Average global air temperatures in 2014 were 0.57 degrees Celsius (1.03 degree Fahrenheit) higher than the long-term average of 14 C (57.2 F) in a 1961-1990 reference period, the World Meteorological Organization (WMO) said in a statement.
“Fourteen of the fifteen hottest years have all been this century,” said WMO Secretary General Michel Jarraud.
“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,” he added.
UN members will meet in Geneva next week for talks on a global climate pact that must be signed in Paris in December for curbing emissions of greenhouse gases.
The UN seeks to limit warming to no more than 2 C over pre-Industrial Revolution levels, but scientists warn the Earth is on target for double the target, a scenario that could be catastrophic.