The laughing gas – no laughing matter

By Thulwaneng Mashifane, Postdoctoral Research Fellow, SAEON Egagasini Node Tweet

Nitrous oxide, commonly known as the laughing gas, is a greenhouse gas with a climate warming potential 300 times that of carbon dioxide, according to the United States Environmental Protection Agency (USEPA).

The 2013 Intergovernmental Panel on Climate Change (IPCC) reported a 22% increase in the atmospheric concentration of nitrous oxide since 1750. Oceans contribute an estimated 4 Tera-grams of nitrous oxide to the atmosphere every year.

In October 2018, the Ocean Carbon and Biogeochemistry (OCB) network held a workshop at the University of California Los Angeles (UCLA) Lake Arrowhead conference centre to discuss the current chemical analysis, microbial metabolism, as well as observational and predictive capabilities for oceanic methane and nitrous oxide. Over 50 scientists from 11 countries participated in the workshop to address questions related to the present and future scenarios of oceanic methane and nitrous oxide. The participants list can be found here.

Prior to the workshop, a methane and nitrous oxide intercomparison study was published to compare the accuracy of concentration measurements across different laboratory groups. Results from the study provided valuable insights into nitrous oxide and methane measurements, which were discussed during the workshop.

On behalf of SAEON, I was selected to participate in this workshop and present a poster on nitrous oxide production in the Benguela. The Benguela upwelling system is both a sink and source of nitrous oxide, which is generated from the associated oxygen minimum zone. The region off Walvis Bay is estimated to contribute 0.8% of the nitrous oxide emissions in the Benguela.

MEMENTO database and modelling of oceanic methane and nitrous oxide

I also participated in two breakaway sessions to discuss the MarinE MethanE and NiTrous Oxide (MEMENTO) database and modelling of oceanic methane and nitrous oxide. The MEMENTO database currently contains more than 100 000 surface and depth profile measurements of nitrous oxide and over 20 000 measurements for methane in the global ocean.

During the breakaway session, participants discussed progress made with MEMENTO to date, use of common units and metadata structure of the datasets uploaded to the database. Recent parameterisations in nitrous oxide models use the MEMENTO database to optimise estimations, and for validation.

Workshop participants resolved to develop Standard Operating Protocols (SOPs) for analysis of dissolved methane and nitrous oxide to standardise and improve measurements. A review article on the current state and future directions of methane and nitrous oxide is also planned.

All these activities will continue in 2019 and are expected to facilitate collaborations between participants and set themes for future workshops.