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We know the world needs an answer to global warming. There are many good ideas at work including wind and solar. There are green buildings. Concerned people are trying to reduce their personal carbon footprint. But all this together is not enough.

If we do not act fast, hurricanes will continue to increase in intensity and at the same time we will see rapid sea level rise – each with accompanying tragic consequences.

What if we could mitigate hurricanes,
reduce ocean temperatures,
reduce atmospheric CO2,
and improve fisheries?

There is a new scientifically sound proposal to do that.
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This page presents a somewhat technical introduction to the topic. For those who want to begin with a brief, less technical overview, please click here.

Reflecting Sunlight

The National Academies of Science, Engineering & Medicine (NASEM) recently released a major study entitled Reflecting Sunlight.  This is an extensively researched and full-throated recommendation for a major commitment to solar geoengineering (SG) to prevent the climate catastrophe we are otherwise headed for.  It’s important to state from the outset that solar geoengineering – efficient engineering solutions to reflect about 1% of the sunlight that strikes the earth – has never been advocated as an alternative to rapid decarbonization (renewables, carbon sequestration, nuclear power, and other mitigation measures).  However, it has become clear over the past few years that it is essential to supplement decarbonization – for at least a few decades – to forestall the impending disaster that otherwise is coming to coastal cities around the world from melting glaciers and the collapse of large ice shelves and ice sheets.

If a 50% increase in low-cloud fraction could be achieved over just 6% of the tropical seas, it would be sufficient to offset the warming from the current increase in atmospheric CO₂ levels over pre-industrial levels. 

A careful consideration of the current proposed SG concepts, however, has not led to a great deal of enthusiasm or action towards them.  Either economic considerations or concerns over viability or possible side effects have all served to keep discussions of these concepts muted, despite a clear and desperate need for a solar geoengineering solution.  We look at each of the current SG concepts on another page of this website and conclude it doesn’t seem likely they can be implemented at scale – at least without some significant technological breakthroughs.  It’s clear that these concepts need further research and hopefully some of the uncertainties may prove to bear out according to the most optimistic hopes.  But it is also clear that a viable path towards SG – which is desperately needed – has not been presented.  At least not until now.

Here, we present a new SG method that truly appears viable:

Tropical Cloud Generation (TCG) by Patchy Sea Mixing

Our efforts began by looking for a scientifically sound method for taming hurricanes.  We figured out that with some outside-the-box thinking that will be possible, and at low annual cost. Our approach is based on sound physics, simulations, and a serious look at the costs.

Our plan is to reconfigure retiring naval vessels into large “Sea Mixers”. These sea mixers would create cool patches on the sea surface by driving down the warm surface waters, which then forces the cold deep waters to upwell.  We would do this in locations that are most likely to be productive toward the goal of increasing tropical cloud cover far out at sea – essentially the way sea breezes on tropical islands or Florida beaches create afternoon showers.  In order to create the needed clouds (which cool the seas, by reflecting sunlight) the cool patches would likely be 40 to 60 km in diameter – and they need to be created fairly quickly (within about a month) so lots of clouds are formed around them before they begin to slowly warm.

However, to be clear, we’re talking about surface mixing over ultimately a total of perhaps 0.5% of the ocean’s surface, and cooling the rest of the region by the induced regional weather effects. The primary objective is to generate atmospheric turbulence, clouds, and rain in targeted regions of tropical seas, and almost all of the sea cooling comes from the increased cloud cover.

The NASEM study Reflecting Sunlight notes that “the existence of the cloud is 50 to 100 times more important for reflectance than brightening of a cloud” (p. 47).  However, no prior efforts have been aimed at significantly increasing cloud coverage. That’s what TCG would do.

As a solution to hurricane taming began to evolve from our calculations and simulations, we realized that what we were on to could not only end destructive Atlantic hurricanes, but could be scaled up to limit global warming and the collapse of major ice sheets. However, let’s start here with Atlantic hurricanes. 

