Levels of heat-trapping greenhouse gases in the atmosphere have reached another record high, according to a report issued on Thursday by the United Nations weather agency, which reveals that there is no sign of reversal of this trend, responsible for climate change, sea level rise, ocean acidification and extreme weather.
“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,” said World Meteorological Organization (WMO) Secretary-General Petteri Taalas.
The WMO Greenhouse Gas Bulletin shows that global concentrations of carbon dioxide (CO2), methane and nitrous oxide have been increasing steadily over the past years. In addition, the report notes 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.
The WMO Greenhouse Gas Bulletin reports specifically on atmospheric concentrations of greenhouse gases, which are what remains in the atmosphere, following a complex process of emissions and absorptions.
Since 1990, there has been a 41 per cent increase in the warming effect by the various greenhouse gases on the climate – known as “radioactive forcing.” CO2 specifically accounts for about 82 per cent of the increase in radioactive forcing over the past decade, according to figures quoted in the WMO report.
“The last time the Earth experienced a comparable concentration of CO2 was three to five million years ago, when the temperature was 2 to 3°C warmer and sea level was 10 to 20 meters higher than now,” said Mr. Taalas.
The WMO report comes on top of the evidence presented in the Intergovernmental Panel on Climate Change (IPCC) special report on global warming issued in October, which sounded the alarm on the need to reach zero net emissions of CO2 by mid-century, in order to keep temperature increases to below 1.5°C.