Indonesian girls pose for photographs as they hold candles for the Earth Hour environmental campaign in Surabaya.
The 13th edition of Earth Hour, organized by green group WWF, saw millions of people across 180 countries turn off their lights at 8:30 pm to highlight energy use and the need for conservation.
The event comes after some of the most dire warnings yet on the state of Earth's natural habitat and species.
"We are the first generation to know we are destroying the world. And we could be the last that can do anything about it," WWF said.
"We have the solutions. We just need our voices to be heard."
"It's about individuals taking personal action but joining with hundreds of millions of people around the world to show that not only do we need urgent action on climate change but we need to be protecting our planet," he added.
Dozens of companies around the world said they would take part in this year's campaign, which also saw Singapore's skyline go dark and Hong Kong turn off the lights along Victoria Harbour.
In New York, the riverfront United Nations headquarters turned black, as did the Brandenburg Gate in Berlin and Saint Peter's Basilica in the Vatican.
Other global landmarks that flicked the switch included Sydney's Opera House, the Eiffel Tower and Arc de Triomphe in Paris, Dubai's Burj Khalifa -- the world's tallest skyscraper -- the Acropolis in Athens, Shanghai Tower and the Kremlin building in Moscow.
"Earth hour still is the world's largest grassroots movement for people to take action on climate change.
WWF's own "Living Planet" report in October said 60 percent of all animals with a backbone -- fish, birds, amphibians, reptiles and mammals -- had been wiped out by human activity since 1970.
In Cali, Colombia, people lit candles to form a "60+" sign as part of the Earth Hour events.
Another study said a recent decline in bugs that fly, crawl, burrow and skitter across still water -- fueled by deforestation, urbanization and the rise of commercial farming -- was part of an unfolding mass extinction event, only the sixth in the last half-billion years.
Last year, Earth Hour was observed in more than 7,000 towns and cities in 187 countries, according to the organizers.
While the lights-off event is a symbolic gesture, Earth Hour has led successful campaigns over the past decade to ban plastics in the Galapagos Islands and plant 17 million trees in Kazakhstan.
The world population is expected to climb to 9.7 billion in 2050 from 7.7 billion today, with the population of sub-Saharan Africa doubling, a United Nations report released Monday said.
The protests were organised by the campaign group Extinction Rebellion, which was established last year in Britain by academics and has become one of the world's fastest-growing environmental movements.
African Clean Up Initiative (ACI) a non-governmental organisation that aims to raise environmentally responsible citizens, launched a project in December 2018 called RecyclesPay Education Project.
An estimated 37.9 million people now live with HIV — a record 23.3 million of those have access to some antiretroviral therapy (ART), UNAIDS said in its annual report.
“Two people have been declared dead and over 40 are trapped under the debris,”
Iran’s state TV says 18 people were killed and 14 injured in two separate road accidents in the country.