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  • Writer's picturePeter Yolles

In a hotter world, cold water is the ultimate luxury (or necessity)

Updated: Aug 7, 2023

OK, you’ve all heard that July was the hottest month on Earth ever with average air temperature at 62.5° F and the average global ocean temperature at 70° F. (Source). People in Florida are sweating but can’t find relief in the oceans there. Florida coastal waters are like a hot tub at 101° F and scientists are rushing to create coral zoos for safekeeping.

July was the hottest on record for the earth.

While corals are bleaching, whales are beaching, and algae is blooming, some of us are paying gobs of money to chill out in cold plunges. The Renu Cold Stoic plunge bath retails for $9699. Wim Hoff, a guru of the ice bath and the cold swim, charges $3000 to swim in ice cold mountain waters in Poland. SwimTrek and other operators offer swim tours for open-water swimmers in the Lake District of the UK, among other cold water locales. “Huberman Husbands,” as devotees of Dr. Andrew Huberman’s podcast sometimes are known, can make do with one to three minute cold showers, we are told, to manage our dopamine baseline. For those in Austin, TX, a selection of public natural pools fed by groundwater exist to chill off. These might be easier to access than public pools in other urban areas like in the Bronx, New York, where there is just one public pool for every 175,000 people.

All these stories suggest that human access to cold water is becoming, if not exclusive, then certainly more rare or even scarce.

At Echo River, I’m interested in what are the effects of extreme heat on water management are, and what can be done about it?

First, cold water in rivers is at a premium. Many fish species can survive only within certain temperature ranges. For example baby salmon cannot withstand for very long temperatures above 12°-15° C (54°-60° F) and migratory adults cannot sustain water temperatures above ~76° F. Groundwater springs create naturally cold rivers from snowmelt or glacial melt that can keep temperatures low. Some of salmon’s favorite rivers protect their cold waters with shade, deep pools and woody debris. These conditions create refuges where salmon can rest on their journey upstream to their spawning beds and downstream back to the ocean, or to grow across a hot summer. One of those places is dear to me — Shasta Big Springs Ranch on the Shasta River in Siskiyou County, California. I worked to preserve and protect the cold water springs at this ranch with colleagues at The Nature Conservancy where up to 50,000 coho salmon once returned each fall. The snow melt from Mount Shasta would melt and flow through lava tubes until releasing their super cold waters into the headwaters of the Shasta River, a location now protected by the state.

Surprisingly, large dams are able to store and release cold water because of stratification, referring to layers of water behind the dam are at different temperatures. The Shasta Dam on the Sacramento River, for example, now has a Temperature Control Device that enables the dam operators to vary the flow, timing and temperature of water releases below the dam to support fish with water temperatures appropriate for the right life cycle.

Second, even warm water species such as corals have upper limits. “Many [corals] grow optimally in water temperatures between 73° and 84° Fahrenheit (23°–29°Celsius), but some can tolerate temperatures [even higher] for short periods.” (Source: NOAA) This July, the Atlantic Ocean off Florida recorded water temperatures as high as 101.1° F, a world record for sea surface temperatures. This was caused by lots of sun, too little wind, and few storms which limit upwelling. (ABC News) Scientists are rushing to capture and preserve some of the corals before they perish with a resulting bleaching of the vibrant colors. Coral reefs are the nurseries of ocean life and combined with ocean acidification, may portend a limited future for corals and all carbonaceous life forms (think shell fish and vertebral fish). Oceans provide 15 percent of all the protein humans consumed, so ultimately our own lives are dependent upon healthy, temperate and alkaline (pH 8.1) ocean waters.

Third, rising water temperatures reduces available oxygen. Sea surface temperatures have increased by 1.8 degrees F over the last 40 years leading to more prevalent fish die-offs. Sudden temperature spikes of 3-5 degrees Celsius in oceans have been observed to lead to sudden fatal bacterial infections in fish (PNAS 2022).

Cold water is becoming scarcer for humans and animals alike. While humans may have access to private and public pools, many aquatic animals can’t migrate to colder waters when and where needed. Fish and other aquatic species don’t have the luxury of ordering a cold plunge tub. What we can do is stop burning fossil fuels, protect cold groundwater sources, and replenish and reconnect groundwater with surface waters, encourage temperature controls behind dams, and reduce fertilizer runoff into warm water that lead to harmful algal blooms.

For example, Swan Systems and Verdi Ag enable farmers to apply measurably less fertilizer, preventing nutrient runoff, the engine of harmful algal blooms. Gybe monitors water quality and temperature in rivers using satellites and sensors, allowing us to monitor this issue and hence, bringing us a step closer to its solution. At home, people can stop burning fossil fuels to heat water by switching to heat pump water heaters and induction cooktops. (Go to Rewiring America for help electrifying your home). The best way to protect cold water is to stop heating it in the first place.


Thank you for reading my recent post and following Echo River Capital.

- Peter

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1 Comment

Matthew Stotts
Matthew Stotts
Aug 14, 2023

Upon reading your "hotter world, cold water" post, I immediately recalled the disturbing scene early in The Ministry for the Future by Kim Stanley Robinson. I benefit from reading you perspective. Keep up the great work!

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