HUMAN EFFECT ON NITROGEN RISKS GLOBAL DAMAGE

An authoritative study published in the October 8 issue of Science magazine (the publication of the American Association for the Advancement of Science) sounds the alarm over what humans are doing to the Earth's nitrogen cycle.

Micro-organisms have been controlling the cycle since life began on the planet. With life evolving around it, nitrogen became both an essential nutrient and a major regulator of climate.

The study in Science (pages 192-196, Vol 330, Oct 8 2010) reviews the major changes there have been to the nitrogen cycle throughout the Earth's history. Most of the time they coincided with the arrival of new organisms that provided new metabolic pathways.

But the last century has seen humans push the biological nitrogen cycle into a very different stage. Adding large amounts of fixed nitrogen in the form of fertiliser chokes out aquatic life that relies on run-off, and significantly increases the amount of NO2 in the atmosphere ( a greenhouse gas 300 times more potent than CO2).

Micro-organisms may one day restore balance in the nitrogen cycle that they helped shape for billions of years, but humans must change their behaviour, or risk causing irreversible changes to life on Earth.