Western megadrought is worst in 1,200 years, intensified by climate change

https://www.latimes.com/environment/story/2022-02-14/western-megadrought-driest-in-1200-years

by lisper • 4 years ago

53 24 4 years ago

latimes.com

forgotmyoldacc• 4 years ago

I wonder why they specifically picked 22 years, as opposed to 25 or 20.

codetrotter• 4 years ago

This section of the article answers that:

Williams was part of a team that published a similar study in 2020. At the time, they found the drought since 2000 was the second-worst after the late 1500s megadrought. With widespread heat and dryness over the past two years, the current drought has passed that extreme mark.

So when they first looked, it was the year 2020 and they looked at the period between year 2000 and 2020. And now they are looking at that plus the additional 2 years that has passed since last time they looked.

syntaxing• 4 years ago

I’m not very educated in this subject, but wouldn’t the West coast be the best place for some sort of “clean” desalination water plant?

toomuchtodo• 4 years ago

Desalination requires enormous amounts of energy (although California has large amounts of solar available, ~10GW continuous on most sunny days per ElectricityMap.org [1]), but also creates a high salinity brine that is toxic to most marine life that must be discharged somewhere to mix with existing ocean water.

For drinking water, it could be done (at significant cost), with a shift to reclaimed water for landscaping needs. But it is absolutely untenable for agriculture. It's also likely that Hoover Dam's electrical generation output will need to be replaced, in some part, with battery backed utility scale solar (as Lake Mead's water level declines below turbine intake at 950 feet; current water level is ~1050 feet [2]).

We've known for over 100 years Western development was unsustainable (due to water) when the Colorado River Compact was originally formed [3] [4], and it was done anyway.

[1] https://i.imgur.com/yIoTgJi.png (sourced from https://app.electricitymap.org/zone/US-CAL-CISO?wind=false&s...)

[2] https://earthobservatory.nasa.gov/images/148758/lake-mead-dr...

[3] https://www.usbr.gov/lc/region/pao/pdfiles/crcompct.pdf

[4] https://news.ycombinator.com/item?id=27909108

mdavis68904• 4 years ago

It takes a gallon of water to grow a single almond, and 95%+ of the worlds almonds come from CA. It takes FIFTY gallons to grow an avocado, and 95% of the WORLD's come from CA also. These are not cherry-picked examples. I could have chosen dozens of other crops.

So, in effect, California's farmers are selling roughly half of its water (in the form of produce) to other states and countries. It's a bit like Saudi Arabia in this sense, but with water instead of oil. Unlike oil, of course, water does replenish, but nevertheless the rate of export is so high that the aquifers are nearly empty now.

Do make sure to take shorter showers though, fellow Californians!

mdavis68904• 4 years ago

Got a downvote or two, so I thought I'd add some references:

First, I retract my numbers about 95% of world almonds and avocados coming from CA - I was typing from memory from research I did a year ago, and now I can't find sources to corroborate this. Nevertheless:

https://en.wikipedia.org/wiki/Almonds_in_California "The state produces 80% of the world's almonds and 100% of the United States’ commercial supply."

https://www.cdfa.ca.gov/Statistics/ "Over a third of the country's vegetables and two-thirds of the country's fruits and nuts are grown in California." "In 2020 California's farms and ranches received $49.1 billion in cash receipts for their output." "California agricultural exports totaled $21.7 billion in 2019"

https://spoonuniversity.com/lifestyle/the-problem-with-drink... "...between 33 and 248 gallons of water go into producing just a half-gallon of almond milk. I'll let that sink in for a second, before I remind you that 99% of almonds grown in the United States are grown in California..."

https://www.truthordrought.com/almond-milk-myths "8% of CA ag water is used to grow almonds" (and keep in mind that ag water is 90% of the total usable)

https://www.researchgate.net/publication/281474989_How_much_... "On average, about 2,500 liters of water need to be supplied (by rainfall and/or irrigation) to a rice field to produce 1 kg of rough rice." - That's 2.5L per GRAM of rice.

https://news.yahoo.com/many-california-farmers-water-cut-130... "A handful of districts supplying farmers including Gallagher are receiving nearly 2 million acre feet of water this drought year, enough to supply the city of Los Angeles for roughly four years." People like to talk about the cities being problems, or that it's the water we send down south, or whatever like that. Meanwhile, a handful of (farm) districts, in a single year, are using the equivalent of a 4-year supply of water for the entire city of LA. Wow.

And yet: https://abc7news.com/san-jose-water-california-drought-conse... "Whaley said the [San Jose Water] company is asking customers to cutback 15-percent from their 2019 water use levels, and pay $7.13 in surcharges for every unit of water used beyond that amount."

mjfl2• 4 years ago

warmer climates lead to much wetter climates. invariably.

