GWX — Drought

Drought

Drought accounts for about 7% of global weather/climate economic losses but the single largest share of deaths, about 33%, 1980-2025 (see Loss Normalization) -- famine-driving droughts in Africa dominate that toll. A live drought index here comes from ARCO-ERA5 precipitation, percentile-ranked against each grid cell's own calendar-month history and classified into USDM-equivalent D0-D4 categories. Two series run alongside each other: precipitation-only (SPI-style) and precipitation minus atmospheric evaporative demand (SPEI-style), extending Vicente-Serrano et al. 2022's finding that AED-inclusive metrics reveal regional drying precipitation alone misses.

Summary Judgment

Consistent with IPCC AR6

The SPEI-style (precipitation minus evaporative demand) series shows a detected drought increase at every severity level, matching the mechanism AR6 names, while the precipitation-only series shows no detected change, agreeing that precipitation alone isn't the driver.

IPCC finding (AR6 WG1 SPM A.3.2): "Human-induced climate change has contributed to increases in agricultural and ecological droughts in some regions due to increased land evapotranspiration (medium confidence)." — see the full Detection & Attribution comparison for every phenomenon this site tracks.

Drought — Global Severe-or-Worse Land Area

Monthly

% of global land area (5°-coarsened grid) at a selectable USDM-equivalent drought severity level or worse each month, from two live indices built directly from ARCO-ERA5 -- SPEIbase, the standard global-gridded-SPEI source, has published no release since July 2024. Unit: % of land cells.

Series

Source: ARCO-ERA5 (ECMWF ERA5 reanalysis, Google Cloud mirror)

Computing trend…

Select a drought severity level (D0 through D4) and series above -- the precipitation-only (SPI-style) series and the precipitation-minus-evaporative-demand (SPEI-style) series often diverge; D2+ SPI-style runs as the default. See Methodology for the construction and the Vicente-Serrano et al. 2022 finding this site replicates.

The precipitation-only (SPI-style) series matches two independently well-documented global drought years: 2021 ranks as the single highest year in this 1979-2026 record (the Horn of Africa's worst drought in 40 years began that year, alongside a severe western North America megadrought and Madagascar's near-famine drought), with 2011 second (the Horn of Africa famine, the historic Texas/Southern Plains drought).

The precipitation-minus-AED (SPEI-style) series replicates and extends through the present the central finding of Vicente-Serrano et al. 2022 ("Global drought trends and future projections," Phil. Trans. R. Soc. A 380: 20210285): including atmospheric evaporative demand reveals a much stronger drying trend than precipitation alone shows. Comparing 1980-2002 to 2003-2025, the precipitation-only series' global drought trend rises +0.93 percentage points, while the AED-inclusive series rises +3.35 pointsover the identical window -- more than 3x larger. 2023, the hottest year on record globally at the time and a documented case where extreme heat (not just low rainfall) drove severe drought, shows the AED-inclusive series notably worse (13.4%) than the precipitation-only series (10.8%) for that year. See the methodology page for the Hargreaves-method simplification this uses in place of the source paper's full Penman-Monteith calculation.