Not an easy fix

Global warming could be depleting forests and grasslands of a key macronutrient, nitrogen. This will have far-reaching consequences on the growth and survival of the animal world

- ROHINI KRISHNAMURTHY

NITROGEN IS all pervasive. It is more abundant in the air than oxygen and constitutes 78 per cent of the atmosphere. Nitrogen is also vital to life-it is essential for plant nutrition and thus, sustains all the other beings. But plants cannot use atmospheric nitrogen directly the way they absorb carbon dioxide (CO₂) for photosynthesis. For this, they depend on a biogeochemical cycle which, with the help of some bacteria or even lightning, combines the inert gas with other elements to form reactive compounds like ammonia and nitric oxide and "fix" them in the soil. Scientists have known for quite a while that this cycle is getting disrupted; as per a 2019 study published in Frontiers in Ecology and the Environment, the levels of reactive nitrogen have increased tenfold since the pre-industrial era due to rampant use of synthetic nitrogen fertiliser and burning of fossil fuels. This has caused algal blooms, created dead zones in oceans and accelerated biological diversity loss in aquatic and terrestrial ecosystems. A recent study, however, states that scientists have so far only partly understood the scale of this disruption and where it is unfolding.