Western North American Temperature Atlas (WNATA)

Across western North America (WNA), 20th-21st century anthropogenic
warming has increased the prevalence and severity of concurrent drought
and heat events, also termed hot droughts. However, the lack of
independent spatial reconstructions of both soil moisture and temperatures
limits the potential to identify these events in the past and to place
them in a long-term context. Here, we develop the Western North American
Temperature Atlas (WNATA), a data-independent 0.5° gridded
reconstruction of summer maximum temperatures back to the 16th century.
Our evaluation of the WNATA with existing hydroclimate reconstructions
reveals an increasing association between maximum temperature and drought
severity in recent decades, relative to the past five centuries. The
synthesis of these paleo-reconstructions indicates that the amplification
of the modern WNA megadrought by increased temperatures, and the frequency
and spatial extent of compound hot and dry conditions in the 21st century
are likely unprecedented since at least 1553 CE.