Tropical Forests Carbon Balance Under Threat

Tropical forests retain their importance in the global carbon cycle and keep their role as important sinks that absorb a large fraction of anthropogenic emissions. However, continued deforestation, forest degradation, and climate change threaten these ecosystems and compromise their roles in carbon storage and climate mitigation.

Ongoing deforestation and rising temperatures are likely to turn tropical forests from net carbon sinks into net carbon sources, threatening global climate objectives such as holding warming below 2°C. How those forests balance carbon uptake against emissions in response to changing conditions is crucial to the working out of effective climate policy.

We demonstrate in this paper that the contemporary balance between carbon uptake and emissions in tropical forests is likely to be short-lived because of continued deforestation and forest degradation. If left unchecked, tropical forests are poised to become a net source of emissions, hastening climate change. Tropical forests have long played an important role in absorbing atmospheric carbon, but the impact of widespread deforestation and increased temperatures that limit tree growth is undermining that role. In extreme years, such as those with El Niño events, tropical forests could even emit more carbon than they absorb.

While international efforts like the Paris Agreement and REDD+ promote a reduction in deforestation and encourage restoration, respectively, the absence or unavailability of data for monitoring and validation severely confines such progress. This paper again underlines the urgent need for enhanced data acquisition, including large-scale experimentation, to understand how tropical forests respond to climate. This implies that the tropical forests should be protected and restored, as they have a great ability to maintain the carbon cycle with other ecological and social benefits. Restoring and protecting tropical forests requires their preservation through coordination among global actions to prevent loss of the function of these ecosystems to absorb carbon.

Reference

Mitchard, E.T.A. The tropical forest carbon cycle and climate change. Nature 559, 527–534 (2018). https://doi.org/10.1038/s41586-018-0300-2