Lights at landmarks, businesses and homes were switched off for Earth Hour on Saturday.
The annual event aims to highlight the impact humans have on the planet due to climate change, pollution, plastic and food production.
Over 7,000 cities in more than 170 countries took part in 2019.
Organisers at conservation charity WWF said they hoped the event would send a message to international leaders that protecting the Earth should be top of their agenda.
Proceedings kicked off this year in the Pacific island nation of Samoa at 8:30pm local time.
The event has since swept across Australia, Asia and Europe.
Earth Hour events have spread to more than 180 countries since the movement started in 2007.
Activists at events on Saturday called for greater awareness and more sparing use of resources, especially fossil fuels that produce carbon gasses and lead to global warming.
WWF said that people living today were the first generation to experience the effects of climate change, and the last to be able to change it, while the planet is also suffering plastic pollution and deforestation.
The charity encouraged people to pledge personal actions as part of this year’s Earth Hour, such as turning the washing machine down to 30C, avoiding single-use plastics, planning a staycation or holiday nearer to home, changing the way they eat or helping restore nature in their local area.
If you would like to see how Earth Hour 2019 unfolded, please see what was our live coverage below:
