Watch: New York welcomes 2018 in sub-zero conditions

A packed Times Square in New York welcomed in the New Year at what was 6pm tonight in New Zealand. 

Hundreds of thousands of revellers braving sub-zero conditions to cheer the annual drop of a crystal ball.

Pop legend Mariah Carey was just one of the stars keeping spirits up, a brave call after bungling last year's performance.

Police were taking no chances with thousands of extra officers, including snipers, creating a so-called "ring of steel".

And tight security was in place as European capitals ushered in the new year.

From London to North Korea, extravagant fireworks displays marked the start of 2018.