The 20th Century Pluvial

Stuff I wrote elsewhere: another attempt to spread my meme – why climate variability on decadal scales is so important to life here in the arid western U.S.:

It snowed like crazy Nov. 23, 1922, as representatives of seven western states hunkered down at Bishop’s Lodge outside Santa Fe to negotiate what amounted to the future of the West.

They were working out the final details of an agreement dividing the waters of the Colorado River, and if the climate gods were sending a message with the snowstorm, it was a misleading one.

It wasn’t just a single storm. For much of the preceding two decades, it had been unusually wet across much of the West, new research suggests.

The people gathered at Bishop’s Lodge did not know they were living in unusual times. They expected the bounty to last forever, and the Colorado River Compact that they signed the next day divvied up the Colorado’s waters accordingly, assigning shares of water to each of the states in the river’s basin.

Their assumption about the Colorado’s flows turned out to be, in the words of climate researcher Ken Kunkel, “very optimistic.”

The result is a future in which there may not be enough water to go around.

The story’s based in significant part on a new paper by Connie Woodhouse, Ken Kunkel and others that offers new details on the nature and extent of the rainy early 20th century. I also relied heavily on the Severe Sustained Drought study, which resulted in a voluminous and incredily useful set of papers published back in 1995 in Water Resources Bulletin.