9th International Symposium on
Non-CO2 Greenhouse Gases (NCGG9)

June 21-23, 2023, Amsterdam, The Netherlands




Keynote Speakers


Keynote Speakers

Wednesday, June 21

Arjan Hensen

Scientific Researcher, TNO, The Netherlands

Formal opening of the conference

Professor Arjan Hensen is researcher at TNO in Petten at a research station on the Dutch shoreline. He started his career at ECN helping to install the first inlet lines at the Cabauw tall tower. That station is now an ICOS level 1 station documenting greenhouse gas concentrations over the Netherlands. Since the start at Cabauw in the ‘90s he was involved with that work on the National scale trying to evaluate the sum of GHG contributions from all kind of sources. Going to the individual source studies were the next step. The aerodyne CH4/N2O tunable diode laser measurements in a van was the start of a 3 decades sequence of campaigns. Subsequent instrument and methodological development helped to evaluate emissions from landfills, farms or oil and gas installations. These studies brought him to many places, like coffee plantations in Costa Rica, oil and gas installations at the North sea or at the wonderful Jungfraujoch measurement station in Switserland. Arjan joined the NCGG conferences from version 2-8 and will now chair version 9 in Amsterdam where he also started as professor at VU in January this year. Realising that, in spite of all the research work done, greenhouse gas concentrations continuously increased for almost all greenhouse gas species (except for some halocarbons), he will challenge you at the conference with an important question: what should scientist do now to help make the urgently needed changes.


Ute Skiba

Biogeochemist, Centre for Ecology and Hydrology, United Kingdom

The Cinderella soil Nitric oxide source

I am a biogeochemist at UK CEH, Edinburgh with 30 years’ experience of soil NO2 & N2O fluxes.

Since 1990 atmospheric concentrations of NO2 have declined by 36%. Thus, NO2 fossil fuel/soil ratios are changing and soil NO2 emissions become more prominent. This shift is of concern, as there are not sufficient soil NO2 data for atmospheric chemistry models, and predictions of air quality impacts on human health are uncertain. A concerted action is required to identify regions prone to large soil NO2 emissions, quantify their emission factors required for atmospheric chemistry models and develop mitigation options: to be discussed.


Thursday, June 22

Wim de Vries

Professor Nutrient impact assessment, Wageningen University and Research, The Netherlands

Impacts of anthropogenic nitrogen fixation on greenhouse gas exchange at global scale

My name is Wim de Vries and I am professor at the Environmental Systems Analysis Group of Wageningen University, where I hold the chair "Integrated nutrient impact assessment”. I am a researcher in the field of biogeochemistry with special reference to nutrient cycling, soil acidification, greenhouse gas emissions and metal pollution. My research is organized around large scale impacts of the elevated use of nutrients (especially nitrogen and phosphorus) in agriculture on air-, soil - and water quality and related boundaries in view of those impacts. I wrote more than 500 publications as an author or co-author on the above mentioned topic, including ca 200 publications in international peer reviewed journals Wim de Vries - Google Scholar Citations.

My key note is focusing on the overall “Impacts of anthropogenic nitrogen fixation on greenhouse gas exchange at global scale”. I think this is important since knowledge of many climate researchers on is limited to a contribution by the emission of nitrous oxides (N2O) due to the use of N fertilizer and related N manure increase in agriculture. However, there are many more impacts, including warming effects by N-induced increases of both N2O and CH4 emissions from soils, sediments and water bodies and also NOx emission-induced tropospheric O3 formation, leading to reduced C sequestration in forest biomass and soils. However, there are also cooling effects caused by N-induced increases in net ecosystem production and related C sequestration in terrestrial and aquatic ecosystems and due to methane lifetime reduction and particulate matter formation. The overall impact of N fixation in agriculture is thus not simply warming by N2O emissions but it can also be cooling depending on the region in the world and this is relevant to know in view of agricultural policies.


Adriana Gomez Sanabria

Research Scholar, International Institute for Applied Systems Analysis (IIASA), Austria

To burn or not to burn, what do we do with waste?

Dr. Adriana Gomez-Sanabria is a research scholar at the International Institute for Applied Systems Analysis (IIASA). Her research focuses on the analysis of strategies to mitigate greenhouse gases and air pollutant emissions from solid waste and wastewater management.

At NCGG9, she will give a presentation on how the adoption of circular waste management systems can contribute to the achievement of the Global Methane Pledge. In addition, she is organizing a panel discussion on “To burn or not to burn: what do we do with waste?”. This topic is relevant since facing out landfilling of waste is an important strategy towards sustainability. Therefore, waste to energy plants are becoming a central way to deal with waste and generate energy in many countries. However, if an incinerator is not meeting high quality standards, it can be a potential source of GHG, air pollutants and toxins that endanger human health and the environment. So, should we continue sending refuse to landfills or to incinerators?


Friday, June 23

Sybrig Smit

Climate Policy Analyst, NewClimate Institute, Germany

Corporate climate ambition and non-CO2 GHG accounting loopholes

(Info not yet provided)


Prof. dr. ir. Guus Velders

Professor Air quality and climate interactions, Utrecht University, The Netherlands
Senior Scientist, RIVM - National Instiitute for Public Health and the Environment

The Montreal protocol does work... what lessons to take on board

(Info not yet provided)


Prof. dr. Andreas Engel

Professor Experimental Atmospheric Research, Goethe Universität Frankfurt, Germany

Expanding the European observational network for halogenated greenhouse gases

Halocarbons and in particular F-gases are the strongest greenhouse gases currently observed in the atmosphere. Therefore, despite their low atmospheric abundances, they contribute significantly to global warming. The observational network for these gases is, however, very sparse. The currently available observations and also present and discuss efforts to expand the observational network in Europe with in the frame of the project PARIS funded through the European Commission. The options, problems and benefits of such an expansion will be discussed in relation to improving the understanding of European emissions of halogenated greenhouse gases.


Latest News

Conference diner & excursion

Date: 01 June 2023
Conference Diner Have you already registered for the conference dinner on the first day of NCGG9?Join us at De Vergulden Eenhoorn on Wednesday 21s... Read more

To news archive

In cooperation with

Water Systems and Global Change Group, Wageningen University & Research
WIMEK Graduate School 


Symposium Secretariat

NCGG9 is organized by:


p/a UCo
2e Daalsedijk 6a
The Netherlands

T +31 (0)30 - 232 29 89
E eciffo.[antispam].@ncgg.info



Stichting MilCon (Foundation for Environmental Congresses, a separate legal entity that is linked to VVM) is responsible for the logistic and financial management of NCGG9. The contents of the symposium is the responsibility of VVM and its co-organisers. Logistic services for NCGG9 will be provided by the VVM-bureau.