Last year was the hottest on record, US space agency NASA and the National Oceanic and Atmospheric Administration (NOAA) have said. El Nino accounts for only part of the record heat.
Data from NASA and NOAA show the average temperature on land and ocean surfaces in 2015 was 1.62 Fahrenheit (0.90 Celsius) above the 20th century average, making last year the hottest since recording began in 1880.
Last year the annual global temperature record was also broken by the largest margin, surpassing 2014's previous record by 0.29 F (0.13 C).
"2015 was remarkable even in the context of the larger, long-term warming trend," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.
Global temperatures have been on a steady upward trajectory, with records being set already four times since the turn of the century.
"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.
US scientists said record breaking heat last year was only partially attributable to El Nino, a periodic weather cycle in the Pacific. The El Nino that started in late 2015 and will continue until spring of this year only added to what was already a global temperature rise.
The ever increasing temperature and weather anomalies come as the international community reached a landmark climate deal in Paris in December to cut human induced greenhouse gases to limit temperature increases to well below 3.6 F (2.0 C).
cw/xx (AFP, Reuters)