Is Catalonia facing a Megadrought episode?

Drought is a defining feature of the Mediterranean climate, characterized by frequent periods of precipitation significantly below average. However, the ongoing drought episode affecting Catalonia shows a severity never recorded in the instrumental period 1915-2023. In the case of the city of Barcelona, where precipitation data stretches back to 1786, one must go back to the early 19th century to find a similar 3-year drought period. 

Observing the trend of drought episodes over last few decades, the current drought is the latest in a series of episodes of shorter duration and intensity, but which can be also locally classified as exceptional at the time of their occurrence. Consequently, some areas of North-eastern Catalonia have endured conditions similar to semi-permanent drought over the past decade, or even beyond. 

The current drought in Catalonia is not an isolated event but part of a broader regional pattern. In general, the entire South-western Europe and Northern Africa have been under drought conditions to a greater or lesser extent in recent years (Faranda et al, 2023). Moreover, other Mediterranean climate regions across the globe, such as Central Chile and California, have lately witnessed record-breaking droughts during the instrumental period, some being classified as Megadroughts (Garreaud et al., 2020; Williams et al., 2022). 

More recently, some authors (Cook et al, 2022) have further explored the concept of Megadrought. These episodes have common characteristics beyond their impacts that justify this qualification, including remarkable temporal persistence, unprecedented nature compared with previous events, links with external climatic forcings, or their connection with SST anomalies.  

Currently, the global climate system is strongly forced by the increase in CO2 concentrations in the atmosphere. Climate projections point to a reduction in precipitation for the Mediterranean climate area, which, combined with the increase in temperature values, will lead to greater aridity and the occurrence of droughts with a magnitude never recorded before. In light of these projections and the characteristics exhibited by the current Catalan drought, the question arises: Is Catalonia facing a Megadrought episode? 

REFERENCES

Cook, B.I., Smerdon, J.E., Cook, E.R. et al. Megadroughts in the Common Era and the Anthropocene. Nat Rev Earth Environ 3, 741–757 (2022). 

Faranda D., Pascale S., Bulut B. Persistent anticyclonic conditions and climate change exacerbated the exceptional 2022 European-Mediterranean drought. Environ. Res. Lett. 18, 034030 (2023) 

Garreaud RD, Boisier JP, Rondanelli R, Montecinos A, Sepúlveda HH, Veloso-Aguila D. The Central Chile Mega Drought (2010–2018): A climate dynamics perspective. Int J Climatol. 2020; 40: 421–439.  

Williams, A.P., Cook, B.I. & Smerdon, J.E. Rapid intensification of the emerging southwestern North American megadrought in 2020–2021. Nat. Clim. Chang. 12, 232–234 (2022).