GENEVA, Nov. 22 (Xinhua) -- Heat-trapping greenhouse gases in the atmosphere have reached another new record high, which, with no sign of a reversal trend, is likely to drive long-term climate change, sea level rise and more extreme weather, the World Meteorological Organization (WMO) warned on Thursday.
According to its latest report released on Thursday, the WMO Greenhouse Gas Bulletin, the global averaged concentrations of carbon dioxide (CO2) reached 405.5 parts per million (ppm) in 2017, up from 403.3 ppm in 2016 and 400.1 ppm in 2015.
Concentrations of methane and nitrous oxide also rose, while there was a resurgence of a potent greenhouse gas and ozone depleting substance called CFC-11, which is regulated under an international agreement to protect the ozone layer.
Since 1990, there has been a 41 percent increase in total radiative forcing, which has the warming effect on the climate, by long-lived greenhouse gases, and CO2 accounts for about 82 percent of the increase in radiative forcing, the report says.
"The last time the Earth experienced a comparable concentration of CO2 was 3 to 5 million years ago, when the temperature was two to three degrees Celsius warmer and sea level was 10 to 20 meters higher than now," said WMO Secretary-General Petteri Taalas.
"The science is clear. Without rapid cuts in CO2 and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth. The window of opportunity for action is almost closed," he warned.
According to the Intergovernmental Panel on Climate Change (IPCC), net emissions of CO2 must reach zero around 2050 in order to keep temperature increases to below 1.5 degrees Celsius. That means the amount of CO2 entering the atmosphere must equal the amount that is removed by sinks, natural and technological.
The 1.5-degree target shows that "deep and rapid reductions of emissions of carbon dioxide and other greenhouse gases will be needed in all sectors of society and the economy," said IPCC Chair Hoesung Lee.
Due to the emergency needed, the WMO has initiated the development of observational based tools that can guide the emissions reduction actions and confirm their results, for instance in the oil and gas sector.
A new Integrated Global Greenhouse Gas Information System (IG3IS) will provide the framework for the development and standardization of the observational based tools, the WMO said. Such a system, implemented by countries on a voluntary basis, will feed into the national emission reporting mechanism to the UN Framework on Climate Change and the annual Conference of the Parties.