Global Aridity and PET Database



The Global Potential Evapo-Transpiration (Global-PET) and Global Aridity Index (Global-Aridity) dataset provides high-resolution global raster climate data related to evapo-transpiration processes and rainfall deficit for potential vegetative growth.

These datasets are based on modeling and analyses by Antonio Trabucco (CSI-Alumni/currently at the Forest, Ecology and Management Research Group, K.U. Leuven), with the support of the International Water Management Institute (IWMI) and the International Centre for Integrated Mountain Development (ICIMOD), and are provided online by the CGIAR-CSI with the support of the International Center for Tropical Agriculture (CIAT).

The Global-PET and Global-Aridity datasets are provided for non-commercial use in standard ARC/INFO Grid format, at 30 arc seconds (~ 1km at equator), to support studies contributing to sustainable development, biodiversity and environmental conservation, poverty alleviation, and adaption to climate change globally, and in particular in developing countries. The methods used to derive these datasets and the data dictionary are described briefly below and discussed also in Zomer et al. (2007) and Zomer et al. (2008).

The Global-PET and Global-Aridity are both modeled using the data available from WorldClim Global Climate Data (





Following files are available to download:

  • Data files
    • Extraterrestrial Solar Radiation
    • Global Aridity – Annual
    • Global PET – Annual
    • Global PET – Monthly
  • Documentations
    • Global Aridity and Global PET – Methodology
    • Carbon, Land and Water: A Global Analysis of the Hydrologic Dimensions of Climate Change Mitigation through Afforestation/Reforestation (Zomer et al., 2007)
    • Climate change mitigation: A spatial analysis of global land suitability for clean development mechanism afforestation and reforestation (Zomer et al., 2008)
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DISTRIBUTION: Users are prohibited from any commercial, non-free resale, or redistribution without explicit written permission from the CGIAR-CSI. Users should acknowledge CGIAR-CSI Global-Aridity and Global-PET Database as the source used in the creation of any reports, publications, new data sets, derived products, or services resulting from the use of this data set.

NO WARRANTY OR LIABILITY: Neither the author of this dataset, nor CGIAR-CSI, can bear any responsibility for the consequences of using it, which are entirely the responsibility of the user. It is inevitable that a data-set of this size will contain some errors and inconsistencies. However, these have been kept to a minimum and when they are identified they are corrected when resources permit. Updates to this dataset are announced through the CGIAR-CSI web site.

ACKNOWLEDGMENT AND CITATION: We kindly ask any users to cite this data in any published material produced using this data, and if possible link web pages to the CGIAR-CSI website ( The creator of this data set retains full ownership rights over it. The data set may be freely used for non-commerical scientific and educational purposes, provided it is described as the CGIAR-CSI Global-Aridity and Global-PET Database and attributed to:

Zomer RJ, Trabucco A, Bossio DA, van Straaten O, Verchot LV, 2008. Climate Change Mitigation: A Spatial Analysis of Global Land Suitability for Clean Development Mechanism Afforestation and Reforestation. Agric. Ecosystems and Envir. 126: 67-80.

Zomer RJ, Bossio DA, Trabucco A, Yuanjie L, Gupta DC & Singh VP, 2007. Trees and Water: Smallholder Agroforestry on Irrigated Lands in Northern India. Colombo, Sri Lanka: International Water Management Institute. pp 45. (IWMI Research Report 122).

DATA USE AND DISTRIBUTION: This data has been generated by not-for-profit institutions with the objective of supplying accessible and useful information to developing country organizations. We actively encourage use of these products for scientific purposes. This is not however the case for commercial purposes. The entire dataset is available for commercial use at a modest cost, but permission must be sought. Commercial sectors interested in using this data should contact Antonio Trabucco at:

Global Aridity and Global PET – Methodology (PDF)

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