Guardian: Drought, rising temperatures and deforestation are causing tropical forests to change from carbon sinks into a major carbon emitter, warn scientists from the UK and Australia. Climate modellers had assumed, the scientists said, that rising levels of CO2 in the atmosphere would increase the growth of trees because CO2 can encourage plants to grow, and in turn absorb more of the greenhouse gas. However, the models are said to have left out one key factor: trees also die younger as their …