20 November 2018: Atmospheric greenhouse gas (GHG) levels have reached a record high, according to the World Meteorological Organization (WMO). The Organization has determined that this trend shows no signs of reversing.

The November issue of the WMO Greenhouse Gas Bulletin, which reports on atmospheric GHG concentrations, shows that atmospheric carbon dioxide (CO2) concentrations reached 405.5 parts per million (ppm) in 2017, up from 403.3 ppm in 2016 and 400.1 ppm in 2015. Methane (CH4) and nitrous oxide (N2O) concentrations increased to 1,859 parts per billion (ppb) in 2017 and 329.9 ppb, respectively, with the latter also contributing to ozone destruction. These numbers represent 257% of preindustrial levels for CH4 and 122% of preindustrial levels for N2O. The Bulletin also shows that the rate of decline of CFC-11 (trichlorofluoromethane), a potent GHG and an ozone depleting substance regulated under the Montreal Protocol, has slowed.

The Earth has not experienced a comparable CO2 concentration for 3-5 million years.

Speaking about the Bulletin, WMO Secretary-General Petteri Taalas said that the Earth has not experienced a comparable CO2 concentration for 3-5 million years, when the temperature was 2-3°C warmer and sea level was 10-20 meters higher.

The Bulletin aims to “provide a scientific base” for decision makers at the UN Climate Change Conference, convening from 2-14 December 2018 in Katowice, Poland. The Bulletin follows the release of the IPCC Special Report on Global Warming of 1.5°C (SR15), which shows that deep and rapid emission reductions will be needed in all sectors of society and the economy.

The WMO, which contends that more tools are needed at national and sub-national levels to help stakeholders take actions to reduce emissions, has initiated the development of observation-based tools to guide emission reduction actions and confirm their results, for example in the oil and gas sector. The Integrated Global GHG Information System (IG3IS) provides the framework for the development and standardization of such tools, is implemented by countries on a voluntary basis, and will feed into the national emission reporting mechanism under the UNFCCC.

The GHG Bulletin is based on observations from the WMO Global Atmosphere Watch Programme, which tracks changing GHG levels as a result of industrialization, energy use from fossil fuel sources, intensified agricultural practices, increases in land use and deforestation. [WMO Press Release] [WMO GHG Bulletin Landing Page] [WMO GHG Bulletin] [SDG Knowledge Hub Coverage of IPCC Special Report on Warming of 1.5°C]