Is the Climate of the Congo basin Becoming Less Able to Support a Tropical Forest Ecosystem?

Ongoing degradation of the Congolese rain forest is documented, but the individual roles of climate change and deforestation are unknown. A modified version of the Centro de Previsao de Tempo e Estudios Climaticos (CPTEC) potential vegetation model (PVM) forced by ERA5 reanalysis data translates decadal climate states (1980-2020) into natu-ral vegetation distributions to identify regions where climate change could have played a role in changing vegetation. These areas are then examined to understand how and why these climate changes could affect the tropical rain forest coverage. Between the 1980s and the 2010s, the climate over the northern and southern Congo basin rain forest margins becomes less able to support the forest. In the north, strong, negative meridional moisture gradients in boreal winter separate warm, dry conditions to the north from the cooler, moist rain forest. By the 2010s greenhouse gas warming deepens the low-level trough in the north, enhancing the inflow of drier subtropical air. A similar drying response occurs over the southern mar -gin during austral winter when the low-level westerly transport of Atlantic moisture decreases in association with warming and reduced low-level heights over the equatorial Congo basin. In the interior, climate conditions also become less favor-able along major transportation routes by the 2010s due to human intervention/deforestation. Along coastal Angola, the climate becomes more favorable for tropical forest vegetation when coastal upwelling weakens and SSTs warm in response to changes in the South Atlantic subtropical anticyclone. These results have implications for the future as global warming continues.

Automated summary

This study examines the individual impacts of climate change and deforestation on the degradation of the Congolese rainforest. By using a modified version of the CPTEC potential vegetation model forced by ERA5 reanalysis data, the researchers identify regions where climate change has influenced vegetation change. They find that climate change has made the climate less suitable for the rainforest in the northern and southern margins of the Congo basin, while deforestation has worsened the climate conditions along major transportation routes in the interior. However, the climate becomes more favorable for tropical forest vegetation in coastal Angola due to changes in ocean currents. These findings have important implications for the future as global warming continues.