How to Stop a Hurricane

The annual impact of Atlantic hurricanes in supply disruptions, dollars, and lives is well appreciated by everyone.  The average U.S. damages over the 2017-2021 period exceeded $130B/yr.  A number of efforts over the past two decades by first-rate research groups – most notably one led by Bill Gates and Ken Caldeira – have attempted to devise a method for taming hurricanes, but none has been found to be practical.  

Our solution begins by appreciating (as have many researchers) that hurricane genesis and growth depend first on sea surface temperature (SST) being above 26°C – and that there is a massive reservoir of cold water not too far below the surface in the hurricane genesis regions. Simple physics says mixing deeper cool waters with surface waters would reduce the SST.  The first problem is how to efficiently achieve the needed upwelling of deep cold (nutrient-rich) waters – and do so at rates over 1000 times those of previously proposed methods, discussed here.  The second problem is how to keep the mean ocean temperature from increasing since the mixing that cools the surface waters also warms the deeper waters. A light bulb went off. Focus on creating the clouds. That’s the key.

We checked our analytical models with preliminary Computational Fluid Dynamics (CFD) simulations (and we filed a provisional patent application).  On other pages of this website we discuss some of the problems with other approaches and the advantages of using nuclear-powered vessels.  Below, we summarize our patchy mixing plan. 

Before beginning the next section we should note we first hoped to use wind power or wave pumps but quickly realized that that approach was not viable (very little wind where needed, and other issues, as we explain on another page).  Using nuclear-powered ships is the only option that can provide the needed power and energy. Using retiring naval vessels could provide this at a greatly reduced cost.

Nuclear Powered Sea Mixers

Our analytical model and CFD simulations indicate that a single retired Nimitz-class aircraft carrier (200 MW) converted to a sea-mixer (see the concept illustration) could cool the surface of a 50-km x 50-km patch in a warm tropical sea where the 20°C isotherm is relatively shallow by 3-7°C in about a month.  The cooled SST quickly cools the air above it. In areas where the winds are very low, this leads to cool dry central downflow, anticyclonic outward flow over the cool patch, moist upward flow over the warm waters surrounding the cooled patch, and further SST cooling from cloud generation as the moisture in the rising air surrounding the cool patch condenses.  In areas where the winds are not low, the cool surface will cool the winds as they travel over the patch, generating sea breeze effects, specifically forming Horizontal Convective Rolls (HCR’s) that cause cloud development patterns that align with the upward convective portion of these rolls.  These cloud patterns could extend for hundreds of km.

In either case, the nuclear-powered sea mixer would then move on to create another cool patch (and generate clouds and storms) perhaps ~150 km away.

Most of the year, the skies over most of the Caribbean Sea, the Gulf of Mexico (GOM), the region just South of the Cape Verde islands (where over 75% of Atlantic hurricanes originate) and many other tropical waters are clear, and in many places the 20°C isotherm is quite shallow – under 50 m in the spring and under 100 m in the fall.  The cooled patches that would be produced by the sea mixers in strategically chosen locations will lead to a dramatic increase in mean low-level cloud cover, thus substantial cooling from increased shortwave (solar) reflection. The descending air over the cool patch will be dry, which takes away another of the pre-requisites for hurricane genesis (there must be high humidity all the way up through the mid troposphere for a hurricane to form).   Currently, the SST in the Gulf stream (which is ~100 km wide) in the GOM is over 26°C from early April through mid-December.  Cooling the Equatorial flows that then feed into the Caribbean Current and the Gulf Loop by means of Tropical Cloud Generation (TCG) would end hurricane genesis and intensification in the region, and would moderate climate change within the region due to the cooler Gulf waters.

There are 10 Nimitz-class carriers in the US fleet.  The first of these, the USS Nimitz, is scheduled to be decommissioned in a few years and replaced by a new Ford-class carrier with 260 MW of shaft power.  Every 3 to 4 years another is scheduled to be retired and replaced by a new Ford-class carrier.  Repurposing decommissioned carriers as sea mixers should eventually be sufficient to not only end most Atlantic hurricanes but also to slow global warming and maybe even prevent collapse of the West Antarctica ice sheet.  (More information on how TCG could help stabilize the West Antarctic and Greenland Ice Sheets will be coming soon.)

