Chemical compounds containing reactive nitrogen are major drivers of air and water pollution worldwide, and hence of diseases like asthma or cancer, researchers said.
If no action is taken, nitrogen pollution could rise by 20 per cent by 2050 in a middle-of-the-road scenario, according to a study by scientists of the Potsdam Institute for Climate Impact Research, Germany. Ambitious mitigation efforts, however, could decrease the pollution by 50 per cent. The analysis is the very first to quantify this.
"Nitrogen is an irreplaceable nutrient and a true life-saver as it helps agriculture to feed a growing world population - but it is unfortunately also a dangerous pollutant," said Benjamin Bodirsky, lead-author of the study. In the different forms it can take through chemical reactions, it massively contributes to respirable dust, leads to the formation of aggressive ground-level ozone, and destabilises water ecosystems. Damages in Europe alone have been estimated at around 1-4 per cent of economic output, worth billions of Euro. About half of these nitrogen pollution damages are from agriculture.
This is why the scientists ran extensive computer simulations to explore the effects of different mitigation measures. Both farmers and consumers would have to participate in mitigation, said researchers. "It became clear that without mitigation the global situation may markedly deteriorate as the global food demand grows," said Bodirsky, who is also affiliated to the International Centre for Tropical Agriculture, Colombia (CIAT).
"A package of mitigation actions can reverse this trend, yet the risk remains that nitrogen pollution still exceeds safe environmental thresholds," Bodirsky said. Only combined mitigation efforts both in food production and consumption could substantially reduce the risks, the study shows.
Currently, every second tonne of nitrogen put on the fields is not taken up by the crops but blown away by the wind, washed out by rain or decomposed by microorganisms. To reduce losses and prevent pollution, farmers can more carefully target fertiliser application to plants' needs, using soil measurements.
Moreover, they should aim at efficiently recycling animal dung to fertilise the plants, researchers said. "Mitigation costs are currently many times lower than damage costs," said co-author Alexander Popp.