Volume 579 Issue 7797, 5 March 2020

Saturation point

Tropical forests, such as the one in the Democratic Republic of the Congo pictured, are important carbon sinks, removing about 15% of anthropogenic carbon dioxide over the course of the 1990s and early 2000s. In this week’s issue, Wannes Hubau and his colleagues examine the rates at which such forests in Africa and Amazonia have taken up carbon between 1983 and 2015 — and find marked differences between the two regions. They reveal that the ability of forests in Africa to act as a carbon sink was stable until the 2010s when it began to decline, in contrast to the previously documented decline in Amazonian forests since the 1990s. They conclude that both continents show a pattern of carbon-sink saturation and decline, with asynchronous timing and different rates of reduction. The researchers extrapolate their findings to predict that by 2030 the carbon sink in Africa will have shrunk by 14% compared with 2010–15, and that the Amazonian sink will reach zero in 2035. This decline has significant implications for the goal of limiting global warming to below 2 °C.

Cover image: Jabruson/NPL

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