MIAMI • Not only was 2015 the warmest worldwide since 1880, but also it shattered the previous record held in 2014 by the widest margin ever observed, said a report by the National Oceanic and Atmospheric Administration (NOAA).
"During 2015, the average temperature across global land and ocean surfaces was 1.62 deg F (0.9 deg C) above the 20th-century average," said the NOAA report.
"This was the highest among all years in the 1880-2015 record."
Compared with 2014, last year was 0.16 deg C warmer, the "largest margin by which the annual global temperature record has been broken".
United States space agency Nasa, which monitors global climate using a fleet of satellites and weather stations, confirmed that last year broke records for heat in contemporary times.
Nasa said that the temperature changes are largely driven by increased carbon dioxide and other human-made emissions into the atmosphere.
"Today's announcement not only underscores how critical Nasa's Earth observation programme is, it is a key data point that should make policymakers stand up and take notice - now is the time to act on climate," said Nasa administrator Charles Bolden.
The latest finding adds to a steady rise in heat across land and sea surfaces that has seen records repeatedly broken over the years.
"Since 1997, which at the time was the warmest year on record, 16 of the subsequent 18 years have been warmer than that year," said the NOAA report.
Last year alone, 10 months had record-high temperatures for their respective months.
The heat was felt worldwide, with unprecedented warmth covering much of Central America and the northern half of South America.
High temperatures were observed in parts of northern, southern and eastern Europe, as well as western Asia and a large section of east-central Siberia.
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.
Last year was also the second driest year on record for Singapore, with a total annual rainfall of 1,266.8mm, following 1997's 1,118.9mm, said the Meteorological Service Singapore.
According to Dr Tom Karl, director of NOAA National Centres for Environmental Information, new heat records would have been set even without the El Nino weather phenomenon, which leads to warmer waters in the equatorial Pacific.
"But El Nino pushed it way over the top," Dr Karl told reporters.
NOAA's announcement came against the backdrop of the recently completed Paris climate talks, at which the goal of capping global warming at 2 deg C above pre-industrial levels was enshrined.
Many scientists say the planet is already about halfway to that milestone, with no sign of slowing down. "This trend will continue," said Mr Gavin Schmidt, director of Nasa's Goddard Institute for Space Studies.
Because of the strong El Nino influence at the beginning of this year, "2016 is expected to be an exceptionally warm year and perhaps even another record", he told reporters.