Inconsideration of nature and scale of intensive livestock production,this type of agricultural activity produces large quantities ofgreenhouse gases (contributing to global warming, i.e. increase inglobally averaged temperatures), including carbon dioxide, methane andnitrogen oxides. Greenhouse gas emissions from livestock productionaccounts for around 18% of total anthropogenic greenhouse gas emissionsworldwide (more than the transportation industry). In 2007, agriculturalcontribution to greenhouse gas emissions in the EU was 9.2% (excludingemissions from energy consumption and transportation in agriculture, andemissions from the international trade in agricultural products andinputs). For example, it is estimated that one pig (sow) produces 0.089kg CO2/h (1 LU ? 0.223 kg/h) and 0.238 kg NH3/h (1 LU ? 0.595 kg/h).
It is estimated that around 9-10% of total greenhouse gas emissions (CO2)is generated by agricultural transportation, heating and production.However, crop production is the highest source of emissions ? around 60%of all energy consumed by agriculture is used for land cultivation.
Methane is much more dangerous than CO2,its global warming potential is 21-times higher. Agriculture accountsfor over 50% of total methane emission (40% is contributed by livestockproduction). Digestion by ruminants (cattle, sheep, goats) is the mainsource of methane emissions in agriculture (around 74-90% of emissionsfrom agricultural sources). The remaining share is attributed to methanelosses from natural fertilisers. Farm animals produce around 75 millionMg CH4 annually (80% comes from cattle and buffalo). 30% ofglobal methane production has its source in agriculture, itscontribution to the global warming effect is estimated at 18%. A singlecow can produce around 65 kg (80 m3) of methane annually.Methane emissions from agriculture is estimated at 587,000 Mg/year,including 438,000 Mg from colonic fermentation, and 148,000 Mg fromlivestock waste (GUS, 2009).In Poland, methane emissions fromagriculture have been observed to systematically increase, especiallyfrom livestock waste.
Nitrousoxide is mainly released from fertilised soil (around 83% ofagricultural emissions) and is lost during fertiliser storage andtransportation. According to many sources, agriculture is the mainsource of nitrous oxide, whose contribution to the global warming isestimated at 6-8%. In 2009, N2O emissions in Poland amounted to 75,000 Mg (GUS).