Justice! When do want it? Now!"

Foley Square overflowed, and a number of streets had to be closed due to the sheer number of those marching. There's a range of people, with many school students marching in groups.

While there was excitement among those marching, there was also a sense that this collective action must spur some change.

For many of the younger activists the stakes are too high to ignore.

"It’s either we miss school or we miss life," says 17-year-old Phillip Austin.

Since the early days of his administration, President Trump has made it clear his priority is to create jobs and reduce America’s dependence on foreign oil by expanding drilling. He also hasn’t been shy, external about his scepticism toward renewable and alternative energy sources. “We’ve lost four years.” But activists and Obama-era officials insist it’s possible to be both pro-environment and pro-business. Nat Keohane worked in the Obama administration to help create many of the rules Trump is now rescinding. He says the lack of American leadership on climate change has not only impacted the US but the rest of the world as well.

As protesters march across the US to demand action on climate change, the BBC’s Cut Through the Noise, external examines President Donald Trump's record on the environment and climate change.

His administration has rolled back more than 80 environmental rules and protections.

Jessica Murphy, BBC News, Toronto

In Canada, a handful of cities are participating in the global marches on Friday, including Whitehorse, Calgary and Saint John.

But the main event will take place at a Montreal march next week, on 27 September.

Youth climate campaigner Greta Thunberg is also expected to attend that one.

The largest school board in the province of Quebec - the Commission scolaire de Montréal - will give its students the day off.

A number of universities and colleges have also cancelled at least some classes for that day.

The event will take place during Canada's federal election campaign, where climate change is among the top policy issues for voters.

Image source, MARTIN OUELLET-DIOTTE/AFP/Getty Images

Paula Adamo Idoeta, BBC News, Brazil

Image source, Courtesy Mariana Bombonato

In Brazil’s largest city, São Paulo, a large number of young kids are expected to attend the climate march starting at 20:00 GMT – and some of them are toddlers.

The recent fires in the Amazon have raised environmental awareness in the country, and some parents are concerned about how to explain their concerns to small children without worrying them.

"They are very young, so we didn’t tell them everything [about the recent climate debates]. But we are taking them to the march," said Mariana Bombonato about her daughter Manuela, two, and the other children at the parental nursery her daughter attends. They will all be at the march later on Friday.

"We told the children that everyone would wear special T-shirts today to show their concern for the planet, and I bought Manuela a book about planet Earth. We've been talking about ways to protect the environment, and when we shower she says, 'we can’t stay long because the water belongs to the planet.'"

Flora Monteiro, another mother from the group, says her son Bento, who turns three in two months' time, hasn’t fully understood the events planned for this Friday, "but he knows it’s a move to take care of the nature and the trees".

"More than the environmental cause itself, I’m happy to show him that he can mobilise for whatever he believes in and have an active voice," says Monteiro.

Millions took to the streets today to demand government action on climate change.

Here's our round-up of the day.

Shrai Popat
BBC News, New York City

Thousands have gathered in Foley Square for a march that will end in Battery City Park.

The school district has given the city’s 1.1 million school children permission to skip school to take part in the day’s demonstrations.

They are here to show solidarity and encourage law makers to take action and hold polluters accountable. Many parents have also accompanied their children to the march.

Sanjay Patil, who lives in Queens, brought along some of the day’s youngest protesters: his daughters Anika, six, and Reyha, who is just one.

Reyha's shirt - "I really do care. Why don't you?" - was a reference to a coat worn by US First Lady Melania Trump that sent social media into meltdown.

"We want to show solidarity with all the kids striking," Patil said. He also stressed the importance of bringing his daughters to the rally. "They are going to inherit the mess we created, so they should know that everyone should be a part of the solution."

Image source, Shrai Popat

Image source, Shrai Popat

Meanwhile, in Scotland, thousands of young people have also taken part in school strikes to demand urgent action on climate change.

One of the young people who took to the streets was 15-year-old Dylan Hamilton who helped to organise the march through Edinburgh, where more than 20,000 protesters are thought to have shown up.

BBC Scotland News followed him as he was joined by his family, friends and thousands of others on the streets of the Scottish capital.

Holly Honderich
BBC News, Washington DC

Image source, nofuturepledge

Earlier this week, 18-year-old climate activist Emma Lim went to Parliament Hill in Ottawa, Canada, to publicly take the "No Future Pledge, external" - vowing not to have children until the government takes "serious action" on climate change.

Over 2,000 Canadians have signed on to the pledge, according to the campaign's website.

"Even though I want to have children more than almost anything - what kind of a mother would I be if I brought a baby into a world where I couldn’t make sure they were safe?" Ms Lim wrote on the site.

Image source, Twitter/Sophie Price

Emma-Jane Burian, 17, wrote: "I am taking this pledge because I don't want my children, or another generation to have to live in a world where their entire lives are at risk and yet there is no action".

Ms Lim, a student at McGill University in Montreal, also launched the hashtag #NoFutureNoChildren on Twitter.

The students are part of a growing movement of environmentalists and youth who say they will not be having children - or, like Prince Harry, limiting the number of children they do have - in order to help protect the planet.

Roland Hughes
BBC News, London

Our colleagues on the BBC World Service's Newsday programme have handily put together a series focusing on the people working hard to improve the world's climate.

You can watch their videos and listen to their interviews here.