This Q&A is part of the Guardian's ultimate climate change FAQ.
|Link to The Guardian|
"The lifetime in the air of CO2, the most significant man-made greenhouse gas, is probably the most difficult to determine, because there are several processes that remove carbon dioxide from the atmosphere. Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation.
"This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years."