Ammonia consists of nitrogen and hydrogen and is explored by the shipping industry and others as a possible climate-friendly fuel. But the climate effect of nitrogen emissions is uncertain and increased knowledge is crucial. Photo: iStock/ Visuals Fervor LLC
Climate effect of nitrogen emissions is uncertain
The climate effect of nitrogen emissions is uncertain, according to a new study led by CICERO and published in Nature. Increased knowledge is crucial before introducing new zero carbon-fuel technologies on a large scale.
The air surrounding us consists of 78% nitrogen. Although most of this has no impact on Earth’s climate, a tiny fraction of the nitrogen influences climate considerably. The new Nature study shows that nitrogen’s effects act in the direction of both warming and cooling. While some nitrogen compounds lead to strengthening of the greenhouse effect, others cool the climate, for instance through shading of sunlight by tiny particles. A better understanding of nitrogen’s climate impact is not least important for industries that explore ammonia - which consists of nitrogen and hydrogen – as a climate friendly fuel.
In the new Nature publication, climate effects of anthropogenic nitrogen emissions from pre-industrial times until today were studied. By using five state-of-the-art atmospheric chemistry models, the authors concluded that quantities of individual warming and cooling terms are highly uncertain. Considering that some climate effects are not even assessed, this means that we do not know with confidence the net effect on climate of how humans have altered the nitrogen cycle.
The study was part of the CICERO-led AMMONIA project, which involves collaboration with researchers at LSCE in France, and NASA, NOAA, UCI and Princeton University in the US. The project is funded by the Research Council of Norway and five industry partners.
A need for enhanced knowledge on the climate impact of nitrogen is especially important for ammonia. Ammonia is a gas that consists of nitrogen and hydrogen and is foreseen as a climate-friendly fuel, especially within the shipping sector. CO2 emissions from international shipping currently constitute approximately 2% of the world’s total fossil CO2 emissions. While there is strong potential for ammonia to reduce these emissions, potential side-effects that involve harm to the climate and environment need to be assessed and quantified.
The AMMONIA project represents an important step to more robustly quantify the climate and environmental impacts of nitrogen compounds, but there will be a need for scientific developments on this topic for several years to come.