Climate protests are planned in at least 125 countries on every continent.
Youth activists say their governments have been too slow to implement policies to curb global warming.
Hundreds of thousands of school students around the world walked out of class on Friday to urge their governments to take greater action in slashing greenhouse gas emissions.
Climate protests are planned in more than 1600 towns in over 125 countries and organizers say the number of strikers is expected to surpass the 1.6 million people who took part in the first Global Climate Strike in March.
The protests on Friday started in New Zealand and Australia, which recently experienced its hottest summer on record.
Strikes are planned in countries across every continent, from Nepal to Nigeria.
Jake Woodier of the UK Student Climate Network (UKSCN) told CNN that tens of thousands of students were taking part in 120 strikes across the UK, from Cornwall to Scotland.
“Since March we have witnessed an entire narrative shift around climate breakdown. The climate crisis has been driven right to the top of the agenda and politicians and the media are starting to at least have conversations about the need for action,” he said.
Despite increased awareness about the climate crisis, activists say governments have been too slow to implement policies to curb global warming.
“The UK government is dragging its heels on climate action,” Woodier said.
The UK is the first country in the world to declare a climate emergency and is a signatory of the 2015 Paris climate agreement, which calls on countries to reduce their carbon output and halt global warming below 2 degrees Celsius by the end of the century.
Earlier this month, climate experts urged the UK government to slash greenhouse gas emissions to net zero by 2050.
Ahead of the Global Climate Strike in March, youth activists told CNN about their personal experiences of climate change – ranging from wildfires in California to rising sea levels in Mauritius.
13-year-old Alexandria Villasenor, who leads the climate movement in the United States, told CNN, “I’m upset with how world leaders are treating the climate crisis. [The youth] need to make sure that people in power start taking action because we don’t have time to wait until we can.”
Last year, global carbon emissions reached a record high and a UN report warned that unprecedented global action is needed to limit global temperature rises to 1.5C above pre-industrial levels.
Scientists warned earlier this month that one million species are threatened with extinction due in part to climate change and pollution caused by humans.