Some people -- including Harvard researcher Ye Tao -- believe that even aggressive decarbonization will still leave the Earth too hot to bear. He has developed a new idea for large-scale geoengineering: he wants to directly cool the Earth's atmosphere by covering large swathes of land & ocean with cheap mirrors. It's brash & ambitious, but the numbers show it could work.
This is really compelling - thanks David. Has Dr. Tao published anything peer reviewed on this? The most compelling piece for me is the idea of local benefits for deploying a global solution - I'd be curious to learn more about the results of his studies on agricultural productivity & urban comfort. I'll keep digging around & post anything I find here but if anyone else finds something worthwhile please do the same.
I also was excited by this and spent some time trying to find any published work on it. If there is any, it's exceedingly well hidden. Not on the MEER website, not on Google Scholar (except for a poster), not on the Tao Lab page. That, the slickly produced website, the rather aggressive disparagement of competing approaches, it all feels very wrong for a scientist. It's normal for commercial startups pushing vaporware, but it's not how honest scientists operate. I hope there are publications forthcoming, but if we're talking about the future of the planet and altering the weather, we really need a clearly argued document that can be checked by others, not some slides and youtube videos containing one guy's assertions. Every so often the crank/outsider is the guy with the best idea, so I want to keep an open mind, but even someone whose ideas are rejected by the mainstream can self-publish easily enough these days.
I was *very* pleasantly surprised by this podcast. I was expecting a crank (except that it was on Volts), and got someone who has an amazing handle on the scales of both the problems and solutions. Echoing comments below, I'd love to see peer-reviewed work and/or other scientists' takes on his arguments and work (including materials scientists on whether the structures are as durable as he claims). I especially thought his point that farmers are already shielding their crops with something fairly similar was quite compelling, from a "could this actually be implemented widely" perspective.
For anyone tempted to comment without listening - give it a listen first; he probably addresses your question/concern.
This was a very interesting discussion (as always!). We need as many tools in the climate fight as we can get, and mirrors are a fresh addition to the toolkit. The fact that they can deliver local benefits, thus yielding "selfish" motivations that could drive deployment, is promising.
However, I'm confused about the things Dr. Tao says about the trajectory that we're on if we don't find some dramatic new intervention (such as mirrors). Specifically:
1. His statement that we have about 1.5°C of additional warming already locked in due to inertia effects (from the 1.5 W/m^2 of current net energy influx). This seems blatantly inconsistent with the IPCC scenario forecasts?
2. His statement that CO₂ capture (DAC) is "dishonest", in that at best it can barely provide enough cooling to compensate for the emissions generated to build and operate the capture process. I can't begin to do the math on this, but plenty of people who'd I assume *can* do the math, are on board with DAC as being part of the solution.
3. The warming spike that we'll get when we stop emitting aerosols. That's true, but there are counterbalancing effects that he did not mention. If we're able to reduce emissions of short-lived GHGs such as methane and carbon monoxide, that should more or less balance the loss of aerosol cooling. (Explanation at https://climateer.substack.com/p/aerosols; disclaimer, that's my personal blog.)
I was also surprised that he just assumes that no one realised the locked-in heating from these 1.5W/sqm. I'm sure the IPCC reports translate this and have a firmer timescale than his handwavey "decades or whatever" time frame over which this temperature rise will be realised.
I understand that this might be a good solution and that heat is the actual problem so this stuff needs research but creating urgency by being fast and loose with the science when it suits you is one sure way to lose serious engagement with the topic.
I wish he was more honest and David I wish you challenged him on this in the interview.
Zhou, Chen, Mark D. Zelinka, Andrew E. Dressler, and Minghuai Wang. 2021. Greater committed warming after accounting for the pattern effect. Nature Climate Change Vol. 11 February" this paper asserts that more than 2° C is committed.
> ...surface warming to date has been large in certain regions but small in others, which has temporarily allowed Earth to shed heat more efficiently. Ignoring this “pattern effect”, as has been done in previous studies, gives the false impression that Earth’s energy budget is nearly balanced and implies that committed warming is only about 1.3°C (2.3°F) above pre-industrial levels. The team’s updated estimate is substantially larger, with a most likely value of 2.3°C (4.1°F).
Poking around at random, I found a fairly strong critique here: https://judithcurry.com/2021/01/19/committed-warming-and-the-pattern-effect/. I am not qualified to evaluate the merits of either the original paper, or the critique. I *will* say that the idea that we have another 1.5°C locked in (per Dr. Tao; this paper gives a smaller figure) is clearly controversial, and I don't like that Dr. Tao cited it as fact without any elaboration.
If we survive, it will because we learn to work with nature, rather than trying to control it. Much work is ongoing in the field of regenerative agriculture which provides a mechanism to transform deserts into productive, cooling, water retentive grass lands. An excellent example can be found at:
These types of improvements can be accomplished on all sorts of physical scales and climates and has the benefits of cooling the earth, improving soil health, reducing chemical inputs, increasing water infiltration, reducing labor, and increasing profits, all while capturing and sequestering carbon. All free and all you need is a diverse selection of seeds, grazing animals, human labor and a year or two for the changes to begin. This approach also produces food. It is nature based geoengineering. It is not something agribusiness is interested in due to the reduction in required inputs. The disinterest is similar to the interaction between solar and the fossil fuel industry, because both approaches reduce our dependence on these industries.
The human race has a long and well established history of desertification: the process by which fertile land becomes a desert, typically as a result of drought, deforestation, but mostly because of inappropriate agriculture practices. Counter these approaches and great things can happen. Imagine turning all the deserts our species has created back to fertile productive land. This is possible. So I would like to see a calculation that proves that mirrors are better than a nature based approach to cooling our planet. I think nature will out perform the mirrors. Similar work can be done in the oceans of the world.
Peter thanks for your comment, my intent was not to create a false dichotomy and I do not think that i do. De-desertification is not mentioned or considered as an alternate approach at any length although Dave does bring it up. Why does the analysis focused on agriculture lands rather then deserts ? There is a discussion of the possible creation of small micro-climates and local cooling, nature already has this covered. We need to push to implement solutions that we know work know while developing additional mitigation techniques. We will need them all.
Hi Christopher, thanks for the response. This episode was really interesting and many questions popped into my head. I was actually thinking how this technology could help places like Las Damas Ranch and other places bordering areas undergoing desertification. I truly believe regenerative agriculture is a big part of the solution, actually I think I've sent a message or two to David Roberts asking for an episode on it, but with all the strengths of regen ag, I worry about the extremes like the heat domes the world have been experiencing lately. Even with the best practices would something similar devastate a place like Las Damas Ranch?
That conversation was the most vertiginous ride I've been on in a while - from despair that we're already past 2 deg, to discovering a new source of much-needed hope that there might be a relatively simple, quick, reversible cooling solution with possible co-benefits. Eager to see how this develops.
Having 2 geoengineering pods on my feed within days, I of course had to listen to them both. This is a more general view than David's deep dive as its aimed at a more general audience. No mention of mirrors at all which one can take as a sign that it's not yet a viable option or just not the expertise of the interviewee here.
I hope this link works and some may find it interesting. There are interesting fairly varied people who come to this one so you may want to sub too. 😊
[People I (Mostly) Admire] 79. Solar Geoengineering Would Be Radical. It Might Also Be Necessary. #peopleIMostlyAdmire
Looking for climate/sustainability-related book recommendations! I have $500 worth of professional development funds available to me at work and I'd like to spend it on books - thought this would be the perfect place to get recs! Thanks in advance!
How deep do you want to go and where do you want to start?
For hopeful context solidly in the core of where our solutions will arise, I'd start with Saving Us by Katharine Hayhoe, Electrify by Saul Griffith, and Solar Power Finance Without the Jargon by Jenny Chase. These are great baseline, current, and hopeful books about what we can do individually and collectively. The financing book, in particular, provides a look under the covers on how the transition actually gets done, revealing that progress isn't a steady climb of deliberate success piled upon deliberate success. Add Timefulness: How thinking like a Geologist can help save the world by Marcia Bjornerud, a very good book that places today's wackiness in geologic context.
If you want a fun scare: Global Catastrophic Risks, Uninhabitable Earth, and The Ministry for the Future.
I just picked up The Overstory by Richard Powers on strong recommendations but haven't started yet. And there are always the free options of the IPCC reports parts I, II, and III that'll go as deep as one could desire. If you count the BEvERages you'll need to finish them you can polish off that professional development credit.
