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| The mirror of the universe (Sachiko Tamashige) |
Introduction from a 2020 video (an edited transcript) with Ye Tao:
"First take a step back. We have a planetary energy imbalance problem. We can look on the possible solutions (inlet vs outlet). Traditionally we try to “open the outlet” of the IR radiation by trying to drawdown GHG through cleaning up the atmosphere. But this is a very energy intensive process. You can achieve the same effect by “closing the inlet”, by rejecting a portion of incoming sunlight back into space. That is the basic idea of MEER from a conceptional point of view. When we try to reject light using mirrors, it is a two-dimensional engineering problem because light reflection happens on a 2-D plane. This is more manageable than sifting through and filtering a 3-D volume of atmosphere or ocean, which would require a much bigger operation from an engineering practical point of view. So first of all we look at the two possible solutions: the inlet vs outlet. And select the one that is the most simple, in concept and practice. A 2-D problem versus a 3-D problem. And then we look to the abundance of materials we have on Earth to implement such a strategy. Which involves making glass composed of silicon and oxygen with a thin film of aluminum. Those are the most abundant elements on Earth. So we have enough material that we can leverage to make an impact. You need only a 10-100 nm aluminum coating to achieve 80-90% reflectivity. To give you a idea how big this is, your cell is 10 micrometer. And the thickness you need is 1/100th of your cell. So by compressing a 3-D problem into a 2-D problem we achieve significant cost and material savings. This makes MEER affordable and scalable.
Which locations have the highest efficiency? As expected, these are equatorial regions. But the ocean is much better. In general, the reason is that the amount of heat or light available for rejection is the difference between what is coming down and what is absorbed by the ground or the ocean. The oceans have a very low albedo, very little light is reflected away, so you have the potential to reject an enormous amount of light by putting mirrors on the ocean. But from a practical point of view it is more difficult to make mirrors float on the ocean, so it is a more involved engineering challenge. But you get roughly a factor to 2-3 improvement in cooling efficiency when the mirrors are implemented in the ocean compared to land.
How much surface area do we need? Calculations show you need roughly a 10 x10 foot square of horizontal mirror laid out in the sunny areas of low albedo, or tilted toward angle that the sunlight is arriving to save space, to offset one ton of CO2. So that is roughly 100 sqft to offset one ton of CO2. The average roof space of a person will be around a couple hundred sqft. This shows that if all roofs and backyards were covered with mirrors we could offset only months or years, and this is obviously not sufficient. And as emissions go down we need more mirrors (since more renewable production of energy means less dimming). The area that needs to be covered on annual basis, assuming 2019 CO2 emissions rates, would be equivalent to the surface area of Belarus. Per year!
While mirrors “close the inlet”, carbon sequestration “opens the outlet” by removing GHG. [This is the difference between SRM and CDR.] Carbon sequestration works the best from concentrated emission sources, for example coal fired power plants. When we allow CO2 to escape into the atmosphere and freely mix, the process is called entropic mixing. Basically it takes work (energy) to sort and filter it out. It is easy to mix a gas, but it takes energy to reverse this process. Calculations of how much energy direct air capture (DAC) takes to reduce CO2 concentrations is more than the world consumes in primary energy per year, and that is the theoretical number! Any thermodynamic engine or process is never 100% efficient and our current technology would only enable 5% efficiency. Which means 20 years of the world’s primary energy consumption is necessary for DAC to capture all the CO2 of the industrial age. That is a huge problem. It is even difficult to spend only one 1% of the primary energy consumption and 5% is even harder to do any mitigation efforts. Which means we are looking at timescales of centuries if we entertain the idea of direct air capture. That is why the only efficient carbon capture is from concentrated sources of CO2, for example coal power plants. But another problem is where do you put the carbon once it is captured? It does not seem to be likely that we will find enough space to store even one year of CO2. So when it comes to carbon capture, it is possible, but it is not really feasible to store it. That is why people are looking into ways to store CO2 in solid forms by mixing it into concrete or into giant reactors to transform it into rocks to undergo a geological transformation. The problem with these schemes is that they are not scalable into what is necessary, regardless of the amount invested."
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| Hyperolius marmoratus (Piotr Naskrecki) |
An Analogy (AllatRa interview): "Imagine you want to fill a bathtub with hot water to a certain level. You have an inlet faucet and you have a drain. You plug the drain and turn on the faucet. If you just keep the faucet on while the drain is closed eventually it will overflow. Now imagine that you kept the faucet on and the drain open. You are now putting water into the bathtub at the same time that water is draining out. By adjusting how much water you let in you can keep the level of the bathtub more or less constant. A stable level of water can be achieved. This is like the Earth’s climate. The hot water is analogous to the incoming energy that's given to us by the sun. And at the same time the Earth itself drains away excess heat in the form of long wavelength radiation (IR radiation in between roughly five to fifty microns). We want to keep the Earth somewhat warm, at a level that's comfortable for the planet's ecosystems, but we do not want to have an overflow of heat.
"The problem with CO2 is that it's like your plug for the drain. We're blocking the exit path for the long wave radiation, just as a plug for the drain in your bathtub keeps the water from leaving. And that would cause the water to overflow. We want to keep the bathtub from overflowing, so there's two interventions: we can either try to open the plug in the drain, or we can just turn down the faucet. We’ve been trying to open the drain for decades (it’s not really working that well, and there's other problems). Or we could simply shut off some of the inlet, but we have to do that very carefully to prevent negative consequences. At MEER that's our main focus, finding ways to do that with a net positive impact on ecology and agriculture in the process. We believe that it's much simpler to turn down the faucet rather than to open a stuck drain plug that’s blocking the exit.”
Decoupling temperature from GHG (David Roberts interview): "The conceptual distinction to make is that energy provisioning and global warming are two separate challenges. There's a natural tendency to link them - "because energy provisioning created the problem, therefore we have to solve the global warming problem by addressing energy provisioning" - but that's not conceptually correct." There's an analogous principle in endangered species management: the factors that caused a species to decline are not necessarily the ones preventing its recovery.
