Holly Honderich
BBC News, Washington DC

America's future in a warming world depends a lot on what part of this vast country you're in. But broadly speaking, by the end of the century, it’s going to be warmer.

By 2050, the average daily max temperature might be 3F higher in San Francisco or Houston, and 4F higher in New York, according to the US Climate Resilience Toolkit, external.

That may not sound like much, but it’s the average over the entire year - including winters. And the pattern of increased temperatures is true almost everywhere.

The National Oceanic and Atmospheric Administration has a host of potentially dire projections: that by 2050, the risk of very large fires could be six times higher, external; that the risk of "rapidly intensifying hurricanes" could be higher along the east coast, external; that the south could have more summer dust storms, external and that "extreme" rainfall will be more likely, external, particularly in the north.

Some states are taking preventative action. California, for example, started planning responses to climate change in 2008 under Governor Arnold Schwarzenegger. And the threat of rising seas and increased flooding has led New York City to build a miles-long sea wall along the Staten Island coast to defend against the risks.

Image source, NOAA Climate.gov

BBC News asked a group of children taking part in the protests in London what questions they would like answered regarding climate change.

We then put those questions to the BBC's Environment Analyst, Roger Harrabin.

Next we have Frida, aged 10, from John Stainer Community Primary school in Brockley, south-east London.

Q: Do you think the government knows how fast the poles are melting?

Image source, BBC News

A: Most governments, especially in the developed world, are aware of the seriousness of the situation.

The problem is that politicians face so many different challenges which appear more pressing at the time.

In the UK, for instance, we’re having a Brexit crisis which makes decision-making very tough.

Each country has its own issues.

Roland Hughes
BBC News, London

It's now 16 hours since we started covering the first climate strikes in the Pacific - our teams in Sydney and Singapore are now deep asleep, and now Ashitha Nagesh, Keiligh Baker and I are all leaving the London office.

We'll leave you in the hands of our team in Washington DC, who will bring you up to date with the growing marches across the US.

Robert Misigaro
BBC Africa, Burundi

Image source, Marlene Shima

In Burundi's capital, Bujumbura, a group of young people took part in today’s global climate protest - but added their own a twist.

Instead of protesting, they took to the beaches of Lake Tanganyika and spent the day clearing up some plastic debris and other rubbish.

The level of pollution on the shores of Lake Tanganyika is starting to worry environmentalists.

Friday's clean-up was attended by a modest group of 35 boys and girls who say they now plan to make it a regular event.

Image source, Marlene Shima

Flora Drury
BBC Asia online desk

As the world’s attention turns to New York and the finale of the climate strike, it may be worth considering the two men who have just held a press conference a few hundred miles to the south.

Because down in Washington DC, President Donald Trump and Australia’s Prime Minister Scott Morrison have been singing the coal industry’s praises.

Perhaps it should come as no surprise. After all, these are two men who have faced more than a little criticism for their views on the climate crisis.

Mr Trump famously announced he was pulling the US out of the Paris accord, rolled back protections on federal lands and emissions and ignored warnings from his own agencies on the effects of climate change.

Image source, Reuters

Mr Morrison, meanwhile, has rebuked child activists in Australia for walking out during school hours, and told CEOs to keep their thoughts to themselves on the issue.

He is also particularly fond of coal, famously brandishing a lump in parliament and declaring “don’t be afraid” to his somewhat baffled colleagues during his time as treasurer.

As far as both of them are concerned, their countries are doing enough to tackle the crisis – something activists strongly dispute.

However, one suspects those who marched in the streets of Sydney, along the boulevards of Paris and through central New York are pinning their hopes on the size and scale of today’s action moving the small talk at tonight’s State Dinner away from golf, and towards emissions.

Keiligh Baker
BBC News, London

Organisers say that about 100,000 people took part in a rally in central London, with more than 20,000 thought to have marched in Edinburgh and 10,000 in Brighton.

In Belfast, organisers put the turnout at between 3,000 and 4,000, with young people taking over the Corn Market area of the city centre and staging a "mass die-in", before marching towards City Hall.

In Birmingham around 3,000 protesters, including hundreds of children, many wearing school uniform, gathered in the city's Victoria Square before marching through nearby streets.

We're still getting numbers for how many people walked out in Wales.

Ashitha Nagesh
BBC News, London

As the US gets ready for climate strikes, we're taking a look at some of the young American activists leading the movement there.

If you want to learn more about young activists around the world, BBC Newsround has profiled seven people you need to know.

Image source, Getty Images

Alexandria Villasenor

Alexandria, 14, is a Fridays for Future organiser in New York - and every Friday she stages a strike outside the UN headquarters.

"I'm too young to vote," she said at an event earlier this month, external. "When I strike, I feel like I am taking back some agency in my future."

Xiya Bastida

Xiya, 17, is a Fridays for Future activist who grew up in the Mexican town of San Pedro Tultepec, but now lives in New York.

