Carbon dioxide (CO2) levels surged past the 400 parts per million climate change benchmark for the first time in 2016.

The increase is a continuation of the rising CO2 levels in 2015 when some months even passed the threshold for the first time in history.

According to World Meteorological Organization's (WMO) Greenhouse Gas Bulletin, 2016 would likely be the first full year to exceed the mark, largely to due to this year's strong El Niño event.

Carbon dioxide emissions have since remained fixed between 2014 and 2015. But the onset of El Niño--a weather phenomenon characterized by warming, nutrient-poor ocean waters--caused a dramatic spike in the levels of gas in the atmosphere. El Niño has caused drought in tropical regions, which reduced the capacity of forests, oceans, and vegetation to absorb excess CO2. Apart from this, wildfires sparked by the dry weather have also contributed to carbon emissions. WMO said that these conditions caused CO2 levels to grow above the average for the last 10 years.

"The year 2015 ushered in a new era of optimism and climate action with the Paris climate change agreement. But it will also make history as marking a new era of climate change reality with record high greenhouse gas concentrations," WMO Secretary-General Petteri Taalas said in a statement. "The El Niño event has disappeared. Climate change has not."

According to the report, the greenhouse gas monitoring station at Mauna Loa in Hawaii predicted that CO2 concentrations will stay above 400ppm for the entire 2016 and will remain so for many generations.

The last time carbon dioxide levels reached more than 400ppm was three to five million years ago, BBC reports. Before this, atmospheric levels remained at 280ppm.

The report also highlights the growing levels of other greenhouse gases, including methane and nitrous oxide. According to the report, atmospheric methane had reached about 1845 parts per billion (ppb) in 2015, 2.5 times greater than in the pre-industrial era, while nitrous oxide was at 328ppb, 1.2 times above historic levels.

"Without tackling CO2 emissions, we cannot tackle climate change and keep temperature increases to below 2 degrees C above the pre-industrial era," Taalas said. "It is therefore of the utmost importance that the Paris Agreement does indeed enter into force well ahead of schedule on 4 November and that we fast-track its implementation."

In November, 200 nations who signed the Paris Climate Agreement will be meeting in Morocco to discuss the next steps.