Final answer:
Methane (CH4) is the greenhouse gas produced by domestic livestock, significantly contributing to global warming due to its high global warming potential. Livestock emit this gas through the digestive process known as enteric fermentation.
Step-by-step explanation:
The greenhouse gas produced by domestic livestock such as cows is methane (CH4). Methane is a potent greenhouse gas with a global warming potential much higher than carbon dioxide. Domestic livestock, particularly ruminants like cows, produce methane through a process called enteric fermentation that occurs in their digestive system. This process fundamentally begins when microbes decompose and ferment the food in the stomach of the livestock, creating methane as a byproduct. The methane is then expelled by the animals primarily through belching.
Though other activities such as the burning of fossil fuels and large-scale deforestation also contribute significantly to the emission of greenhouse gases, agriculture - specifically through livestock farming - is a notable source of methane. A substantial portion of agricultural greenhouse gas emissions is due to methane released by livestock. The impact of this methane on global warming is profound as it is approximately 28 times more effective than carbon dioxide at trapping heat in the atmosphere over a 100-year period.