How does agriculture release so much greenhouse gas?

Ripping Up the Land: Deforestation and Land Use

Imagine a lush forest, soaking up carbon for decades. Now picture that forest gone, replaced by a field of crops or grazing land. That’s a problem. When we clear forests (or even peatlands) for agriculture, we release all that stored carbon back into the atmosphere as CO2. It’s like unlocking a carbon vault. Agriculture is responsible for a whopping 70-90% of deforestation, so you can see how quickly this adds up. To put it in perspective, deforestation due to cattle ranching alone releases 340 million tons of carbon into the atmosphere each year, which is 3.4% of global greenhouse gas emissions. Overall, changes in land use account for almost a fifth of the total emissions from agrifood systems.

Happy Cows, Gassy Planet: Livestock Production

Ah, the cows. We love ’em for their milk and burgers, but they’re also major methane producers. It’s all down to their unique digestive system. Ruminants (like cows and sheep) have this process called enteric fermentation. Basically, they have bacteria in their stomachs that help them break down tough plant matter, and that process creates methane, which the animals then belch out. And it’s not just the burps! Manure management is another big source of both methane and nitrous oxide. When manure sits around in big piles or lagoons, it decomposes without oxygen, releasing those gases into the air. It’s estimated that livestock supply chains account for 14.5% of global greenhouse gas emissions, and enteric methane represents 30% of global methane emissions.

Fertilizers: A Necessary Evil?

We need fertilizers to grow enough food, but they come with a downside. Synthetic nitrogen fertilizers are a major source of nitrous oxide emissions from the soil. When the nitrogen in these fertilizers gets processed by microbes in the soil, nitrous oxide is released as a byproduct. Tilling the soil – you know, turning it over to prepare for planting – also releases CO2. It’s like stirring up the soil and letting all the stored carbon escape. Fertilizer use alone is linked to around 720 million tonnes of CO2 equivalent a year. And get this: agriculture is responsible for nearly three-quarters of all human-caused nitrous oxide emissions.

Paddy Fields and Methane: The Rice Connection

Rice is a staple food for billions of people, but growing it, especially in flooded paddies, creates a perfect environment for methane production. When the fields are flooded, the soil lacks oxygen, which leads to the anaerobic decomposition of organic matter and, you guessed it, the release of methane. Rice cultivation is responsible for about 1.2% of total emissions.

Fueling the Farm: On-Farm Energy Use

Think about all the tractors, trucks, and other equipment used on farms. They all run on fossil fuels, which release CO2 when burned. Even activities like tilling and shipping products contribute to carbon emissions.