A recent study conducted by an international research team has found that while tropical forests have long been considered important carbon sinks, boreal and temperate forests are equally crucial, if not more so. The team, led by the French Commission on Alternative Energies and Atomic Energy, mapped annual changes in global forest biomass from 2010 to 2019.

The findings reveal that tropical forests, although older, have significantly decreased due to deforestation, forest fires, and droughts, meaning their carbon neutrality has been compromised. In contrast, boreal and young forests are playing an increasingly vital role in climate change mitigation strategies. As the biomass of these forest areas increases, they contribute to more effective carbon capture.

The balance of biomass carbon is determined by increases through plant growth and forest cover expansion, as well as losses resulting from harvesting, deforestation, degradation, tree mortality, and natural disturbances. Monitoring changes in carbon biomass reserves over time is crucial for better understanding the effects of climate change and human activities on ecosystems, as well as informing climate change mitigation policies.

Researchers used surface biomass data to calculate global biomass carbon reserves and their distribution from 2010 to 2019. The results indicate that terrestrial biomass carbon reserves increased by approximately 500 million metric tons of carbon annually during the study period. Boreal and temperate forests were identified as the main contributors to the global carbon sink, while tropical forests became small carbon sources due to deforestation and tree mortality caused by drought.

Previous studies have shown that tropical forests are losing their ability to effectively store carbon. However, research also suggests that restoring these forests can increase their carbon sink capacity. Currently, old-growth tropical forests, with an average tree age of over 140 years, are nearly carbon-neutral. In contrast, temperate and boreal forests, where trees are 50 years or younger, have become the largest carbon sinks globally.

These new findings challenge existing prediction models that consider all old-growth forests as significant carbon sinks. The importance of forest demography and the impact of deforestation and degradation in tropical forests, which are experiencing biomass loss, have not been properly taken into account.

The results of this study can play a crucial role in predicting future carbon sink dynamics and formulating climate change mitigation policies. By understanding the carbon storage potential of different types of forests, policymakers can develop more effective strategies to combat climate change.

– French Commission on Alternative Energies and Atomic Energy