Geography: Ways to achieve more accurate carbon budgets

How strongly do deforestation, reforestation, and agricultural expansion influence the carbon cycle? A team led by LMU researchers investigated why CO₂ fluxes from land use are still so uncertain and what can be done to better understand them. The findings are published in the journal Nature Reviews Earth & Environment.

CO₂ fluxes from land use: One of the largest uncertainties in the carbon cycle

Understanding how human land use affects carbon stocks in ecosystems is crucial for accurate climate projections and effective climate change mitigation strategies.

While deforestation releases CO₂, reforestation and sustainable forest management can increase the storage of carbon in vegetation and soil. However, the magnitude of these effects remains one of the key uncertainties in the global carbon cycle.

The new publication, led by LMU geographers Dr. Wolfgang Obermeier and Dr. Clemens Schwingshackl with the participation of Raphael Ganzenmüller and Professor Julia Pongratz as well as other researchers, sheds light on why different studies on CO₂ fluxes from land use sometimes differ greatly from one another and what methodological steps are necessary to harmonize the estimates in the future.

Comparison of key approaches

The team examined the most used methods for quantifying CO₂ fluxes from land use and land-use change. The result: differences in definitions, data sources, and model assumptions lead to substantial discrepancies and uncertainties.

The researchers show that none of the existing methods fully reflects all relevant processes. On this basis, they formulate proposals on how measurements, models, and reporting can be linked more consistently in the future.

Ways to achieve more accurate carbon budgets

To increase accuracy, the authors recommend, among other things:

• Closer collaboration between Earth-observation scientists, modellers and producers of national greenhouse gas inventories
• More transparent communication of methodologies
• Better integration of remote sensing, inventory, and modelling data

These steps can help reduce uncertainties and improve carbon accounting worldwide as a basis for effective climate policy.

Significance for research and policy

The study clearly shows that technical measurement errors account for only part of the uncertainties. Systematic differences in definitions, data sets, and reporting systems are at least as important. The findings from the publication thus create an important basis better understanding the importance of land use for the global climate, making international reporting more transparent, and efficiently implementing ecosystem-based CO2 removal from the atmosphere.

Wolfgang Obermeier, Clemens Schwingshackl, Raphael Ganzenmüller et al.: Differences and uncertainties in land-use CO2 flux estimates. Nature Reviews Earth & Environment 2025