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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."
Multiscale implementation (How Can Mirrors Help to Cool the Planet?) Question (John): “We've got a jet stream pattern, and ocean currents, and polar vortex, which all work because the equatorial regions get more energy than the polar regions. So if you were to deploy this at scale, how would you be sure that you could scatter these in the right proportion around the globe, without changing major weather patterns?”
Answer (Ye Tao): “At the current time I think MEER is predominantly an adaptation effort to provide local cooling. But regarding large scale circulation pattern changes, there is one sort of preliminary experiment in Spain. Over the past 40 years they have been progressively increasing the coverage of land with white roofed greenhouses that partially reflect sunlight. (The whole region appears rather white from space and has a very high albedo.) This has resulted in more solar energy escaping the region, which has consequently undergone about one degree Celsius of air and ground cooling over the past 30 or 40 years. In the same time period the neighboring towns and regions have undergone a temperature increase of three degrees Celsius. So if we take the difference, a 10 percent rejection of light has regionally induced a four degree Celsius cooling. That’s a strong indication that it might be possible to create “local oases” of habitable regions on Earth, even as the whole planet on a large scale gets hotter. It’s notable that in the same region precipitation has not been observed to change. So, at least on a regional scale, there is hope that MEER, as an adaptation technology, can work. City and urban planners seeking to increase passive cooling might value both thermal efficiency as well as greater reflectivity, as in Almeria in Spain, but also a more contiguous topography, as in the sunken courtyards (yaodong) in China or at the UNESCO Headquarters in Paris. The topographic inversion of urban areas that utilize sunken courtyards, with the more contiguous profile they present when compared to that of other urban skylines, could make albedo modification far simpler while also economizing on material use. The potential layout of courtyards is unrestricted, whether adopting a typical grid or the more imaginative biomimicry of Turing patterns. As a design template it holds possibilities for optimizing vegetation, recreation, mixed use, and many other variations of form. Designing urban areas for passive cooling of all types is increasingly critical in regions already experiencing intense heat waves.
“On the larger continental scale we should be concerned about potential cloud moisture feedbacks which can either aid the goal of reducing solar energy or, in the case of diminishing the amount of clouds formed over these arrays, potentially have a self-defeating impact through secondary interactions given atmospheric cloud microphysics. So to answer questions at the mesoscale, we really need to look into existing data that is just emerging in studies on forest and deforestation patterns. The crucial factor is not just how much moisture that you're able to transport into the atmosphere, but actually how efficiently you can transport that moisture to a height that's compatible for cloud formation. As it turns out, very heterogeneous patterns of light absorption on the ground (for example, a city next to a forest next to a field next to a city), at very high spatial frequencies, are generally more conducive to cloud formation. So this emerging understanding, in just the past year or two, is pointing to the possibility for actually making a beneficial impact on cloud formation. But of course this field is still in its infancy, and that is something we would be very interested in looking at, and potentially participating in some experimentation.
“When the project moves beyond the local (individual household or individual village scale type of implementation), as far as global circulation goes, one major concern is the collapsing of the jet stream. That's a problem of the temperature gradient disappearing. Would putting mirrors over the North Atlantic reduce surface temperature enough to boost that? We haven't done the calculations to give an answer on whether that's possible. Our understanding right now is limited by the quality of the available Earth System models. As they improve in their ability to reproduce real world observations, it might be possible to ask whether surface albedo perturbations through mirrors might keep some of these circulations going, and whether there's ways to both provide a local benefit and assist the global circulation in a way that's favorable for the future of the planet.”
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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. This is heat mitigation using precision technologies to finely tune local albedo, "precision SRM", and nobody else is doing that. So calling it PSRM might help it to stand out more in a very crowded field of approaches, all of which are looking for attention and funding, or perhaps the already established term "passive daytime radiative cooling" (PDRC).
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, cellulose crystals are possible as well. 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.