Five years ago, when she and her family were still living in San Pedro Tultepec, the town was hit by severe drought followed by torrential rain and flooding. This, she told the website New Mexico In Depth, external, is when she became fully aware of the climate crisis.

Image source, Getty Images

Jamie Margolin

Jamie, 16, co-founded the Zero Hour movement in 2017.

Zero Hour, according to its website, is a campaign group that focuses on the "systems of oppression that [it] names as root causes of climate change... including capitalism, racism, sexism, colonialism, and how these systems intersect with the climate movement to form climate justice".

BBC News asked a group of children taking part in the protests in London what questions they would like answered regarding climate change.

We then put those questions to the BBC's Environment Analyst, Roger Harrabin.

Secondly we have Sebastian, aged nine, from John Stainer Community Primary school in Brockley, south east London:

Image source, BBC News

Q: How are we going to stop using polluting coal before 2050?

A: That is a very good question. Our prosperity has depended on coal since the industrial revolution, and there’s a huge lobby persuading governments – especially in the developing world – that it’s their right to follow the dirty path rich nations have trod.

Even China, the world leader in solar and wind power, is also investing hugely in coal-fired power stations which will need to be closed down or radically altered before the end of their normal lives if we’re to protect the climate.

Chinese banks are awash with cash and they’re busy lending to other nations to buy coal-fired plants.

Roland Hughes
BBC News, London

It might be easier to say where they haven't been happening.

We've tried to give you a taste of the true global flavour of today's climate strikes, but here's just a glimpse of where people have turned out.

[Deep breath]

The UK, Poland, Germany, Japan, Solomon Islands, Vanuatu, Kiribati, North Macedonia, Romania, Ireland, France, Pakistan, India, South Korea, Indonesia, Malaysia, Nigeria, Ghana, Kenya, South Africa, Ukraine, Belgium, Sweden, Turkey, the Netherlands, Philippines, Australia, New Zealand, Bangladesh, Austria, Thailand, Senegal, Denmark, Burundi, Greece, Cyprus...

We could go on, but we won't.

Keiligh Baker
BBC News, London

We are heading in to the latter stages of the climate strike now, with the US protests starting right about now.

Over the past 14 hours, our teams in Sydney, Singapore and London have read, watched and seen thousands of photos, tweets and stories come in from across the world.

The schoolchildren and young people who are taking part in the protests come from very different countries and backgrounds – yet they are all united under this common cause.

Teenager Gina Hale was among the thousands of who kick started the global protests in Australia.

The 16-year-old student, from Brisbane, told the BBC: “The people who are in charge aren’t doing anything. I’m here today today to step up and say ‘no more.”

Image source, AFP

Ushnik Banerjee, a pupil at Methodist College in Belfast, spoke on Friday afternoon at City Hall in Belfast, where up to 4,000 protesters attended a march.

He said: "It's incredible and it's so inspiring that people realise how important today and how important striking is."

“I am the daughter of a forest ranger but what will he protect if there is nothing left to protect?” asked Banashree Thapa, 23.

“This is beyond climate change,” she said at a protest in Delhi. “This is nature’s wrath. And it’s coming for us. That’s what brought me here.”

Image source, Getty Images

Eight-year-old Sohan and Nayan, five, from south-east London, joined protesters in the British capital along with their mother, Celine. Sohan said: "We want to save our planet and we hope that marching will help."

Seye Adegbpye, 37, was at the Lagos protest. She told the BBC: "I'm here today because this is important, we have 12 years to turn things around.

"Even though there aren’t many of us here today, I’m hoping our government will hear our requests and implement policies such as increasing the number of trees that are planted around the city."

Ashitha Nagesh
BBC News, London

The key to standing out in any protest is a placard that grabs people's attention. It might make people laugh, it might make them think, or - ideally - both.

These are some of the most eye-catching signs we've seen at the climate strikes so far.

Image source, AFP

Image source, AFP

Image source, PA Media

Image source, PA Media

Roland Hughes
BBC News, London

Image source, Reuters

We're starting to see the first pictures of crowds gathering in major US east coast cities, more than 15 hours after the first demonstrations on Pacific islands.

There are big groups in Boston, and in New York, where about 1.1 million schoolchildren are being given the day off school. This is where Greta Thunberg will speak later.

In about 90 minutes, we in London are going home, and our colleagues in Washington DC will guide you through the rest of the day's events.

Ashitha Nagesh
BBC News, London

Image source, Getty Images

Hundreds of thousands of people have taken part in the climate strikes across the world - but in some cities, people's attempts to join in have apparently been shut down.

Azhara Rustamova tried to organise a march through Bishkek, the capital of Kyrgyzstan, but was reportedly made to cancel it. A court also banned all demonstrations in the city between 17 and 30 September.

Ms Rustamova told local news site Kloop that she was confronted by two officials who "behaved extremely aggressively", external.

"The ban was justified with very vague reasoning, like 'LGBT people are going to join your march', and the unrest on the border [with Tajikistan]," she told the site. "They also told me that if the procession did take place, then all the protesters would be arrested and I would be responsible."

