Global Climate Zones (1970 - 2000) Derived via the Mean Annual Biotemperature and the Inverted Aridity Index: global raster layers and maps at 30 arc-second resolution.

Audebert et al. (2026) have proposed 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. Here the decision framework proposed by Audebert et al. (their Figure 2) was applied to global raster layers that directly correspond to the climatic variables used to differentiate the global climate zones: A global map of six Holdridge Biotemperature Zones was obtained from a previous Zenodo archive (zenodo.org ), selecting a 30 arc-seconds raster layer obtained via the maximum and minimum monthly temperatures available from WorldClim 2.1 (Fick & Hijmans 2017 ; worldclim.org). Annual precipitation data (bioclimatic variable BIO12) were obtained via WorldClim 2.1 (Fick & Hijmans 2017 ; worldclim.org). The same raster layer (30 arc-seconds) was used to calculate the Inverted Aridity Index (R = PET / P). Two different geospatial layers (both 30 arc-seconds) were used to source Potential Evapotranspiration for the calculations of R. Previously these layers had been used to create global Climatic Moisture Index maps (zenodo.org). Potential Evapotranspiration (ET0) obtained from the Global Aridity Index and Potential Evapotranspiration (ET0) Database (GAIPED; Zomer et al. 2022; version 3.1 from 2025). To create this database, the FAO Penman-Monteith Reference Evapotranspiration equations were used. Potential Evapotranspiration (PET) calculated via the envirem package (Title and Bemmels 2018). Envirem applies the modified Hargreaves-Thornton equations that were used to generate version 1.0 of GAIPED.   Following zones are included Code Zone Biotemperature (BIOT) Inverse Aridity 11 Polar BIOT <= 1.5 °C - 21 Subpolar 1.5 °C < BIOT <= 3 °C - 31 Boreal Dry 3 °C < BIOT <= 6 °C R >= P/250 32 Boreal Moist 3 °C < BIOT <= 6 °C R < P/250 41 Cool Temperate Dry 6 °C < BIOT <= 12 °C R >= P/500 42 Cool Temperate Moist 6 °C < BIOT <= 12 °C R < P/500 51 Warm Temperate Dry 12 °C < BIOT <= 24 °C R >= P/1000 52 Warm Temperate Moist 12 °C < BIOT <= 24 °C R < P/1000 61 Tropical Dry BIOT > 24 R >= P/500 62 Tropical Moist BIOT > 24 P/2000 <= R < P/500 63 Tropical Wet BIOT > 24 R < P/2000   Raster layers and maps included in this archive were created via the terra package (Hijmans 2025, version 1.8-70) in the R 4.5.1 environment. Added country boundaries were obtained from Natural Earth as Admin 0 – countries vector layers (version 5.1.1). An additional set of maps was produced where areas located in water were masked. This was done after reprojecting the ESACCI-LC-L4-WB-Map-150m-P13Y-2000-v4.0 raster (Lamarche et al. 2017 doi.org  ) onto the projection system of the Global Climate Zone raster layers.   References Philip Audebert, Eleanor Milne, Laure Sophie Schiettecatte et al. 2026, Aligning climate zoning to ecological zoning: A harmonized classification approach, 07 April 2026, PREPRINT (Version 1) available at Research Square. doi.org Zomer, R.J.; Xu, J.; Trabucco, A. 2022. Version 3 of the Global Aridity Index and Potential Evapotranspiration Database. Scientific Data 9, 409. nature.com Title, P. O., & Bemmels, J. B. (2018). ENVIREM: An expanded set of bioclimatic and topographic variables increases flexibility and improves performance of ecological niche modeling. Ecography, 41(2), 291–307. doi.org Fick, S. E., & Hijmans, R. J. (2017). WorldClim 2: New 1‐km spatial resolution climate surfaces for global land areas. International Journal of Climatology, 37(12), 4302–4315. doi.org Hijmans, R. (2025). terra: Spatial Data Analysis. R package version 1.8-70, cran.r-project.org . Kindt, R. (2026). TreeGOER Biotemperature Zone Distributions: Observations for 48,129 tree species across 6 Global Holdridge Biotemperature Zones based on Monthly Temperature Data for 1970-2000 (Version 2026.08) [Dataset]. Zenodo. doi.org Kindt, R. (2026). Global Climatic Moisture Index Zones Derived via the FAO Penman-Monteith Reference Evapotranspiration (ET0) and the Modified Hargreaves-Thornton Equations (Version version 2026.08) [Dataset]. Zenodo. doi.org Lamarche, C.; Santoro, M.; Bontemps, S.; D’Andrimont, R.; Radoux, J.; Giustarini, L.; Brockmann, C.; Wevers, J.; Defourny, P.; Arino, O. Compilation and Validation of SAR and Optical Data Products for a Complete and Global Map of Inland/Ocean Water Tailored to the Climate Modeling Community. Remote Sens. 2017, 9, 36. doi.org   The development of this archive was supported by Norway’s International Climate and Forest Initiative through the Royal Norwegian Embassy in Ethiopia to the Provision of Adequate Tree Seed Portfolio project in Ethiopia, by the Green Climate Fund through the IUCN-led Transforming the Eastern Province of Rwanda through Adaptation project and through the Readiness proposal on Climate Appropriate Portfolios of Tree Diversity for Burkina Faso, by the Bezos Earth Fund to the Bezos Quality Tree Seed for Africa in Kenya and Rwanda project and by the German International Climate Initiative (IKI) to the regional tree seed programme on The Right Tree for the Right Place for the Right Purpose in Africa.