This is my attempt at contributing to "A Layperson's Introduction" series, here on Tildes. It's why it's here on ~science, rather than ~enviro

Many people have heard about how global warming works. “We are emitting greenhouse gases, and these trap heat, leading to further warming.” So how does this process occur in more detail? What is its physical basis? In this post, I will try to explain the physical basis of these questions in a simple way that is a bit more detailed than what is usually seen.

Electromagnetic Spectrum and Thermal Radiation

The electromagnetic spectrum is a broad spectrum that includes visible light. There are long wavelengths, such as radio waves and infrared light, and short wavelengths, such as ultraviolet light, X-rays, and gamma rays.

Visualization of the electromagnetic spectrum

Thermal radiation is the radiation emitted by the molecules of an object due to thermal movement. It can be in the visible light wavelength, shorter wavelength, or longer wavelength. The length of these wavelengths varies depending on the temperature of the object that is the source of thermal radiation. For example, the thermal radiation emitted by Earth falls into the infrared spectrum, which is at lower energy, because Earth is not as hot as a star. The shift of thermal radiation emitted by colder objects to longer wavelengths is also known as Wien's law.

Energy Budget and Stefan-Boltzmann Law

Our planet Earth has a certain energy budget. In other words, the energy coming to the planet and the energy going out from the planet are specific. The source of the energy coming to the Earth is the Sun, and on average, approximately 340 Watt/m² energy reaches the surface of the planet. In order for this energy to be balanced, the energy radiated from Earth into space must be equal to this amount. This happens in two ways. First, some of the incoming energy is reflected into space by the Earth itself. Both the atmosphere (especially clouds) and the surface make this reflection. The second part can be explained by a physical law called Stefan Boltzmann law. According to this law, each object emits a certain amount of energy as thermal radiation, and the amount of this energy increases with temperature. This increase does not occur linearly, but as the fourth power of temperature. The mathematical expression of the law is given below.

E = σT⁴

In this equation, "E" is the energy, "σ" (sigma) is the Stefan-Boltzmann constant, and "T" is the temperature in Kelvin. However, the law cannot be applied to any object in its current form. The above equation is valid for ideal bodies called "black bodies". In physics, a black body is the name given to an ideal body that absorbs and emits all incoming radiation. However, Earth differs from a black body due to reflection. Therefore, the following equation is more appropriate.

E = εσT⁴

Here, ε (epsilon) means emissivity. Emissivity is the effectiveness of the surface of a material in emitting energy as thermal radiation. For a black body, ε = 1. The Earth's mean ε is less than 1, because it is not a black body. At the same time, emissivity changes depending on which part of the Earth is examined. For example, the emissivity of a vegetated surface and a desert or glacier are different. However, it is more important for us at this point to remember that the mean ε is less than 1.

When we look at the formulae above, we see that, in accordance with the Stefan-Boltzmann law, the Earth emits thermal radiation depending on the temperature, even though it is not a black body. This constitutes the second part of the Earth's energy budget, namely thermal radiation. In summary, Earth receives energy from the Sun and radiates this energy through reflection and thermal radiation.

Radiative Forcing and Greenhouse Effect

The energy budget is very important for our planet. Any change in the budget causes Earth to warm or cool. Natural or human-induced changes that change the balance between incoming and outgoing energy are called radiative forcing. This is the mechanism by which greenhouse gases warm the planet. Some gases in the atmosphere, such as carbon dioxide (CO²) or methane (CH⁴), have physical properties that absorb the thermal radiation emitted by Earth. If you remember, Earth's thermal radiation was in the infrared spectrum. That is, these gases absorb at certain points in the infrared spectrum. As a result of this absorption, the gases emit it again in the form of thermal radiation in all directions. While some of the emitted radiation escapes into space, some of it remains on Earth, causing warming. Since the energy emitted by Earth will increase as it warms up, at a certain point, the incoming and outgoing energy becomes equal again.

CO² emissions, concentration, and radiative forcing

In the image above, in different climate change scenarios, emissions of the greenhouse gas CO²) (left), the corresponding increase in CO² concentration in the atmosphere (middle), and the increasing radiative forcing due to this increase are shown (right). Note that the radiative forcing is shown in Watts/m². It is shown this way because it is calculated based on the change in Earth's energy budget, and Earth's energy budget is shown as Watt/m².

