This year is expected to be one of the hottest on record, with temperatures more than 1C above pre-industrial levels, the World Meteorological Organisation has said.
While 2017 is not on track to outstrip the record heat of 2016, it is expected to be the second or third warmest year recorded - and the hottest without the influence of an "El Nino" natural weather pattern which pushes up global temperatures.
High temperatures has been accompanied by "extraordinary weather" from record-breaking hurricanes to heatwaves, flooding and drought, many of which bear the tell-tale sign of climate change caused by human activity, the WMO said.
In an announcement as annual UN climate change talks hosted by Fiji begin in Bonn, Germany, the WMO said the average global temperature from January to September 2017 was 1.1C above the pre-industrial era.
As a result of a powerful El Nino, 2016 is likely to remain the hottest year on record, but 2017 is expected to join 2015 as the second or third hottest year.
The years 2013 to 2017 are likely to be the hottest five-year period on record.
Parts of southern Europe including Italy, North Africa, parts of eastern and southern Africa and the Asian part of Russia experienced record warm conditions.
Other indicators of rising temperatures include Arctic sea ice, which was well below average throughout 2017 and was at record low-levels for the first four months of the year. while sea ice cover in Antarctica also hit record lows.
Globally, sea surface temperatures in 2017 are on track to be among the three highest on record, with some significant coral "bleaching" caused by over-warm oceans, including on Australia's Great Barrier Reef.
Major, high-impact hurricanes battered the US, with Harvey in August, followed by Irma and Maria in September.
Ophelia reached major hurricane status more than 600 miles further north-east than any previous North Atlantic hurricane and caused significant damage in Ireland.
While there is no clear evidence climate change is making hurricanes such as Harvey more or less frequent, it is likely human-induced global warming is making rainfall more intense and rising sea levels worsens storm surges, the WMO said.
During 2017, exceptionally heavy rain caused a landslide in Sierra Leone, many parts of the Indian subcontinent were hit by flooding, as was Peru and area of southern China, while east Africa remained gripped by drought.
Italy saw drought and record temperatures, heatwaves hit parts of South America, eastern Australia and southwest Asia, and wildfires raged in Chile, Portugal and the US.
WMO secretary-general Petteri Taalas said: "The past three years have all been in the top three years in terms of temperature records. This is part of a long term warming trend.
"We have witnessed extraordinary weather, including temperatures topping 50C (122F) in Asia, record-breaking hurricanes in rapid succession in the Caribbean and Atlantic reaching as far as Ireland, devastating monsoon flooding affecting many millions of people and a relentless drought in East Africa.
"Many of these events - and detailed scientific studies will determine exactly how many - bear the tell-tale sign of climate change caused by increased greenhouse gas concentrations from human activities," he said.