The UN's weather agency says the last five-year period beat 2006-10 as the warmest such period since records began in the 19th century.
The past five years were the hottest on record with mounting evidence that heat waves, floods and rising sea levels are stoked by man-made climate change, the United Nations weather agency says.
Some freak weather events would have happened naturally but the World Meteorological Organization (WMO) on Tuesday said greenhouse gas emissions had raised the risks of extreme events, sometimes by a factor of 10 or more.
"We just had the hottest five-year period on record, with 2015 claiming the title of hottest individual year. Even that record is likely to be beaten in 2016," WMO Secretary-General Petteri Taalas said in a statement.
Among the worst extremes, a 2011-12 drought and famine in the Horn of Africa killed more than 250,000 people and Typhoon Haiyan in the Philippines killed 7800 in 2013, the WMO said.
Superstorm Sandy caused $US67 billion ($A87 billion) of damage in 2012, mostly in the United States, it said in a report issued to a meeting of almost 200 nations in Morocco tasked with implementing a 2015 global agreement to combat climate change.
The last five-year period beat 2006-10 as the warmest such period since records began in the 19th century.
The heat was accompanied by a gradual rise in sea levels spurred by melting glaciers and ice sheets. The changes "confirmed the long-term warming trend caused by greenhouse gases", the WMO said of the report.
And the amount of carbon dioxide, the main greenhouse gas, reached 400 parts per million in the atmosphere for the first time in records in 2015, it said.
Last year was the first in which temperatures were one degrees Celsius above pre-industrial times, partly because of an El Nino weather event that warmed the Pacific.
The 2015 Paris Agreement set an overriding target of limiting warming to "well below" 2 degrees above pre-industrial times, ideally just 1.5 degrees.
But pledges so far to curb greenhouse gas emissions are too weak and put the globe on target for about 3 degrees, UN data shows.