Nitrous oxide, the funniest of the greenhouse gases ...

Credit: pixabay

I'm taking part in Future Learn and the University of Exeter's course on Climate change: the science. This is my first bit of research, on N2O. Bear with me, it's week one and it's a long time since I did GSCE chemistry.

My research questions are:

• Which human activities lead to the emission of your chosen greenhouse gas? 
• What is the impact of your chosen greenhouse gas on the blanket effect? 
• How will your chosen greenhouse gas impact important climate feedbacks? 

I chose N2O, cos CO2 is a bit passé.

The main human activities that contribute to N2O emissions are farming and the massive increase in the addition of nitrogen fertilisers to the soil over the past 100 years in order to produce more food to feed a growing global population. Microbes link the nitrogen in the soil with oxygen in the air to form N2O.

In a similar way, changes in land use also release N2O, particularly converting forest land to pasture for grazing animals.

Other human activities that emit N2O include: burning fossil fuels and wood; sewage plants; nitric acid manufacturing.

N2O has an impact on the blanket effect as, although there is much less of it in the atmosphere than water vapour or CO2, it traps heat more effectively than other GHGs do. Also, it lasts in the atmosphere much longer than other GHGs, resulting in a much higher global warming potential.

There are four key ways in which N2O affects climate feedbacks:

1. N2O depletes the ozone layer as it passes through the atmosphere, reducing the protection that the ozone layer gives against the warming effect of ultraviolet radiation from the sun. 
2. Using nitrogen fertiliser results in N2O emissions, which increase global warming. A warmer planet means more CO2 in the atmosphere, and plants may require more nitrogen fertiliser if there is more CO2 in the air. 
3. Global warming is thawing the permafrost in Arctic regions. This thawing releases more N2O as microbes in the soil link the nitrogen in the soil with the newly accessible oxygen in the atmosphere. 
4. Loss of nitrogen from the soil through soil degradation and runoff makes it harder for plants to grow, and plants are important for containing global warming as they remover carbon dioxide from the atmosphere. 

Sources: BBC; Nasa; the Conversation; Global Change Biology journal; Earth Island Journal.