The central Chile megadrought: World 's champion?

The last decade (2010–2021) was drier than average in all major Mediterranean Climate Regions (MCRs), except for the Mediterranean Basin, with mean rainfall deficits from -2% (Southwest Australia) to -33% (central Chile). In most cases, dry years have prevailed but intermingled with wet years except for central Chile, along the west coast of subtropical South America, where all years since 2010 were below average. This conforms the so-called central Chile mega drought, the driest decade in local history since at least the 14^th century and, as we show in this work, for any of the MCRs since 1901. Within the megadrought, accumulation dropped to <70% of the mean during 2019 and 2021, causing an unprecedented decline in vegetation, shortage of potable water and other detrimental impacts in central Chile.

In addition to placing the central Chile megadrought in planetary context, we summarize the underlying mechanisms behind this climate extreme. While climatic anomalies during the last decade are broadly consistent with projections, natural variability originating in the subtropical southwest Pacific was conducive for dry conditions across the Pacific has been acting in concert with climate-change signal. As a result, the observed mean precipitation deficit was about three times larger than expected for the early decades of this century, more akin to those predicted for 2070-2090 under a heavy greenhouse gases emission scenario.