The mixer-driven upwellings would also provide the nutrients needed to feed phytoplankton in surface waters, thereby increasing CO₂ uptake by the ocean.  The combination of the deep mixing and the phytoplankton growth would oxygenate the waters down to the 1% light level (~300 m) and lead to many tropical seas that are currently ocean deserts becoming highly productive fishing areas. More information on the benefits of sea mixing for increasing marine productivity and ocean CO₂ uptake can be found here.

How Sea Mixers Work

There are three keys to achieving the needed mixing efficiency and upwelling rates:

(1) The vertical stream velocity should be low but not too low – not much more than necessary to balance the buoyancy head of a 300-400-m column of surface water in the sea’s mean density over that depth,

(2) the stream’s total diameter needs to be at least a quarter of the target depth, and

(3) the vertical streams needs to be driven by an array of four huge downward-directed propellers below a nuclear powered ship (that is the only way to get anything close to the needed power and energy).  The CFD simulations showed that four optimally designed propellers (with blade lengths of ~35 m), positioned 30 m below the sea surface, each driven by a 40-MW power-take-off from one of the ship’s four steam turbines, could drive warm surface waters downward at the combined rate of ~40,000 tonnes/s – about 10 times the mass flow rate over the Niagara Falls.  That gargantuan downflow induces an equal amount of upwelling of deep cold waters that reduce the nearby sea surface temperature.

Conventional ship propulsion propellers look quite different partly because they are intended for the case where the ratio of downstream to upstream fluid velocities is close to unity and partly because they need to develop high thrust at high speeds.  Whether the application is a wind turbine, a helicopter blade, a ship propeller, or a sea mixer, the equations are basically the same. Of course, a big difference between the case for helicopter blades and sea propellers is that the fluid density is over 800 times greater in the sea.  From the perspective of torque, power, thrust, and rpm, the closest prior propeller analogy would be large wind turbines, though the sea mixer propellers would be smaller, with lower relative pitch (to keep the torque more manageable) and higher solidity.

The steady-state CFD simulations thus far were constrained by available software (COMSOL-CFD-Mixer) and hardware.  Still, as seen in flow velocity color plot from a steady-state CFD simulation, they provided crucial support for our analytical model, which indicated the power available from a few Nimitz-class carriers should be sufficient to achieve sea surface cooling at the scale needed to end most Gulf-coast hurricanes.

A few numbers can help to establish the physical basis for TCG ending GOM hurricanes.  From mid-April through mid-October, there are a number of places in the GOM where the temperature at 100 m depth is ~10°C below the SST and mixing to a depth of only 150 m would reduce SST by ~5°C.   The mass of water in the upper 70 m of a patch 60 km in diameter is 2E14 kg.  Four 40-MW 80-m mixer propellers operating at propeller efficiency of 80% should generate a combined flow of 4E7 kg/s at a mean downward velocity of ~2.5 m/s.  (Again, that will achieve over 1000X the cold upwelling likely to be possibly by various methods that others have proposed.)  The Sea Mixer would then cruise back and forth (like a farmer plowing a field) over the area to be cooled.  (While the above mentioned stream velocity isn’t high by normal propeller standards, it is 50 times what was calculated for a proposed wave pump of 100-m diameter; and both velocity and flow rate matter.  A high kinetic energy in the flowing stream means the churning continues long after the ship passes, and the total mixing will be several times what one calculates from the simple ratio of water mass to propeller pumping rate.  At some point, when we have the resources, we’ll do the complete time-dependent simulation.)  The cooled patch would grow, and should be large enough to begin increasing local fog and cloud cover in a few days and inducing storms within a week.

A small fleet of nuclear-powered Nimitz-class sea mixers could produce sufficient cool patches over the primary hurricane genesis regions in the tropical Atlantic to largely end the threat of highly destructive hurricanes in a matter of years.