This is great, thank you so much Geoff! I'm looking for pretty much anything under the umbrella of "sustainability" (whether that's related to clean energy, climate policy, urban planning, circular economy etc). Trying to build on my current foundation without getting into anything TOO technical -- I don't currently work in the climate space but want to make the pivot so am trying to learn more and figure out what I specifically want to pursue
Some books I've enjoyed have been Natural Capitalism (Paul Hawken), Doughnut Economics (Kate Raworth), Superpower & the boom (both by Russell gold), Sustainable tourism on a finite planet (Megan epler wood), Electrify & uninhabitable earth (both of which you mentioned)
Others on my to-read list - fighting traffic (Peter Norton), Power struggle (Richard Rudolph - mentioned by David on one of these podcast episodes), Braiding sweetgrass (Robin Wall Kimmerer)
For broad surveys across the solution/problem space you can always start at https://www.withouthotair.com/ and then dig deeper into the topics/references that resonate. MacKay transitioned into sustainability in 2006 and passed only 10 years later but this broad survey coupled with additional context as Chief Scientific Advisor of the Department of Energy and Climate Change for the United Kingdom really grounds the problems and solution space in things that fit the problem(s) at hand. He'd be pleased at the advance of learning curves in solar and wind, but probably not surprised that incumbent stakeholders are the greatest obstacle to progress.
To that latter point, reading Thucydides isn't wasted because the problems of today are exactly the problems of... always when it comes to organizing and collaboration among humans. Social action and coordination are the problems of sustainability, be it Big Cement advertising against Glulam or fossil fuel gaslighting and regulatory capture - we're looking at a people problem. Anyone who is interested in that work has my sympathy and thanks, relatively speaking the science and technology parts of the problems are easy.
MacKay hits on this in his preamble describing his transition into sustainability, with three additional book recommendations that together show the contrast in view among smart people and, in hindsight, how quickly our knowledge can become dated: https://www.withouthotair.com/c1/page_2.shtml Goodstein's Out of Gas, Lomborg's The Skeptical Environmentalist, and Lovelock's The Revenge of Gaia. Many of the figure specifics in WithoutHotAir need updating, but the relationships and equations still hold. The national-scale renewable energy mix maps are illustrative of just how big some of the proposed solutions become when deployed in good faith.
As an aside, the introduction to Goodstein's states of matter is the best introduction to statistical mechanics, and perhaps any book, possible. Out of Gas, on the other hand, was overly pessimistic about how rising costs induce technological development in any field, and how learning curves work to change the terms of problems once they graduate from the lab and theoretical world and into the dirty world of engineering and deployment. He's on much firmer ground in physics of condensed states. We've identified and reduced processing and extraction costs for a mind-numbing quantity of oil over the last 20 years and will easily exhaust our carbon budget for a survivable climate well before we 'run out of oil,' in some ways this has been the perpetual story echoing again from the 1981 National Geographic talking points on energy independence and supply. This common storyline keeps recurring because it is useful to a specific set of stakeholders - again, the people problem and it trumps everything else (until the implacability of climate physics and chemistry deals with the people - and end we all would prefer to avoid). To the good, drilling advances will transform hot-rock geothermal as the last 15 years of technological advances drift out of fracking and into renewable geothermal production. Crustal geothermal potential comically dwarfs every other source of energy available, and is available everywhere once we get past a real but straightforward technological barrier. No magic of controlled fusion required.
* This does not address the increasing acidification of the oceans, which is seriously threatening all sea life--especially that which we depend on most.
* It did not address the likely problems of weather phenomena resulting from the use of such cooling agents. Any time a cool front meets a hot front, there is turbulence and a potential for storms. Doing this on a level that could change the course of the climate emergency could promote major weather phenomena. This was not mentioned.
I vote we reduce fossil fuel use on an emergency basis. If this was being addressed as the emergency it is, we would already be reducing speed limits to 55 mph, and connecting our grid up as though it were a wartime project. This may seem extreme now, but it will not in 4 years, to say nothing of 7 years.
Dr Tao has ranked the constraints and tackled them in order. CO2 is bad, but it kills us well after the heat does the job so he's looking to tackle the heat part first - as he explained. In the IPCC reports from last year, you will note there is a difference between radiative forcing that we're trending towards and the temperature we're trending towards - the bulk of that difference is the aerosol effect retarding warming. With radiative forcing at 3.5C... that's very bad, and while removing the CO2 alone, today, will stop warming from CO2 feedbacks swiftly, we'll change a bunch of other stuff at the same time. Stopping combustion will rapidly drop many 'bad' things in the air that are coincidentally keeping the temperatures down - so transitioning away from fossil fuels makes the heating problem worse before it makes it better. There was a lot of speculative work around seeding ship wakes with bubbles or filling aqueducts and reservoirs with white plastic balls to deliberately modify the planet's albedo. Geoengineering for albedo doesn't require every deployment to work, or work optimally, at every time - but it does require operation on a global scale. Fortunately, glass making is an ancient technology and raw materials are some of the most common in the earth's crust. It becomes a social problem, and a hard one due to the impact on every person everywhere to affirmatively participate in the solution (it'll be everyone's land/home/farm).
Dr. Tao has spent a lot of time making a solution stupid enough to scale and should be commended for that. If you are pushing a chemical reaction to remove CO2 you exhaust all electricity generation worldwide at about 1MT CO2. That's a problem, certainly because we need more electricity generation to displace fossil fuel consumption first. None of the popularly funded solutions are yet stupid enough to compete with changing albedo or planetary shading.
I cannot imagine the deployment to go smoothly on sufficient scale to register, however. Between property rights and water coverage, physical mirrors represent a possible pathway, perhaps not a plausible one. Moving the mirrors into space reduces the required surface area by a factor of 8 and prohibitions on work there are notoriously lax, but does dramatically increase the installation cost/investment. A space based shade system needn't be glass or even any particular color, very thin structures can cast shade - when thermal management and station keeping are managed. I'd much prefer a rogue billionaire building a solar shade to performing a stratospheric aerosol injection - reducing the incident radiation before it gets to us at all is a knob with less variability in interactions - though we cannot yet estimate all interactions on any of this.
The IPCC reports and scientists keep saying as loudly as possible, we must stop burning fossil fuels now--not 30 years from now, or 50 as some plans indicate--and most of the world is not coming anywhere near what they say they plan to do.
There are major issues with both the delays in stopping the burning of fossil fuels and the geoengineering that is supposed to save the world from the worst effects.
When considerations like ocean acidification are set aside--mentioned, but not addressed as relevant, then one is performing a kind of red-lining. One has divided the world into those who will have efforts made to save them and their children, and those that are being tossed into a horrific future. Specifically, those hundreds of millions of people who depend on the ocean for their food, their living, and their future.
The second point that is highly questionable is how the world can keep absorbing energy into the oceans at one atom bomb per second 24/7/365, over three fourths of the planet while some fantastic cooling is occurring over the remaining one fourth. Yes, the cooling might well occur exactly as outline, and that is the problem--the energy differential manifests as weather. Local weather will be profoundly changed, and along coastlines more than is already now experienced.
When engineers propose this kind of solution, they are asking us for the authority to make global changes with no intention of accepting responsibility for all the outcomes. Too often it results in the voices of too many people being silenced so the experiment can proceed. It would be an experiment of global proportions, with no one able to anticipate the scope of the impact, much less prevent disasters from occurring.
We need to put more human effort and creativity into getting us off fossil fuels, and less into evasive engineering of red lines that do what those red lines have always done--destroy the lives and welfare of people who are economically safe to ignore.
Given the thermal impact of such a solution as proposed, it does not require too much imagination to forecast that hurricanes may well increase in destructive power as they meet cooler land masses. But, this was not a consideration in the information presented. Anyone pursuing any geoengineering project should read "Under a White Sky". Otherwise, the project risks becoming little more than well, smoke and mirrors.
Dr. Tao is just pointing out that if we only fixate on getting off fossil fuels we'll step on a rake of consequentially lowering aerosol effects on radiative forcing - and we should have an answer for that too. Both the podcast and the IPCC report note that the radiative forcing for greenhouse gases in the atmosphere today is higher than the temperature change we've seen to date. Aerosols currently in the atmosphere are suppressing observed warming by about 1.2C (through albedo and direct effects). Aerosols have a shorter lifetime than the CO2 meaning they'll drop out first when we stop burning things - leaving us with decades of higher radiative forcing before drawdown catches up. As a consequence of halting fossil fuel consumption and clearing the air of (otherwise harmful) aerosols we'll jump up an additional 1.2C making things worse for the ocean heat, storm formation, ocean dependent ecosystems, etc. The proposed solution to stop burning fossil fuels (alone) is also as problematic as a steady as we go approach for those people who depend on the ocean for their food, their living, and their future. Hence the interest in complementary solutions to offset the undesirable consequences of the desirable course of action.
