Details and strengths of the new dataset released by the CMCC Foundation and available for free on the Data Delivery System (dds.cmcc.it) for all users interested in drought assessment at a global level. 

Agricultural and ecological drought refers to soil moisture deficits causing crop and plant stress, and is one of the four categories of drought that are classified in scientific literature. Other types of drought include meteorological drought, which considers precipitation deficits, hydrological drought, which is about water shortages in surface or subsurface water bodies, and socioeconomic drought, which concerns water supply–demand imbalance, also known as water scarcity.

The Standardized Precipitation Evapotranspiration Index (SPEI) is one of the two indexes selected by the Intergovernmental Panel on Climate Change (IPCC) and used in its Sixth Assessment Report (AR6) for agricultural and ecological drought assessment.

Based on the SPEI agro-ecological drought indicator, the CMCC Foundation has recently released a new global dataset, now available for free on its Data Delivery System (dds.cmcc.it), through which the CMCC makes data produced and used by its research activities available for various interested users.

The new multiscale dataset is provided for historical (1960–1999) and two future time horizons (2040–2079 and 2060–2099) under the climate scenarios RCP 8.5 and RCP 4.5. The RCP 8.5 indicates a scenario of comparatively high greenhouse gas emissions, and RCP 4.5 an intermediate scenario that assumes imposition of effective emissions mitigation policies. The dataset is fed by the bias-corrected time series of precipitation and temperature provided by the ISIMIP initiative, which were integrated with data from the CMCC Earth System Model.

“There are many datasets already available to assess drought at regional and global level based on the SPEI. Our dataset brings four main areas of improvement” explains Monia Santini, Director of the CMCC Division on Impacts on Agriculture, Forests and Ecosystem Services. “First, it considers alternative ways of formulating the potential evapotranspiration (PET), which is an input to the Index and represents the process by which water is transferred from the land to the atmosphere through soil and plants. Second, our dataset is characterized by a high resolution (0.5° × 0.5° horizontal resolution, or about 50 x 50 km grid cells) for global scale studies. The third and forth areas of improvement refer to the multiscale dimension of the dataset at the temporal level: regarding the “duration” dimension of drought, the dataset allows the analysis on a monthly basis, spanning from very short (1 month) to very long lasting (18 months) droughts. Moreover, looking at the “timing” dimension of drought, it allows the user to make analyses in terms of drought occurrence in every period of the year, from summer to winter”.

The dataset is available for free for different uses on the CMCC DDS and is described in detail in the publication A Global Multiscale SPEI Dataset under an Ensemble Approach.