(NanoScientific Conference 2019): "The current problem we have is overheating. The thermal content of the oceans is driving extreme weather and coral bleaching events. By cooling the oceans we will help coral communities to rebuild. The research consensus is that temperature is the common forcer, or stressor that's killing ecosystems. CO2 will have an effect when it's on the order of a thousand PPM, but not at the current level. And when you remove the temperature forcer, generally tolerance to CO2 increases much more. We want to cool the planet, and that's what we intend to do. Of course we don't want to cool too much. But given how much CO2 there is in the atmosphere for the next few centuries we will not cool enough. The fear is not that we will cool too much, the fear is that we will not be able to cool enough to restore ecosystems to their pre-industrial levels."
Low hanging fruit of decarbonization: "We really need to restructure the transportation infrastructure, especially in this country. There's no need to drive a car in which you haul 90% or more dead mass, while what you're actually transporting is less than 10% of the mass. An intermediate step is to move to one or two person enclosed electric velomobiles. These are 100 pounds or less in weight, and they can travel 60 mph for a fraction of the energy costs. Velomobiles are by far the most efficient way of transportation. You can then divide each highway lane in two, because they're narrow. This would solve congestion problems for all major cities. And there would also be fewer safety issues, because if everybody's in a light vehicle collisions would be less dangerous."
Socioeconomic context (Jem Bendell interview, with intro): "Continuing the current paradigm of capitalistic exploitation of resources and humans will just lead to nowhere and we are basically on the cusp of societal decay due to overuse of resources and the environmental conditions that support life... When they're simple, close to the ground, individual people and permaculture communities can also maintain and move the mirrors and modify them as they need for local applications. If somehow ground-based solar radiation management could be put into the hands of people, and provide very strong local benefits, then it provides a natural and democratic way to achieve global scalability. Our team is currently working in Africa and India to help communities that are already suffering from extreme heat events to have a better quality of life. If we could just replace their roof with combinations of mirrored tiles, or reflective flexible mirror sheeting, or even in some cases just white paint we can really have an immediate local impact for many people, not to mention the global cooling impact such humanitarian efforts would also bring."
Infrastructure synergies (Jamen Shively interview): "The infrastructure required for offshore wind power can be used as anchoring points for floating mirror arrays that use actuators to rise and sink. During the day and in good weather, the mirrors would float, rejecting excess sunlight and keeping ocean temperatures cool for organisms including algae and fish. And at night or in inclement weather, sinking the arrays protects them from damage. These arrays can in turn be used as anchor points for vertical ocean farming [an aquaculture technique popularized by Bren Smith]. Daily vertical migrations through the water column brings the farm to 100 - 200 meter depths where nitrogen concentrations are higher, providing fertilization at night. This is one example of a combined implementation that produces electricity and seafood, and offers thermal refuge to many species of fish."
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| (Imagine mirrors instead of PV panels) |
It's a legitimate question to ask "Which is a greater threat: rising greenhouse gases or rising temperatures?" because there's a real choice that can be made here. We know that Earth's average surface temperature is determined by several variables, and among the most influential of these are its albedo and the greenhouse effect. What does this tell us? If all variables are held constant, then by only raising GHG concentrations the temperature will increase. And if all variables are held constant, by only raising surface albedo the temperature will decrease. So what happens if we raise GHG concentrations and raise surface albedo? Potentially, the temperature could remain constant, since these climate drivers act in opposite directions. In short, GHG concentrations aren't the only climate lever available to us for reducing global temperature.
In the last 150 years or so we've been very good at raising GHG levels and consequently overheating the planet. Now that it's too hot and we want to cool down we have several options available: decarbonization, which has been difficult and slow, and albedo enhancement, which may potentially be easier and faster. Of course, we can and should do both. But from a strategic perspective, given current conditions, is our solution portfolio appropriately balanced? The relative effect of albedo enhancement depends on the scale and method of implementation. Achieving global scale is the biggest obstacle. But if the obstacles to that are addressed, then increasing surface albedo can offset higher GHG levels than currently exist (up to 1000 PPM). That said, it's not a free pass to ignore the GHG issue. Rather, it's a stop gap measure that slows or prevents escalating temperature induced impacts and feedbacks, buying us the time we need to complete decarbonization. That will likely take decades if not centuries, but once complete surface albedo can be reduced as well.
"We cannot stop being planet changers" per David Grinspoon, what we have to figure out is "how to be smart planet changers". Grinspoon's book Earth in Human Hands includes a lengthy discussion of geoengineering. Broadly, we can speak about solar radiation management (SRM) or carbon dioxide removal (CDR). These can in turn be divided according to form of action. This is important since technology has biases. Some technologies tend to concentrate the agency to change the planet into the hands of the few, other technologies enable that agency to be more evenly distributed among many people, by providing them with the tools they need to create the change they seek. Typically, we associate geoengineering with SRM and with technologies that concentrate agency. But Ye Tao says SRM can be achieved with technologies that distribute agency. Moreover, in his interview with David Roberts, he noted that we can compare many different intervention strategies to find those that respect values of democracy, durability, ecosystem health, efficiency, etc.
Common criticisms
Climate sensitivity to CDR - According to IPCC SR15, carbon dioxide emissions cuts implemented today would affect the rate of future warming immediately. Michael Mann has noted that while there's a positive energy imbalance (climate inertia), there's a negative carbon imbalance (carbon cycle inertia) as well, and these cancel each other. That means "warming stops when emissions stop". Atmospheric CO2 levels begin to decrease due to ocean uptake, which balances thermal inertia, so surface warming stabilizes (but deep ocean warming continues). In other words, the "baked in" human heating is matched by the "built in" earth system cooling. Mann and Mark Jacobson defend this conclusion, but there remains some skepticism within the environmental community, and more recently concern about positive feedbacks and "cascading tipping points" due to inherent uncertainty. Leon Simons pointed out that "thermal inertia will only be compensated by carbon inertia if carbon sinks stay strong" and the biosphere maintains integrity. Mann responded that this, and methane, sulfate aerosols, VOCs, black carbon, etc. are accounted for in models. Ye Tao earlier noted that under current BAU practices the 2C mark will be surpassed. Although we should "err on the side of caution" and retain the potential to return as much as possible to the climatic conditions that existed on Earth before the Industrial Age, the "climate controls" do not exist exclusively within any single CDR or SRM conceptual approach. (Iain McGilchrist has noted we must remain skeptical of the appeal that overly reductive "command and control" strategies have for the left hemisphere, "whose raison d’être is control".) As Zeke Hausfather wrote, “To stop these impacts may require reducing global temperatures through [as yet unknown methods to achieve] net-negative global emissions, not just by reaching net-zero.” Hausfather focused his article solely on CDR, not SRM approaches. Nonetheless, given carbon cycle interia, mitigation through CDR may be effective if it occurs within the next few decades. Uncertainty remains over potential feedbacks, as some climate subsystems could switch from carbon sinks to carbon sources if decarbonization is delayed much further. So far we have not succeeded in bending the Keeling curve downward.
