Researchers: Human nitrogen emissions slow down global warming
Published: Wednesday, Jul 24th 2024, 17:10
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Nitrogen compounds released into the environment as a result of human activities are slowing down global warming. This is the conclusion reached by an international team of researchers with the participation of the University of Bern.
The research group, led by the Max Planck Institute for Biogeochemistry in Jena (Germany), published its analysis of the complex effects of nitrogen compounds from agriculture and the burning of fossil fuels on the global average temperature on Wednesday.
Overall, this results in a cooling effect, the researchers reported in their study, which has now been published in the journal "Nature". Without human nitrogen input, the climate would have heated up even further. In view of the various negative consequences of nitrogen emissions for humans and the environment, however, the experts do not see this as positive.
"Air pollution leads to over 2,000 premature deaths per year in Switzerland alone, and nitrogen plays an important role in this," co-author of the study and professor at the Institute of Physics and the Oeschger Center for Climate Research at the University of Bern, Fortunat Joos, was quoted as saying in a press release.
No remedy against global warming
According to the researchers, the results are no reason to gloss over the environmental balance of nitrogen inputs or even to see additional nitrogen supply as a possible "remedy against global warming".
Nitrogen is a naturally occurring gas in the atmosphere. However, humans release additional nitrogen compounds in various ways, one of the main sources being manure and synthetic fertilizers for agriculture. Another important source is the combustion of fossil fuels such as oil and coal, which produce nitrogen oxides and disperse them in the air.
However, the direct and indirect climate effects of the various nitrogen compounds differ. According to the researchers, nitrous oxide escaping from fertilized soils acts as an extremely powerful greenhouse gas. Its effect is almost 300 times stronger than that of carbon dioxide. At the same time, however, the nitrogen input allows plants to grow better, so that they bind more carbon dioxide.
Responsible for smog
Nitrogen oxides released by combustion also have contradictory effects. Among other things, they promote the formation of suspended particles in the atmosphere, which block sunlight and therefore cool. This phenomenon is also known as smog near the ground. At the same time, however, they also lead to an increase in the formation of ozone, which in turn is a very powerful greenhouse gas.
In total, the research team calculated a cooling effect of 0.34 watts per square meter due to human nitrogen inputs. For comparison: According to the Intergovernmental Panel on Climate Change (IPCC), humans heated up each square meter by an average of 2.7 watts between 2011 and 2020, primarily through the emission of greenhouse gases. This resulted in an average temperature rise of 1.1 degrees Celsius during this period.
However, the experts from Jena emphasized that it is not possible to directly convert the cooling effect of nitrogen inputs to the global average temperature. On the one hand, there are local effects, and on the other, the climate system reacts slowly and in a complex way to the shifts.
Researchers: more targeted use of fertilizers
At the same time, the researchers pointed out the negative environmental and health consequences of nitrogen compounds - for example in the form of eutrophication of water bodies or their role in the formation of particulate matter and the development of respiratory diseases.
"The study underlines the urgency of finally stopping emissions from fossil fuels and using fertilizers in a more targeted way," explained Joos. "This would not only slow down global warming, but also reduce exposure to harmful ozone and particulate matter concentrations for all of us in rural and urban areas."
©Keystone/SDA
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