By Jim Steele
The science of solar ponds shows useful inexpensive natural heating, without the need for exotic materials. Furthermore, an understanding of the science of solar pond heating will profoundly change how you view climate crisis narratives.
Jim Steele is Director emeritus of San Francisco State University’s Sierra Nevada Field Campus, authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism, and proud member of the CO2 Coalition.
This is the transcript to the video at https://youtu.be/wl3_YQ_Vufo
Today I want to demonstrate how the science of solar ponds can provide useful inexpensive heating, without the need for exotic materials. Furthermore, an understanding the science of solar pond heating will profoundly change how you view climate crisis narratives. Despite air temperatures averaging 68F, solar ponds can fantastically almost triple temperatures in their bottom layer to over 190F.
There are 2 major ways to raise a solar ponds’ temperature:
Radiative heating and Dynamical heating.
Radiative heating, increases the amount of light energy. Sunny days raise temperatures more than cloudy days. But high solar pond temperatures can peak without any change radiative heating due to dynamical heating. Dynamical heating happens by suppressing convection & cooling, so that heat accumulates and drives very high temperatures.
Solar pond dynamical heating suppresses cooling by creating a density gradient, with fresh water at the surface and dense salt water at the bottom. Because the dense salty bottom water is heavier, it doesn’t rise to the surface, despite warming to 190F.
Bottom layer heat can only ventilate via its micron thick skin surface. Unable to rise to the skin surface, heat rapidly accumulates in the bottom layer.
Solar pond science is based primarily on an 8th grade understanding that things less dense than water will float and denser things will sink.
A pot of water on your stove first heats the bottom layer. Heating makes the bottom layer expand and become less dense. That causes a convection current with the warmer water rising and cooler denser water from the top sinking.
But that dynamic doesn’t happen in a salt pond, because the bottom water’s high salt concentrations overcome any heating effect.
Typical density demonstrations for 8th grade science use colored water to visualize salinity effects and are available online. For example, on the left side of the container, the yellow water is fresh. The blue-green water with added salt, here measured at 35 parts per thousand, was added but immediately sank below the fresh water. To continue the demonstration, green water separated on the right side had only half the salt, 17 ppt. When the separator was removed, that water inserted between the fresher and denser layers.
Adults have embraced this science, making layered cocktails using liqueurs with different densities, such as this Patriot drink for the 4th of July. Hopefully, adults can extend that understanding to better understand our changing climate.
Here’s a closer look at salt pond dynamics. Ponds are typically just 10.5 feet deep. An upper layer of fresh water must be maintained at a depth of 1.6 feet. Temperatures in this layer never get hot enough to be useful as it is constantly cooled by radiating heat away or by losing it via evaporation and contact with the air.
The pond’s bottom half is nearly 5 feet thick and saturated with salt. That water is too dense to rise and mix with the fresh surface layer. So unable to convect upwards and cool, the heat accumulates.
The trapped hotter bottom water is then circulated to heat a building or a greenhouse. Or the near boiling temperatures can drive turbines that generate electricity. Although solar ponds can never solve all our energy needs, the most promising environmental application is desalinization. Ocean water provides an endless cheap supply of salty water. Producing fresh water for desalinization reduces water withdrawal from our streams and rivers, thus benefitting aquatic animals. Desalinization would also reduce ground water withdrawals that have caused many coastal cities to sink closer to and below sea level.
The same dynamical heating seen in solar ponds is ubiquitous throughout nature. Antarctica’s Lake Vanda (highlighted by red rectangle and red dot in upper left), provides a testimonial to the power of dynamical heating. Despite brutal sub-freezing air temperatures averaging from -22F to 5 F, heat accumulates in its bottom layers and reaches room temperature, 70F.
That amplification of solar heating is more amazing when you consider Lake Vanda receives very little sunshine for half the year, receiving just 40% of the sunshine entering tropical waters. Furthermore, the sunlight that reaches the bottom layers is minimal, being at the depth limit of sunlight penetration.
Nor does greenhouse warming from CO2 contribute at all. Researchers have shown Antarctica gets so cold, that uniquely, greenhouse gases there have a cooling effect. Like the bottom layer of a salt pond, it is the salty bottom layer of Lake Vanda that accumulates heat.
Although short wave energy from the sun and longwave energy from greenhouse gases are all measured in W/m2, they affect water very differently! (For those unfamiliar with Watts, it is simply a measure of energy per second. More Watts simply indicate more energy). Using 260 W/m2 as the average shortwave solar energy entering the water, the uppermost layers absorb the most energy. Without a salinity effect the upper layers are the warmest. Solar penetration then declines with depth. In completely clear water, absorbed solar energy is reduced to near zero at a 100 meters depth.
The added red line approximates the typical solar pond depth of 10.5 feet. At that depth, enough heat is absorbed and accumulates quickly enough for efficient practical use of its heat, by raising temperatures to over 180F. Deeper ponds are avoided because as solar penetration declines, the average bottom temperatures also decline making it less efficient for any practical use.
