Australia's tropical rainforests have become the first in the world to release more carbon than they absorb, in a trend linked to climate change, a study has found. Rainforests are usually regarded as so-called "carbon sinks" as they absorb more emissions than they emit with new trees offsetting the carbon released by dead ones. But a study looking at data from Queensland forests found that extreme temperatures have caused more tree deaths than growths. The lead author of the study, which was published in science journal Nature, said the findings have significant implications for global emissions reduction targets which are partly based on how ecosystems—such as rainforests—can absorb carbon. Source: https://www.bbc.com/