How much carbon dioxide gas have humans added to the atmosphere?
The Earth’s atmosphere weighs 5.1 million billion tons. The burning of fossil fuels adds an additional 10 tons of CO per year to the atmosphere—for each person in the developed countries. But how much carbon dioxide gas was in the Earth’s atmosphere before the start of the industrial revolution and the widespread burning of fossil fuel? Chemists of the seventeenth century didn’t even know about C0 much less how to measure it. But a clever late twentieth-century atmospheric chemist found a way to get the measurement. By drilling deep in glacial ice in Greenland, and by analyzing the air trapped within myriad small bubbles, CO levels as far back as 1530 have been dated. The result showed that pre-industrial CO was approximately 280 parts per mil lion. Current values are well above 350 parts per million. During the last ice age, some 18,000 years ago, CO levels were even lower, about 200 parts per million.