GHG levels in atmosphere hit record high
World Meteorological Organisation (WMO) has revealed that the level of heat-trapping greenhouse gases (GHGs) in the atmosphere has reached a record high.
In its Greenhouse Gas Bulletin, the world body expressed fears that the trend, which is driving long-term climate change, sea level rise, ocean acidification and more extreme weather, might not reverse.
The United Nations climate summit holds next week in Poland.The document is based on observations from the WMO Global Atmosphere Watch Programme, which tracks the changing levels of GHGs as a result of industrialisation, energy use from fossil fuels, intensified agricultural practices, increases in land use and deforestation.
The bulletin provides a scientific base for decision-making at the UN climate change negotiations, which will be held in Katowice, Poland, to adopt the implementation guidelines of the Paris Climate Change Agreement, which aims to hold the global average temperature increase to as close as 1.5°C.
“The science is clear. Without rapid cuts in carbon dioxide (CO2) and other GHGs, climate change will have increasingly destructive and irreversible impact on life on earth. The window of opportunity for action is almost closed,” said secretary-general of WMO, Petteri Taalas.
The new data showed that globally averaged concentrations of 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 GHG 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 per cent increase in total radiative forcing – the warming effect on the climate – by long-lived GHG. CO2 accounts for about 82 per cent of the increase in radiative forcing over the past decade, according to figures from the United States National Oceanic and Atmospheric Administration quoted in the WMO bulletin.
“The last time the earth experienced a comparable concentration of CO2 was three to five million years ago, when the temperature was two to three degrees centigrade warmer and sea level was 10 to 20 metres higher than now,” said Mr. Taalas.