This doesn't ignore the importance of Ocean Acidification, just recognizing that the ocean acidification system is a lot less sensitive to change in annual emissions than aerosol contributions to global cooling - and hence the greater importance in dealing with that heat influx while we drawdown CO2 emissions and eventually CO2 content from the atmosphere. As we drawdown CO2 from the air the Ocean will become a CO2 pump which improves the ocean acidification position. But, drawing down CO2 is going to take a lot longer than we like to pretend and during that time we'll have this unmoderated heat input because we got rid of the aerosols when we stopped burning fossil fuels. We've got a lot more work to do than the simple make it stop narrative suggests. How much more? Atmospheric CO2 is measured in gigatons, ocean currents are measured in sverdrup which is a silly big unit that means the AMOC will turn over as much mass as all the CO2 in the atmosphere in a matter of minutes (2 minutes covers global annual emissions). Ocean concentrations of CO2 are about 100x atmospheric, and the surface vs. deep ocean reservoirs are truly vast - silly big. Scale matters. Not dealing with the reduced radiative forcing retardation during the transition is a sure way to detrimentally change surface ocean character and everything that depends on it for survival.
No one asked permission to start burning coal to do work and indeed the last 200 years of progress has been a celebration of that insight. We are already geoengineering, and on a scale that we do not recognize from any historical record. It is true that the kind of thinking that got us into this problem won't likely be the thinking that gets us out of it, but vetoing responses and forbidding research and development into new mitigations leads us away from successful transition rather than towards it.
We are not in a zero-sum game here. Taking us off fossil fuels in a decade or two is 10x faster what it took to get into this predicament - it is a huge bet and itself an exercise in geoengineering. It would be easy and human to fixate on one part of the problem at the expense of the whole system and score a pyrrhic victory. Engineers and scientists checking the math and assumptions are essential for our shared success - the work of getting off fossil fuels is a social problem, after all. The technology has been here all along - and now is economically optimal to deploy.
I understand the problem well. I do not question the basis for the research, nor do I oppose it. I do think this needs attention by the IPCC and a deep discussion at a future COP. I would be much more comfortable if respected climatologists like Michael Mann found the consequences of creating massive thermal differences to be acceptable and helpful. I have my doubts about that, especially because this aspect is not addressed.
And yes, I am equally concerned about the environmental justice of playing a global game of "Russian roulette" with the climate in order to benefit nations that contribute most to the problem, and are unwilling to change the dynamics. The nations who contribute least are likely to get no benefit at all from a wide scale implementation of this technology.
There are other ways to increase the earth's albedo to compensate for aerosol depletion, including increasing grasslands, sea grass, and appropriate planting in degraded areas. Those remove carbon, too.
What happens if . . .
The OPEC nations decide that it is in their best interest to massively implement this strategy through the Middle East, South Asia, and North Africa? They can afford it, and may feel the cooling can at least benefit them directly. The unbalancing of weather and climate factors could be catastrophic for other nations around the world. And OPEC and US fossil fuel interests make it clear that they will do pretty much anything to extend fossil fuel use into the far future.
Other solutions are possible:
Guest post: Reducing material use could cut emissions from cars and homes by at least a third - Carbon Brief
Hi Gary, have you considered all the people who will die in the middle east, south Asia and north Africa and many other places around the world waiting for the rest of the world to get their act together? People can't live in 50C heat. Do you have a solution for them? It's happening right now. It's only going to get worse. It's not like the United States is a beacon of hope. And as for the IPCC they've been extremely conservative, they still don't properly account for permafrost melt. If I was someone in India who needed to turn the temperature down a couple of degrees to survive, I wouldn't have a lot of patience for your dismissal of this technology. This isn't just an academic exercise, I think many forget that. If the rest of the world doesn't like well maybe they should do something.
I am aware of the current and on-going death toll from burning fossil fuels. That is precisely why I believe in doing what the climate scientists are telling us to do--stop burning fossil fuels"--and instead of engaging in techno-optimism and academic exercises, we need to meet our obligations to other nations for the 1.9 trillion dollars we have already done to the environment. We could begin by cleaning up the air, and that takes us back to taking an effective stance on no longer burning fossil fuels. There is so much more we can and could do *now* without engaging in geoengineering experiments of dubious benefit to the planet.
The reality is that 90% of the sun's heat is being absorbed into the oceans, and only about 10% on land. Cooling the land sufficiently to reduce the heat balance is a bad idea even from an elementary physics perspective--which is about all I have.
I am not going to be convinced otherwise by sarcastic or caustic remarks in regard to my opinion. I personally reduce my carbon footprint, have solar panels, heat pump, etc. Are those making remarks about my contributions doing as much? I hope so.
I found this discussion to be fascinating and would love to learn more, and to hear perspectives from folks who might disagree with Dr. Tao's analysis. A question I have for Dr. Tao: I have seen the idea of white roofs discussed now for a number of years as a potential approach to ameliorating climate change. It seems to be a similar logic to your proposal of mirrors. I am curious about the pros and cons of white roofs vs mirrors vs some combination of both?
Albedo approaches struggle with just how big a planet is and how rapidly natural processes are going the other way. We're growing darker much faster via snowpack and ice loss than we could achieve with white roofs, roads, and reservoirs (or wakes, even with multi-week dwell times). Any spot on the earth is contributing only a fraction of the time as well - the whole rotating sphere thing. That white roof in space is 8x more effective just from the geometry, and much more when you consider avoiding the in-atmosphere interactions of the incident radiation. Part of why we call it a greenhouse effect is that once the power makes it into the atmosphere it is heating things up - even if we're bouncing it back out from the surface instead of just soaking it up on the spot. There is also a radiation effect with the structure - a black roof will emit heat faster so if there is more heat in the building that white roof is hurting, for instance at night or in winter. For the people in the home, a comfortable temperature is the primary driver. Everything is more complicated when you solve the problem at ground level.
Sunshades at L1 are a grand sci-fi tradition, and with now vastly reduced launch costs per kg, and better understanding of large scale space structures these things might be buildable in the trillion dollar range? James Webb is at L2 so it always sits in Earth's shadow, putting a sunshade at L1 replicates that arrangement for Earth itself and would be both tunable and diffuse in impact. I'm not holding my breath, but it sits in the same class as a mirror ball or white roof approach.
As with most things that are good for the environment or meant to repair other people's damage there is no buyer. The expectation that our solutions will themselves become viable businesses naturally narrows one's perspective to things one can sell or convince others might have value - like removal offsets. A solar shade with a high up front cost and ongoing upkeep might minimize global costs but doesn't make one's yield targets.
Are you aware of any estimates of how many debris collision events per year would be expected for a roughly earth-sized shade or mirror at L1? It strikes me, so to speak, that the ongoing repair costs might well be greater in short order than the original construction cost...
If it is too good to be true, maybe take a deep dive. I for one see no depth to MEER. No numbers, no modeling, no equations, no PHYSICS. Maybe before Dr. Tao worries about how to explain MEER to non-scientists, he should worry about explaining it to scientists?
Paul, a simple google search will find numerous recorded presentations from Tao that include all kinds of models & equations. It was all I could do to keep the pod from being overrun by numbers. It doesn't sound like you looked very hard.
David, I love your podcasts and I will continue to listen to them, but I respectfully disagree on this one. Yes, a mirror will reflect visible light back up into the sky. There may be some potential there. It may be worth investigating. But Dr. Tao's presentations appear to me to be junk science. We definitely should stop burning coal, contrary to what Dr. Tao says. We absolutely should keep building wind mills, despite what Dr. Tao says. (Friction between the air and the blades is warming the planet? Give me break!) Have you tried to look up any of the sources on his presentation? I have and failed miserably. I may not work as hard at this as you do David, but should I really have to work all that hard to verify what your guests say?
That wind turbines create heat in the process of converting energy from one form to another is definitionally true. Laws of Thermodynamics and Carnot Efficiency level fundamentals of how the world works. So, outrage at this most tautological of findings is curious. Outrage at the lack of practicality of the finding might be more appropriate.
