New Delhi: The World Meteorological Organization (WMO) on Wednesday said 2015 is likely to be the warmest year on record, thanks largely to El Niño, but also on account of human-induced global warming.

For months in a row this year, the US National Oceanic and Atmospheric Administration has been declaring each month the hottest on record.

A few days ahead of the UN climate change conference in Paris, WMO said the global average surface temperature in 2015 may even reach the significant milestone of 1° Celsius above the pre-industrial era.

The 2011-15 period has been the warmest five-year period on record, with many extreme weather events—especially heat waves—influenced by climate change, said WMO.

“The state of global climate in 2015 will make history for a number of reasons," said WMO secretary-general Michel Jarraud. “Levels of greenhouse gases in atmosphere reached new highs and in the northern hemisphere, (during) spring 2015, the three-month global average concentration of carbon dioxide crossed the 400 parts per million barrier for the first time. This is all bad news for the planet," he added.

Jarraud further said this year the earth is experiencing a powerful El Niño event, which continues to gain strength and is influencing weather patterns across the world. A preliminary estimate based on data from January to October shows the global average surface temperature for 2015 so far was around 0.73°C above the 1961-1990 average of 14°C, and approximately 1°C above the pre-industrial 1880-1899 period.

El Niño is a weather phenomenon resulting from warming in Pacific Ocean regions, leading to atmospheric changes.

Going by the global average temperatures over land from January to October, WMO said 2015 is also set to be one of the warmest years on record over land. South America is having its hottest year on record, as is Asia, while Africa and Europe are having their second hottest.

As is typical during El Niño years, large areas of Central America and the Caribbean recorded below average rainfall, even as Argentina and Peru were affected by heavy rain and floods. WMO also took note of the major heat wave that affected India and Pakistan in May and June, with average maximum temperatures exceeding 42°C and touching 45°C in some areas.