Although same-sex relationships are legal in Kyrgyzstan, members of the LGBT community frequently face discrimination and harassment. On 8 March this year, what is thought to have been Central Asia's first ever Pride march was held in Bishkek - but it was met with a fierce backlash from the country's conservative politicians.

Camilla Mota
BBC Brasil, Sao Paulo

Image source, Charton Jahn Locks

Environmental engineer Charton Jahn Locks has been on leave from his position at the Brazilian Ministry of Environment since March to dedicate himself full time to his project, named Aliança da Terra.

Back in 2006 he joined forces with an American cattle breeder based in the Amazon forest to help create what he calls a “positive ecosystem” in the region. Aliança da Terra works close to producers giving them technical assistance so they can produce more sustainably and according to local regulations.

Today they work with more than 1,500 companies, producing in the Amazon “with zero deforestation” and selling to multinationals such as Unilever (45 of them are soy suppliers for Hellmann's mayonnaise).

“Without private sector engagement we won’t be able to face the environmental challenges that lie ahead. Government initiatives alone are not enough”, he says.

The project also has its own elite fire brigade that for years now has been training producers, indigenous people and local populations to fight the blazes that hit the Amazon region this time of the year.

Kevin Keane
BBC Scotland energy correspondent

Image source, PA Media

It's no surprise there are upwards of 15 protests taking place across Scotland with many thousands in attendance.

Here, climate change is firmly on the agenda with the Scottish Government already committing to reach net-zero greenhouse gas emissions by 2045.

That's five years ahead of the UK and one of the "most ambitious targets in the world," as the mantra goes.

But for the 15,000 people here in Holyrood Park, just across from the Scottish Parliament, that’s still not enough.

Posters read “It’s now or never” and “There is no planet B”. In short, they want action immediately.

But it’s difficult for politicians here. Scotland has an oil and gas sector which props up its third biggest city.

An instant end to using fossil fuels would devastate its economy. That makes the arguments much more nuanced.

But not for the thousands attending these protests in the searing sun who see their own future being destroyed by what’s happening today.

BBC News asked a group of children taking part in the protests in London what questions they would like answered regarding climate change.

We then put those questions to the BBC's Environment Analyst, Roger Harrabin.

First up is Mariah, aged 10, from John Stainer Community Primary school in Brockley, south east London.

Q: How are we going to limit the damage that cars do to the environment? Why don’t we make ALL cars electric?

Image source, BBC News

A: It’s the biggest challenge humanity has ever faced because every one of us lives a life that involves emitting greenhouse gases.

From heating and cooking, to the goods and food we buy – we have to tackle everything.

Just switching to electric cars won’t solve it – experts say we have to get out of our cars and on to feet, bikes or buses.

As protests around the world rumble on, eyes are beginning to turn to the US and the global protests' finale - Greta Thunberg speaking in New York on Friday evening.

About 1.1 million students from 1,800 public schools have been allowed to skip school in New York in order to protest.

Throughout the day Greta Thunberg has followed the strike as it travelled across the world, tweeting and retweeting pictures and videos coming live from events in places including Uganda, Germany, India and Turkey.

She will lead a demonstration at 12:00 local time (17:00BST) followed by a rally and march.

Then on Saturday young leaders and activists from around the world, including Greta, will gather at the UN's Youth Climate Summit in New York.

You can read Newsround's Greta Thunberg profile here.

Ashitha Nagesh
BBC News, London

The demonstrations in London are pretty big, but they're far from the biggest the city has ever seen.

Berlin, however, is a different matter.

Aerial footage taken of crowds in the German capital and posted on Twitter show huge numbers of people on the streets - up to 270,000 by some estimates.

As protests were held in about 500 German cities and towns, Chancellor Angela Merkel signed a €54bn (£48bn) climate deal which will set a price on carbon emissions in buildings and transport. Taxes on long-distance train tickets will fall, while those on air travel will rise.

The government's goal is to cut greenhouse gases by 55% by 2030 - but strikers have said it doesn't go far enough.

Over the past few months, we’ve been taking your questions on climate change via a Facebook Messenger bot. Over the day, our science and climate team will help answer some of those questions.

Q: Should I change my diet?

A: You don’t *have* to, but avoiding meat and dairy products is one of the biggest ways to reduce your environmental impact.

Cutting these from your diet could reduce a person's carbon footprint from food by two-thirds, according to one Oxford study, external.

Beef and lamb have a big environmental impact, as the digestive systems of livestock produce methane - a powerful greenhouse gas.

The UN says we need to eat more locally-sourced seasonal food, and throw less of it away.

How and where your food is produced is also important, as the same food can have very different impacts.

For example, beef cattle raised on deforested land is responsible for 12 times more emissions than cows reared on natural pastures.

You can read more about your diet and the climate here

Protests haven't just been on the streets of British towns and cities - they've even spread as far as the beaches...