Since the Industrial Revolution, anthropogenic activities like industrial, economic, land use, and population growth have significantly impacted climate by increasing atmospheric CO₂ and other heat-trapping gases. In 2010, CO₂ continued to be the main anthropogenic GHG, contributing 76% (383.8 Gt CO₂ eq/year) of all anthropogenic GHG emissions. CH₄ contributes 16% (781.6 Gt CO₂ eq/year), N₂O contributes 6.2% (311.9 Gt CO₂ eq/year), and fluorinated gases contribute 2.0% (100.2Gt CO₂ eq/year). According to the IPCC, by 2100, the average surface temperature could have increased by more than 6 °C. From 280 parts per million in the pre-industrial era to 400 parts per million in 2014, the atmospheric CO₂ concentration grew by 42.8% over the course of the twentieth century, and an increase in CO₂ concentration and other GHGs (CH₄, N₂O) led to an increase in the global mean temperature of 0.85 °C (0.65–1.06 °C) (IPCC 2014) (Fig. 4.1).