Andreas Illmer
Singapore

Here's some more on Greta Thurberg, the teenager credited with inspiring these protests.

Back in 2018, Greta started ditching school to sit by herself outside parliament in Stockholm with a protest sign calling for climate action.

Her action soon snowballed into demonstrations across Europe, the US and Australia. As they're usually on a Friday, they became known as Fridays for Future or School Strike for Climate. Students are essentially calling on their governments to put their money where their mouth is and take urgent action.

Since those early days in Sweden, the now 16-year old has gone from solitary activist to global figurehead, speaking in front of the US Congress and fist bumping Barack Obama.

Even under a best-case global warming scenario, coastal Sydney is expected to be at least 1.5C hotter in 2100 than it was in 1900.

Under a worst-case scenario, some Australian cities could be 4.5C hotter.

• Australia records hottest summer ever

Frances Mao
Sydney

The Australian masses have caught the eye of Greta Thunberg - the 'OG' climate protester, who has tweeted her praise. The Swedish teenager inspired a global climate movement with her solitary protests last year.

Arguably the most famous climate activist in the world today, she's been nominated for the Nobel Peace Prize and will address the UN's climate summit next week.

Her sharp words to US Congress on Thursday also generated plenty of chatter. "Sorry, you're not trying hard enough" was what she said - a message echoed by many teenagers in Australia too.

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

Our correspondent Phil Mercer is among thousands of people at The Domain in Sydney.

He tells us that their overriding message is being "angry and scared with the world on the edge of catastrophe", adding: "There is an unmistakable air of defiance here."

The protesters are chanting "we will win" and "we are only just getting started".

Image source, Annabelle Johnson

The last summer was Australia's hottest on record, and it has coincided with extreme weather events. Within the past 12 months, the continent has been lashed by bushfires, heatwaves, floods and cyclones.

A protracted drought, one of the worst on record, is affecting much of the country.

While Australia has always experienced such events, scientists say climate change is making them more frequent and severe.

It's only the start of bushfire season now, for instance, but blazes are already causing chaos - as this video explains.

Frances Mao
Sydney

Protests are under way across this vast continent - in drought-stricken towns and the major coastal cities.

Organisers are expecting more than 150,000 people to turn out. While many will be young people - the driving force behind this movement - they're hoping this time around to be joined by more adults.

Thousands of workplaces have signed up to a national campaign encouraging office workers to "take a long lunch" or a day off to participate.

Chief among the protesters demands here are calls for the government to end plans for new coal mines.

Image source, Getty Images

Jay Savage
BBC News Online Australia Editor

The protests have kicked off in Pacific island nations, with large crowds turning out in Vanuatu and the Solomon Islands.

Low-lying states in the region are on the frontline of climate change, and battling already some of its worst impacts.

Rising sea levels pose an existential threat to nations like Tuvalu, where the highest point is less than 5m (16 feet) above sea level, and some residents have already been forced to relocate.

Regional leaders met there for the Pacific Islands Forum last month, where Australia drew blame for stifling a statement on stronger climate action.

The UN has said that what is happening to the Pacific island countries “is a sign of what is in store for the rest of us”.

The strike will follow the sun around the globe, and so will we. So we're starting with the BBC team in Sydney, who have been watching things get under way in the Pacific. Huge numbers of people - including students and schoolchildren skipping school - are beginning to join events in cities in Australia and New Zealand.

The climate of the planet is always changing, and it has constantly been changing over time. The global average temperature today is about 15C (59F), but geological evidence suggests it has been much higher and lower in the past.

But the period of warming we’re seeing right now is happening more quickly than during many events in the past. Scientists worry that our climate’s natural fluctuation is being overtaken by rapid human-induced warming. This could have serious implications for the stability of the planet's climate.

Here's our quick guide to climate change if you want to bring yourself up to speed or share it with someone you think might be interested.

Anna Jones
Singapore

Hello, welcome to our live coverage of Friday's Global Climate Strike. Millions of people - overwhelmingly children and teenagers - are expected to turn out at protests and events across the globe, calling on their governments to take serious action to protect our planet and their futures.

We'll be with you as the world turns, checking in on events big and small, and updating you on the various climate issues affecting different parts of the globe. Our reporters and correspondents will also be telling you how those regions are affected by rising pollution or other environmental issues. We'll also be showcasing people who are taking matters into their own hands, and ways you can take action on climate change.