"Alaska looks the best place to live in the U.S., and cities will need to be built to accommodate millions of migrants heading for the newly busy Anthropocene Arctic. With agriculture newly possible, the 'New North' will be transformed," Gaia Vince writes in Nomad Century: How Climate Migration Will Reshape Our World (2022). Is anyone in Alaska modeling these sort of decade scale projections and making plans accordingly? "Developing a radical plan for humanity to survive a far hotter world includes building vast new cities in the more tolerable far north while abandoning huge areas of the unendurable tropics." This echoes what James Lovelock wrote in his 2006 book, The Revenge of Gaia, where he described vast regions of Earth becoming uninhabitable for humans by the middle of this century. Forty years prior to this he said that "a large proportion of the total energy turnover will go towards the avoidance of ecological disaster". The future is paradoxical like this, and energy will be divided between creating new ways of living, preserving what we can from older ways of living before they are lost, and restoring what we once had. Our influence on the planet has resulted in more energy in the system, and we see the effects of this on the land, and in the sea and sky. Mitigating the risk this exposes us to will involve carbon emissions reductions, carbon removal strategies, and restoring surface albedo. This particular excerpt from Nomad Century focused on how the exodus northward could impact the North. It's an imaginative and hopeful story of "a planned, managed, peaceful transition to a safer, fairer world", the sort that Graeber and Wengrow encouraged in The Dawn of Everything, but it could easily go sideways. Another interesting story, though likely more tragic than hopeful, is how this exodus will impact the South. Mitigation strategies in equatorial regions may focus on leveraging the efficiencies conferred by latitude and therefore favor surface albedo modification (SAM). The story of saving what we can and potentially restoring what we once had will be just as uncertain in the New South as it will be in the New North. Vince writes, "Everywhere will undergo some kind of transformation in response to changes in the climate, whether through direct impacts or the indirect result of being part of a globally interconnected biophysical and socioeconomic system." One of the biggest problems today is that most people don't fully appreciate just how interconnected we really are. I look forward to reading the rest of Vince's book.
Allan Savory's 2013 TED Talk, "How to green the desert and reverse climate change," claimed that holistic grazing could reduce carbon dioxide levels to pre-industrial levels in a span of 40 years. That may have been too ambitious, as later studies found the actual rate at which improved grazing management could contribute to carbon sequestration is likely seven times lower. This suggests 280 years is more likely. And that's assuming "all else being equal", which is a very big assumption. But Savory's agroecological approach of using livestock to restore soil carbon and ecological productivity has gained a lot of attention, it's been described in many books and films (see Dan Dagget's Gardeners of Eden, or Netflix's "Kiss the Ground" for example), and many similar projects have been started that are based on this central idea: animals can be the key to healing the planet. Today "regenerative agriculture" is one of the biggest buzzwords in both agriculture and climate solutions. There's a lot of good reasons for that. For a significant number of people the animating logic runs: "If increasing (carbon emissions, techno-fixes, human interventions, and alienation from food production) all combined to lead to our current environmental problems, then decreasing all these should be a part of the solution". In theory, regenerative farming does appear to address each of these points: it acts through carbon drawdown and removal (CDR), and it appears low-tech while attempting to restore more harmonious biological relationships, rather than relying on human interventions. In short, regenerative agriculture is very appealing, for very good reasons. We need more common sense solutions like this. In fact, given the enormous costs of environmental destruction today, the question should really be: Why aren't we doing more of it, and can we do it faster? Can we cool the planet, reduce the impact of droughts and desertification on soil moisture content, build more carbon rich soil, and do it all in a far shorter time than 280 years, or even in less than 40 years? (I mean, can anyone really imagine the full cost of 40 more years of global drought, like the summer of 2022? Let alone 280 years? Not me.) It may be possible to make regenerative agriculture work faster and more effectively. If we combine low-tech CDR with low-tech SAM (surface albedo management), we could restore the carbon content of soils and the albedo of Earth, both of which have been declining precipitously. Take a look at this popular map of land use in America. Cow pastureland is more than enough surface area for integrated CDR and SAM. Rangeland/ grasslands occupy a similarly large area on other continents as well. Can the agricultural methods promoted by the Allan Savory Institute for CDR be combined with MEER's approach to SAM? "Regenerative agriculture" is the biggest buzzword in agriculture today, but it hasn't yet been clearly defined. Perhaps we should consider how regenerative agriculture standards can incorporate SAM standards to realize the full promise of addressing environmental degradation exacerbated through Earth's energy imbalance (EEI).
