Ashitha Nagesh
BBC News, London

From South Africa to Ukraine, Germany to the Solomon Islands, the scale and co-ordination of the climate strikes today has been phenomenal.

It shows, if nothing else, how the climate crisis has now become a mainstream, global issue of increasing urgency.

And of course, we still have more to come later on when the US wakes up.

Here are just some of the many places across the world where children and adults have held protests so far.

Image source, AFP

Image source, Reuters

Image source, Reuters

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Image source, Getty Images

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Image source, Getty Images

If you live in a city, you might have noticed that it can get much hotter there, compared with the countryside.

In the US, cities can be up to 22F hotter than surrounding rural areas, thanks to buildings blocking wind and trapping waste heat, and concrete absorbing heat from the sun.

But there are ways to work around this - including planting trees in strategic areas to provide shade, and painting roofs - or even the street - white.

Have a look at what people are trying to do in the US to survive the heat.

David Molloy
BBC News, London

We're seeing some (fairly small) late-night protests in the bright lights of Tokyo - demonstrations are continuing in Asia even as the ones in the US are gearing up.

Image source, Getty Images

Japan’s temperatures are already rising noticeably faster than other countries. Tokyo is about 2.3C hotter than it was a century ago; in a worst-case scenario, it could be 5C hotter by 2100.

This has the potential to damage Japan’s food security as farmers struggle in more difficult conditions.

Higher temperatures are already resulting in lower-quality rice, “sunburned” fruit, and infected shiitake mushrooms, a Japanese government report says.

Even more worrying is the potential impact of extreme weather events - which may be more likely in the future if global warming continues. Japan already suffers typhoons, heavy rainfall, and associated landslides, and all have caused loss of life in recent years. If mountain-top snow is replaced with more rain, it could have a major impact on safety in many towns in the mountainous country.

And Japan is an island nation - made up of more than 6,000 of them. The possibility of rising sea levels may not have a widespread impact on the four main islands where most people live, but could cause widespread coastal flooding.

Ashitha Nagesh
BBC News, London

Image source, EPA

Schoolchildren and adults took part in the strike in Bangladesh, one of the countries most vulnerable to the effects of the climate crisis. Our reporter in Dhaka, Shahnaz Parveen, tells us that about 3,000 children marched in front of parliament.

Bangladesh is vulnerable because it's both low-lying and densely populated, with about 168 million people living there. Rising sea levels are flooding its coastal towns, while the increased salinity of the water is threatening the country's fishing industry. Paddy fields, which were common up until the 1990s, are now rare.

Another side-effect researchers have warned about is an increase in miscarriages.

Last year, researchers suggested a link between climate change and an increased rate of miscarriages in small villages along Bangladesh's eastern coast.

Faced with regular flooding, some families have been able to move further inland, while those with less money have had to stay on the coast.

Researchers found that, compared with the women who were able to relocate, women on the coast were 1.3 times more likely to miscarry. They believe this could be down to the increased salt in the water.

Read more in our feature here.

Ashitha Nagesh
BBC News, London

Earlier this month the Global Commission on Adaptation, a group of 34 leaders in politics, business and science, released their recommendations on how to stem some of the negative effects of climate change.

These were published in a hefty 81-page report - which our Science correspondent Victoria Gill has handily broken down into five main points.

BBC Monitoring
The world through its media

The Armenian Environmental Front has announced it is joining the global climate strike as part of its on-going battle over a controversial gold mine.

Earlier this month activists and environmentalists announced that the government had until 20 September to make a final decision on the mine or they would face a campaign of civil disobedience.

The organisation said on Friday that various actions would be held throughout the day, ending with a march scheduled for 18:30 (15:30BST).

They are protesting against the development of the Amulsar gold mine, which they say is the home of several endangered animal species including the world's rarest big cat, the Caucasian Leopard.

Armenian Environmental Front's event on Facebook said in Armenian and English: "In tandem with the Global Climate Strike, we declare 20 September as a day of unprecedented decentralised events voicing environmental problems and demanding urgent solutions form Armenia's government.

"As a first step, the government needs to revoke permits for the illegal Amulsar mining project."

Keiligh Baker
BBC News, London

Image source, EPA

Thousands of protesters from across the country have arrived in London to make their voices heard.

The capital alone has several protests taking place across the day, with hundreds more taking place across the rest of the world.

Londoner Jessica Ahmed, 16, said she emailed her school to warn that she would be walking out on Friday to take part in the strike.

Image source, PA

Speaking at a protest in Westminster, she said: "There are no excuses in this. School is important but so is my future.

"If politicians were taking the appropriate action we need and had been taking this action a long time ago when it was recognised the world was changing in a negative way, then I would not have to be skipping school.

Image source, Billy Beckett

"I would be doing the maths exam I have studied for."

Slogans such as "if you breathe air you should care", "us snowflakes are melting", "learn to change or learn to swim", and "don't be a fossil fool", were among the homemade banners spotted in the .

