The past five years have been the warmest in recorded history, with 2015 claiming the title of hottest individual year.
Heatwaves, floods and rising sea levels are stoked by man-made climate change, the United Nations weather agency has said.
Some freak weather events occur naturally but the World Meteorological Organization (WMO) 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 on Monday. It said the last five-year period is the mounting evidence for that.
Among the extreme examples, a 2011-12 drought and famine in the Horn of Africa killed more than 250,000 people and Typhoon Haiyan in the Philippines killed 7,800 in 2013, the WMO said
Superstorm Sandy caused $67 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 past five years 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 (1.8 Fahrenheit) 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 C (3.6F) above pre-industrial times, ideally just 1.5 (2.7F).
But pledges so far to curb greenhouse gas emissions are too weak and put the globe on target for about 3C (5.4F), UN data show. The Marrakesh meeting is trying to work out ways to step up actions and write rules for the Paris Agreement.
Getting on track "means a global transformation" of the world economy to cleaner energies in sectors from energy to transport, Moroccan Environment Minister Hakima El Haite told Reuters.