In other words, although the incoming energy is the same, there is a certain decrease in the energy going into space due to the greenhouse effect. This leads to what we call radiative forcing. As a result of radiative forcing, the temperature of Earth increases, and as the temperature increases, the thermal radiation energy emitted by the planet increases. This causes the incoming and outgoing energy to become equal again. As a result, in the long run, radiative forcing (and the greenhouse effect) does not lead to a change in the energy budget. However, it causes solar energy to remain in the atmosphere for a longer period of time, causing a certain amount of warming. This is what we call global warming due to the greenhouse effect.

This process is, of course, more complex than described here. Since the atmosphere has a layered and fluid structure, there are factors that make the job more complicated. For example, while the increase in CO² warms the troposphere (what we call global warming), the lowest layer of the atmosphere, it causes the stratosphere, its upper layer, to cool. Despite these and similar complexities, the physical basis of global warming is still based on the mechanisms described in this post.

Sources

• Schmittner, A. (2018). Introduction to Climate Science. Oregan State University
• van Vuuren, D. P., Edmonds, J., Kainuma, M., Riahi, K., Thomson, A., Hibbard, K., Hurtt, G. C., Kram, T., Krey, V., Lamarque, J.-F., Masui, T., Meinshausen, M., Nakicenovic, N., Smith, S. J., & Rose, S. K. (2011). The Representative Concentration Pathways: An overview. Climatic Change, 109(1-2), 5–31. https://doi.org/10.1007/s10584-011-0148-z
• Wild, M., Folini, D., Schär, C., Loeb, N., Dutton, E.G., König-Langlo, G. (2013). The global energy balance from a surface perspective. Clim Dyn 40, 3107–3134. https://doi.org/10.1007/s00382-012-1569-8
• Zohuri, B., McDaniel, P. (2021). Basic of heat transfer. Introduction to Energy Essentials, 569–578. https://doi.org/10.1016/b978-0-323-90152-9.00017-7

Image Sources

• Image 1: https://science.nasa.gov/ems/01_intro/
• Image 2: van Vuuren et al., 2011

Zacklabe is a site, created by the climate scientist and National Oceanic and Atmospheric Administration researcher, Zachary Labe, that has many great visualizations of data regarding climate change, especially about the Arctic and Antarctic. It gathers its data from scientific observations, which are cited. You can access the visualizations following this link. Here are the visualizations, with many graphics for each entry.

Arctic Climate Seasonality and Variability
Arctic Sea Ice Extent and Concentration
Arctic Sea Ice Volume and Thickness
Arctic Temperatures
Antarctic Sea Ice Extent and Concentration
Climate Change Indicators
Climate model projections compared to observations in the Arctic
Global Sea Ice Extent and Concentration
Polar Climate Change Figures

Note: I briefly created a similar topic, but it was only about a single link from here. I deleted because I realized it's much better to create a thread about the site in general.

Preamble ... this is another rambling, jumbled soliloquy that may or may not make any actual points ... or, you know, sense.

"Climate Change is causing the rise in populism".

That is a theory I have entertained for many years -- going back to before the 2016 US Presidential election. And--confirmation bias being what it is--since I believe the theory, I keep seeing anecdotal evidence all over the place connecting the two.

But, thinking about it this morning, looking at it logically ... I still think there is probably a connection, but I'm not really sure. It may well just be a coincidence of timing. And even if there is a connection, I'm just not quite sure what it is. If it is true ... why? What is the actual connection?

So ... why do countries keep electing populist "Trump-like" leaders?

That's already a hard question to answer clearly, without quickly descending into personal attacks and ad hominems and such.

Plus, of course, generalization is problematic ... we're talking about different countries, different cultures, different histories driving each vote. It's not all the same. And yet, over and over again, election after election, it sure looks the same.

I think the main reason is a tribal "fear of invaders" reaction, mostly against the rise of immigration, particularly immigration from (to paraphrase Trump) "the shit-hole countries". Maybe it's an even more basic "fear of change" reaction. But I definitely think, in the US, the rise of Trump was a direct result of the illegal immigration issue -- not exclusively, but that was a big piece of the puzzle. In particular, Trump equating Muslims with terrorists, and Mexican immigrants with criminals, etc.

