Comment: Human contribution to climate change increasingly clear



[A response to the Forum article, “Human Contribution to Climate Change Remains Questionable” by Fred Singer (April 20, 1999)] In 1957, Roger Revelle and H. E. Seuss wrote that “human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future. Within a few centuries we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of millions of years.”