Posters riffing on well known memes also proved popular with the young crowd.

Strikes are taking place in cities including Cambridge, Birmingham, Belfast and Edinburgh, with students letting off alarm bells at 1pm to "raise the alarm" for the climate.

Roland Hughes
BBC News, London

We've set up a live feed near the Houses of Parliament in London showing some of the protest taking place. Here's a link, and it's also embedded at the top of this page.

Honestly, it's a little bit far away, and you can't really read all the protest signs, but at the very least you can admire the nice weather in London today.

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: What can I do?

A: Lots. The UN Intergovernmental Panel on Climate Change (IPCC) says the world can’t meet its emissions targets without people making changes to their daily lives.

It says you could:

• Buy less meat, milk, cheese and butter and more locally sourced seasonal food - and throw less of it away
• Change how you get around. Drive electric cars but walk or cycle short distances. Take trains and buses instead of planes
• Use video-conferencing instead of business travel
• Use a washing line instead of a tumble dryer
• Insulate homes
• Demand low carbon in every consumer product

Research reported by the IPCC also said people tend to overestimate the energy-saving potential of lighting, and underestimate the energy used to heat water.

It also says people don't think a lot about the energy used for the creation of products they buy.

David Molloy
BBC News, London

Image source, Reuters

Anyone who lives in the UK can tell you the weather is wet and cold for half the year. But it’s getting wetter, the Met Office says.

In the past 10 years, winters have been 5% wetter on average than they were between 1981-2010; and 12% wetter than 1961-1990. Summers, too.

But by 2070, that could change, with drier summers and wetter winters in a “high emission scenario”.

By 2070, summer days could be 3.7-6.8C hotter, the Met Office says - and as a reminder, the hottest day on record was just this year.

Sea levels are also expected to rise by the end of the century - by anywhere from 0.3m to 1.15m in London, and less in Edinburgh - with the south seeing higher rises than the north in general (but it depends a lot on the landscape).

Image source, Franck Noudofinin

The BBC's Franck Noudofinin is at the protest march outside Dakar, Senegal.

He says more than 200 schoolchildren and students have gathered in the suburb of Rufisque for the climate strike.

Many of the young people taking part carry signs which say "legui legui" - "right now".

Senegal is particularly vulnerable to climate change.

It it is already experiencing "desertification" - the persistent degradation of dry land ecosystems by human activities and climate change.

The UN predicts more than 50 million people will be forced to leave their homes by 2020 because their land has turned to desert.

You can read our report about desertification in Senegal here.

Image source, Franck Noudofinin

Roland Hughes
BBC News, London

As America's east coast wakes up, we're already almost 12 hours in to the global climate strike. We've seen protesters take to the rising seas of the Solomon Islands in the Pacific, young activists storm a government office in Bangkok, hundreds of thousands of people march in Australia and massive crowds building across Europe.

The big event will be in New York in about four hours - we'll bring you the latest pictures there as we get them.

Keiligh Baker
BBC News, London

As we mentioned previously, it's proving tricky to definitively say how many people are at each of the protests as they are still growing.

For instance in Germany alone more than 10,000 people registered to attend the protest in Berlin - but the pictures suggest there are a lot more than that, and Greta Thunberg (who's in New York) tweeted that 80,000 people are thought to be there.

In Bremen 30,000 people are taking part in the strike while 17,000 people are in attendance at the protest in Freiburg.

You'll soon be able to see for yourself how many people are in the London protest - we're hoping to get a live feed up and running in a bit.

Ashitha Nagesh
BBC News, London

Protests are a time for drawing attention to serious issues, but they're also an opportunity to show off your incredible placard-making skills.

Some are funny, others make you think - and the really good ones make you do both.

Here are some of the most striking ones from today's protests so far.

Image source, Reuters

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We've put together a gallery of the best images from around the world - you can look at it here.

Keiligh Baker
BBC News, London

Right now, there are protests taking place simultaneously in dozens of countries across Europe, Africa and parts of Asia. We'll be honest: there are so many, it's proving a bit tricky to keep on top of them all.

Hundreds of university and high school students have skipped classes in the Philippines to march while dozens of people have gathered in central Hong Kong as part of the global strike.

In Germany protesters have gathered at the Brandenburg Gate ahead of the country's main protest.

Pictures from the strike show thousands of people packed in to the area waving flags, placards and giant balloons.

Image source, AFP/ Getty Images

In London schoolchildren from across the country have descended on the capital to make their voices heard.

Outside Westminster, where organisers are expecting tens of thousands of people, the crowd is steadily growing.

The Metropolitan Police, London's force, tweeted that it has already arrested two protesters who were taking part in the strike on alleged public order offences.

And in Nairobi climate change protesters wearing recycled plastic accessories have gathered in Uhuru Park.

Hundreds converged with placards and banners before marching through the streets of Nairobi to the Kenyan Ministry of Environment office.

