Last year was officially the hottest since records began, leading to warnings that man-made climate change is pushing the world into “uncharted territory”.
The global temperature in 2015 was 0.75C above the long-term average for 1961 to 1990, and 1C above the pre-industrial average, according to the Met Office.
Their joint analysis with the University of East Anglia's (UEA) Climatic Research Unit shows the world is already halfway to the 2C rise nations agreed as a limit to avoid dangerous climate change.
Peter Stott, head of climate monitoring and attribution at the Met Office’s 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."
The rise has partly been blamed on the El Nino effect, a natural wind-driven warming of ocean surface temperatures, but researchers warn humans are also to blame.
Professor Phil Jones from the UEA 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."
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The 2015 figures broke a record set the previous year and the Met Office predicts average temperatures will soar again in the next 12 months.
Global average temperatures in 2016 are expected to be between 0.72C and 0.95C above the long-term average of 14C.
