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Setting up the “laughing gas” budget

From the NILU Annual Report 2017: “Laughing gas” sounds harmless enough. Known also as nitrous oxide, it is in fact the third most important greenhouse gas in the atmosphere, and no laughing matter.

Besides being an important greenhouse gas, nitrous oxide or N2O is also one of the main ozone depleting substances in the atmosphere, since the Montréal protocol put a stop to the use of chlorofluoro­carbons (CFCs). Thus, it is important to know as much as possible about all the processes producing N2O.

Covering all angles

Senior scientist Rona L. Thompson co-leads the N2O budget of the Global Carbon Project. Photo: Ingar Næss

Rona L. Thompson is a senior scientist at NILU’s deptartment of atmosphere and climate, and co-leads the N2O budget of the Global Carbon Project.

– I was asked to co-lead this new activity in December 2015, she says, – and we started working on it the following year. My part is related to atmospheric observations and modelling of N2O.

Other scientists involved with the project work on agricultural emissions, natural emissions, wastewater emissions, and other aspects of the budget – namely, accounting for all N2O emissions, sinks and changes.

Fertilisers are the main source

– The use of fertilisers in agriculture is the main source of nitrous oxide today, explains Thompson. – If we can decrease the use of nitrogen fertilisers, we would also see a decrease of N2O in the atmosphere.

However, it is not so easy to reduce the use of nitrogen fertilisers, as they are necessary to grow enough food. In well-developed countries, farmers are now trying to use fertilisers more efficiently, managing to maintain or even increase crop yields with less. This is not the case in several emerging economies, such as in Asia, where the use of fertilisers is rising while the efficiency is going down.

Making N2O visible to the world

At the end of 2017, the project group has finished gathering data and estimates for all aspects of the N2O budget.

– We are now starting to look at how it all fits together, Thompson says, – checking how the atmospheric increase in N2O matches up with all the emissions and sinks. We are also planning to publish scientific articles as well as put all the results in the form of interactive graphics on the Global Carbon Project website, making it possible to view N2O emissions globally and regionally.

Read NILU’s annual report 2017 here:

Annual report 2017

Read the annual report online here (www.issuu.com):