Anthropogenic GHG emissions interact with much larger geochemical cycles, which is to say that this isn't a closed cycle. But carbon sinks are by no means limitless, magical portals into which carbon simply disappears forever, and even oceans will eventually find a higher equilibrium point with the atmosphere, given a sufficiently large carbon pulse. For example, paleoclimate data suggests that during the Eocene the atmosphere had sustained levels higher than 500 ppm CO2 that was driven by greater volcanic activity than occurs today. If similar conditions existed now, carbon drawdown below 350 ppm would be impossible. Shulter and Watson wrote "Before the Industrial Revolution, the ocean was actually a net source of CO2. However, the increasing atmospheric CO2 concentrations, driven by human-caused emissions are forcing the ocean to now absorb this gas." We are quite fortunate to enjoy our current conditions, which are of course subject to change. Given the unpredictable assaults that Gaia must endure occasionally, while he was looking back on a long life in the pages of his book Novacene, James Lovelock reflected on the precarity of existence, and our general inability to take anything for granted. Today we are trying to decarbonize industry (mining, manufacturing, construction, waste processing), agriculture, and energy (heating, electricity, and transportation). According to Rebecca Dell these tasks are not inherently hard, "we're just at a much earlier stage in our decarbonization journey" in some sectors than others. As we engage in the essential CDR work, we would do well to maintain the integrity and capacity of natural buffers as much as possible. While there may be opportunity costs when prioritizing mitigation strategies, it is overwhelmingly an exercise in pursing multiple, synergistic solution paths simultaneously. Let's close this with a quote from the paper by Matthews and Solomon (below). They note that climate inertia and carbon cycle inertia effectively cancel each other out. But these aren't the only drivers to consider. What really has us locked into a 2C pathway is social-technological inertia, and it is due to these physical dynamics that we see no signs of flattening the Keeling curve. I think that's an important distinction, and it's much harder to dispute. It’s why CDR has not been effective thus far, and likely will never be sufficient, and addressing the Earth Energy Imbalance (EEI) by utilizing SRM is very probably unavoidable in our future. From Matthews and Solomon's paper "Irreversible Does Not Mean Unavoidable":
"If emissions were to abruptly cease, global average temperatures would remain approximately constant for many centuries, but they would not increase very much, if at all. Similarly, if emissions were to decrease, temperatures would increase less than they otherwise would have. Our dependence on CO2-emitting technology therefore generates a commitment to current and near-future emissions... technological development and diffusion is subject to substantial inertia. Thus societal inertia, rather than the inertia of the climate system, is the critical driver for urgency if we wish to begin to decrease the rate of CO2-induced global warming in the near future. The strong dependence of future warming on future cumulative carbon emissions also implies that there is a quantifiable cumulative amount of CO2 emissions that we must not exceed if we wish to keep global temperature below 2C above pre-industrial temperatures. Given uncertainties in both the climate and carbon cycle responses to CO2 emissions, as well as the climate response to emissions of other greenhouse gases and aerosols, there is large uncertainty in any estimate of this allowable cumulative emissions budget."
(artistic impression)
Due to changes in GHG, aerosols, surface albedo, etc. the planet has absorbed about a Watt more solar energy per square meter than it lets off, as James Hansen recently noted, throwing Earth's energy budget dangerously out of balance. Most of that energy is absorbed by the oceans, with the remainder heating the land, melting snow and ice, and warming the atmosphere. This led Dvorak and coauthors to recently conclude in their assessment of a hypothetical scenario, "Following abrupt cessation of anthropogenic emissions, decreases in short-lived aerosols would lead to a warming peak within a decade..." It's for reasons such as these, where climate drivers have not yet established a new system equilibrium, that there's still going to be some warming "in the pipeline" as Hansen noted. Dvorak then adds that this peak is "followed by slow cooling as GHG concentrations decline", confirming the establishment of a new state of radiative equilibrium that Matthews and Solomon referred to in their paper. Dvorak notes that "This implies a geophysical commitment to temporarily crossing warming levels before reaching them." This may be why James Hansen ends on a note of cautious optimism: "We can still deal with the situation if we begin to make fossil fuels pay their costs, and do that in a way which can be made global." This brings up numerous questions of course, as uncertainties remain. Can we accurately predict the size and duration of the peak? Will it lead to additional tipping points in climate subsystems and further destabilization? And the biggest uncertainty of all is, as Matthews and Solomon rightly point out, societal inertia. If that's not addressed then these scenarios will be continually revised again and again. We may need stop gap measures like MEER in that eventuality.
Although growth in renewables has consistently outpaced IEA predictions, it has not been able to displace existing fossil fuel energy in order to meet rapid CDR targets. The demand for energy, due to military escalations, growing economies, etc., has meant an increased demand for fossil fuels as well as renewables. In other words, while the renewable energy slice of the energy pie chart is relatively larger, the entire pie has grown overall as well. What this means is that, despite the predictions of many techno-optimists (like Tony Seba), and the actual gains that have been made in efficiency, societal inertia has consistently frustrated the pursuit of sustainability goals. Overcoming this inertia will require a paradigm shift in our approach to EEI (such as a reappraisal of SRM strategies), and dramatic increases in efficiency, durability, and scalability. Seba is right about one thing, disruption is needed. But with societal inertia we are seeing the escalation of existing trends instead. Will MEER be able to help disrupt the existing paradigm where others have fallen short?
