International Symposium on non-CO2 Greenhouse Gases (NCGG) - Utrecht, 2026
Author: Phillip Agredazywczuk
I had the chance to present a poster at the 10th International Symposium on Non-CO2 Greenhouse Gases (NCGG10) in Utrecht, a three-day gathering that brings together researchers, policymakers, and industry on non-CO2 greenhouse gases: methane (CH4), nitrous oxide (N2O), fluorocarbons (CF), and other halogenated species. I presented a poster on the rapid nitrous oxide separator (RAPTOR) system (Poster 12), the preconcentration setup I've been developing and characterising. RAPTOR aims to enhance the precision of N2O isotope measurements below 0.1 permil, which will better resolve global N2O budgets, interhemispheric gradients, and long-term atmospheric trends.
One of the key discussions that came up after keynotes from Sönke Zaehle and Tim Butler was the tension between climate and air quality mitigation, particularly around reactive nitrogen (Nr). Reducing NOx emissions is a public health win, as a dangerous pollutant for humans. Its reduction produces benefits that are immediate and visible: better regional air quality, less smog, fewer respiratory health impacts. Populations can witness these improvements in real time, which makes NOx reduction politically and socially easy to advocate for.
All the conference attendees enjoyed seeing the beautiful city of Utrecht
The complication is what NOx is doing to the chemistry of our atmosphere. In the troposphere, the layer of the atmosphere we live in, NOx plays an active role in the chemistry that governs ozone (O3) and CH4 lifetimes, and it interacts with the broader halocarbon chemistry as well. Through these pathways, NOx has a net cooling effect on climate. So when we reduce NOx for air quality, we're also removing some of that cooling effect, which means an air quality win can translate into a climate penalty, a positive feedback that works against the global warming we're trying to slow.
It's the kind of tradeoff that doesn't have a straightforward answer, optimising one, e.g. public health now, or climate stability over decades, pull against each other, and as scientists, we must communicate this honestly, sensitively, and factually to policymakers and the public.