Protests are taking place concurrently in Frankfurt, Oslo, Johannesburg, Lagos and dozens of other major cities across the world.

Image source, PA Media

Earlier on Friday there were staged 'die-ins' in Thailand and protesters calling for climate justice in India and Bangladesh, which is threatened by rising sea levels.

And in Australia, more than 300,000 kids, parents and supporters rallied, organisers said, more than double the turnout at climate strikes in March

Millions are expected to take part in the protests, which are being held in 150 countries.

The strike will culminate in New York on Friday evening when Greta Thunberg, who has been nominated for a Nobel peace prize for her climate activism, will speak outside the United Nations headquarters.

Image source, Reuters

Dilnawaz Pasha
BBC Hindi, Delhi

It started off with just a few dozen people but the crowd quickly swelled to several hundred, mostly school and college students.

They gathered outside Delhi’s historic Lodhi garden, a sprawling park that is home to medieval royal tombs, to join the global climate strike.

“What do we want? Climate justice! When do we want it? Now!” they chanted as they walked down the street on a humid afternoon, carrying hand-made banners and posters.

“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 says. “This is nature’s wrath. And it’s coming for us. That’s what brought me here.”

I spoke to several students and their demand was clear: immediate action by the government to tackle climate change.

“My message for everybody is: We need to strike now,” declared 20-year-old Samra Shahzad, who calls herself a climate activist.

“We need to do this now. It’s our future.”

The Dutch are fighting a daily battle against the rising tides. With almost a third of the country below sea level it's hard not to be climate conscious.

My daughter has just turned three. She's aware most cars cause pollution, and that by cycling the only thing we're burning is calories.

Strolling on the beach near our home the other day, she spotted a stray scrap of plastic, scooped it up and deposited it in the bin declaring: "There you go fish, now you won't get sick..."

We also read stories about selfish dragons who damage the planet with their reckless behaviour.

Raising my girl in a time of climate change has meant an almost subconscious incorporation of environmental awareness. Just as I teach her to brush her teeth, she knows that same commitment to cleanliness must be shown on the streets.

Image source, Anna Holligan

This densely populated nation is synonymous with windmills, those iconic beacons of wind power. And cycling: there are more bikes than people in a country criss-crossed with bike paths.

The irony is, the Netherlands has Europe’s highest number of children with asthma caused by traffic pollution.

A report in medical journal The Lancet found that one in five Dutch children has pollution-induced asthma, with the number rising to more than half in the big cities like The Hague, where we live.

Nitrogen oxide from diesel cars and lorries are the main cause: the Netherlands has some way to go to achieve its climate goal of 49% less emissions in 2030 compared with 1990.

We're raising superheroes who'll protect the planet in the future.

I'm acutely conscious my daughter's relationship with the environment today will determine what it looks like tomorrow.

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: How much hotter has the world got, and how much hotter will it get?

A: Global temperature rises are generally compared to "pre-industrial times". Many researchers define that as 1850-1900 - before the world was chugging out greenhouse gases on a global scale.

The world is now about 1C warmer than it was back then, according to the UN Intergovernmental Panel on Climate Change (IPCC).

For decades, researchers argued the global temperature rise must be kept below 2C by the end of this century to avoid the worst impacts.

But scientists now argue that keeping below 1.5C is a far safer limit for the world.

It's hard to know much hotter the world will get. But if current trends continue, the World Meteorological Organization says temperatures may rise by 3-5C by 2100.

Navin Singh Khadka
Environment correspondent, BBC World Service

Just as young people are gathering in their hundreds of thousands to stage climate strikes in cities across the world, the Russian capital, Moscow, offers a unique picture: just one protester in the heart of the city.

Arshak Makichyan has been staging the Fridays For Future strikes all by himself for nearly six months.

His application for group protests in central Moscow has been rejected by the Russian government. Any protest by more than one person in central parts of the city must be approved.

“They said we could protest in a park but no one even goes there,” the 24-year old told the BBC.

Image source, Arshak Makichyan

A violinist by profession, Arshak says he was inspired by Greta Thunberg, the Swedish teenage climate activist who began the Fridays for Future strike.

“I thought climate change was just science, but Greta had the right words to explain why it should worry all of us.”

He says his initiative has motivated youths in other parts of the country to stage strikes demanding action against climate change.

“But my main effort is to garner support of youths here in central Moscow so that we can influence the government to act.”

Russia is the fourth largest emitter of greenhouse gases after China, the US and India.

The country has suffered from what scientists say are climate-related events like wildfires in Siberia, and buildings and infrastructure collapsing because of permafrost thawing and floods.

Moscow is yet to ratify the Paris climate agreement while it is increasingly involved in drilling the Arctic for fossil fuels.

Ashitha Nagesh
BBC News, London

As lunchtime nears, protests in the UK continue to grow. Our reporter Hannah Richardson, who's in Westminster among the crowds, says it's getting a lot busier.

Here are a few of the best images we've seen so far from across Britain:

Image source, PA

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Image source, PA