How Nitrogen is causing Global warming

• Nitrogen is all pervasive. It is more abundant in the air than oxygen and constitutes 78% of the atmosphere. Nitrogen is also vital to life as 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.
• 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 fertilizer 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.
• While forests with high nitrogen availability suffer from less diversity as they allow certain species to flourish at the cost of others, low-nitrogen forests are more likely to have plants growing slowly with fewer leaves.
• Scientists have analyzed and collated data on nitrogen availability across ecosystems between 1750 and 2017. In their review paper, they have found that nitrogen availability is declining in “many non-agricultural terrestrial ecosystems” that do not

receive additional reactive nitrogen because of human activities.

Looming Crisis

• As per US National Oceanic and Atmospheric Administration, Atmospheric CO2 concentration has increased by 50% since the 1750s. This has quickened the rate of photosynthesis in plants up to a saturation point, leading to higher nitrogen demand

by plants.

• Rising temperatures are also known to stretch the growing seasons. 
• The study thus warns that large parts of Australia, sub-Saharan Africa, parts of Asia and South America and vast swathes of boreal forest, that have remained free of additional reactive nitrogen, could lose their natural deposits of nitrogen in a warming world.
• Eg: The researchers refrain from drawing a general conclusion as they found a high load of  reactive nitrogen in non-agricultural ecosystems in China, Panama and the Democratic Republic of the Congo alongside reduced nitrogen availability in Europe and North America.
• Reduced levels of nitrogen in plants can have a worrying impact on the health of insects and grazing mammals that depend on leaves for protein. Herbivores may initially respond to the situation by increasing consumption, but it eventually affects their growth, survival, reproduction and population size.
• The understanding of the nitrogen cycle in its entirety is crucial as it is a key component of amino acids that form the building blocks of plant proteins and enzymes.