Global warming is mostly caused by the "greenhouse effect" - the emission of greenhouse gases as a result of human activity. Main greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide and fluorinated gases.
Sunlight that enters the earth is either reflected or absorbed by the Earth's surface. The Earth can also emit the energy through the atmosphere into space. However, greenhouse gases trap the radiation in the atmosphere, warming the earth.
Although methane's concentration is much lower than that of carbon dioxide, it is one of the most potent greenhouse gases and is the third most abundant after water vapour and carbon dioxide. Thus, methane emissions do not need to be nearly as high as carbon dioxide to have significant impact.
[greenhouse effect diagram from medium.com(1)]
While there are natural sources of methane, human activity heavily influences the concentration of methane by farming livestock and rice cultivation. Cattle produces large amounts of methane while grazing and farming crops such as rice, leads to methane release. Furthermore, even if gases like methane contribute to global warming, carbon dioxide remains the top priority with a global warming potential (GWP) of 1.
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