2014 has been ranked as the hottest year on record by the UN’s weather and climate body.
World Meteorological Organisation (WMO) analysis shows that 14 of the 15 hottest years on record have all occurred this century, and experts warned they expected the warming trend to continue as greenhouse gases rises.
The analysis by the WMO of different international datasets, including the UK’s Met Office and Climatic Research Unit at the University of East Anglia, put average global temperatures last year 0.57C (1.03F) above the long term average.
This puts 2014 above previous record years of 2010, when temperatures were 0.55C above the long term average of 14C (57.2F), and 2005, when temperatures were 0.54C (0.98F) above average.
But the difference in temperature between the warmest years falls within the margin of uncertainty, so while 2014 is “nominally” the hottest on record, there is very little difference between the warmest years, the WMO said.
Two key datasets by US government agencies Nasa and the National Oceanic and Atmospheric Administration (NOAA), which are used in the analysis by the WMO, have already declared 2014 the hottest year on record.
The Met Office and CRU said it was one of the warmest, nominally coming joint first with 2010.
WMO secretary-general Michel Jarraud said: “Analysis of the datasets indicates that 2014 was nominally the warmest on record, although there is very little difference between the three hottest years.
“Fourteen of the 15 hottest years have all been this century. We expect global warming to continue, given that rising levels of greenhouse gases in the atmosphere and the increasing heat content of the oceans are committing us to a warmer future,” he said.
Much of the energy trapped in the atmosphere by greenhouse gases from burning fossil fuels ends up in the oceans, where it influences the climate, and global sea surface temperatures reached record levels in 2014.
Mr Jarraud added: “In 2014, record-breaking heat combined with torrential rainfall and floods in many countries and drought in some others - consistent with the expectation of a changing climate.”