Australian tropical rainforest trees have become the first in the world to switch from being a carbon sink to an emissions source due to increasingly extreme temperatures and drier conditions.

The change, which applies to the trees’ trunk and branches but not the roots system, began about 25 years ago, according to new research published in Nature.

Trees store carbon as they grow and release it when they decay and die. Overall, tropical forests are thought to be carbon sinks – absorbing more CO 2 than they release – and uptake is assumed to increase amid rising atmospheric concentration.

But nearly 50 years of data collected from tropical forests across Queensland has revealed this crucial carbon sink could be under threat.

About 25 years ago, tree trunks and branches in those fore

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