This paper (https://www.cell.com/joule/fulltext/S2542-4351(18)30446-X) in Joule goes further on that topic and establishes a modelling relationship in atmospheric mixing that drives a much larger warming impact due to the interaction of wind turbines in the atmosphere. This isn't implausible, though this also isn't an experimental result. It describes a mechanism that might lead us to an unanticipated consequence. When a new experiment generates data to invalidate this theory, the theorist can turn around and create a new theory in light of the new data rather swiftly and keep more experimentalists spinning for another decade (or three). This is literally how we learn new things about the world.
The main gist of that paper is that PV is superior to Wind from an avoided warming perspective and comes with a laundry list of modelling assumptions, most of which can invalidate any amount of mathy analysis. For instance, while this is a good journal and a careful paper it doesn't address economic, social, or political costs or even the material lifecycle of the two power generating systems. Wind Turbines can payback in a year and PV at about 12 years, this dollars payback is tied to manufacturing costs, land use, deployment, and maintenance. And of course the direct impacts like PV albedo vs. the Wind column mixing - many poorly understood variables in an open system. Both are clearly better options than continued fossil fuels - noted at 30x better on the radiative forcing replacement of PV for fossil fuels here (cited in the Joule paper): https://pubs.acs.org/doi/abs/10.1021/es801747c
Probably the most eye-catching caveat in the Joule paper is that it will take 100 years for the wind turbines to net out lower heating than the fossil fuel capacity they replace. I think the explanation here is that the wake of the fossil fuel combustion runs through 100 years of consequences (10 years for methane, 100 for CO2, 114 for N2O - for 3 of the 7 GHGs) that are in steady state today. Swapping to a wind turbine puts us into a "paying for both" worst of both worlds state as we wait to unwind the fossil fuel legacy. This seems trivially true, and unfair as a measure of comparison - even academic journals can go for the attention grabbing head to drive engagement. It is also not a step function, so it is not clear why and how this inflection point drops out of their model. Legacy emissions warming, if we stop emitting instantly, should cause a rapid increase warming as aerosols drop out (+1.2C - global thermal inertia and radiative flux willing) followed by a slow decline in warming effect as the GHGs age out on their own lifecycles. The 0.2C boost from large scale wind roll-out, compared to the 2.5 ish already in the air from fossil fuel GHGs puts it into perspective - except the small one is a theoretical finding and the big one empirical.
This isn't nothing, but it also isn't the most important thing. What it does do is help us avoid the unexpected and a counter narrative of "we turned off the fossil fuels and the temperature went up!" It is true that if we stop emissions today we will stop warming the planet, while it is also true that if we stop emissions today the planet will warm significantly in the near term. The difference is that we've already banked the warming potential and have been temporarily suppressing - largely on accident (cleaner fossil fuels are better for our lungs and worse for the global temperature).
I'm not sure what source(s) you've seen so I cannot comment on it(them). But I would be surprised if the conclusion of someone discussing global albedo modification was to continue burning fossil fuels without end. Coal burning does have a global albedo modification effect, but the whole reason we are talking about other global albedo modifications is because the aerosol emissions are short lived reductions to heating and GHG heating is long lived. Stopping all aerosol emissions (as a partner effect to stopping all fossil fuel GHG emissions) will cause a heating across the planet as the aerosols drop out and the GHGs remain - it will be releasing the latent heating potential we've already put into the atmosphere. This is the whole criticism of deliberate SO2 aerosol seeding - the short term retardation comes with huge costs and does nothing to remediate the underlying problem of there being too many GHG in the air, leaving us with a permanent tax of maintaining the system in ever increasing doses. This is also an applicable criticism of a mirror-ball world, it doesn't solve all the problems on its own. But here, at least, is a more robust incarnation of "aerosol seeding for albedo modification on a global scale." It doesn't replace transition, but describes a potential solution to an essential complement necessary for surviving the transition.
I too was thinking that the actual impacts even on his small scale projects are still unknown. He didn't touch on frost for example which I heard can be an issue from windmills and must be much more an issue here. A single site in new Hampshire to 10-15% of arable land in all sorts of climates scale. My guess is that it looks like a niche solution as part of a toolbox that can be installed together with PVs, until there's more research.
Wondering what you think of the approaches Peter Fiekowsky suggests in his new Climate Restoration book. They're not exactly geo-engineering but related, and address the same issue that we have to remove carbon as well as stop adding it.
A Gigaton is a big unit. The largest Olivine deposit in the US is north of Seattle, a mountain with 2GT of CO2 fixing capacity. We're emitting at 40GT annually. You'll blow the energy budget doing the work, not to mention be sluicing mountains into the sea, before we get to sufficient scale. Olivine in seawater fixes CO2 at close to 1:1; basalt is another popular option but is much less favorable at 450:1 by mass, there is a lot of basalt in the crust but those are mind-bending volumes.
There are few natural systems that operate on sufficient scale or mass to make a difference quickly. Albedo control is one of those systems, as it moderates the input energy to the planet in one go and doesn't (usually) require annual contributions to maintain historic effectiveness (unlike captures against continued emissions).
The Great Kelp hope got a lot of attention recently, but we'd need a width of 160' of kelp forest on every coast everywhere to get into gigaton range... and the dwell time and actual carbon flux are both in doubt as the kelp forest is a far richer ecosystem than the natural ocean it paves over.
We need to be doing all the things, and firstly and above all stopping the geologic carbon pump into the contemporary carbon cycle. But we should also understand that we're not all yet grappling with the size of the problem yet and the hard global constraints against action. Things like how much energy is available for industry each year, how much mass we manufacture each year as a planet - CO2 is #1 by the way. To think we'll create an industry 500x the size of the greatest material output worldwide just to fix the current system (e.g. using a basalt CO2 fixing plan, like at Climeworks), it just isn't at the right scale for the problem at hand.
I would definitely use synthetic routes for feedstock materials, plastics from carbon capture could be delightfully circular, but not for the primary task of quickly taking control of the global temperature. Basalt weathering to remove CO2 is normally a 500,000 year process; the Earth will eventually work through our CO2 backlog. Not all of us can afford to have a geologist's patience about it though.
Space is pretty big and L1 is definitely not a crowded place like low earth orbit, but James Webb just took a larger than expected micrometeorite strike at L2 so it isn't empty either.
The good news is that a micrometeorite strike doesn't cause a lot of trouble if you don't resist it. Let it blow through and avoid absorbing its kinetic energy. A micro-scale hole in a 2M sq. km array isn't a large degradation. There are several approaches to creating a solar shade and very few envision a rigid structure that takes a hit and shrugs it off. Mostly there are micro-mirror satellites in a cloud and if one gets hit it just gets popped out of the array, or ultra thin materials that are easily pierced. Shedding heat and station keeping around the saddle point are bigger problems for anything large at L1 - even if the thing is just serves as a diffraction grating in space to scatter the sun.
The good news, there will be plenty of solar power available to put to work. The challenges are around mass and coordination of such a large array.
Any array wouldn't be earth sized, though. We're only trying to adjust a few percent of solar incidence; but a 2,000km per side 'thing' in space is still silly-big no matter how small its component parts or thin its pieces.
Good question! (Presumably the answer must be yes.) Also, how do the mirrors fare in a strong wind? I'd love to see a careful published analysis of feasibility and impact for this proposal. Unfortunately, there doesn't appear to be any, which is a bad sign.
I was a little bothered when Ye Tao said that the solar insolation was 1.5 Watts/square meter. I always knew that that the sun's power was 1.0 Watt/square meter. Otherwise, it was and interesting proposal. However, I believe that increased solar and wind power can stop continued global warming.
I think it's possible you're confusing the solar insolation (about 1500 W/m^2 at top of atmosphere, maybe closer to 1000W/m^2 at sea level) with the imbalance between radation (mostly visible) in and IR out, which is a much smaller quantity.
Yes, Jim, it is 1.0kW/square meter of sun power that hits the earth. However, Ye Tao was talking about what hits the earth, where he deploys his mirrors, not 1.5kW/square meter.
I was pointing out that kilowatts are not the same as watts (in fact, they're 1000 times greater). And "power in minus power out" (What Tao was talking about) is not the same as "power in" (the value you're referring to).
This is really compelling - thanks David. Has Dr. Tao published anything peer reviewed on this? The most compelling piece for me is the idea of local benefits for deploying a global solution - I'd be curious to learn more about the results of his studies on agricultural productivity & urban comfort. I'll keep digging around & post anything I find here but if anyone else finds something worthwhile please do the same.