One alternative proposal for CDR, called geotherapy, has been contrasted with the more mechanistic sounding "geoengineering". “Geotherapy refers to the process of restoring the earth’s health by strengthening natural biogeochemical and physiological mechanisms that regulate the earth’s planetary life support systems and control global temperature, sea level, atmospheric composition, soil fertility, food, and fresh water supplies.” This is similar to ideas within agroecology, permaculture, regenerative farming, and rewilding. Recently The Weathermakers have proposed ambitious plans to green the deserts, following the success of regreening the loess plateau of northern China. Gijs Bosman pointed out that “The climate regulator on earth is the biosphere. All cycles depend on it. In the last 10,000 years we have removed more than half of this biosphere.” Millán Millán distilled this to a simple maxim: “Water begets water, soil is the womb, vegetation is the midwife.” Recognize this logic? It is common to all CDR approaches. "Because disrupting the atmosphere/ biosphere created the problem, therefore we have to solve the global warming problem by restoring the biosphere." The SRM response is that yes, we must restore the atmosphere/ biosphere to health, however (this is key) restoring geochemical cycles is likely to take decades, decades that we may not have before we reach adaptive limits for critical ecological subsystems, especially given unprecedented rates of heating. Hypothetically, the SRM proposal from MEER would buy the time needed for natural biogeochemical and physiological mechanisms. It should also be noted that there is no reason why both technologically novel and more traditional methods for ecological restoration cannot proceed simultaneously, complementarily in parallel. This is because, despite the attempt to draw a dichotomy between geotherapy and geoengineering, there are considerable areas of overlap in the Venn diagram of proposed methodologies utilized by each. To provide just one example, The Weathermakers proposed the use of hundreds of greenhouses to revegetate the Sinai Peninsula. These agricultural methods use materials that are substantially identical, if not more complex, than those proposed by MEER, mechanically speaking. It should also not be forgotten that expanding agricultural capacity within regions that are currently heat and water stressed has also been a central goal for MEER from its inception.
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| Shaman toli (National Museum) |
As the Earth decarbonizes through clean energy and "natural CDR" (the result of carbon cycle inertia today), "global brightening" will occur, meaning that more solar energy will reach the surface, and fewer pollutants will be available to absorb any direct light, or light reflected from the surface. Urban areas must be able to mitigate the heat island effect that greater light levels create, in effect they will need to become urban cool islands during periods of surrounding high heat. If Jacobson is right, this may cause locally reduced cloud cover (and hence even brighter skies). Decarbonization efforts also promote greater energy efficiency, leading to reduced heating needs in winter through a combination of approaches that may include heat pumps, better insulation, and/or other energy saving tools (incorporated into Passivhaus construction standards). This implies that solar radiant energy could be less critical to meeting some of these needs as heat is increasingly conserved, retained, and sourced in other ways. Nonetheless, solar thermal and solar reflection can and should be used simultaneously, as needed, absorbing energy to replace local losses and rejecting the surplus.
When Daniel Cziczo was asked to contrast the effectiveness of two different SRM methods (stratospheric aerosol injection versus surface-based brightening) he responded "As long as clouds are taken into account, overlying clouds in the case of the surface or underlying clouds in the case of what you're doing in the stratosphere, then I don't think there's really a fundamental difference between those two, other than at the surface if that photon coming down was reflected back by a cloud you can't say that you've reflected it back. If that cloud is in between, and you bounce it, you have to take those things into account. So as long as that's done, I think those two things are equivalent. We have some understanding of what surface modification does and the impact it has. Humans have already done this, both intentionally and unintentionally through loss of sea ice, deforestation, agriculture, urbanization, and other changes. And scientists have some understanding of this. But the unintended impacts of ‘designer’ aerosols on the ozone layer, clouds, and precipitation are harder to anticipate."
Published studies - There's no peer reviewed general circulation models (GCM) showing effectiveness for this intervention strategy at this time. Tao has noted interest within the research community, and is conducting experiments at several locations. We should evaluate SRM proposals, such as those offered by MEER, as part of a larger, complete portfolio of strategies, and simulate them under a range of possible scenarios. Wider ecological interactions can be a part of these simulations, as both heliostats and PV panels can (and have) affected wildlife. It's suspected that birds have occasionally mistaken these smooth surfaces for water when they are viewed from certain angles. The "business as usual" scenario, in which temperatures continue to rise, is causing escalating harm to ecological communities today. Research on the intersecting issues of balancing energy and wildlife must lead to better practices and reduced deaths. There's reason to believe improvements in design and implementation can and will be made. I look forward to reading later research and publications on MEER's specific proposal for SRM.
There are, of course, many other SRM proposals, such as Sergey Zimov's Pleistocene Park, or Leslie Field's Arctic glass beads, and various versions of a space sunshade (satirized recently in the first episode of Mike Myers' show The Pentaverate) to name a few. All of these face unique obstacles, risks, and restrictions. About the glass beads Tao remarked, "we could use MEER to offset the same amount of global heating, thereby stopping the the melting trend and stabilizing ice, but at a more manageable location than the Arctic". Given Tao's analysis and proposal, we can ask: What are the next steps? He suggested that "oases" could be created through the localized use of mirrors. If just one of these were in fact realized, it could help drive both greater awareness for MEER and wider adoption. Tao also mentioned "We're in the process of trying to make DIY instruction booklets to make mirrors that you can plant in your backyard as well just to draw attention, and also mirrors that you can give to or have your kids make to bring to their Friday for Future strikes to educate or to communicate to their peers." Durability of mirrors is important for an SRM approach that will effectively reduce the EEI. But for promotional materials it may be a secondary consideration. And in northern climates there may also be a role for reflective materials that can be deployed in the summer heat, and stored away in the winter, such as aluminet reflective shade cloth, parasols, or umbrella hats. Can MEER be coupled to SkyCool Systems’ radiative cooling panels (or similar) to transmit various residential/ commercial/ industrial waste heat into the universe? Tao mentioned SkyCool in an earlier presentation: "SkyCool uses a bit more fancy reflectors, to not only do what the humble glass mirror does, but also radiate some IR through a transparency window in the atmosphere in the IR range. The problem from addressing climate change is scalability. We don't have enough roof, road, or built infrastructure to really have the area to achieve a global impact. That's why we need to couple it with something in the human system that's already highly engineered, which is, in our belief, agriculture. That's where we have a sufficient area to do this. And if we can simultaneously bring about co-benefits then that's obviously a plus." SkyCool tech was designed to narrower tolerances for refrigeration applications, and therefore has higher material and manufacturing costs. Some aspects of that technology are relevant to MEER as well, but only if the associated costs can be reduced. It’s a numbers game! With a “war time effort” those costs might be reduced in a very short order, given economies of scale. The other way to reduce costs is to use extremely common materials, as Tao noted above. These obstacles also apply to space mirrors, another technologically intensive SRM proposal. But space mirrors have other drawbacks too, including negatively impacting renewable energy capacity on Earth, and durability challenges posed by the millions of meteoroids, micrometeoroids and other space debris entering Earth's atmosphere each day.
