Aligning climate zoning to ecological zoning: A harmonized classification approach

The world will likely overshoot the Paris Agreement goal to keep the global average temperature increase below 2°C. As shifts in crop and tree species suitability as well as vegetation distribution occur in a changing climate, a new scientifically sound, consistent, and flexible approach is needed to classify global ecological and climate zones and track their shifts – however, the current global classification framework used by the IPCC is inconsistent and thus may create mitigation reporting errors and will be less useful in informing adaptation actions. This study proposes a new dynamic, globally consistent and universally applicable Global Climate Zoning (GCZ) approach based on the Holdridge Life Zone system, which can be used as a consistent land-based climatic classification for the entire agriculture, forestry and other land use (AFOLU) sector. The approach ensures exact correspondence with the Global Ecological Zones (GEZ), aligning with the key principles of the Intergovernmental Panel on Climate Change (IPCC) to allow for bottom-up reporting of greenhouse gas (GHG) emissions that can be aggregated at the global level, which represents a critical improvement compared to current static climatic classification systems.