The generalized temperature gradient in lakes and oceans is just the opposite of what is observed in solar ponds, or Lake Vanda or everywhere there is a salinity effect. Without a salty layer to trap subsurface heat, upper layers are always warmer than deeper layers. The upper layer can have a uniform temperature because the winds and convection constantly mix the water. Below 200 meters, the deep water uniformly averages 39°F (4°C)
However, the mixed layer’s temperature is not completely uniform. The skin layer is almost always cooler than the warmer mixed layer below. The skin layer averages just a few microns deep. But any heat absorbed in the mixed layer of the ocean, or a salt pond, can only escape via that very shallow skin layer. The skin layer is cooler because it is constantly losing heat to the atmosphere.
The mixed layer is warmer because its heated water must first rise next to the skin layer, where heat is slowly transported via conduction and warms the skin layer. Only then can the mixed layer’s absorbed solar heat be radiated away or be lost via evaporative cooling. That delay in cooling causes a daily temperature cycle with a warm solar-heated diurnal layer that cools during the night. Similarly deeper waters will accumulate heat during the summer and ventilate it during the winter.
In contrast to deep solar heating, longwave greenhouse energy behaves very differently. Although greenhouse energy supplies nearly twice the energy to the skin layer, that energy does not penetrate any deeper than a few microns. Thus, unlike the delayed cooling of deeper layers, absorbed greenhouse heat can be radiated back to space immediately.
A 2018 ocean study measured 410 W/m2 of greenhouse longwave energy entering the ocean’s skin surface, while simultaneously the skin surface radiated away 470 W/m2. The skin layer almost immediately radiated the 410 W/m2 of greenhouse heat back to space plus an additional 60 W/m2 of radiation from the rising solar-heated layers. In addition, the skin surface lost latent heat (LH) via evaporation and sensible heat (SH) via contact with the atmosphere.
Like the dense salty layers of a solar pond that trap and accumulate heat, oceans naturally have salty Barrier Layers, trapping heat that affects climate and extreme weather. Ocean “Barrier Layers” were first detected just 30 years ago, but since then 100s of studies point out the importance Barrier Layer heating and the need for such dynamical heating to be included more realistically in global climate models.
While this 1992 diagram may seem a bit confusing at first glance, the science of a Barrier Layer isn’t much more complex than concepts taught in 8th grade.
The black line shows how measured temperatures change with depth. The blue line shows salinity changes and the red line shows density changes. Based on density, in this study the ocean’s upper 40 meters represents the ocean’s well “mixed layer” where temperature and salinity are homogeneous.
The middle layer highlighted in orange, is the Barrier Layer between 40 & 80 meters depth. Despite declining solar penetration, the Barrier Layer contains warm water similar to the upper mixed layer. Below the Barrier Layer is the colder thermocline where temperatures rapidly cool as solar penetration declines.
The increasing salinity and density of the Barrier Layer minimizes both any upward mixing of colder thermocline waters while trapping heat much longer than possible in the mixed layer. Barrier Layers are often detected because that trapped heat raises temperature higher than the upper mixed layers.
Several studies have recently shown that understanding ocean Barrier Layers provides valuable knowledge for predicting intense deadly hurricanes and cyclones. Without a Barrier Layer, hurricanes rapidly pull cool thermocline waters into the mixed layer, weakening the heat supply that drives the storms. In contrast, a thick Barrier Layer helps a storm maintain its intensity by inhibiting that upward circulation of cooler water.
In contrast to media fear mongering, the international disaster database, shows climate-related deaths since the 1920s have plummeted from nearly 250 per million to less than 10. Our increasing ability to predict and prepare for devastating storms has largely been responsible for this success. And our increasing understanding of the effects of Barrier Layers is improving that knowledge.
Also, as illustrated by this study in England, the number of deaths, (represented by the vertical bars) increase, as temperatures decrease (represented by the curves). Peak deaths correlate with the coldest temperatures from December through February. The good news is, there is reason to believe that any accumulation of heat in our oceans’ Barrier Layers could drive warmer & milder temperatures and reduce winter deaths.
The Pacific Warm Pool is the earth’s greatest example of a natural solar pond. The warm pool contains the earth’s warmest body of ocean water averaging between 82F and 90F. Because the warm pool generates the earth’s greatest amount of heat and moisture which then gets transported across the world and affects global climates, it is nicknamed the “earth’s climate heat engine”. The warm pool has been increasing since the end of the Little Ice Age, correlated with our 150 years of global warming. Warm pool warmth has also sustained the greatest diversity and abundance of coral reefs, giving the region another nickname “the Coral Triangle”.
The size of the warm pool and its stored heat increases during La Nina-like conditions, and La Nina-like conditions have predominated over the past 150 years. During La Nina -like conditions the trade winds remove surface water heated in the eastern Pacific and sweeps it westward to the warm pool. There, with the assistance of a strong Barrier Layer, heat is stored as deep as 200 meters.
The removal of warm surface water results in a cooler eastern Pacific which reduces cloud cover. That increases solar heating and increases evaporation, producing saltier surface waters.
The red regions here represent the areas where ocean evaporation exceeds precipitation, increasing surface salinity. The trade winds then transport that warm salty water westward, where the higher salinity drives dynamical heating of the warm pool.
