GENEVA, Nov. 25 (CGTN) -- The concentration of greenhouse gases responsible for causing global warming has "reached another new record high," paving the way for intense climate crisis in the coming years, warned the World Meteorological Organization (WMO) on Monday.

The level of carbon dioxide reached 407.8 parts per million in 2018, up from 405.5 parts per million (ppm) in 2017. The increase of 2.3 ppm last year was very close to that recorded from 2016 to 2017, found the WMO Greenhouse Gas Annual Bulletin.

The increase in the carbon dioxide level last year was above the average growth rate over the last decade, researchers calculated. "There is no sign of a slowdown, let alone a decline, in greenhouse gases concentration in the atmosphere despite all the commitments under the Paris Agreement on Climate Change," said Petteri Taalas, secretary-general of the WMO.

The concentration level of the gas averaged over three decades from 1985 to 2015 has been spiraling, and each decade is surpassing the previous one.

Levels for 1985–1995, 1995–2005 and 2005–2015 increased from 1.42 parts per million to 1.86 parts per million per year and to 2.06 parts per million per year, respectively, with the highest annual growth rates observed during El Niño events.

Greenhouse gases — like carbon dioxide, methane and nitrous oxide — are emitted by natural sources and from human activity. But the emissions caused by the latter, mostly from burning fossil fuels, are continually rising.

In order to reduce emissions, countries signed the Paris Climate Change accord in 2016, pledging to cut down on fossil fuel use. However, this has not been put into practice as countries continue to extract and use the climate damaging fuels: coal, oil and gas.

"We need to translate the commitments into action and increase the level of ambition for the sake of the future welfare of the mankind," said Taalas.

Methane concentration levels also reached a "new high" of 1869 parts per billion (ppb) in 2018. For nitrous oxide, the gas responsible for the destruction of the ozone layer, the level was 331.1 ppb last year.

"For CH4 [methane], the increase from 2017 to 2018 was higher than both that observed from 2016 to 2017 and the average over the last decade," the report added.

A half of emitted greenhouse gases are absorbed by natural sources – oceans, trees and land. However, a significant amount of the gases remain trapped in the atmosphere for centuries, heating the planet. Every year, the WMO calculates the remaining level of greenhouse gases trapped in the Earth's atmosphere.

Carbon dioxide concentration levels breached the symbolic 400 ppm mark in 2015, triggering a global alarm to reduce emissions.

Since 1990, the warming effect from these gases has increased by 43 percent, with carbon dioxide contributing 80 percent. Methane contributes 17 percent to global warming and nitrous dioxide share is around six percent.

"It is worth recalling that the last time the Earth experienced a comparable concentration of carbon dioxide was three-to-five million years ago. Back then, the temperature was two-to-three degrees Celsius warmer, the sea level was 10-20 meters higher than now," reminded Taalas.