Here in the EU, immigration -- particularly the 2015 refugee crisis caused by the wars in the Middle East -- was probably the top reason for Brexit, as has been most of the populist surge over here since then. One country after another here keeps electing right-wing leadership based on the "we'll keep out the dirty immigrants" campaign promises. Hungary, Italy, Sweden, Finland, the Netherlands, Poland, the list just keeps going. I live in Germany these days, and I gotta tell you, there is nothing scarier than seeing a huge surge in popularity in the German far-right.

The other top reason that seems to be driving it is some kind of sense of nationalistic self-determination. People feeling like their country--their home--is being changed by Outside Forces, and trying to lock it down, trying to find a way back to the good old days when the white people ran things and the brown people cooked and cleaned for them.

In Hungary, Orban routinely gets massive support with his constant rants about "Brussels" (meaning the EU) trying to force their gay liberal anti-Christian agenda down the throats of decent God-fearing Hungarians, and I see variations of that theme in most of the populist movements.

Right now, I want to say the populist trend is a response to (or rather, a denial of) the consequences of Colonialism and resource depletion. I think (again, over-simplified), people here in the Industrial Western World do not want to hear that the problems in the rest of the world are our fault, and that we have a responsibility to the people there, to try to help address some of the problems we've helped cause ... and instead, people are electing leaders who tell them the rest of the world is going to hell but it's not their fault and if they just lock down their borders, everything will stay "nice" in their country.

Something like that, anyway.

Okay ... so, resource depletion and a backlash against the consequences of Colonialism.

Does that seem like a fair and reasonable generalization of what is driving the rise in populism?

Because none of that is really connected to Climate Change. Sure, it depends on "which" resources we're talking about, but even in a magical hypothetical world where burning fossil fuels doesn't cause the planet to heat up ... wouldn't we still be seeing just about the same results from the Colonialism-and-resource-depletion issues?

But then again, at a global level, everything is pretty much connected to everything else. I feel like, coming at it from that angle, I could make a fairly good argument that Climate Change and resource depletion are pretty closely related, regardless of which resources you're talking about.

Oh yeah ... one more wrinkle. I'm primarily talking about populism in the US, Canada, UK, EU. I actually know a lot less about the situations in other regions. Asia. Latin America. Bolsonaro. Millei. I know there are others, but names elude me at the moment, and I don't have an understanding of why they are getting elected. Are they part of this trend? Do they blow a hole in my logic? IDK.

tl;dr

Okay ... I guess that's my new thesis -- populism is primarily being driven by a denial of the consequences of Colonialism and resource depletion ... which may or may not be closely related to Climate Change itself; I'm still just not sure.

Or, more broadly, more Climate-Change-inclusive -- populism is about people seeing that the world is dying, and electing leaders who A) tell them it's not their fault, and B) promise to save their country, even as the rest of the world burns.

Thoughts?

This sci-fi book starts out as a first contact novel. Aliens show up and say "Your planet is dying--we're here to rescue you! Come join our galactic federation!"

Here's the twist: the protagonist emphatically refuses. The world is sick, but humanity is healing it. Successfully. They have been for decades. And they refuse to leave Earth and go explore the stars until the job is done.

Thus begins this story's major conflict. The aliens have visited a few other planets with signs of advanced civilization, and in every case they've arrived too late--the other civilizations have extincted themselves by the time they arrive. The aliens are emphatic that technological societies cannot thrive on a planet's surface; in every other case, either the planet or the civilization dies. The humans are unfazed. Repairing an ecosystem is possible, they say. We've proven it. Are proving it. Yes, there's a hurricane bearing down on us, but the storms get a little less intense every year.

This is a story about meeting people utterly unlike you and finding common ground with them. It's about imagining a better future and working doggedly toward it.

Eco-focused stories usually have a back-to-the-land, pastoral vibe; they want to get in touch with nature by reducing our use of technology as much as possible. That's not this book at all. Our heroes use neural interfaces and networked decision-making algorithms to manage the restoration of the ecology. They write algorithms that weight the vote in favor of community-defined ethical preferences. Technology isn't the enemy--corporations are, which is why the corps were exiled decades ago. Networks and algorithms can be powerfully good when they're used to benefit the many instead of the few.

