I don't think I understand your actual question. What does the size of oil fields have to do with size of continents? If you are confused about why you'd need

I don't think I understand your actual question. What does the size of oil fields have to do with size of continents? If you are confused about why you'd need to plant a whole continent of trees to offset our CO2 emissions, rememeber(or discover for the first time) that your average oil field(or coal mine for that matter) is a product of literally millions of years worth of carbon deposits - that's why oil is so incredibly energy dense. According to some quick googling one tree absorbs about 25kg worth of CO2 per year. My car emits that much by just driving ~100 miles (using about 10L of petrol in the process). If I do 10k miles per year, that is a lot of trees just to offset emissions of a single vehicle, and there are millions of personal cars out there - and they aren't even the largest source of emissions.