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| Sea Ice |
A final discursion, this time to reflect (pun intended) on the prevalence of reflective surfaces in other domains outside SRM. We see them virtually everywhere. Dante used mirror imagery throughout his work, providing an organizing principle in the Paradiso as a hierarchy of specula from the mirror of nature to the mirror of God. A multifaceted cut gem can dazzle the eye with a rainbow of colors, a shiny polished chrome coating can be both beautiful and protective of the underlying surface, and aluminized fire proximity suits protect firefighters, foundry workers, and volcanologists. Polished stainless steel has inspired many public art installations, from Anish Kapoor's Cloud Gate in Chicago to Hamilton and Vandermeer's Polaris in Fairbanks. A "survival mirror" can signal one's location and a doctor's "head mirror" can direct light where it is needed. Classic American diners often have an exterior layer of stainless steel siding, as did the DeLorean car, and trailers make by Airstream, Bowlus, and the Spartan Mansion all had polished aluminum siding, as was the fuselage of many aircraft. Shiny exteriors are synonymous with retrofuturism, the world of George Jetson and Buckminster Fuller (see his sheet metal clad Dymaxion house). There's even hypothetical mirror matter. Retroreflectors can be found in a variety of both artificial and natural objects. Three U.S. lunar landing missions left retroreflectors on the moon. (They are the only items there that are still in use since they don't require any power.) A natural example is the phenomenon of eyeshine produced by the tapetum lucidum. Animals can also create structural color. The beetle Chrysina limbata utilizes a chirped multilayer reflector composed entirely of chitin making it appear like a silvery dewdrop on a leaf, as likely do “mirror spiders” (Thwaitesia species). Is it possible to create a mirror entirely of chitin? It may not be too far-fetched. When the sun climbs high over the Great Rift Valley of central Mozambique, small reed frogs (Hyperolius marmoratus) turn snow-white, allowing them to not only persist but flourish. They can change color from darkly patterned to white by contracting or expanding skin cells called chromatophores, cells that produce color and are found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. (Mammals and birds, in contrast, have a class of cells called melanocytes for coloration.) White skin reflects sunlight effectively lowering body temperature. Conservationist Piotr Naskrecki said "Their water retention mechanism and the ability to reflect solar energy are simply remarkable." Some geoengineering methods mimic these living processes better than others. The bright, metallic sheen of fish skin is due to a sophisticated system of crystals that enhance light reflection.
Chameleons are also able to reflect a broad spectrum of light using chromatophores. Their ability to reflect a significant amount of infrared radiation plays a role in internal temperature control and may explain why they can beat the heat for longer durations than other lizards. The word chromatophore comes from the Greek chrōma (χρῶμα) meaning color. (The metal chromium also derives from the same Greek word, as many chromium compounds are intensely colored.) Mature chromatophores are grouped into subclasses based on their color. While most chromatophores contain pigments that absorb specific wavelengths of light, the color of leucophores and iridophores is produced by their respective scattering and optical interference properties. Iridophores reflect light using plates of crystalline chemochromes, sometimes forming microscopic Bragg mirrors. Also known as dielectric mirrors, these are composed of multiple thin layers, and can produce ultra-high reflectivity values of 99.999% or better over a narrow range of wavelengths. Alternatively, they can be made to reflect a broad spectrum of light, such as the entire visible range. Further research on these forms of structural coloration may point to a natural method for developing materials, fabrics, and surfaces that change color in response to external stimuli. The most tantalizing application would be for structures and clothing that are designed for better thermal regulation and energy efficiency. A recent paper remarks:
"the fabrication of Bragg mirrors is mainly accomplished by physical and chemical vapor deposition processes, which are costly and do not allow for lateral patterning. We report for the first time the fabrication of Bragg mirrors by fully inkjet printing. The photonic bandgap of Bragg mirrors is tailored by adjusting the number of bilayers in the stack and the layer thickness via simply varying printing parameters. An ultra-high reflectance of 99% is achieved with the devices consisting of ten bilayers only, and the central wavelength of Bragg mirrors is tuned from visible into near-infrared wavelength range. Inkjet printing allows for fabricating Bragg mirrors on various substrates (e.g., glass and foils), in different sizes and variable lateral patterns. The printed Bragg mirrors not only exhibit a high reflection at designed wavelengths but also show an outstanding homogeneity in color over a large area. Our approach thus enables additive manufacturing for various applications ranging from microscale photonic elements to enhanced functionality and aesthetics in large-area displays and solar technologies."
Temperature induced albedo change for thermal regulation would be extremely useful for smaller structures, allowing hour to hour adaptive change, between transparency, reflection, and absorption as needed for heating needs. However, on the enormous spaciotemporal scale of the Earth system, such fine grain precision may not be necessary. It's well known that an array of reflectors can create a very functional solar oven for cooking food. And in Rjukan (Norway) and Viganella (Italy), both situated in deep valleys where the sun is blocked for up to six months every year, mirrors were installed to reflect the sun's light downwards (a powerful visualization of how much energy can be redirected.) MEER uses the same principle to cool Earth by reflecting that energy away from the planet instead. More theoretically, James Lovelock's simulations of radiative forcing contributed to the Gaia hypothesis. Not only do we see a wide distribution of reflectors in nature, but the fractal pattern of their distribution itself repeats at multiple scales. Continents float on magma, cracked sea ice floats on water, and spectral mirrors may one day hover over agrarian villages, appearing like dew drops on diaphanous gossamer webs that billow in the faintest breeze, Indra's net in which the whole is reflected in each part. In this way MEER might recapitulate a natural pattern, just as art recapitulates life. This has been called biomimicry by Janine Benyus, and symbiomimicry by Glenn Albrecht. For Iain McGilchrist it might represent the continuity of fragmentation, which is itself an example of the Heraclitean/ Jungian concept of a dynamic coincidentia oppositorum. Heraclitus described the balance of two opposing forces with the metaphor of a bow maintaining a taut string. Global temperature is the balance of many forces, some of these work in opposition and others work in concert. Our challenge is to identify the most effective places to intervene in the system (Donella Meadows). McGilchrist further noted that the capacity to mirror, to "imaginatively inhabit" or imitate, is the defining characteristic of humanity.