I also was excited by this and spent some time trying to find any published work on it. If there is any, it's exceedingly well hidden. Not on the MEER website, not on Google Scholar (except for a poster), not on the Tao Lab page. That, the slickly produced website, the rather aggressive disparagement of competing approaches, it all feels very wrong for a scientist. It's normal for commercial startups pushing vaporware, but it's not how honest scientists operate. I hope there are publications forthcoming, but if we're talking about the future of the planet and altering the weather, we really need a clearly argued document that can be checked by others, not some slides and youtube videos containing one guy's assertions. Every so often the crank/outsider is the guy with the best idea, so I want to keep an open mind, but even someone whose ideas are rejected by the mainstream can self-publish easily enough these days.
I was *very* pleasantly surprised by this podcast. I was expecting a crank (except that it was on Volts), and got someone who has an amazing handle on the scales of both the problems and solutions. Echoing comments below, I'd love to see peer-reviewed work and/or other scientists' takes on his arguments and work (including materials scientists on whether the structures are as durable as he claims). I especially thought his point that farmers are already shielding their crops with something fairly similar was quite compelling, from a "could this actually be implemented widely" perspective.
For anyone tempted to comment without listening - give it a listen first; he probably addresses your question/concern.
This was a very interesting discussion (as always!). We need as many tools in the climate fight as we can get, and mirrors are a fresh addition to the toolkit. The fact that they can deliver local benefits, thus yielding "selfish" motivations that could drive deployment, is promising.
However, I'm confused about the things Dr. Tao says about the trajectory that we're on if we don't find some dramatic new intervention (such as mirrors). Specifically:
1. His statement that we have about 1.5°C of additional warming already locked in due to inertia effects (from the 1.5 W/m^2 of current net energy influx). This seems blatantly inconsistent with the IPCC scenario forecasts?
2. His statement that CO₂ capture (DAC) is "dishonest", in that at best it can barely provide enough cooling to compensate for the emissions generated to build and operate the capture process. I can't begin to do the math on this, but plenty of people who'd I assume *can* do the math, are on board with DAC as being part of the solution.
3. The warming spike that we'll get when we stop emitting aerosols. That's true, but there are counterbalancing effects that he did not mention. If we're able to reduce emissions of short-lived GHGs such as methane and carbon monoxide, that should more or less balance the loss of aerosol cooling. (Explanation at https://climateer.substack.com/p/aerosols; disclaimer, that's my personal blog.)
Can anyone shed light on this?
I was also surprised that he just assumes that no one realised the locked-in heating from these 1.5W/sqm. I'm sure the IPCC reports translate this and have a firmer timescale than his handwavey "decades or whatever" time frame over which this temperature rise will be realised.
I understand that this might be a good solution and that heat is the actual problem so this stuff needs research but creating urgency by being fast and loose with the science when it suits you is one sure way to lose serious engagement with the topic.
I wish he was more honest and David I wish you challenged him on this in the interview.
Zhou, Chen, Mark D. Zelinka, Andrew E. Dressler, and Minghuai Wang. 2021. Greater committed warming after accounting for the pattern effect. Nature Climate Change Vol. 11 February" this paper asserts that more than 2° C is committed.
Interesting. The paper is paywalled so I couldn't read it, but the key claim (from a summary at https://climatemodeling.science.energy.gov/research-highlights/greater-committed-warming-after-accounting-pattern-effect) appears to be:
> ...surface warming to date has been large in certain regions but small in others, which has temporarily allowed Earth to shed heat more efficiently. Ignoring this “pattern effect”, as has been done in previous studies, gives the false impression that Earth’s energy budget is nearly balanced and implies that committed warming is only about 1.3°C (2.3°F) above pre-industrial levels. The team’s updated estimate is substantially larger, with a most likely value of 2.3°C (4.1°F).
Poking around at random, I found a fairly strong critique here: https://judithcurry.com/2021/01/19/committed-warming-and-the-pattern-effect/. I am not qualified to evaluate the merits of either the original paper, or the critique. I *will* say that the idea that we have another 1.5°C locked in (per Dr. Tao; this paper gives a smaller figure) is clearly controversial, and I don't like that Dr. Tao cited it as fact without any elaboration.
If we survive, it will because we learn to work with nature, rather than trying to control it. Much work is ongoing in the field of regenerative agriculture which provides a mechanism to transform deserts into productive, cooling, water retentive grass lands. An excellent example can be found at:
https://understandingag.com/case_studies/las-damas-ranch-case-study/
There are many more.
These types of improvements can be accomplished on all sorts of physical scales and climates and has the benefits of cooling the earth, improving soil health, reducing chemical inputs, increasing water infiltration, reducing labor, and increasing profits, all while capturing and sequestering carbon. All free and all you need is a diverse selection of seeds, grazing animals, human labor and a year or two for the changes to begin. This approach also produces food. It is nature based geoengineering. It is not something agribusiness is interested in due to the reduction in required inputs. The disinterest is similar to the interaction between solar and the fossil fuel industry, because both approaches reduce our dependence on these industries.
The human race has a long and well established history of desertification: the process by which fertile land becomes a desert, typically as a result of drought, deforestation, but mostly because of inappropriate agriculture practices. Counter these approaches and great things can happen. Imagine turning all the deserts our species has created back to fertile productive land. This is possible. So I would like to see a calculation that proves that mirrors are better than a nature based approach to cooling our planet. I think nature will out perform the mirrors. Similar work can be done in the oceans of the world.
I think you're creating a false dichotomy. It doesn't need to be either or, there are probably advantages to doing both.
Peter thanks for your comment, my intent was not to create a false dichotomy and I do not think that i do. De-desertification is not mentioned or considered as an alternate approach at any length although Dave does bring it up. Why does the analysis focused on agriculture lands rather then deserts ? There is a discussion of the possible creation of small micro-climates and local cooling, nature already has this covered. We need to push to implement solutions that we know work know while developing additional mitigation techniques. We will need them all.
Hi Christopher, thanks for the response. This episode was really interesting and many questions popped into my head. I was actually thinking how this technology could help places like Las Damas Ranch and other places bordering areas undergoing desertification. I truly believe regenerative agriculture is a big part of the solution, actually I think I've sent a message or two to David Roberts asking for an episode on it, but with all the strengths of regen ag, I worry about the extremes like the heat domes the world have been experiencing lately. Even with the best practices would something similar devastate a place like Las Damas Ranch?
That conversation was the most vertiginous ride I've been on in a while - from despair that we're already past 2 deg, to discovering a new source of much-needed hope that there might be a relatively simple, quick, reversible cooling solution with possible co-benefits. Eager to see how this develops.
Having 2 geoengineering pods on my feed within days, I of course had to listen to them both. This is a more general view than David's deep dive as its aimed at a more general audience. No mention of mirrors at all which one can take as a sign that it's not yet a viable option or just not the expertise of the interviewee here.
I hope this link works and some may find it interesting. There are interesting fairly varied people who come to this one so you may want to sub too. 😊
[People I (Mostly) Admire] 79. Solar Geoengineering Would Be Radical. It Might Also Be Necessary. #peopleIMostlyAdmire
https://podcastaddict.com/episode/140998014 via @PodcastAddict
Looking for climate/sustainability-related book recommendations! I have $500 worth of professional development funds available to me at work and I'd like to spend it on books - thought this would be the perfect place to get recs! Thanks in advance!
How deep do you want to go and where do you want to start?
For hopeful context solidly in the core of where our solutions will arise, I'd start with Saving Us by Katharine Hayhoe, Electrify by Saul Griffith, and Solar Power Finance Without the Jargon by Jenny Chase. These are great baseline, current, and hopeful books about what we can do individually and collectively. The financing book, in particular, provides a look under the covers on how the transition actually gets done, revealing that progress isn't a steady climb of deliberate success piled upon deliberate success. Add Timefulness: How thinking like a Geologist can help save the world by Marcia Bjornerud, a very good book that places today's wackiness in geologic context.
If you want a fun scare: Global Catastrophic Risks, Uninhabitable Earth, and The Ministry for the Future.
I just picked up The Overstory by Richard Powers on strong recommendations but haven't started yet. And there are always the free options of the IPCC reports parts I, II, and III that'll go as deep as one could desire. If you count the BEvERages you'll need to finish them you can polish off that professional development credit.
