Forests and Carbon
World forests absorb ~7.6 Gt CO₂/year through photosynthesis growth — roughly 20% of annual fossil CO₂ emissions. But deforestation and forest degradation release ~5 Gt CO₂/year. The net forest carbon flux is a sink of ~2.6 Gt CO₂/year. Tropical forests have flipped from net sink to near-neutral or slight source in recent years; temperate and boreal forests remain sinks.
Key insights
Tropical forests are the largest gross sink
Tropical forests absorb ~3 Gt CO₂/year gross — the largest single component. But tropical deforestation releases ~3-4 Gt CO₂/year, making tropical forests net-near-neutral or slight source. Amazon eastern regions are now established carbon sources due to combined deforestation and degradation. Temperate forests in Europe, US, China are reliable sinks of ~0.6-1.5 Gt CO₂/year. Boreal forests (Russia, Canada) sequester ~0.6-1.0 Gt CO₂/year but face increasing fire and pest risk.
Deforestation rates have fallen but remain high
Annual deforestation peaked around 1990 at ~16 million hectares. Currently ~10 million hectares per year — largely in Brazil, DRC, Indonesia, Bolivia. Brazil saw deforestation surge 2019-2022 under Bolsonaro; Lula government reduced rates ~50% in 2023-24. Indonesia deforestation has fallen substantially since 2016 peak. DRC remains a major frontier as forest carbon escapes attention compared to Amazon.
REDD+ has produced mixed results
Reducing Emissions from Deforestation and Forest Degradation framework operating since COP13 (2007). Countries can receive performance-based payments for verified emission reductions. Funding has reached billions of dollars (Brazil's Amazon Fund, Norway's funding to Indonesia, World Bank Forest Carbon Partnership Facility). Effectiveness debate: payments have aligned with reduced deforestation in some cases, but causality is hard to establish.
World forest area 1990–2024
Billion hectares
Key Finding: Net loss of ~178 million ha (4.4%) since 1990. Loss has slowed but continues.
Annual primary tropical forest loss — top countries (2023)
Million hectares
Key Finding: Brazil dominates absolute primary forest loss; DRC and Bolivia second tier.
Methodology & caveats
Gross vs net forest emissions
Gross emissions: total CO₂ released from forest loss. Gross absorption: total CO₂ taken up by growing forests. Net flux: difference. Headlines often quote net flux (-2.6 Gt), which obscures the large gross fluxes in both directions. Both numbers matter for policy.
Forest definitions
FAO defines forest as land with tree canopy cover above 10% (or natural ability to reach this). Different definitions include or exclude: tree plantations, savanna woodland, agroforestry. 'Primary forest' (intact, never logged) is the most-protected category — but only ~30% of total forest area. Most 'forest' is secondary or managed.
Why tropical forests are turning to sources
Combination of: direct deforestation (clearing for cattle, soy, palm oil), degradation from selective logging, increased fire frequency, drought stress reducing photosynthesis. East Amazon is already net carbon source. West Amazon still net sink. Tipping-point models suggest larger fractions could flip with continued warming/deforestation pressure.