The reflection in the face of a mirror is completely dependent upon embodied context. One can seemingly look through its surface as though it wasn't even there because it's responsiveness is nearly instantaneous. It appears to be empty of any intrinsic qualities of its own, of any intention or bias. Therefore mirrors have long symbolized truth, and in Eastern spirituality they additionally symbolize the nature of mind as it is directly, intuitively understood. Symbolic associations are ancient, see the Tibetan melong, Mongolian toli, Manchurian panaptu, Tuvan küzüngü, Japanese shinkyō, Ainu shitoki, etc. (and "karma mirror"). Richard Rorty had earlier argued that "The picture which holds traditional philosophy captive is that of the mind as a great mirror" (many examples, including the "clear reflection" of Xunzi, and the "bright mirror" of Huineng, that for Wang Yangming is "always shining"). But Rorty saw a more active and relative (rather than a passive and objective) role for the mind, and so he was skeptical of any mirror metaphor that was "always trying to transcend itself... the notion of a mirror which would be indistinguishable from what was mirrored, and thus would not be a mirror at all." Can a mirror embody another sort of coincidentia oppositorum, and be at once both passively reflective and actively productive in its effects and processes? As a physically embodied object, any reflective surface certainly must effect some active agency within a system, and physicists like Rovelli have provided interpretations that are very suited to supporting this. The applications for reflectors are inevitably both symbolic, and actively energetic.
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| Daisyworld climate (Lovelock 2014) [cf. observed temps] |
Lovelock's Daisyworld model is probably the most frequently cited gedanken experiment in support of Gaia theory. And as a thought experiment, it is not literally true, but merely an oversimplification of how "high precision negative feedbacks" allow the climate of Gaia to maintain homeostasis within a range hospitable to life. A recent paper suggested that perhaps "Soilworld", regulating GHG through enhanced weathering, might've been a more apropos example than "Daisyworld", regulating the amount of reflected solar energy through albedo. But the key idea here isn't specifically daisies or albedo, nor strictly soil and GHG, rather it is that the entire planet functions as a vast homeostatic superorganism that actively modifies its planetary environment to produce the conditions necessary for its own survival. As Lovelock noted, the degree of complexity with which these positive and negative feedback loops interact means that we are still discovering them. Vladimir Vernadsky had developed the concept of the biosphere in the late 1920s, and was recognized by Lovelock and Margulis as a seminal contributor to the theory of Earth as a living system. As David Grinspoon wrote, “In other words, fifty years before Lovelock and Margulis, Vernadsky largely described Gaia." Grinspoon goes on: "Furthermore, he hinted at a fundamentally new stage in the life of the biosphere that was being brought about by the actions of humanity. In his later life he became obsessed with the idea of the noösphere. …The lithosphere had given rise to the biosphere, and now the biosphere had birthed the noösphere. Earth had become alive and then developed a mind. …the beginning of Earth’s fifth eon.” (But why stop there? Ideas of a living planet are probably timeless.) In his book Novacene (2019), James Lovelock wrote:
"Since it began, life has worked to modify its environment. This is not easily explained in full because it is a complex, multi-dimensional process. I can, however, illustrate how it works with a simple computer simulation. This is called Daisyworld, which, with the atmospheric scientist Andrew Watson, I published in 1983. A main sequence star like our Sun gradually heats the planet Daisyworld until it is just warm enough for a species of black daisies to colonize the entire surface. Black daisies absorb heat so they thrive in these low temperatures. But there are mutant white daisies which reflect heat and, as the temperature rises even further, these begin to flourish. So Daisyworld is cooled by white daisies and warmed by black ones. A simple flower is able to regulate and stabilize the environment on a planetary scale. Moreover, this stabilization emerges from a strictly Darwinian process.
"Scale up this model to include all the flora and fauna of Earth and you have the system I have called Gaia. In fact, you cannot actually scale it up because the system is too complex; so complex in fact that we are nowhere near fully understanding it. Perhaps it is hard to understand because we are an intrinsic part of it. But also, I suspect, it is because we have been too reliant on language and logical thinking and have not paid enough attention to the intuitive thinking that plays such a large part in our understanding of the world. So, in short, humans may, at any moment, become extinct because of forces far beyond our control. But we can do something to save ourselves by learning to think."
The Daisyworld simulation is notable in that, while it highlights the vast adaptive capacity of a diverse biosphere, it should also prompt us to ask two very simple and important questions: 1) Why is homeostasis important to Gaia? 2) What role might we play in this? Later in his book Lovelock writes: “I cannot say too strongly that the greatest threat to life on Earth is overheating. High temperatures make us vulnerable. A rise in temperature of 5 or even 10 degrees could probably be withstood, but not if the system is disabled… our present efforts to combat mere global warming are vital.” Gaia is one of those big ideas that has instant superficial appeal, and thus becomes invoked frequently, but whose depth and real import is easily overlooked. Still today. Lovelock, surprisingly alive and lucid at 102, is a bit of an iconoclast himself. As for the pedigree of the notion of Gaia, I do like David Grinspoon's recounting of it in his book The Earth in Human Hands. And in Iain McGilchrist's recent massive tome The Matter with Things he cited Arran Gare's paper "From Kant to Schelling to Process Metaphysics: On the Way to Ecological Civilization" to point out that it was Schelling who was the first to describe the central concept of homeostasis. It should almost go without saying, that it is quite nearly impossible to understand Earth without understanding the Gaia hypothesis, and likewise it's impossible to understand the Gaia hypothesis without understanding homeostasis, allostasis, and related concepts (such as, perhaps, active inference). And yet, here we are.
