The main factors of this phenomenon are gasses, especially CO2, which man produces every day through:

• Consumption of electricity, considering that the majority of the electricity is obtained through the burning of coal, petroleum and gas
• Motor transportation and heating systems, which are based on fossil fuels such as coal, diesel oil and gas
• Irresponsible consumption; the sale of every product has an energy cost related to its production and transportation (if the product is produced a great distance away, the cost will be greater, and also if it is made up of primarily plastic and other petroleum by products). (Source: canalsolidario.org)