This is great, thank you so much Geoff! I'm looking for pretty much anything under the umbrella of "sustainability" (whether that's related to clean energy, climate policy, urban planning, circular economy etc). Trying to build on my current foundation without getting into anything TOO technical -- I don't currently work in the climate space but want to make the pivot so am trying to learn more and figure out what I specifically want to pursue
Some books I've enjoyed have been Natural Capitalism (Paul Hawken), Doughnut Economics (Kate Raworth), Superpower & the boom (both by Russell gold), Sustainable tourism on a finite planet (Megan epler wood), Electrify & uninhabitable earth (both of which you mentioned)
Others on my to-read list - fighting traffic (Peter Norton), Power struggle (Richard Rudolph - mentioned by David on one of these podcast episodes), Braiding sweetgrass (Robin Wall Kimmerer)
Let me know if anything else comes to mind :)
For broad surveys across the solution/problem space you can always start at https://www.withouthotair.com/ and then dig deeper into the topics/references that resonate. MacKay transitioned into sustainability in 2006 and passed only 10 years later but this broad survey coupled with additional context as Chief Scientific Advisor of the Department of Energy and Climate Change for the United Kingdom really grounds the problems and solution space in things that fit the problem(s) at hand. He'd be pleased at the advance of learning curves in solar and wind, but probably not surprised that incumbent stakeholders are the greatest obstacle to progress.
To that latter point, reading Thucydides isn't wasted because the problems of today are exactly the problems of... always when it comes to organizing and collaboration among humans. Social action and coordination are the problems of sustainability, be it Big Cement advertising against Glulam or fossil fuel gaslighting and regulatory capture - we're looking at a people problem. Anyone who is interested in that work has my sympathy and thanks, relatively speaking the science and technology parts of the problems are easy.
MacKay hits on this in his preamble describing his transition into sustainability, with three additional book recommendations that together show the contrast in view among smart people and, in hindsight, how quickly our knowledge can become dated: https://www.withouthotair.com/c1/page_2.shtml Goodstein's Out of Gas, Lomborg's The Skeptical Environmentalist, and Lovelock's The Revenge of Gaia. Many of the figure specifics in WithoutHotAir need updating, but the relationships and equations still hold. The national-scale renewable energy mix maps are illustrative of just how big some of the proposed solutions become when deployed in good faith.
As an aside, the introduction to Goodstein's states of matter is the best introduction to statistical mechanics, and perhaps any book, possible. Out of Gas, on the other hand, was overly pessimistic about how rising costs induce technological development in any field, and how learning curves work to change the terms of problems once they graduate from the lab and theoretical world and into the dirty world of engineering and deployment. He's on much firmer ground in physics of condensed states. We've identified and reduced processing and extraction costs for a mind-numbing quantity of oil over the last 20 years and will easily exhaust our carbon budget for a survivable climate well before we 'run out of oil,' in some ways this has been the perpetual story echoing again from the 1981 National Geographic talking points on energy independence and supply. This common storyline keeps recurring because it is useful to a specific set of stakeholders - again, the people problem and it trumps everything else (until the implacability of climate physics and chemistry deals with the people - and end we all would prefer to avoid). To the good, drilling advances will transform hot-rock geothermal as the last 15 years of technological advances drift out of fracking and into renewable geothermal production. Crustal geothermal potential comically dwarfs every other source of energy available, and is available everywhere once we get past a real but straightforward technological barrier. No magic of controlled fusion required.
Two points seem to have been missed:
* This does not address the increasing acidification of the oceans, which is seriously threatening all sea life--especially that which we depend on most.
* It did not address the likely problems of weather phenomena resulting from the use of such cooling agents. Any time a cool front meets a hot front, there is turbulence and a potential for storms. Doing this on a level that could change the course of the climate emergency could promote major weather phenomena. This was not mentioned.
I vote we reduce fossil fuel use on an emergency basis. If this was being addressed as the emergency it is, we would already be reducing speed limits to 55 mph, and connecting our grid up as though it were a wartime project. This may seem extreme now, but it will not in 4 years, to say nothing of 7 years.
The podcast did address ocean acidification and Dr. Tao does argue for rapid decarbonization. Listen to the podcast, it’s quite interesting.
Dr Tao has ranked the constraints and tackled them in order. CO2 is bad, but it kills us well after the heat does the job so he's looking to tackle the heat part first - as he explained. In the IPCC reports from last year, you will note there is a difference between radiative forcing that we're trending towards and the temperature we're trending towards - the bulk of that difference is the aerosol effect retarding warming. With radiative forcing at 3.5C... that's very bad, and while removing the CO2 alone, today, will stop warming from CO2 feedbacks swiftly, we'll change a bunch of other stuff at the same time. Stopping combustion will rapidly drop many 'bad' things in the air that are coincidentally keeping the temperatures down - so transitioning away from fossil fuels makes the heating problem worse before it makes it better. There was a lot of speculative work around seeding ship wakes with bubbles or filling aqueducts and reservoirs with white plastic balls to deliberately modify the planet's albedo. Geoengineering for albedo doesn't require every deployment to work, or work optimally, at every time - but it does require operation on a global scale. Fortunately, glass making is an ancient technology and raw materials are some of the most common in the earth's crust. It becomes a social problem, and a hard one due to the impact on every person everywhere to affirmatively participate in the solution (it'll be everyone's land/home/farm).
Dr. Tao has spent a lot of time making a solution stupid enough to scale and should be commended for that. If you are pushing a chemical reaction to remove CO2 you exhaust all electricity generation worldwide at about 1MT CO2. That's a problem, certainly because we need more electricity generation to displace fossil fuel consumption first. None of the popularly funded solutions are yet stupid enough to compete with changing albedo or planetary shading.
I cannot imagine the deployment to go smoothly on sufficient scale to register, however. Between property rights and water coverage, physical mirrors represent a possible pathway, perhaps not a plausible one. Moving the mirrors into space reduces the required surface area by a factor of 8 and prohibitions on work there are notoriously lax, but does dramatically increase the installation cost/investment. A space based shade system needn't be glass or even any particular color, very thin structures can cast shade - when thermal management and station keeping are managed. I'd much prefer a rogue billionaire building a solar shade to performing a stratospheric aerosol injection - reducing the incident radiation before it gets to us at all is a knob with less variability in interactions - though we cannot yet estimate all interactions on any of this.
The IPCC reports and scientists keep saying as loudly as possible, we must stop burning fossil fuels now--not 30 years from now, or 50 as some plans indicate--and most of the world is not coming anywhere near what they say they plan to do.
There are major issues with both the delays in stopping the burning of fossil fuels and the geoengineering that is supposed to save the world from the worst effects.
When considerations like ocean acidification are set aside--mentioned, but not addressed as relevant, then one is performing a kind of red-lining. One has divided the world into those who will have efforts made to save them and their children, and those that are being tossed into a horrific future. Specifically, those hundreds of millions of people who depend on the ocean for their food, their living, and their future.
The second point that is highly questionable is how the world can keep absorbing energy into the oceans at one atom bomb per second 24/7/365, over three fourths of the planet while some fantastic cooling is occurring over the remaining one fourth. Yes, the cooling might well occur exactly as outline, and that is the problem--the energy differential manifests as weather. Local weather will be profoundly changed, and along coastlines more than is already now experienced.
When engineers propose this kind of solution, they are asking us for the authority to make global changes with no intention of accepting responsibility for all the outcomes. Too often it results in the voices of too many people being silenced so the experiment can proceed. It would be an experiment of global proportions, with no one able to anticipate the scope of the impact, much less prevent disasters from occurring.
We need to put more human effort and creativity into getting us off fossil fuels, and less into evasive engineering of red lines that do what those red lines have always done--destroy the lives and welfare of people who are economically safe to ignore.
Given the thermal impact of such a solution as proposed, it does not require too much imagination to forecast that hurricanes may well increase in destructive power as they meet cooler land masses. But, this was not a consideration in the information presented. Anyone pursuing any geoengineering project should read "Under a White Sky". Otherwise, the project risks becoming little more than well, smoke and mirrors.
Dr. Tao is just pointing out that if we only fixate on getting off fossil fuels we'll step on a rake of consequentially lowering aerosol effects on radiative forcing - and we should have an answer for that too. Both the podcast and the IPCC report note that the radiative forcing for greenhouse gases in the atmosphere today is higher than the temperature change we've seen to date. Aerosols currently in the atmosphere are suppressing observed warming by about 1.2C (through albedo and direct effects). Aerosols have a shorter lifetime than the CO2 meaning they'll drop out first when we stop burning things - leaving us with decades of higher radiative forcing before drawdown catches up. As a consequence of halting fossil fuel consumption and clearing the air of (otherwise harmful) aerosols we'll jump up an additional 1.2C making things worse for the ocean heat, storm formation, ocean dependent ecosystems, etc. The proposed solution to stop burning fossil fuels (alone) is also as problematic as a steady as we go approach for those people who depend on the ocean for their food, their living, and their future. Hence the interest in complementary solutions to offset the undesirable consequences of the desirable course of action.
