The main global contributing factors to greenhouse-gas emissions are:

Explanation:

Greenhouse-Gas:

• Greenhouse gases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere.
• The sources of greenhouse gas emissions include electricity production, transportation, industry, agriculture, forestry, etc. 
• Globally, the primary sources of greenhouse gas emissions are electricity and heat (31%), agriculture (11%), transportation (15%), forestry (6%), and manufacturing (12%).
• Two main sources electricity generation and transportation both contribute to about 47 to 50% of greenhouse gas emissions.

Important Points

• Gases responsible for global warming are also known as greenhouse gases.
• Greenhouse gases CO₂, N₂O, CH_4, CFC, water vapour, and ozone.
• CO₂ gas is the biggest contributor to global warming.