Answer :
You have said that 540 million metric tons of carbon dioxide is released
in the air per year.
So the answer to the question is: 540 million metric tons of carbon dioxide
are released in the air per year, regardless of the source or sources.
in the air per year.
So the answer to the question is: 540 million metric tons of carbon dioxide
are released in the air per year, regardless of the source or sources.