This doesn't ignore the importance of Ocean Acidification, just recognizing that the ocean acidification system is a lot less sensitive to change in annual emissions than aerosol contributions to global cooling - and hence the greater importance in dealing with that heat influx while we drawdown CO2 emissions and eventually CO2 content from the atmosphere. As we drawdown CO2 from the air the Ocean will become a CO2 pump which improves the ocean acidification position. But, drawing down CO2 is going to take a lot longer than we like to pretend and during that time we'll have this unmoderated heat input because we got rid of the aerosols when we stopped burning fossil fuels. We've got a lot more work to do than the simple make it stop narrative suggests. How much more? Atmospheric CO2 is measured in gigatons, ocean currents are measured in sverdrup which is a silly big unit that means the AMOC will turn over as much mass as all the CO2 in the atmosphere in a matter of minutes (2 minutes covers global annual emissions). Ocean concentrations of CO2 are about 100x atmospheric, and the surface vs. deep ocean reservoirs are truly vast - silly big. Scale matters. Not dealing with the reduced radiative forcing retardation during the transition is a sure way to detrimentally change surface ocean character and everything that depends on it for survival.
No one asked permission to start burning coal to do work and indeed the last 200 years of progress has been a celebration of that insight. We are already geoengineering, and on a scale that we do not recognize from any historical record. It is true that the kind of thinking that got us into this problem won't likely be the thinking that gets us out of it, but vetoing responses and forbidding research and development into new mitigations leads us away from successful transition rather than towards it.
We are not in a zero-sum game here. Taking us off fossil fuels in a decade or two is 10x faster what it took to get into this predicament - it is a huge bet and itself an exercise in geoengineering. It would be easy and human to fixate on one part of the problem at the expense of the whole system and score a pyrrhic victory. Engineers and scientists checking the math and assumptions are essential for our shared success - the work of getting off fossil fuels is a social problem, after all. The technology has been here all along - and now is economically optimal to deploy.
I understand the problem well. I do not question the basis for the research, nor do I oppose it. I do think this needs attention by the IPCC and a deep discussion at a future COP. I would be much more comfortable if respected climatologists like Michael Mann found the consequences of creating massive thermal differences to be acceptable and helpful. I have my doubts about that, especially because this aspect is not addressed.
And yes, I am equally concerned about the environmental justice of playing a global game of "Russian roulette" with the climate in order to benefit nations that contribute most to the problem, and are unwilling to change the dynamics. The nations who contribute least are likely to get no benefit at all from a wide scale implementation of this technology.
There are other ways to increase the earth's albedo to compensate for aerosol depletion, including increasing grasslands, sea grass, and appropriate planting in degraded areas. Those remove carbon, too.
What happens if . . .
The OPEC nations decide that it is in their best interest to massively implement this strategy through the Middle East, South Asia, and North Africa? They can afford it, and may feel the cooling can at least benefit them directly. The unbalancing of weather and climate factors could be catastrophic for other nations around the world. And OPEC and US fossil fuel interests make it clear that they will do pretty much anything to extend fossil fuel use into the far future.
Other solutions are possible:
Guest post: Reducing material use could cut emissions from cars and homes by at least a third - Carbon Brief
https://www.carbonbrief.org/guest-post-reducing-material-use-could-cut-emissions-from-cars-and-homes-by-at-least-a-third/?utm_campaign=Daily%20Briefing&utm_content=20220609&utm_medium=email&utm_source=Revue%20newsletter
Hi Gary, have you considered all the people who will die in the middle east, south Asia and north Africa and many other places around the world waiting for the rest of the world to get their act together? People can't live in 50C heat. Do you have a solution for them? It's happening right now. It's only going to get worse. It's not like the United States is a beacon of hope. And as for the IPCC they've been extremely conservative, they still don't properly account for permafrost melt. If I was someone in India who needed to turn the temperature down a couple of degrees to survive, I wouldn't have a lot of patience for your dismissal of this technology. This isn't just an academic exercise, I think many forget that. If the rest of the world doesn't like well maybe they should do something.
I am aware of the current and on-going death toll from burning fossil fuels. That is precisely why I believe in doing what the climate scientists are telling us to do--stop burning fossil fuels"--and instead of engaging in techno-optimism and academic exercises, we need to meet our obligations to other nations for the 1.9 trillion dollars we have already done to the environment. We could begin by cleaning up the air, and that takes us back to taking an effective stance on no longer burning fossil fuels. There is so much more we can and could do *now* without engaging in geoengineering experiments of dubious benefit to the planet.
The reality is that 90% of the sun's heat is being absorbed into the oceans, and only about 10% on land. Cooling the land sufficiently to reduce the heat balance is a bad idea even from an elementary physics perspective--which is about all I have.
I am not going to be convinced otherwise by sarcastic or caustic remarks in regard to my opinion. I personally reduce my carbon footprint, have solar panels, heat pump, etc. Are those making remarks about my contributions doing as much? I hope so.
I found this discussion to be fascinating and would love to learn more, and to hear perspectives from folks who might disagree with Dr. Tao's analysis. A question I have for Dr. Tao: I have seen the idea of white roofs discussed now for a number of years as a potential approach to ameliorating climate change. It seems to be a similar logic to your proposal of mirrors. I am curious about the pros and cons of white roofs vs mirrors vs some combination of both?
Albedo approaches struggle with just how big a planet is and how rapidly natural processes are going the other way. We're growing darker much faster via snowpack and ice loss than we could achieve with white roofs, roads, and reservoirs (or wakes, even with multi-week dwell times). Any spot on the earth is contributing only a fraction of the time as well - the whole rotating sphere thing. That white roof in space is 8x more effective just from the geometry, and much more when you consider avoiding the in-atmosphere interactions of the incident radiation. Part of why we call it a greenhouse effect is that once the power makes it into the atmosphere it is heating things up - even if we're bouncing it back out from the surface instead of just soaking it up on the spot. There is also a radiation effect with the structure - a black roof will emit heat faster so if there is more heat in the building that white roof is hurting, for instance at night or in winter. For the people in the home, a comfortable temperature is the primary driver. Everything is more complicated when you solve the problem at ground level.
Sunshades at L1 are a grand sci-fi tradition, and with now vastly reduced launch costs per kg, and better understanding of large scale space structures these things might be buildable in the trillion dollar range? James Webb is at L2 so it always sits in Earth's shadow, putting a sunshade at L1 replicates that arrangement for Earth itself and would be both tunable and diffuse in impact. I'm not holding my breath, but it sits in the same class as a mirror ball or white roof approach.
As with most things that are good for the environment or meant to repair other people's damage there is no buyer. The expectation that our solutions will themselves become viable businesses naturally narrows one's perspective to things one can sell or convince others might have value - like removal offsets. A solar shade with a high up front cost and ongoing upkeep might minimize global costs but doesn't make one's yield targets.
Are you aware of any estimates of how many debris collision events per year would be expected for a roughly earth-sized shade or mirror at L1? It strikes me, so to speak, that the ongoing repair costs might well be greater in short order than the original construction cost...
If it is too good to be true, maybe take a deep dive. I for one see no depth to MEER. No numbers, no modeling, no equations, no PHYSICS. Maybe before Dr. Tao worries about how to explain MEER to non-scientists, he should worry about explaining it to scientists?
Paul, a simple google search will find numerous recorded presentations from Tao that include all kinds of models & equations. It was all I could do to keep the pod from being overrun by numbers. It doesn't sound like you looked very hard.
David, I love your podcasts and I will continue to listen to them, but I respectfully disagree on this one. Yes, a mirror will reflect visible light back up into the sky. There may be some potential there. It may be worth investigating. But Dr. Tao's presentations appear to me to be junk science. We definitely should stop burning coal, contrary to what Dr. Tao says. We absolutely should keep building wind mills, despite what Dr. Tao says. (Friction between the air and the blades is warming the planet? Give me break!) Have you tried to look up any of the sources on his presentation? I have and failed miserably. I may not work as hard at this as you do David, but should I really have to work all that hard to verify what your guests say?
That wind turbines create heat in the process of converting energy from one form to another is definitionally true. Laws of Thermodynamics and Carnot Efficiency level fundamentals of how the world works. So, outrage at this most tautological of findings is curious. Outrage at the lack of practicality of the finding might be more appropriate.