The warm pool’s freshwater layer, required to create a natural solar pond, is provided by the Intertropical Convergence Zone, or ITCZ. The ITCZ produces 32% of all global rainfall.
In this December 28th, 2022, screen shot from a national weather service model, the lighter blue represents the regions with the most rainfall, and ITCZ’s location. The observed heaviest rainfall over the warm pool completes the conditions needed to accumulate the warm pool heat that powers our earth’s heat engine. Despite solar pond dynamics, warm pool temperatures never reach the extreme levels observed in solar ponds.
Three major dynamics prevent such extreme warming. First, warmer ocean temperatures enable more intense atmospheric convection that removes heat via evaporation. The second factor is an El Nino. During an El Nino the warm water stored deeply in the warm pool migrates eastward towards the Americas. That brings deeply stored warm water closer to the surface where it can now ventilate and shifts heavy rainfall to the eastern Pacific.
During each El Nino event (represented here by the red arrows), the ventilation of stored ocean heat confusingly raises the global air temperature. The media incorrectly attributes such warmer air temperatures to global warming. But counter-intuitively the earth is really cooling because heat that had been stored in the warm pool for years is now being ventilated back to space.
Long term changes in the Pacific Warm Pool over thousands of years provide scientists with critical information about the most important factors controlling the world’s heat engine and thus our weather today.
During the Holocene Optimum around 10,000 to 8,000 years ago, the thermocline at the bottom of the warm pool, was over 1F warmer than today. Since that time, its temperature has steadily declined. In contrast, most climate models erroneously simulate steadily rising temperatures in the warm pool over the past 10,000 years.
These modeling failures largely happen when warm pool temperatures are incorrectly assumed to be driven by rising CO2. Unfortunately, dynamical heating by the warm pool’s Barrier Layers is not well modeled.
Ice cores find that CO2concentrations were at a low point 10,000 years ago and have increased throughout the Holocene. Despite all the evidence that the warm pool cooled while CO2 concentrations increased, insufficient climate models still suggest that rising CO2 will cause catastrophic ocean warming.
The declining Holocene warm pool temperatures are better explained by increasing El Nino events. 10,000 years ago, El Nino events were more rare and most researchers suggest the Pacific ocean was predominantly in a La Nina-like state. (Note that the timeline direction is reversed in this graph).
Changes in the sun’s strength have also played a role. Based on carbon-14 dating, the coldest period of the Holocene, the Little Ice Age, coincides with a weaker sun and sunspot minimums. Despite higher CO2 concentrations than the Holocene Optimum, during the Little Ice Age, Arctic sea ice reached both its greatest extent and thickness in 10,000 years.
Most researchers have determined the Pacific Ocean was in an El Nino -like state during the little ice age. Although slightly lower solar output during sunspot minimums, would only slightly weaken radiative heating, lower solar heating does weaken the trade winds causing a much greater effect on dynamical heating of the warm pool.
Extreme warm pool temperatures are also prevented because its accumulated heat is constantly exported. The pathways of warm ocean currents emanating from the tropics and moving towards the poles are illustrated here in pink.
Satellite data reveal where more heat enters the ocean than leaves (shown in red). The location of the greatest heat entering the ocean is consistent with La Nina like conditions. Regions shown in blue represent regions where exported tropical heat is ventilated and warms the air in that region, warmer than local radiative heat would.
I’ll end here with an extreme example demonstrating the enormous impact of exported heat from ocean warm pools and its effect on the earth’s climate. When antarctica was part of a single continent called Pangea, Antarctica was insulated from ocean currents, and accordingly much of Antarctica was glaciated. During the Cretaceous period, 94 million years ago, the continents were separating, allowing warm waters from the tropics to reach Antarctica. Despite being centered over the south pole, warm ocean currents promoted a warm Antarctic climate where dinosaurs thrived. Thick coal producing forests survived after the dinosaur extinctions.
As the continents continued to spread, about 35 million years ago, Antarctica became an island surrounded by the Antarctic Circum-polar Current, and once again tropical heat was blocked from reaching Antarctica.
As a result, despite CO2 concentrations 4 times higher than today, glaciers began forming in Antarctica, and Antarctica has continued to became so cold that only one vertebrate species, the Emperor Penguin, can survive its winter.
So before adopting bizarre solutions by egomaniacs like Bill Gates, who is working to block the sun and cool the planet, please examine all the science.
Likewise before believing, we are plunging into a human-caused climate crisis, please ask:
- How does radiative and dynamical heating increase warm pool temperatures?
- How does greenhouse energy possibly heat below the skin surface?
- How does exported heat from warm pools affect our climate and what are the contributions of natural La Nina and El Nino-like conditions.
If you follow all the science undeniably affecting our climate, you just might sleep better tonight knowing there is no climate crisis.
Our democracy depends on a diverse array of good critical thinkers. So, please shun mindless group think. Instead embrace renowned scientist, Thomas Huxley’s advice:
“Skepticism is the highest of duties and blind faith the one unpardonable sin.”
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