More on Clouds, Patchy Mixing, and Sea Breezes

Mean low-level cloud cover over most tropical seas is historically quite low, as seen in the map here of mean low-cloud fraction in the tropics.

Cloud fraction over tropical seas has been decreasing over the past two decades, and the latest climate models predict global warming will further that trend and possibly make that one of the most severe of the various global-warming positive-feedback mechanisms.  The difference between the radiative forcing (net surface heating) seen west of Central America (5% cloud fraction) and that seen off the coast of Peru (60% cloud fraction) is more than 100 W/m².  That is a big part of why one typically sees SST at 15°S,170°E (near American Samoa) 10°C (18°F) warmer than at the same latitude at 80°W (a few hundred km off the coast of Peru, near the “60” in the cloud-fraction map).  Not all the tropics are tropical!

Cloud fraction is not low over most tropical islands, particularly in areas where mid-tropospheric prevailing winds are not high.  On many tropical islands, one sees late afternoon on-shore storms (sometimes on all sides of the island) almost daily.  The land warms during the day, creating an afternoon sea-breeze and evening on-shore storms from the upward convection over the island.  Then the land cools below the sea temperature after sundown, creating downward convection over the island, outflowing land-breeze, and early morning fog and clouds over the island. The land-breeze sometimes produces mild early morning off-shore storms, though often it doesn’t persist long enough for that and the outflowing land-breeze is often too dry.

Targeting the low-hanging fruit

The nuclear-powered sea mixers will create cool patches on the sea surface in locations that are most likely to be productive toward the goal of increasing tropical cloud cover and thereby cooling the seas. The sea mixing will be most effective at reducing SST in hot regions where the 20°C isotherm is relatively shallow.  Such places can be identified from isotherm plots that show temperature profile in the ocean, as seen here near from a track in August near longitude 34°W through the Atlantic.

(Other ocean isotherm plots are available here. Simply click on the “TPOT” button for each section plot.) The 20°C isotherm is only 20-50 m deep in some tropical places where the winds are usually calm, and in many other places it is under 100 m deep. 

The cooled patches will then drift with the local surface currents (which are generally slow, except in the Gulf stream).  If the surface and mid-tropospheric wind speeds above them are low enough, the cooled sea patches will drive anticyclonic storms around them, as the flow over them in the atmospheric boundary layer (i.e., near the sea surface) will be outward.  At other places, these cool patches may cause fog to form over them and clouds and storms around them.  If conditions are not sufficient to cause a storm they will still significantly increase cloud cover.  Of course, the regions with low winds, high SST, shallow 20°C isotherm, low cloud fraction, and low marine productivity will be targeted first because these regions offer the “low hanging fruit” with respect to ending cyclones and bringing other benefits.  (With respect to the enthalpy needed to cool the central downdraft for months, it is useful to remember that the specific heat (C_p) for water is more than four times that of dry air, and the mass (m) of a column of air from sea level to the edge of the atmosphere is similar to that of a column of water just 10 m deep. So, the amount of energy needed to cool a column of air falling through the troposphere by 1 degree C is <1% of the energy needed to warm a similar column of sea-water down to a mixed layer depth of 250 m.)

The cooler surface waters radiate less longwave radiation, which means absent other effects they would tend to increase global warming.  The solution to that problem is cloud creation.  If the SST could be reduced over patches the size of small islands, those cool sea-surface patches would cool the atmosphere above them (this happens rather quickly) and generate the convection needed to create clouds and storms over the warm waters surrounding them.  The clouds and storms then cool the seas below them, and that cooling effect (from the clouds reflecting most of the sunlight striking them) is expected to be an order of magnitude greater than the small heating effect directly over the cool patch.

The convection-driven flow over the cool patches and the warm seas surround them should be much greater than seen around tropical islands for a given thermal gradient, patch size, and wind speed because the gradient (which was ~4°C in this sea-breeze study) will be steady instead of changing directions twice a day. (To get a brief and accessible review of the genesis and mechanics of cyclones (hurricanes), anticyclone storms, and sea breezes, we offer such here.)

