2015 was globally the hottest year on record, with temperatures 1C above pre-industrial levels, the Met Office has confirmed.
The global temperature was 0.75C above the long-term average for 1961 to 1990, the warmest in records dating back to 1850, according to the analysis produced by the Met Office Hadley Centre and the University of East Anglia's (UEA) Climatic Research Unit.
The temperature was 1C above the average for 1850 to 1900, putting the world already halfway to the 2C limit to which countries have agreed to curb temperature rises, in a bid to avoid dangerous climate change.
Peter Stott, head of climate monitoring and attribution at the Met Office Hadley Centre, said: "2015 was a record-breaking year for our climate.
"Global mean temperatures reached 1C above pre-industrial levels for the first time and the year's average global temperature was the highest ever recorded."
Man-made global warming and the effect of a strong natural "El Nino" phenomenon in the Pacific are pushing temperatures to new highs.
Professor Phil Jones, from UEA's Climatic Research Unit (CRU), said: "While there is a strong El Nino-elevated global temperature this year, it is clear that human influence is driving our climate into uncharted territory."
2015's global average temperature was at the top end of predictions for the year made in 2014, and broke the record set in the previous year, the data shows.
Predictions from the Met Office for 2016 have suggested this year will set a new record, with global average temperatures expected to be between 0.72C and 0.95C above the long-term average of 14C.
The dataset produced by the Met Office Hadley Centre and the CRU is based on thousands of temperature measurements taken around the world on land and at sea each day, and is one of three major analyses that are used to assess global temperatures.