(gm) In July 2003 IPCC held a high level scientific meeting in Geneva in order to survey current scientific understanding of processes affecting terrestrial carbon stocks and human influences upon them. The UNFCCC invited the IPCC to develop practicable methodologies to factor out direct human-induced changes in carbon stocks and net greenhouse gas emissions from changes due to indirect human-induced and natural effects.
Some key conclusions mentioned in the meeting report are:
- The scientific community cannot currently provide a practicable methodology that would factor out direct human-induced from indirect human-induced and natural effects for any broad range of LULUCF (land-use, land-use change and forestry) activities. One reason is that the recent focus of carbon science has been on quantifying fluxes rather than on attributing them to mechanisms.
- Different non-linear and non-additive interactions of past practices, of nutrient feedbacks (CO2 and nitrogen) and of changes in climate, pollutants, aerosols and invasive species complicate the factoring out.
- In many circumstance the direct effects of forestry activities on carbon stocks and greenhouse gas emissions and removals will be much larger than the sum of indirect human-induced and natural effects, and the non-linear interactions among all effects.
- Future progress depends on a combination of different approaches and their integration like satellite remote sensing products, economic indicators, flux measurement technologies and a wide variety of high-technology measurements (e.g. FACE or isotopes). A better understanding at the process level is crucial to overcome the present limitations.
You can download the full report (pdf file, 30 pages) at