I have always thought that a simple way of accounting for our fossil fuel use is to remove carbon dioxide from the atmosphere rather than making our consumer society give up carbon use. One way is to plant trees. Another is to scrub the gas from the air using industrial processes. There are two chemical processes called the Bosch reaction and the Sabatier reaction but both require a large energy input.
Richard Branson today put up a $25 million prize for someone to find another way of removing carbon dioxide from the atmosphere. The aim is to remove a billion tonnes of carbon from the air each year.
BBC - Branson launches $25m climate bid