Weakening natural carbon sinks threaten Net Zero plans: Wood Mackenzie
An industry analysis by energy research firm Wood Mackenzie finds that natural carbon sinks (forests and oceans) absorbed roughly 40% of anthropogenic CO2 emissions in 2025, far outweighing the contribution of engineered carbon removal technologies
Oceans absorbed an estimated 12 gigatonnes (Gt) of CO2 and forests an additional 6 Gt, together reducing net global emissions from about 48 Gt to roughly 30 Gt
The report warns that global forest area has shrunk by 1.5 million sq km since 1990, and that the land-use sector reached near-neutral net emissions by 2024, meaning it has effectively stopped functioning as a net carbon sink at the margin
It calls for stronger carbon pricing and dedicated finance for nature protection, noting that current carbon prices do not reflect the true cost of sink degradation
Natural vs. Engineered Carbon Sinks
A carbon sink is any reservoir that absorbs more carbon than it releases. Natural sinks — forests, oceans, soils, wetlands — are distinguished from engineered (technological) carbon removal methods such as Direct Air Capture (DAC) and Bioenergy with Carbon Capture and Storage (BECCS), which mechanically extract or capture CO2. The IPCC's Sixth Assessment Report (AR6, 2021–2023) classifies both as forms of Carbon Dioxide Removal (CDR), a category distinct from simple emissions reduction.
Key Details
- Combined DAC and BECCS removals in 2025 were about 0.08 Gt CO2 — roughly 200,000 times smaller than natural ocean uptake alone, per the cited analysis
- Oceans are estimated to have absorbed roughly a quarter to a third of all anthropogenic CO2 emissions historically, alongside taking up over 90% of the excess heat trapped by greenhouse gases (IPCC AR6)
- Forest/land-based sinks are vulnerable to reversal through deforestation, fire and drought — making them a less "permanent" form of storage than geological CO2 injection used in engineered removal
The report's core warning is that net-zero strategies worldwide lean heavily on natural sinks that are already weakening, while the technological alternatives being promoted as backstops remain minuscule in scale — a mismatch between climate policy assumptions and physical reality.
Net Zero Frameworks and the Residual Emissions Gap
"Net zero" means anthropogenic CO2 emissions are balanced by removals over a specified period, a concept operationalised globally after the Paris Agreement's Article 4 called for a balance between sources and sinks "in the second half of this century." Most net-zero pathways (including the IEA's Net Zero Emissions by 2050 scenario) assume that hard-to-abate residual emissions from sectors like aviation, cement and steel will be offset by a mix of natural and engineered removals.
Key Details
- The report estimates roughly 11 Gt of annual energy-sector emissions would still need offsetting under 2050 net-zero scenarios, even after aggressive decarbonisation
- India's own net-zero target year is 2070, announced at COP26 (Glasgow, 2021), later than most developed-country targets (typically 2050) in line with the CBDR-RC principle
- India's updated NDC (2022) additionally commits to creating an additional carbon sink of 2.5–3 billion tonnes of CO2 equivalent through forest and tree cover by 2030; the India State of Forest Report 2023 records 2.29 billion tonnes achieved so far
If natural sinks continue weakening globally as the report suggests, countries relying on forest-based sink targets (like India's NDC) as part of their net-zero arithmetic may need to front-load engineered removal capacity or deeper emissions cuts to compensate.
Carbon Pricing and Market Mechanisms
Carbon pricing puts a monetary cost on greenhouse gas emissions, either through a carbon tax (a fixed price per tonne) or an Emissions Trading System / cap-and-trade market (a market-set price based on a capped supply of permits). The Paris Agreement's Article 6 establishes mechanisms for countries to cooperate and trade emissions outcomes internationally.
Key Details
- Article 6.2 enables bilateral/multilateral trading of Internationally Transferred Mitigation Outcomes (ITMOs); Article 6.4 creates a centralised, UN-supervised crediting mechanism (the Paris Agreement Crediting Mechanism, successor to the Kyoto Protocol's Clean Development Mechanism); Article 6.8 covers non-market cooperation such as technology transfer
- Current global compliance carbon prices range roughly from USD 5 to USD 90 per tonne of CO2, per the cited analysis — well below most estimates of the "social cost of carbon"
- India notified its own domestic carbon market, the Carbon Credit Trading Scheme (CCTS) 2023, under Section 14AA of the Energy Conservation (Amendment) Act, 2022, initially covering energy-intensive sectors such as iron & steel, cement, aluminium and fertilisers; compliance trading was expected to begin in 2026
The report's argument that carbon prices are too low to reflect sink degradation applies directly to nascent markets like India's CCTS, where credit prices set by market forces may still undervalue the ecological cost of losing natural carbon absorption capacity.
- Natural sinks' share of 2025 anthropogenic CO2 absorption: ~40% (oceans ~12 Gt, forests ~6 Gt)
- Global emissions reduced by natural sinks: from ~48 Gt to ~30 Gt net
- Global forest area lost since 1990: 1.5 million sq km
- Engineered carbon removal (DAC + BECCS) in 2025: ~0.08 Gt CO2
- Current global compliance carbon prices: USD 5–90 per tonne CO2
- Residual annual energy-sector emissions projected under 2050 net-zero scenarios: ~11 Gt
- India's NDC forest carbon sink target: 2.5–3 billion tonnes CO2 equivalent by 2030 (2.29 billion tonnes achieved per ISFR 2023)