Isotope measurements show record-breaking greenhouse gas concentration
The "Greenhouse Gas Bulletin", published by the World Meteorological Organization (WMO) on November 25, highlights the continuing rise in concentrations of the most important atmospheric greenhouse gases. Once again, record breaking concentrations of atmospheric carbon dioxide, methane and nitrogen dioxide were recorded, highlighting the unabated anthropogenic impact on the global climate system.
The data presented in the Bulletin is produced by several international laboratories of the WMO's Global Atmospheric Watch (GAW) programme, which form a network of observational stations around the globe. Central Calibration Laboratories (CCLs) within the network provide reference standards for these measurements to assure that data from all laboratories are comparable.
The CCL for isotopes of atmospheric CO2 is hosted by the Stable Isotope Laboratory (BGC-IsoLab) of the Max Planck Institute for Biogeochemistry in Jena, Germany. The BGC-IsoLab further improves inter-laboratory compatibility of isotopic measurements of CO2 by collaborating with internationally renowned partners in Europe and worldwide, e.g. the National Oceanic and Atmospheric Administration, NOAA, in the USA.
The 2019 WMO Bulletin focusses on the trends of the isotopic composition of greenhouse gases, for example CO2. The carbon isotopic composition describes the relative abundance of lighter (12C) or heavier (13C) carbon atoms in different substances. For example, fossil fuels contain more of the lighter 12C than the heavier 13C, when compared to the atmosphere. Thus, the burning of fossil fuels slowly increases the amount of atmospheric 12CO2 relative to 13CO2, causing a continually decreasing 13C/12C ratio measured in atmospheric CO2. This observed trend, combined with a similar trend of the even heavier radiocarbon (14C), provides rather strong evidence that the current CO2 increase is caused by fossil fuel combustion.
The trend changes of atmospheric methane concentrations in recent decades are still not fully understood. Methane is emitted by several different processes with different isotopic signatures. Such signatures are key to ultimately reveal the quantitative contributions of the processes involved. In order to reach this goal, and to further improve the standardization of isotopic measurements of atmospheric methane, the BGC-IsoLab collaborates closely with European partners and with the New Zealand National Institute of Water & Atmospheric Research (NIWA).