Abstract
Drought and pluvial extremes are defined as deviations from typical
climatology; however, the background climatology can shift over time in
a non-stationary climate, impacting interpretations of extremes. This
study evaluated changes in meteorological drought and pluvial extremes
by merging tree-ring reconstructions, observations, and climate-model
simulations spanning 850 – 2100 CE across North America to determine
whether the Industrial era and projected future lie outside the range of
natural climate variability. Our results found widespread and spatially
consistent exacerbation of both extremes, especially summer drought and
winter pluvials, with west and south drying, the northeast wetting
trends, and increased interannual variability across the east and north.
Our study underscores climate change has already shifted precipitation
climatology beyond pre-Industrial climatology and is projected to
further intensify ongoing shifts.