AnimalMuppet• 4 years ago

Not everywhere. Warmer climates lead to changes in wind patterns, which leave some places drier than they were.

mjfl2• 4 years ago

but it increases the vapor pressure of water everywhere.

mturmon• 4 years ago

That's one effect.

But in the western US, this effect turns out not to be the driver for hydrology. We've seen higher temperatures (causing more evapotranspiration), more highly-variable rainfall (thus, more precipitation lost to runoff), and less possibility for snow accumulation (again, causing lost precipitation due to faster runoff).

I'm not sure where you live, but the higher temperatures and especially the lack of snow accumulation have been noticeable even to casual observers in the area.

For more, see TFA, or the excellent National Climate Assessment. Chapter 25 covers the Southwest, and drought is the first topic. It has references to the literature if you're interested.

https://nca2018.globalchange.gov/chapter/25/

Just one quick excerpt:

Increased temperatures, especially the earlier occurrence of spring warmth, have significantly altered the water cycle in the Southwest region. These changes include decreases in snowpack and its water content, earlier peak of snow-fed streamflow, and increases in the proportion of rain to snow. These changes, attributed mainly to climate change, exacerbate hydrological drought.

gremlinsinc• 4 years ago

Living in southern Utah, I'd actually rather dry + hotter than wet + hotter...at least we avoid dying from wetbulb temps. 125 is survivable in dry heat, a death sentence if you add humidity.

mdavis68904• 4 years ago

Regarding California in particular, there is actually plenty of water for the residents. About 80-90% of usable water is used for agriculture, and the majority of that produce is exported from California to other countries and states. For example, all around the capital of Sacramento there are 1000's of acres of rice fields. About half the rice is exported to Asia. Appx 8% or so of California water is used in and around homes, including landscaping. It takes a gallon of water to grow a single almond, and 95%+ of the worlds almonds come from CA. It takes FIFTY gallons to grow an avocado, and 95% of the WORLD's come from CA also. These are not cherry-picked examples. I could have chosen dozens of other crops.

Do make sure to take shorter showers though, fellow Californians!

totesraunch• 4 years ago

The fact that there's water for people doesn't mean the drought doesn't affect the state. Drought causes large amounts of dead trees (of which California is covered in) these dead trees catch fire and burn cities down. Water isn't just a consumable for humans

adevx• 4 years ago

Pumping excessive amounts of groundwater for agriculture lowers the water table and may be a bigger driver for tree die-off:

https://www.azcentral.com/in-depth/news/local/arizona-enviro...

somewhereoutth• 4 years ago

And don't forget Apple changing reusable porcelain to 'biodegradable' plates to save on /staff costs/ water for washing up!

wobbly_bush• 4 years ago

95%+ of the worlds almonds come from CA

Does this indicate that the climate required to grow an almond is found in very few places, CA being the top of the list? In that case, there really is no alternative to not growing it (apart from abandoning it, similar to the issue some people raise with growing meat in CA and its water requirements).

mdavis68904• 4 years ago

Got a downvote or two, so I thought I'd add some references:

https://en.wikipedia.org/wiki/Almonds_in_California "The state produces 80% of the world's almonds and 100% of the United States’ commercial supply."

https://www.truthordrought.com/almond-milk-myths "8% of CA ag water is used to grow almonds" (and keep in mind that ag water is 90% of the total usable)

amanaplanacanal• 4 years ago

It all sucks, but it does make sense. The water was essentially homesteaded just like the land when white settlers first entered the area. If you were the first to use the water, you owned it.

I guess theoretically the state could take the water and redistribute it using eminent domain, but then they would have to pay the current owners for it. I have no idea what that would cost.

DougN7• 4 years ago

I wonder if these numbers are the amount sprayed on a field/orchard (I assume?) or somehow measures how much was absorbed by the trees/plants which would be less. What I’m getting at, is where does the water not taken in by the plants go? Evaporates? Sinks to the aquifer? What side effect would there be if all almond orchards were no longer watered (other than to the orchard)?

sparker726782• 4 years ago

Honestly, I just found it hopeful that the megadroughts of the past in this study weren't 100 year events, but more on the order of 25ish years.

(Not trying to downplay possibility of future water problems).

unethical_ban• 4 years ago

Question: Is the mass intake of water for ag use a cause of "water export"? Is the water used to produce alfalfa, almonds, etc. consumed by the plants and animals and shipped across the globe as part of the finished product? This would be in contrast to a slightly more closed system of water consumption and release before the ag industry took off there.

nathanaldensr• 4 years ago

So 1200 years ago--before there were nearly any humans on the entire continent--it was just as bad as today? Interesting.

sparker726782• 4 years ago

Isn’t that what makes this important to study? The people aren’t going away, so understudying how drought affects us is valuable.

zorak8me• 4 years ago

Just want to call out - Pre-Colombian North America had a population around 60 million.

Western megadrought is worst in 1,200 years, intensified by climate change

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