The globally averaged temperature, over land and ocean surfaces for 2015, was the highest since record keeping began in 1880, according to NOAA scientists.

NASA and the National Oceanic and Atmospheric Administration (NOAA) announced the news on Wednesday morning, after both agencies separately analyzed global temperature data and came to the same conclusion. And it beat the previous 2014 record by roughly one quarter of a degree, the second-largest year-over-year margin.

In Singapore, last year tied with 1998 and 1997 as the warmest years on record, with an annual mean temperature of 28.3 deg C. The next joint warmest years on record are 2010 and 2002, with an annual mean temperature of 28.1 deg C.

NOAA says 2015's average temperature was 58.62 degrees, passing 2014 by a record margin of 0.29 degrees.

The 2015 record-breaking year continues a long-term warming trend - 15 of the 16 warmest years on record have now occurred since 2001. NOAA put the number at above 99 percent - or "virtually certain", said Tom Karl, director of NOAA's National Centers for Environmental Information. While a warming El Niño was in effect for most of the year, 2015 is still considered "remarkable".

What's worse, 2016 is likely to be hotter than the previous year, said Gavin Schmidt.

It's official: 2015 was Earth's hottest year on record.

"For the first time in recorded history, the Earth's temperature is clearly more than 1.0 C (1.8 F) above the 1850-1900 average".

He said 2015 put a punctuation mark on a period of time during which the rate of warming appeared to slow.

"This record year really is just emphasizing the fact that there is a very, very strong long-term trend in temperature that we have associated very strongly with the human emissions of greenhouse gases", Schmidt said.

The record warmth occurred broadly around the world, including Central America, the northern half of South America, parts of northern, southern, and eastern Europe stretching into western Asia, a large section of east central Siberia and regions of eastern and southern Africa.

El Niño is releasing an vast amount of heat from the Pacific Ocean into the atmosphere that warms the ocean surface every two to seven years.

Locally, the concern with rising temperatures is the impact on the sea level.