Michel Jarraud, Secretary-General of the World Meteorological Organization (WMO) gestures during the presentation of the five-year report on the climate from 2011-2015 at the United Nations European headquarters in Geneva, Switzerland, Nov 25, 2015. [Photo/Agencies]

UNITED NATIONS - The year 2015 is likely to be the warmest on record, according to a report released by the UN weather agency on Wednesday.

Meanwhile, the global average surface temperature in 2015 is to reach the symbolic and significant milestone of 1 degree celsius above the pre-industrial era, according to the five-year analysis by the World Meteorological Organization (WMO).

"This is due to a combination of a strong El Nino weather pattern and human-induced global warming, according to the Organization," Farhan Haq, the deputy UN spokesman, said at a daily news briefing here.

According to the report, the 2011-2015 five-year period has also been the warmest, with many extreme weather events, especially heatwaves, substantially exacerbated by human-induced climate change, in some cases by a factor of 10 or more, according to the UN World Meteorological Organization (WMO).

The report came at a time when world climate negotiators are set to gather at Paris next Monday for the UN Climate Change Conference to thrash out a global climate pact.

"The state of the global climate in 2015 will make history for a number of reasons," WMO Secretary-General Michel Jarraud said, noting that this year's climate has also been affected by El Nino, a cyclical weather pattern of devastating droughts and catastrophic floods that can affect scores of millions of people around the globe.

"Levels of greenhouse gases in the atmosphere reached new highs and in the Northern hemisphere spring 2015, the three-month global average concentration of CO2 (carbon dioxide), crossed the 400 parts per million barrier for the first time," he said. "As such, 2015 is likely to be the hottest year on record, with ocean surface temperatures at the highest level since measurements began."

"It is probable that the 1 degree celsius threshold will be crossed. This is all bad news for the planet. Greenhouse gas emissions, which are causing climate change, can be controlled. We have the knowledge and the tools to act. We have a choice. Future generations will not," Jarraud said.