In contemporary culture, it seems fashionable to perpetually indulge fantasies. One such fantasy is that limitations, whether of a technological or biological sort, no longer apply. The second fantasy is that self-regulation is, if not unimaginable then certainly impossible. Both are false. Life is constrained by physiologically limiting factors, and for that reason the self-regulation of these processes is precisely what allows it to occur. This is why homeostasis is important to Gaia. There are real adaptive limits and life exists within a relatively narrow range, cosmically speaking. The Daisyworld simulation shows that, within its capacity to do so, the planet as a whole has the agency to seek homeostatic control "as if it were" a single life. It also tells us that this capacity is not immune from the threat of extinction. Both are easily demonstrated within the simulation. (Gaia is in fact so fragile, given a history of several Gaian "near death experiences" that Peter Ward suggested there may be no stability at all.) When people no longer believe in self-regulation, and when they do not recognize limits, there are only a few choices they have left. These include: externally imposed regulation (salvation via supernatural means), denialism (limits aren't real/ they don't exist/ don't affect me), or nihilism (we have no agency/ failure is inevitable). Among nihilists, there's a subset that console themselves with the thought that perhaps humans may perish, but other life will persist and flourish in our absence. In Novacene, Lovelock is quick to disabuse us of any such consolations. When he speaks on topics outside his expertise, Lovelock is not always convincing. But on this subject, that of Gaia, homeostasis, and the threat of global heating to an incautious society, his warnings are very well considered and must be heeded. As an aside, his mention of the significance of intuitive thinking in the world is another deep insight (and one which Iain McGilchrist spends considerable time developing as well).
Are we leveraging the explanatory power of this simulation to full effect? How do we mobilize on climate and at the same time avoid the trap of doing so in an ethically utilitarian and mechanistic manner (as many observe is the direction today)? To briefly repeat what has been mentioned earlier, that follows from a tendency which, if taken to its logical conclusion, results in psychological fragmentation. The challenge, then, is to preserve our essential continuity in the face of this fragmentation. Now, there is a very productive sort of Heraclitean tension that must be maintained between the two, between perfect fragmentation on one extreme and seamless continuity on the other, call this "continuity amid fragmentation" if you will. Maintaining this dynamic tension is not easy, but the contours of the terrain were outlined by McGilchrist; it is essentially the task to which we must rise. Lovelock applies the precautionary principle to what might be termed Gaian astrophysics:
"The Earth's environment has been massively adapted to sustain habitability. There have been hot periods and ice ages, but the average temperature of the whole planetary surface does not seem to have varied by more than about 5°C from its current temperature: 15°C. This is because life has controlled the heat from the Sun. If you wiped out life entirely from the Earth, it would be impossible to inhabit. It would become far too hot, and life would not start again. The extreme weather we have experienced recently is only a mild sign of what might be on the way. But I think we have time, time we should spend cooling the planet to make it more robust. Planets, like humans, grow fragile with age. If all goes well, Gaia can expect a productive and pleasant period of decline – but people can have fatal accidents and so can planets.
"Our resilience depends on our state of health. When young, we can often withstand influenza or a car accident, but not when we are close to 100 years old. Similarly, when young, Earth and Gaia could withstand shocks like super-volcanic eruptions or asteroid strikes; when old, any one of these could sterilize the entire planet. An asteroid impact or a volcano could destroy much of the organic life the Earth now carries. The remnant survivors might be unable to restore Gaia; our planet would quickly become too hot for life. A warm Earth is more vulnerable, so keeping Earth cool is a necessary safety measure for an elderly planet orbiting a middle-aged star. It is vital for our survival that the sea is kept cool, since after the Sun, the sea is the primary driver of our climate. It was thinking about the consequences of asteroid impacts and other accidents that made me see why the Earth needs to stay cool. We need to keep the Earth as cool as possible to ensure it is less vulnerable to accidents that might disable Gaia's cooling mechanisms. And we should not simply assume, as most people do most of the time, that the Earth is a stable and permanent place with temperatures always in a range in which we can safely survive."
The history of the biosphere is closely related to the evolution of the Sun and the consequent migration outward of the "habitable zone" (aka Goldilocks zone) in the solar system as the Sun ages. The planets do not migrate with it though. What does that mean? Practically speaking, billions of years ago when life emerged, Earth was comfortably within that zone and received lower levels of solar radiation than it does today. However since the genesis of life, the habitable zone of our solar system has moved farther outward. Perhaps we are only on the ragged inner edge of it today, or maybe it is past us altogether. Why are we all still alive then? Because Gaia can maintain the conditions for life. However if she is dealt too strong of a blow today, she may not recover. As the Sun and Earth continue to age, the risk of overheating increases. If the Earth was a hothouse for most of its history, then, left to its own devices, shouldn't it return to hothouse conditions? That sounds reasonable, although Lovelock shows this is not the case (below). Additionally, it should be noted that our role in liberating fossil fuels makes us culpable for recent warming. Extremes (whether greenhouse or icehouse conditions) and abrupt changes are all associated with mass extinction. Earth has endured many extinction events, and recovered, but eventually one of these will be the death of Gaia. What we can say with relative certainty is that, when death comes, it will be from overheating, not freezing. So cooler isn't just better because that's how things have been for the last 10k years or so during the Holocene. Cooler is better because it is a negative feedback in the face of solar evolution that makes Gaia "more robust", it reduces our exposure to existential risk from black swan events of the sort Lovelock described. It is the precautionary approach, given our current position. As Aldo Leopold famously said, "A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community [or Gaia]. It is wrong when it tends otherwise." In his book The Revenge of Gaia, p43-47, Lovelock provides a more complete picture. He writes:
"In about one billion years, and long before the sun’s life ends, the heat received by the Earth will be more than two kilowatts per square metre, which is more than the Gaia we know can stand; she will die from overheating. Gaia regulates its temperature at what is near optimal for whatever life happens to be inhabiting it. But, like many regulating systems with a goal, it tends to overshoot and stray to the opposite side of its forcing. If the sun’s heat is too little the Earth tends to be warmer than ideal; if too much heat comes from the sun, as now, it regulates on the cold side of ideal. This is why the usual state of the Earth at present is an ice age. The recent crop of glaciations the geologists call the Pleistocene is, I think, a last desperate effort by the Earth system to meet the needs of its present life forms. The sun is already too hot for comfort." [And again, in A Rough Ride to the Future he wrote:] "As we gather more detailed and more accurate estimates of the long-term climate and compositional history of the Earth over tens of millions of years, we see that despite the ever-increasing output of solar heat, the Earth tends to grow colder. As long ago as 1992, the ocean scientist Michael Whitfield and I published a small paper in Nature with the provocative title ‘The Life Span of the Biosphere’. In it we argued that if the goal of the Earth system was to keep its temperature close to glacial levels, the only way open to it in the face of the ineluctable increase of solar radiation was to progressively lower the abundance of CO2. It was almost succeeding, and CO2 levels 17,000 years ago reached 180 parts per million, possibly the lowest since life appeared on the Earth 3 billion years ago. The rise of CO2 abundance to 280 p.p.m. in the interglacial before the Anthropocene had nothing to do with the presence of humans: it was the response of an over-stressed system to a rise in heat received from the Sun due to small cyclical changes in the Earth’s orbit and inclination (the Milankovitch effect)."
