Uncertainties and limitations of IBC module

The IBC module in LEAP utilizes linear GEOS-Chem Adjoint coefficients from 2010, which cannot account for non-linear atmospheric chemical reactions regarding PM2.5 and ozone. Health and crop impact assessments rely on concentration-response functions derived from North American and European research, with crop yield loss calculations specifically capped at 90 ppb of ozone exposure. Additionally, LEAP's deterministic nature means it does not inherently reflect uncertainties in emission factors or activity levels, requiring users to employ external tools or sensitivity analyses.

• The IBC module uses GEOS-Chem Adjoint coefficients for PM2.5 and ozone based on 2010 emissions. Because these are linear coefficients, the methodology fails to account for non-linear chemical reactions in the atmosphere, such as the interaction between NOx, SO2, and NH3 for secondary inorganic aerosols, or the VOC-limited and NOx-limited regimes that govern ozone formation.
• Health impact assessments for premature mortality from PM2.5 and ozone use concentration-response functions from the Global Burden of Disease project. These functions are derived from research in Europe and North America and are assumed to be applicable globally, despite potential differences in PM2.5 composition and higher concentrations in other regions.
• Crop yield loss for wheat, maize, rice, and soy is estimated using functions based on North American experiments for ozone exposure between 20 and 90 ppb. Because the relationship above 90 ppb is uncertain, the module assumes no increase in yield loss beyond this threshold; consequently, mitigation benefits are only estimated when ozone concentrations are reduced to below 90 ppb.
• LEAP calculations are currently deterministic and do not reflect uncertainties in activity levels, energy intensities, and emission factors. Users can address this by performing sensitivity analyses or using external tools like Oracle Crystal Ball for Monte Carlo analysis.

APA

Stockholm Environment Institute (n.d.). Uncertainties and limitations of IBC module. https://leap.sei.org/Help24/IBC/Uncertainties_and_Limitations_in_Using_IBC.htm

Chicago

Stockholm Environment Institute. Uncertainties and limitations of IBC module. n.d. https://leap.sei.org/Help24/IBC/Uncertainties_and_Limitations_in_Using_IBC.htm.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=Uncertainties and limitations of IBC module |url=https://leap.sei.org/Help24/IBC/Uncertainties_and_Limitations_in_Using_IBC.htm |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitutenduncertainties, author = {{Stockholm Environment Institute}}, title = {{Uncertainties and limitations of IBC module}}, institution = {Stockholm Environment Institute}, url = {https://leap.sei.org/Help24/IBC/Uncertainties_and_Limitations_in_Using_IBC.htm}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }