OECD: Drought-affected area doubled in last century

The number of regions affected by drought globally doubled between 1900 and 2020, according to a new report by the Organisation for Economic Co-operation and Development (OECD). According to the analysis, droughts have become more frequent, more severe and longer-lasting due to climate change, with increasingly costly effects on societies, economies and ecosystems.

• One fifth of the Earth's surface under threat of drought

At the beginning of the 20th century, droughts affected around 10% of the planet's land surface. Today, this proportion has exceeded 20%, meaning that one in five terrestrial regions is at high risk of severe water shortages. According to the report, between 2000 and 2020, 40% of the planet's surface experienced a higher frequency and intensity of droughts compared to the period 1950-2000.

• The impact of drought: from food and energy to the economy and biodiversity

"Droughts are becoming a systemic phenomenon, with multidimensional impacts," notes the OECD, warning of a vicious circle in which the security of water supply, agricultural yields, energy production and river trade flows are increasingly affected. Among the direct consequences of these changes: losses in agriculture, decreased hydropower production, reduced river navigability, degradation of landscapes and natural habitats, forced migration of populations from arid areas.

• Methodology: SPEI index

The OECD analysis is based on the Standardized Precipitation-Evapotranspiration Index (SPEI), which combines precipitation and evaporation data to assess soil water status. Permanently arid regions such as the Sahara, the Gobi Desert, the Arabian Peninsula or the polar regions were excluded from the analysis in order not to distort the global average.

• Call for action and investment in adaptation

The report makes a clear call for: urgent climate adaptation measures, investment in water management infrastructure, restoration of ecosystems that help retain water, protection of freshwater sources and reduction of pollution. "Droughts are no longer exceptions, but part of the new climate normal,” warns the OECD, suggesting that without coordinated global action, the economic and human costs will continue to escalate.