Saving Coastal Cities

Research presented at the Dec. 2021 meeting of the American Geophysical Union shows the ice shelf holding back the Florida-sized Thwaites Glacier  (74°S,108°W) in Antarctica is melting much faster than previously thought – because the currents under it have warmed dramatically over the past decade (2°C above freezing was measured in some places).  That makes a world of difference in the melting rate of ice.  Cracks are now propagating into the central part of the ice shelf at the rate of more than 2 km/year.  It could break up in five years – or possibly even in just 3 years. That will be followed by accelerated sliding of the Thwaites and other West Antarctica glaciers into the ocean, which would raise sea levels by 65 cm (2 ft) – possibly as soon as  20 years from now.  Meanwhile, there was rain at the summit of the Greenland Ice Sheet last summer, and temperatures in the Greenland capital of Nuuk reached 13°C on December 20!.  Within four decades enough of the West Antarctica and Greenland ice sheets may have collapsed to raise sea level by as much a meter.  A sea level rise of 2 m is possible (granted, that much is unlikely) by the end of this century.

Such a projection a few years ago would have been considered rabid doom-mongering, as the IPCC models of the various emissions scenarios (except for one disparagingly called “low-likelihood high-impact story line”) assumed stability of all the major ice sheets throughout this century. However, the climate models were calibrated against data from 1970-2010 and essentially ignored the rapid rise in the temperature of the Antarctic Circumpolar Current over the last 7 years, the inverted canyons now forming under the ice shelves, the effects of increasing melt-induced hydrofracturing, and its associated effect of loss of ice-shelf buttressing. According to the standard climate models, Antarctic land ice mass should be increasing, from higher snow fall in East Antarctica. However, the GRACE-FO satellite measurements show it has decreased at the rate of ~220 Gt/yr over the past 3 years, while Greenland has lost ~320 Gt/yr.

To be fair, some of the needed high-accuracy ocean data near the poles from satellite observations did not start becoming readily available until 2014.  These data show that in the 69-71°S, 90-130°W region (near Thwaites Glacier) the mid-February (the warmest month there) sea surface temperature (SST) went from -1.3°C in 2014 to -1°C in 2021.  (The freezing temperature of typical Antarctic sea water is about -2°C.) The mean November (spring) SST on the 55°S parallel around Antarctica went from 2.5°C in 2014 to 3.0°C in 2021, and a similar increase was probably seen throughout the upper 500 m.  That’s six times the warming rate of the global upper ocean of the last two decades (0.12°C/decade in the upper 2000 m). 

A rise in sea level of just 2 ft would have devastating impacts on many of the world’s coastal cities, resulting in many trillions of dollars in infrastructure upgrades in order to protect infrastructure from increasing vulnerabilities to flood damage from storms and tidal surges.  (More information on how most US Gulf Coast and east coast cities will be impacted will be presented later.)

The only way to save critically threatened cities like New Orleans, Miami, Houston, London, Venice, Singapore, hundreds of small islands, low-lying countries like The Netherlands and Bangladesh, entire states like Florida and Louisiana, and literally hundreds of other major coastal cities around the world is to begin cooling ocean surface currents, particularly currents that mix with the Southern Ocean (around Antarctica) and the Gulf stream.   The most plausible method – and the one with maximal other benefits and minimal unintended consequences – is targeted Tropical Cloud Generation (TCG).   (A brief review of alternative proposed SG methods can be found here – these methods may offer some synergies with TCG, and may be able to help where conditions for TCG are less favorable, but we believe that their contributions will come at a much higher cost/benefit or will come with larger unintended consequences – or both – compared to TCG.)

Averting a Climate Catastrophe

The U.S. could realistically undertake nuclear-powered TCG very quickly and at very low net cost, so the initial focal area of TCG will likely be near the U.S. – in the GOM, the Caribbean Sea, off the northeastern coast of Venezuela, and the region just south of the Cape Verde Islands. That would result in maximum benefit toward taming U.S. hurricanes (and make it easier for congress and insurance companies to immediately justify the investment).  However, the greater global threat is that the West Antarctica ice sheet will begin to collapse – possibly within 15 years – if drastic action isn’t taken very soon. 

