An international research team has discovered that nitrogen emissions from fertilizers and fossil fuels have a net cooling effect on the climate. However, they caution that rising atmospheric nitrogen levels pose significant environmental threats, urging immediate action to reduce greenhouse gas emissions to combat global warming.
Published in Nature, the study reveals that reactive nitrogen from human activities cools the climate by -0.34 watts per square meter. Without these emissions, global warming would have progressed further. Yet, this cooling effect doesn’t offset the warming from greenhouse gases.
Led by the Max Planck Institute in Germany, with contributors from the University of Sydney, the research arrives a day after the EU’s Copernicus Climate Change Service reported the hottest day in recent history on July 21.
Cooling Effects and Environmental Warnings
The net cooling effect of nitrogen emissions occurs in several ways:
Fossil Fuel Combustion: Short-lived nitrogen oxides form particles that block sunlight, cooling the atmosphere.
Fertilizers: Ammonia from manure and fertilizers also contributes to this particle formation.
Plant Growth: Nitrogen boosts plant growth, which absorbs more CO2, enhancing cooling.
Methane Breakdown: Nitrogen oxides help break down methane, a potent greenhouse gas.
Despite these cooling effects, the researchers emphasize that increasing nitrogen is not a viable climate solution. Nitrogen fertilizers pollute water, and nitrogen oxides from fossil fuels pollute the air. Professor Federico Maggi from the University of Sydney’s School of Civil Engineering stated, “Increasing nitrogen is not an acceptable solution for climate change as it pollutes water and air.”
Sönke Zaehle of the Max Planck Institute added, “While nitrogen emissions have a cooling effect, they also harm health, biodiversity, and the ozone layer.”
Complex Climate Interactions
Elemental nitrogen is climate-neutral, but reactive nitrogen compounds can both warm and cool the climate. For instance, nitrous oxide (N2O) is nearly 300 times more potent than CO2 as a greenhouse gas.
Professor Maggi highlighted the study’s significance in understanding the global impact of nitrogen emissions. “This research showcases the need for advanced models to capture complex interactions at planetary scales,” he said. Despite nitrogen’s cooling effect, it is minor compared to the need for reducing greenhouse gas emissions, emphasizing the urgency for action.
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The Bottom Line
The study reveals the complex role of nitrogen in climate dynamics and calls for a holistic approach to environmental protection. While nitrogen emissions provide some cooling, the overarching goal remains to drastically cut greenhouse gas emissions to ensure a stable and healthy climate.
