[Vision2020] Williams et al., Science 368, 314–318 17 April 2020; "Large contribution from anthropogenic warming to an emerging North American megadrought"

[Ted Moffett]

Trump spurns science on climate: ‘Don’t think science knows’
https://apnews.com/article/climate-climate-change-elections-joe-biden-campaigns-bd152cd786b58e45c61bebf2457f9930
September 14, 2020
SACRAMENTO, Calif. (AP) — With the smell of California wildfires in the
air, President Donald Trump on Monday ignored the scientific consensus that
climate change is playing a central role in historic West Coast infernos
and renewed his unfounded claim that failure to rake forest floors and
clear dead timber is mostly to blame.
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https://par.nsf.gov/servlets/purl/10148153

DROUGHT

Large contribution from anthropogenic warming to an emerging North American
megadrought

A. Park Williams1 *, Edward R. Cook1 , Jason E. Smerdon1 , Benjamin I.
Cook1,2, John T. Abatzoglou3,4, Kasey Bolles1 , Seung H. Baek1,5, Andrew M.
Badger6,7,8, Ben Livneh6,9

Severe and persistent 21st-century drought in southwestern North America
(SWNA) motivates comparisons to medieval megadroughts and questions about
the role of anthropogenic climate change. We use hydrological modeling and
new 1200-year tree-ring reconstructions of summer soil moisture to
demonstrate that the 2000–2018 SWNA drought was the second driest 19-year
period since 800 CE, exceeded only by a late-1500s megadrought. The
megadrought-like trajectory of 2000–2018 soil moisture was driven by
natural variability superimposed on drying due to anthropogenic warming.
Anthropogenic trends in temperature, relative humidity, and precipitation
estimated from 31 climate models account for 47% (model interquartiles of
35 to 105%) of the 2000–2018 drought severity, pushing an otherwise
moderate drought onto a trajectory comparable to the worst SWNA
megadroughts since 800 CE
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Vision2020 Post: Ted Moffett
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