Greenhouse gas
However, humans are introducing additional greenhouse gases to the atmosphere,  leading to an enhanced greenhouse effect and increase in the  planet's average temperature.The most significant greenhouse gas that contributed by humans is carbon dioxide, currently composing approximately 0.04% of the atmosphere. Human activities like burning fossil fuel such as oil, coal and natural gas for transportation, energy production and industrial processes are the main sources of carbon dioxide emission.  The major contributor to these emissions is the industrial sector.   The Food and Agriculture Organization has reported that emissions associated with livestock, contribute to 7.1 gigatons (GT) of carbon dioxide equivalent (CO2-eq) per year, accounting for 14.5% of all human-caused greenhouse emissions. This exceeds the 13% that contributed by global transportation (including cars and planes) each year.