Congo Basin Rainforest is a Net Carbon Source During the Dry Season

The Congo basin, with an area of about 3.7 million km2 in the tropical region, contains the second largest rainforest and is considered as a carbon sink for the atmosphere. Here, using Orbiting Carbon Observatory-2 satellite observations, we show that the atmospheric CO2 over the Congo basin is similar to 2 ppm higher than the regional background during June-August, which is primarily due to biomass burning and significantly reduced photosynthetic activities during the dry season. The contribution from the biomass burning is larger than that from the biosphere during June-August. Current budget estimations suggest emissions from biomass burning during the dry season alone account for similar to 72% of the Congo basin annual biomass burning emissions and are similar to 40% more than the largest terrestrial uptake in the same region during January-March (wet season). Therefore, better seasonal fire management in this region is an important strategy for achieving timely reductions in global carbon emissions as set by international agreements.