This year will go down as one of the hottest on record, the World Meteorological Organization (WMO) said at the start of the UN climate conference in Bonn, Germany.
Almost 200 nations are meeting from November 6 to November 17 in the German city of Bonn to try to bolster the 2015 Paris climate pact despite a planned U.S. pullout.
Last year was the hottest, fueled by the El Nino weather phenomenon, while 2015 and 2017 are tied for second place, the UN agency said in its preliminary annual report on November 6.
It said that carbon dioxide in the atmosphere has continued to increase this year, while sea levels have risen further and the ice coverage in the Antarctic sea has moved towards a record low.
The report said the global mean temperature from January to September this year was about a half-degree Celsius warmer than the 1981-2010 average.
"We have witnessed extraordinary weather [in 2017]," WMO Secretary-General Petteri Taalas said in a statement.
He pointed to severe hurricanes in the Atlantic and Caribbean, temperatures above 50 degrees Celsius in Pakistan, Iran, and Oman, monsoon floods in Asia, and drought in East Africa.