In The Vanishing Face of Gaia, Lovelock wrote: "If the hotter Earth now were more productive than the cool Earth before the Industrial Revolution, we would be flourishing and so would the Earth. Unfortunately we moved the temperature the wrong way, and we may be eliminated as a result. Cooling would have been much better. This is how Gaia keeps a habitable planet: species that improve habitability flourish and those that foul the environment are set back or go extinct. Are we yet intelligent enough to be a social animal capable of living stably with Gaia and with ourselves now and on the changed Earth that soon will come? As I see it, our hope lies in the chance that we might evolve into a species that can regulate itself and be a beneficial part of Gaia."
James Lovelock noted that instead of "Gaia Theory" he could've gone with the more sedate sounding "Earth System Science" or "geophysiology", but it wouldn't have garnered nearly as much attention if he had. I think this is primarily because Gaia gives a proper name (and the associations of teleonomic agency that come with it) to the particular embodiment of the largest superorganism we are aware of. This reifies something that would have otherwise remained purely conceptual and disembodied. Perhaps at some point later the fractal structure of reality may suggest that the galaxy and universe also display life-like qualities, this might be more apparent if/when extraterrestrial life is discovered. As Lee Smolin said, "If the earth can be understood as a self-organized system, maybe the same thing was true for larger systems, such as a galaxy or the universe as a whole". But if and when they are, we have not observed this. In the case of Gaia we have. At a smaller scale, Peter Corning noted that human society is also a superorganism, or a "collective survival enterprise" where multiple selves join together to form a "superagent". This agentic character of society, as has been frequently observed, can either promote the general health and welfare of the entire biotic community, or it can become an uncoordinated and cancer-like growth that destroys the planet upon which it depends.
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| Slide from COP26 presentation |
An early paper (Feb 2021) describing the MEER project from CFC Together.
Climate Emergency Forum video at COP26 with Ye Tao, Peter Wadhams, Paul Beckwith, and Regina Valdez (slides).
James Lovelock. Novacene. (2019)
James Lovelock. A Rough Ride to the Future. (2014)
James Lovelock. The Vanishing Face of Gaia: A Final Warning. (2009)
James Lovelock. The Revenge of Gaia. (2006)
David Grinspoon. Earth in Human Hands. (2016) Chapter four, "Planetary Changes of the Fourth Kind" is an excellent overview of geoengineering.
Stewart Brand. Whole Earth Discipline. (2009) Chapter nine, "Planet Craft" reviews geoengineering.
Jeff Goodell. How to Cool the Earth. (2010) Chapter five, "The Blue Marble" is about James Lovelock.
Richard Rorty. Philosophy and the Mirror of Nature. (1979)
James Lovelock & M. Whitfield. Life span of the biosphere. (1982) “In human terms the crisis is still infinitely distant but in terms of the life span of the biosphere, rich with familiar metazoans, we might forecast an end to the long spell of cool and favourable climate. ...an increase in albedo by desert cover might sustain an equable climate but as observed by Henderson-Sellers, this is generally neutralized by a concomitant change in cloud cover."
Trenberth and Cheng. A perspective on climate change from Earth's energy imbalance. (2022)
Goode et al. Earth's Albedo 1998–2017 as Measured From Earthshine. (2021)
Adaptive optoelectronic camouflage systems inspired by cephalopod skins (2014) video.
Jodie Moon with Paul Carty. The Magic Mirror Maker (2014), mirror site.
Robert Lamb and Joe McCormick's "Stuff to Blow Your Mind" podcast series on mirrors.
Joseph Romm. Reflecting roofs: A low cost "cool communities" strategy (2009)
Cool Roof Council. Cool Roof or Solar-Reflective Wall Codes, Standards, and Voluntary Programs.
Zhu & Mai. A review of using reflective pavement materials as mitigation tactics to counter the effects of urban heat island. (2019)
Oliver Wainwright. Metropolis meltdown. (2022) "The guidance has always been about maximising daylight and sunlight as an asset. But it hasn’t really acknowledged the problem with having too much of it."
Abdelsalam et al. A New Sustainable and Novel Hybrid Solar Chimney Power Plant Design. (2021) Thomas Reis suggests that this combined solar chimney and cooling tower could be operated with reflective surfaces.
David Cayley. Gaia and the Path of the Earth. (2021) "Purpose was driven out of science and thereby fated to return endlessly as heresy", but one must understand "causal circularity" and how "the range of temperatures and conditions at which life can exist sets the tolerances, the goal of the self-regulating system Gaia". Cayley concluded, "Latour has answered many of Illich’s practical objections to the Gaia theory, such as that it is abstract, other-denying, and earth-denying". Iain McGilchrist may also provide a response to Illich’s concerns, particularly the difference between "model and reality", which he has shown tend to strongly lateralize to the left and right brain hemispheres.
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