Emerging climate impact on carbon sinks in a consolidated carbon budget
Summary
This consolidated carbon-budget study integrates recent observations and process understanding to reconcile long-standing mismatches between reported emissions and sinks. The authors find that the natural land carbon sink is substantially smaller than previously thought, anthropogenic land-use emissions are larger, and the ocean sink is about 15% larger than the land sink. Climate change has already reduced sink efficiency — especially on land — contributing 8.3 ± 1.4 ppm to atmospheric CO2 since 1960. Combined warming and deforestation have shifted Southeast Asian and large parts of South American tropical forests from net sinks to net sources. The results increase confidence in carbon accounting and stress the urgency of halting deforestation and limiting warming to preserve land carbon stores.
Key Points
- Global fossil CO2 emissions continue to rise; atmospheric CO2 reached ~423 ppm in 2024 and anthropogenic warming is about 1.36°C.
- The natural land carbon sink is significantly smaller than earlier estimates, while emissions from anthropogenic land-use change are revised upward.
- The ocean currently takes up more CO2 than land; the ocean sink is ~15% larger than the land sink according to updated observations.
- Climate change has reduced sink efficiency, particularly on land, adding 8.3 ± 1.4 ppm to atmospheric CO2 since 1960.
- Deforestation plus climate impacts have turned Southeast Asian and many South American tropical forests from CO2 sinks into net sources.
- Improved, consolidated estimates of sources and sinks are essential for reliable carbon budgets and effective climate policy.
Content summary
The paper presents an updated, consolidated global carbon budget that combines improved observational datasets and advances in process understanding. By reconciling previous discrepancies between reported emissions and sink estimates, the team shows substantial revisions: a smaller land sink and higher net emissions from land-use change, with the ocean acting as the larger sink. They quantify the contribution of climate change to reduced sink efficiency and map regions where sinks have flipped to sources due to warming and deforestation. The authors argue that these updated estimates increase confidence in tracking progress against climate targets and highlight areas requiring urgent mitigation and conservation action.
The work includes thorough attribution of trends and drivers, and offers new evidence to inform national reporting and international policy. It emphasises the need for immediate measures to halt deforestation and to limit warming to avoid further loss of terrestrial carbon stores.
Context and relevance
This article matters because reliable carbon budgets underpin climate policy, national reporting and net-zero planning. By showing that land sinks are weaker and land-use emissions larger than previously thought, the study implies less remaining “headroom” for future fossil emissions if warming limits are to be met. The finding that climate change has already degraded sink efficiency means mitigation and forest-protection measures are more urgent: continued deforestation and further warming risk turning more ecosystems into CO2 sources. The results are directly relevant to policymakers, climate modellers, carbon accounting practitioners and conservation planners tracking adherence to the Paris Agreement.
Why should I read this?
Quick take: if you care about whether carbon budgets add up (and you should), this paper explains why the old arithmetic was optimistic. It shows sinks are less generous, land-use hits are bigger, and climate itself is already weakening nature’s ability to mop up CO2. Read it to get the updated numbers and the regional hotspots where forests have stopped helping us and started hurting the carbon balance.
Author style
Punchy: this is a high-impact, policy-relevant synthesis from leading carbon-cycle experts. The findings tighten the carbon-budget picture and amplify the need for immediate mitigation and forest protection. Definitely worth digging into the methods if you work in reporting, modelling or climate policy.