Cooling the upper 500 m of the Antarctic Circumpolar Current about 1°C will take considerably more effort than taming U.S. hurricanes, as the flow from southern tropical waters into the Circumpolar Current is limited and not direct.  However, sufficient mixing of three warm southern currents does occur (the Agulhas (Mozambique) Current, the East Australian Current, and the Brazil Current) for properly targeted TCG to slowly cool the Circumpolar Current back to its pre-industrial value. 

The Agulhas Current can be cooled by TCG off the northeastern coast of South Africa, where in February the Mixed Layer Depth (MLD) is about 40 m, the SST is ~28°C, and sea surface currents are southerly.  The East Australian Current can be cooled by TCG east of Brisbane (~27°S), where in February the MLD is about 30 m, the SST is ~27°C, and sea surface currents are southerly. The Brazil Current can be cooled by TCG a few hundred km off Rio de Janeiro, where in February the MLD is about 40 m, the SST is ~27°C, and sea surface currents are southerly.  Mid-tropospheric winds in these areas are highly variable, but most of the time surface winds (generally 6-12 m/s at 200 m altitude) are low enough for fog and clouds to develop at least on the downwind side of the cooled patches.

If the primary goal is to reduce global temperatures, the most productive areas for TCG would be in the tropics where the MLD is less than 50 m most of the year, SST is generally >27°C, low-cloud fraction is <8%, and winds are usually very low, both near the surface and at the mid-tropospheric level. These would be most of the white areas near the equator in the earlier cloud fraction map, where cloud fraction is less than 5%. However, cooling in these areas would have negligible effect on the Antarctic Circumpolar Current.

(More information on Cooling the Circumpolar Current will be coming.)

TCG is very different from other solar geoengineering (SG) methods.  It is unique among the various proposed SG methods in its ability to achieve major localized SST cooling at low cost where specifically needed to dramatically reduce destructive hurricanes, to slow the melting of ice shelves in Antarctica, and to reduce global temperatures. Moreover, it brings with it other major benefits – increasing marine productivity and increasing CO₂ uptake by the ocean. More information on the “side effects” of TCG can be found here.

And again, because it bears repeating:

If a 50% increase in low-cloud fraction could be achieved over just 6% of the tropical seas, it would be sufficient to offset the warming from the current increase in atmospheric CO₂ levels over pre-industrial levels. The benefit from hurricane taming on the US economy could easily exceed $100B/yr – and halting global warming could be worth tens of trillions of dollars.

International Cooperation

Earlier we said there was a slate of problems that have stymied implementation of SG, and we mentioned cost and some poorly understood side effects. There are also international legal issues when large quantities of unnatural substances are being injected into the atmosphere, as is the case for Stratospheric Aerosol Injection (SAI) and Cirrus Cloud Thinning (CCT).  A recent study in Climate Policy tentatively concluded that any country could probably unilaterally implement Marine Cloud Brightening (MCB) in international waters – at least within certain limits –  without violating any international agreements or understandings because it did not involve injecting unnatural materials into the atmosphere or the oceans.  We believe the same conclusion would apply to TCG as long as the effects (other than global cooling) outside of international waters were minimal. This is a subject others with relevant expertise will need to review in more depth.  We believe TCG will be enthusiastically embraced by most nations as the preferred method for supplementing decarbonization after more studies and simulations have been published. We believe it will be recognized as the best option to avert the impending climate disaster we are otherwise headed for.

Cost

The cost of decommissioning each Nimitz-class carrier is expected to be ~$1B.  Much of that decommissioning cost would be avoided (delayed for decades) by repurposing these ships as sea mixers for taming hurricanes and global warming.  The net cost of carrier repurposing then would be very small (perhaps as little as $200M after subtracting the avoided decommissioning cost) compared to the benefits expected for the U.S. and world economies – an investment that even the most polarized congress should be able to embrace.  The near-term benefit to the US economy just from ending severe hurricanes will justify the needed federal support for implementation many hundreds of times over (and insurance companies could be asked to chip in too).  The benefit to the global economy from increased marine productivity could be similar.  

