Levels of greenhouse gases in the atmosphere have again hit a fresh record high, the World Meteorological Organization (WMO) said Monday.

According to its latest Greenhouse Gas Bulletin, globally averaged concentrations of carbon dioxide (CO2) hit 407.8 parts per million (ppm) last year, compared to 405.5 ppm in 2017. This is 47% higher than the estimated pre-industrial level in 1750.



The WMO added that atmospheric methane amounted to 1869 parts per billion (ppb) last year, another new high, while nitrous oxide hit 331.1 ppb in 2018. Methane is over double the pre-industrial level, while nitrous oxide is 23% higher than the pre-industrial level.



In a statement accompanying the bulletin's release, the WMO said there were "multiple indications" that the rise in atmospheric levels of CO2 was "related to fossil fuel combustion."



The bulletin comes before the COP25 climate summit in Madrid, which is scheduled to take place next month.

"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," Petteri Taalas, the WMO's secretary general, said in a statement.

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

The Paris Agreement was reached at the COP21 summit in December 2015. As well as a commitment to make sure global warming stayed "well below" 2 degrees Celsius above pre-industrial levels, world leaders also agreed to "pursue efforts" to limit the temperature rise to 1.5 degrees Celsius.

The Agreement suffered a setback on November 4 when the U.S. Secretary of State, Mike Pompeo, announced in a statement that the country had started the process to withdraw.



"Per the terms of the Agreement, the United States submitted formal notification of its withdrawal to the United Nations," he said. "The withdrawal will take effect one year from delivery of the notification."