CARBON is in the news a lot these days. Story after horrifying story tells of how carbon emissions are turning up Earth鈥檚 thermostat with dire consequences. But when it comes to the environment, there is another element we need to worry about. Nitrogen, carbon鈥檚 next-door neighbour on the periodic table, is at the centre of a different environmental crisis that is rarely in the limelight.
Like so much in life, nitrogen is good in moderation. It is the fourth most common element in your body, an essential ingredient of DNA and other crucial biomolecules. We get this nitrogen from the food we eat. To enter the food chain, the relatively inert nitrogen gas in the air has to be converted, or fixed, to 鈥渞eactive nitrogen鈥� compounds in the soil, which are taken up by plants. Over the past century, we鈥檝e added to the natural processes that do this by producing synthetic fertiliser in huge quantities and slathering it on fields. The average person in the US has a nitrogen footprint of about 41 kilograms per year, mostly thanks to the fertiliser used to grow their food.
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A lot of reactive nitrogen ends up leaching into the wider environment where it disrupts the natural chemical balance. We have known this for decades. Back in 1996, New Scientist was reporting on how nitrogen run-off causes blooms of toxic algae 鈥� 鈥渞ed tides鈥� 鈥� that kill sea life. The long list of effects includes air pollution, acid rain and soil acidification.
Finally, it seems the world might be confronting the problem. A UN-backed group called the International Nitrogen Management System is beginning to chart a well-evidenced course out of the nitrogen emergency. It has helped set a target of cutting nitrogen waste in half by 2030 and put forward a range of ways to pull this off.
It is a welcome start. But we shouldn鈥檛 forget that the seemingly different environmental catastrophes we are facing, not least biodiversity decline and climate change, are intertwined and mutually reinforcing. This is true of nitrogen too: one nitrogen pollutant, nitrous oxide, is a greenhouse gas that is 300 times more potent than carbon dioxide. We need to hear a lot more about nitrogen.