Nations have welcomed 2020 with a bang, as we bid farewell to a decade that brought us the election of Donald Trump, the rise of social media and the start of the Arab Spring, among other defining moments.

Samoa in the South Pacific was the first country to mark the start of the new decade, with fireworks erupting at midnight from Mount Vaea, overlooking the capital Apia.

New Zealand followed shortly afterwards, celebrating 2020 by setting off half a tonne of fireworks from the Sky Tower above the city centre as large crowds celebrated below.

Sydney heralded 2020 with its famous fireworks display over Sydney Harbour, as more than a million people descended on the city to watch the display.

Sydney faced pressure to call off the firework display, in solidarity with fire-hit areas. Credit: AP
Celebrations begin in Seoul, South Korea. Credit: AP
Buddhists light candles to form letters meaning, Credit: AP

Australia's largest city was under increasing pressure to cancel the fireworks, as ferocious wildfires tear through the country, but Sydney's Lord Mayor Clover Moore said the celebration would "give hope to people."

South Korea celebrated the start of a new year with a traditional bell-tolling ceremony, while in Japan, people flocked to temples and shrines to mark the first new year of the Reiwa era.

North Koreans seeing in 2020 in the capital Pyongyang. Credit: AP

In Hong Kong, protesters held up their hands to symbolise the five demands of the pro-democracy movement as New Year's fireworks light up the sky during a demonstration.

Chinese President Xi Jinping used his New Year's address to call for a return to stability following months of pro-democracy protests that began in June over a proposed extradition law, and have spread to include other grievances and demands for more democracy.

Protesters in Hong Kong hold up the five demands of the pro-democracy movement as New Year's fireworks light up the sky Credit: AP
Revellers in Beijing welcome in 2020. Credit: AP

Partygoers celebrated across Europe as the clock ticked closer to midnight in Greenwich Mean Time.

Berliners enjoyed a huge open air party at the iconic Brandenburg Gate with performances from names including East 17, The Rasmus and Hermes House Band.

Meanwhile, in Paris, revellers rang in the New Year at the Arc De Triomphe.