SEI expert gives evidence at UK Parliament nitrogen inquiry

The growing threat of nitrogen pollution

Nitrogen is a fundamental element of life on Earth, making up 78% of the air we breathe in its inert, harmless form. It must be fixed into reactive forms to be of use to plants and is a key component of fertilizers that support global food production. Nitrogen fixation occurs naturally via lighting, fires and biological nitrogen fixation, but human activity associated with fossil fuel combustion and synthetic fertilizer production has resulted in more than a doubling of the amount of reactive nitrogen circulating in the environment.  Nitrogen becomes a potent pollutant when it is lost to the environment, leading to harmful consequences for human health, water quality, biodiversity, climate change, the ozone layer and soils.

For example, nitrogen contributes to air pollution through nitrogen oxide (NO_x) emissions and the formation of fine particulate matter (PM_2.5) and tropospheric ozone (O₃) in the atmosphere, all of which pose serious health risks.

Hicks highlighted the findings of the 2024 Global Nitrous Oxide Assessment, which underscores how nitrous oxide emissions – mainly from fertilizer use in agriculture – are accelerating climate change in the long term and depleting the ozone layer. As a greenhouse gas, nitrous oxide (N₂O) is nearly 300 times more potent than carbon dioxide and remains in the atmosphere for over a century; it is also the most significant ozone-depleting substance today.

Nitrogen inquiry

Recognizing the urgency of this issue, the UK House of Lords Environment and Climate Change Committee, chaired by Baroness Sheehan, launched an inquiry to examine nitrogen’s environmental impact and explore innovative solutions.

On February 5, 2025, the committee held its first evidentiary meeting, featuring insights from leading experts. Among them was Kevin Hicks, Senior Research Fellow at SEI’s University of York Centre. He joined specialists from the Centre for Ecology and Hydrology and the Institute for European Environmental Policy to examine the impact of nitrogen pollution and explore potential mitigation strategies.