Setting fire (IMAGE) Columbia Climate School Caption A new study quantifies how much adding a ton of human-produced carbon dioxide emissions will contribute to human mortality over time. Here, a farmer in the Peruvian Amazon sets a fire to clear land for agriculture. Such fires are a substantial source of emissions. Credit Kevin Krajick/Earth Institute Usage Restrictions Credit must be given. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.