This is a big one. The biggest, actually. There’s a reason you hear about carbon dioxide emissions the most. The atmospheric residence time is a whopping 100 years. This means that the CO2 emissions that are happening today will remain in the atmosphere for the next hundred years. Unfortunately, the residence time says that even if we greatly alter our activity to reduce our greenhouse gas emissions, we will still see global warming over the next 100 years, though it will be somewhat reduced. The global warming potential is somewhat less daunting, however it is still a formidable foe, considering the sheer amount of CO2 already in the atmosphere.
So where is most of this CO2 coming from? Answer: fossil fuel combustion, deforestation, and cement production.
Fossil Fuel Combustion
12% from manufacturing and construction, 16% from transportation, and 30% from electricity generation and heating.
>50% of the world’s remaining forests are in 5 countries: Russia, Brazil, Canada, USA, and China. The United States alone has contributed to 1/3 of global net CO2 emissions since 1850 due to this land-use change.
Calcination releases CO2