Scientists say it's apparent that human activity -- namely burning coal, oil and natural gas -- has been driving a rapid rise of carbon dioxide levels in the atmosphere.

CNN: CO2 levels hit new peak at key observatory

The IPCC Panel's near-consensus was that human activity is having some discernible impact on climate, and that by 2100, a warming earth could result in more frequent storms and droughts, sea level rise of up to three feet, and up to six degrees F. in temperature rise.

CNN: Selected Web sites on climate change

It's unseemly to have commercial activity around human reproductive material.

NPR: Defining the Ethics of Stem Cell Research

Many of Burke's descendants find it difficult to believe that something as big as the earth's climate could really be at risk from human activity, and even harder to think you could do something about it.

ECONOMIST: Disasters are about people and planning, not nature��s pomp

Three quarters of the world's forests have been cleared, degraded or fragmented due to human activity, while a third have disappeared altogether, according to IUCN.

CNN: Forests size of Russia 'could be restored'

Muller conceded that the study's remit did not extend to questions about how much warming has been influenced by human activity.

CNN: New climate study deals blow to skeptics