Is it possible to incorporate solar radiation management into new or existing approaches for renewable energy? Thomas Reis suggests using a single-axis tracking system. In his design mirrors are mounted under photovoltaic panels. They either concentrate solar radiation onto the solar panel surface, or adjust to reflect it back out to space when air temperatures get too hot. This achieves the dual purposes of avoiding the urban heat island effect (due to the poor albedo of photovoltaic panels) and achieving higher panel efficiency. The design attempts to optimize for at least two variables: energy production and albedo enhancement (cooling mitigation). If we add food production as another important variable to optimize, that's three. In turn, we can divide energy production according to whether we want electricity or heat. For example, replacing the solar PV panels with solar thermal panels is possible (and perhaps more useful at mid-to-northern latitudes). The cost/benefit of transporting all these values is also relevant (transporting food is relatively easy, electricity is harder, and transporting heat is the most restricted of all). Depending on how highly we weigh localization and food security, we may want all services at the same place regardless of the globally optimized locations. So let's consider another option: we could combine all these values into the same system and have "agri-albedo-voltaics" which utilize horizontally mounted mirrors and vertically oriented panels on agricultural land. This is something the Experimental Farms in Fairbanks or Matanuska campuses could look into. Anyway, we have the mathematical formalizations and graphical tools to represent all these sorts of things, if not always the data to plug into them to determine the optimal ratio and spacing for a given location. But before any solar farms are built, minimize energy needs through efficiency and degrowth. Minimize material needs through circular economy processes. And then, and only then, develop the infrastructure needed to support society. And when it is developed, do it in the least disruptive way, and anticipate possible changes in radiative forcing. Can installations be designed for negative radiative forcing? Are there business models for incentivizing distributed energy resources? Sealed founder Andy Frank described how his company “covers all the upfront costs and coordinates the work with trusted contractors. Homeowners pay the retrofit back out of energy savings, which means Sealed only gets paid if there are, in fact, measurable energy savings.”
So where is the best place to enhance albedo? If all we wanted to do is reduce global heating in the aggregate, then the best location is at the equator. Why? Here the angle of incidence of solar radiation is 90 degrees and the albedo of the open ocean is extremely low. But there are challenges here. However due to system interactions, it's not necessarily the case that the reduction of global heating would be greatest by enhancing albedo at the equator, or that it would result in the most co-benefits. Given polar amplification and the proximity to system tipping points (in the case of permafrost or sea ice loss), enhancing albedo in the north may be of equal (or in some local situations greater) value. There have been many proposals to address that. Recently Leslie Field's proposal to use glass beads was delivered a significant blow. See Webster and Warren's paper "Regional Geoengineering Using Tiny Glass Bubbles Would Accelerate the Loss of Arctic Sea Ice".
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| Slide from COP26 presentation |
An early paper (Feb 2021) describing the MEER project from CFC Together.
Ye Tao. Solar Radiation Management: Cooling the Planet with Surface Reflectors (2022) Delivered to Healthy Planet Action Coalition, this is an excellent video with some very insightful remarks during the Q&A afterwards. There is also a discussion group.
Climate Emergency Forum video at COP26 with Ye Tao, Peter Wadhams, Paul Beckwith, and Regina Valdez (slides).
James Lovelock. Novacene. (2019)
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) "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)
Dorion Sagan. Gaia versus the Anthropocene. (2020) "Particulate pollution, while blocking light and producing cooling in the daytime, more than makes up for the effect by reradiating solar and terrestrially reflected energy. Various aerosol particles — black carbon, brown carbon, coal fly ash-containing iron oxides that convert into even more absorptive magnetite in forest fires and so on absorb solar radiation and heat the troposphere. The implication is that reducing particulate pollution may lead relatively quickly to lowering Gaia’s temperature." It would also increase the effectiveness of surface-based albedo enhancement. (Interview)
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) See also infrared window.
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.
Catherine Clifford. White House is pushing ahead research to cool Earth by reflecting back sunlight. (2022)
Pablo Campra et al. Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain. (2008)
Alexander Marshak et al. Terrestrial glint seen from deep space. (2017) Satellite imagery frequently detects bright flashes on Earth. These "terrestrial glints" are "specular reflections off tiny hexagonal ice platelets floating in the air nearly horizontally" which "may substantially increase cloud albedo relative to diffuse reflectance from randomly oriented ice particles... and play a major role in the radiation budget." Our ability to better understand such naturally occurring specular reflections could help contextualize surface albedo modification (SAM) efforts, such as those being pursued by MEER. Additional reporting on this paper can be found (1, 2, 3). The Ashalim CSP plant in the Negev desert also appears as a bright dot on the daylit surface of Earth, when viewed from the right angle.
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