Preventing collapse of the West Antarctica Ice Sheet will require repurposing all ten Nimitz-class carriers as sea mixers as quickly as possible (and replacing those decommissioned carriers with new Ford-class carriers).  The first 5-9 could be sent to cool the GOM, the Caribbean, and the region south of the Cape Verde Islands. Subsequent Sea Mixers would then be tasked to target the Agulhas, East Australian, and Brazil currents.  More than just the 10 potential Nimitz-class carriers will be needed for such an undertaking – probably several times more.  New production of Sea Mixer designs not associated with former aircraft carriers should be developed (with even more power) and concurrently produced.

It is possible (and certainly hoped) that other nations may wish to contribute to this effort financially, and other nations with nuclear-powered fleets may also seek to contribute the repurposing of some of their nuclear-powered vessels or producing new Sea Mixers, which would allow the work to progress more quickly.  These nations may have their own strategic interests in producing cool patches to mitigate cyclones that target their cities, or to improve ocean productivity for their fishing industries.  Such efforts would still help with the overall goal of slowing global warming, and would be welcome.

Implementing TCG appears likely to cost an order of magnitude less than any other proposed SG method at the scale needed (3.7 W/m² over the southern hemisphere, and 1 W/m² over the northern hemisphere), and annual continuation cost thereafter may be two orders of magnitude less than for any other proposed SG method, as we explain on our “Other SG Concepts” page.

The key mechanical engineering issues associated with repurposing a retiring nuclear-powered aircraft carrier into a mega sea-surface cooler were scoped out, conceptually addressed, and covered in our pending patent.  More information on that can be found here.

 Increasing Marine Productivity and Ocean CO₂ uptake

Much of the ocean has often been described as a desert because it is nearly devoid of marine productivity.  Marine productivity begins with the phytoplankton, which require not just light and inorganic carbon, but also the nitrates, phosphates, silicates and other micronutrients that come mostly from upwellings of deep waters.  Without the upwellings and inflow from rivers there would be almost no net primary production.  About 25% of total marine fish catches come from five upwellings that occupy only 5% of the total ocean area.  The mixer-driven upwellings would feed the phytoplankton, which together with the mixing would oxygenate the waters at least down to the 1% light level (~300 m) and lead to them becoming highly productive fishing areas instead of ocean deserts, which currently cover >25% of the world’s oceans and are growing at the rate of 1-4%/yr. These biologically rich regions will remain filled with life for many years after the original “cool patch” has long since normalized to the surrounding seas, and they will drift in the ocean currents, eventually coming near to land and becoming a welcome fishing bounty for the local fishing industries.

Ocean waters much below the MLD (a mere 20 m in some of the targeted areas) have been steadily becoming more oxygen depleted, leading to massive die-offs in some regions.  The proposed deep mixing could extend the MLD within the cool patches, ultimately to over 400 m, drive upwelling and increase the depth at which there is sufficient oxygen to support diverse fish species by an order of magnitude in the cooled patches.

The ocean’s CO₂ uptake depends strongly on net primary production (which depends primarily on nutrients) and on the MLD.  Ocean carbon uptake is a very complex problem, and extensive simulations and studies are needed before all the effects of increased mixing can be understood.  However, the increased winds and primary production could increase surface uptake of CO₂ in the targeted areas from its current value of near zero in many places to the 2 mole-CO₂/m²/yr currently seen over parts of the sub-tropical southwestern Pacific where SST is similar to what is expected in large areas after several years of sea-surface mixing.  That could amount to much more than the largest current Carbon Capture and Storage projects for each Sea Mixer in operation.

The mixing would be in well-separated patches, as the primary objective is to generate atmospheric turbulence, clouds, and rain in targeted regions of tropical seas, and almost all of the sea cooling comes from the increased cloud cover. The increased primary production and ocean CO2 uptake are nice side effects.

More information on increased primary production and ocean CO₂ uptake can be found here.