This paper (https://www.cell.com/joule/fulltext/S2542-4351(18)30446-X) in Joule goes further on that topic and establishes a modelling relationship in atmospheric mixing that drives a much larger warming impact due to the interaction of wind turbines in the atmosphere. This isn't implausible, though this also isn't an experimental result. It describes a mechanism that might lead us to an unanticipated consequence. When a new experiment generates data to invalidate this theory, the theorist can turn around and create a new theory in light of the new data rather swiftly and keep more experimentalists spinning for another decade (or three). This is literally how we learn new things about the world.
The main gist of that paper is that PV is superior to Wind from an avoided warming perspective and comes with a laundry list of modelling assumptions, most of which can invalidate any amount of mathy analysis. For instance, while this is a good journal and a careful paper it doesn't address economic, social, or political costs or even the material lifecycle of the two power generating systems. Wind Turbines can payback in a year and PV at about 12 years, this dollars payback is tied to manufacturing costs, land use, deployment, and maintenance. And of course the direct impacts like PV albedo vs. the Wind column mixing - many poorly understood variables in an open system. Both are clearly better options than continued fossil fuels - noted at 30x better on the radiative forcing replacement of PV for fossil fuels here (cited in the Joule paper): https://pubs.acs.org/doi/abs/10.1021/es801747c
Probably the most eye-catching caveat in the Joule paper is that it will take 100 years for the wind turbines to net out lower heating than the fossil fuel capacity they replace. I think the explanation here is that the wake of the fossil fuel combustion runs through 100 years of consequences (10 years for methane, 100 for CO2, 114 for N2O - for 3 of the 7 GHGs) that are in steady state today. Swapping to a wind turbine puts us into a "paying for both" worst of both worlds state as we wait to unwind the fossil fuel legacy. This seems trivially true, and unfair as a measure of comparison - even academic journals can go for the attention grabbing head to drive engagement. It is also not a step function, so it is not clear why and how this inflection point drops out of their model. Legacy emissions warming, if we stop emitting instantly, should cause a rapid increase warming as aerosols drop out (+1.2C - global thermal inertia and radiative flux willing) followed by a slow decline in warming effect as the GHGs age out on their own lifecycles. The 0.2C boost from large scale wind roll-out, compared to the 2.5 ish already in the air from fossil fuel GHGs puts it into perspective - except the small one is a theoretical finding and the big one empirical.
This isn't nothing, but it also isn't the most important thing. What it does do is help us avoid the unexpected and a counter narrative of "we turned off the fossil fuels and the temperature went up!" It is true that if we stop emissions today we will stop warming the planet, while it is also true that if we stop emissions today the planet will warm significantly in the near term. The difference is that we've already banked the warming potential and have been temporarily suppressing - largely on accident (cleaner fossil fuels are better for our lungs and worse for the global temperature).
I'm not sure what source(s) you've seen so I cannot comment on it(them). But I would be surprised if the conclusion of someone discussing global albedo modification was to continue burning fossil fuels without end. Coal burning does have a global albedo modification effect, but the whole reason we are talking about other global albedo modifications is because the aerosol emissions are short lived reductions to heating and GHG heating is long lived. Stopping all aerosol emissions (as a partner effect to stopping all fossil fuel GHG emissions) will cause a heating across the planet as the aerosols drop out and the GHGs remain - it will be releasing the latent heating potential we've already put into the atmosphere. This is the whole criticism of deliberate SO2 aerosol seeding - the short term retardation comes with huge costs and does nothing to remediate the underlying problem of there being too many GHG in the air, leaving us with a permanent tax of maintaining the system in ever increasing doses. This is also an applicable criticism of a mirror-ball world, it doesn't solve all the problems on its own. But here, at least, is a more robust incarnation of "aerosol seeding for albedo modification on a global scale." It doesn't replace transition, but describes a potential solution to an essential complement necessary for surviving the transition.
I too was thinking that the actual impacts even on his small scale projects are still unknown. He didn't touch on frost for example which I heard can be an issue from windmills and must be much more an issue here. A single site in new Hampshire to 10-15% of arable land in all sorts of climates scale. My guess is that it looks like a niche solution as part of a toolbox that can be installed together with PVs, until there's more research.
Wondering what you think of the approaches Peter Fiekowsky suggests in his new Climate Restoration book. They're not exactly geo-engineering but related, and address the same issue that we have to remove carbon as well as stop adding it.
Ocean pasture restoration; synthetic limestone manufacture; seaweed permaculture; and methane oxidation
https://www.rivertownsbooks.com/book-page/climate-restoration-by-peter-fiekowsky-with-carole-douglis
A Gigaton is a big unit. The largest Olivine deposit in the US is north of Seattle, a mountain with 2GT of CO2 fixing capacity. We're emitting at 40GT annually. You'll blow the energy budget doing the work, not to mention be sluicing mountains into the sea, before we get to sufficient scale. Olivine in seawater fixes CO2 at close to 1:1; basalt is another popular option but is much less favorable at 450:1 by mass, there is a lot of basalt in the crust but those are mind-bending volumes.
There are few natural systems that operate on sufficient scale or mass to make a difference quickly. Albedo control is one of those systems, as it moderates the input energy to the planet in one go and doesn't (usually) require annual contributions to maintain historic effectiveness (unlike captures against continued emissions).
The Great Kelp hope got a lot of attention recently, but we'd need a width of 160' of kelp forest on every coast everywhere to get into gigaton range... and the dwell time and actual carbon flux are both in doubt as the kelp forest is a far richer ecosystem than the natural ocean it paves over.
We need to be doing all the things, and firstly and above all stopping the geologic carbon pump into the contemporary carbon cycle. But we should also understand that we're not all yet grappling with the size of the problem yet and the hard global constraints against action. Things like how much energy is available for industry each year, how much mass we manufacture each year as a planet - CO2 is #1 by the way. To think we'll create an industry 500x the size of the greatest material output worldwide just to fix the current system (e.g. using a basalt CO2 fixing plan, like at Climeworks), it just isn't at the right scale for the problem at hand.
I would definitely use synthetic routes for feedstock materials, plastics from carbon capture could be delightfully circular, but not for the primary task of quickly taking control of the global temperature. Basalt weathering to remove CO2 is normally a 500,000 year process; the Earth will eventually work through our CO2 backlog. Not all of us can afford to have a geologist's patience about it though.
Remember the white roof initiative? https://grist.org/climate-energy/cool-roofs-offer-a-salve-for-hot-cities-and-the-climate-too/
Space is pretty big and L1 is definitely not a crowded place like low earth orbit, but James Webb just took a larger than expected micrometeorite strike at L2 so it isn't empty either.
The good news is that a micrometeorite strike doesn't cause a lot of trouble if you don't resist it. Let it blow through and avoid absorbing its kinetic energy. A micro-scale hole in a 2M sq. km array isn't a large degradation. There are several approaches to creating a solar shade and very few envision a rigid structure that takes a hit and shrugs it off. Mostly there are micro-mirror satellites in a cloud and if one gets hit it just gets popped out of the array, or ultra thin materials that are easily pierced. Shedding heat and station keeping around the saddle point are bigger problems for anything large at L1 - even if the thing is just serves as a diffraction grating in space to scatter the sun.
The good news, there will be plenty of solar power available to put to work. The challenges are around mass and coordination of such a large array.
Any array wouldn't be earth sized, though. We're only trying to adjust a few percent of solar incidence; but a 2,000km per side 'thing' in space is still silly-big no matter how small its component parts or thin its pieces.
Is periodic cleaning required?
Good question! (Presumably the answer must be yes.) Also, how do the mirrors fare in a strong wind? I'd love to see a careful published analysis of feasibility and impact for this proposal. Unfortunately, there doesn't appear to be any, which is a bad sign.
I was a little bothered when Ye Tao said that the solar insolation was 1.5 Watts/square meter. I always knew that that the sun's power was 1.0 Watt/square meter. Otherwise, it was and interesting proposal. However, I believe that increased solar and wind power can stop continued global warming.
I think it's possible you're confusing the solar insolation (about 1500 W/m^2 at top of atmosphere, maybe closer to 1000W/m^2 at sea level) with the imbalance between radation (mostly visible) in and IR out, which is a much smaller quantity.
Yes, Jim, it is 1.0kW/square meter of sun power that hits the earth. However, Ye Tao was talking about what hits the earth, where he deploys his mirrors, not 1.5kW/square meter.
I was pointing out that kilowatts are not the same as watts (in fact, they're 1000 times greater). And "power in minus power out" (What Tao was talking about) is not the same as "power in" (the value you're referring to).
Even if you look up the Solar Constant = 1.37kW/m^2, it still is not 1.5kW/square meter.
Great interview. This feels like a thought experiment scaled up insanely.