This book has so much heart and so much beautiful imagery. It is gloriously weird in lots of ways I'm not going to spoil. It's a hopeful book that's giving me ideas I'm starting work on now. You can find it here or in your local library.

Please share your garden plans, ideas, and wildly overambitious green fantasies here!

Weird and treacherous climate change weather is distorting my garden sense. Normally, it's not a good idea to plant anything tender until late May here, but I'm betting we won't get frost past May 1 this year, or nothing that can't be handled with strategic use of row covers and cloches.

My fingers are itching to get the hot peppers started. I'm restraining myself from starting the tomatoes too early (again!), and the snapdragons and other slow annual flowers are starting to germinate. I could probably sow kale now.

We'll see which of last year's bulbs survived the critters until the spring. Reinforcement of the deer fencing is happening as soon as the ground is thawed deeply enough to set proper posts, and dry enough to work with wood frames and cattle panel.

I'm going to get a few logs set up for shiitakes, oysters, maitake, and maybe see if last year's happenstance wood chip pile morels can be encouraged. Fingers-crossed that December's wild garlic (ramps) test planting took hold - if that works, I'll get more slips and expand the patch in more of the shady areas that aren't suitable for much else.

Depending on how my hands and spouse's shoulders are holding up, there's a lot of digging in this year's permaculture expansion. A couple of Hugelkultur beds, some (mostly?) American chestnut trees, more berries and apples, planting the overwintered pawpaws, and another try at elderberries. I've got vague plans for building a grape arbor this year, but that's going to depend on availability of spouse's hands during the busy winery season.

Looking forward to hearing from you!

When talking about climate, the ice age is mentioned a lot. Sometimes it is said that "the last ice age" ended roughly 10,000 years ago, and sometimes we are still said to be living in an ice age. So which one is correct? Technically both are correct. This is due to a complexity in terminology.

The broader climate state of Earth is divided into two categories: Icehouse Earth and Greenhouse Earth (Maslin, 2014). The state when there are continental glaciers (those that cover continents, separate from glaciers seen on mountains) at any point on Earth is called the Icehouse Earth, and the state when they do not exist is called the Greenhouse Earth. Approximately 80% of the last 500 million years has been spent as a Greenhouse Earth (Spicer and Corfield, 1992). During the icehouse state of the Earth, there are glacial and interglacial periods. The glacial period occurs when the glaciers at the poles move towards the lower latitudes of Earth, that is, towards the equator. The interglacial period is the time when glaciers remain at the poles.

Both the Icehouse Earth state and the glacial period are called Ice Age, but this is misleading. The last so-called “ice age” occurred 11,700 years ago (Clark et al., 2016). This event refers to the glacial period seen on Earth. However, the Earth is still in an "ice age" because it is still in the Icehouse Earth state. Even though it is currently in the interglacial warming period, this warming is approximately 15 times faster due to climate change (Clark et al., 2016). As the anthropogenic global warming gets stronger, the rate of warming will also increase.

The glacial periods seen in the last 500,000 years can be seen in this picture. Source for the picture is here.

The cycle of glacial and interglacial periods is clearly visible. One of the main factors that caused the emergence of Icehouse Earth states and glacial periods is the amount of carbon dioxide in the atmosphere. It ended and started the ages by greatly changing the conditions on Earth (Maslin, 2014).

In conclusion, we are currently living in an ice age and also not. The reason for this is that the word ice age refers to two different phenomena. Therefore, it would be more useful to use the terms Icehouse Earth and glacial period instead of ice age. However, how this will be translated into everyday language remains a challenge.

Sources

• Clark, P., Shakun, J., Marcott, S. et al. (2016). Consequences of twenty-first-century policy for multi-millennial climate and sea-level change. Nature Clim Change 6, 360–369.
• Maslin, M. (2014). Climate change: a very short introduction. OUP Oxford.
• Spicer, R. A. & Corfield, R. M. (1992). A review of terrestrial and marine climates in the Cretaceous with implications for modelling the ‘Greenhouse Earth’. Geological Magazine, 129(2), 169-180 pp.

I moved to a place with an "actual" winter just over a decade ago -- snow, freezing temperatures, etc. In the first couple of years, I got what felt like a genuinely solid winter. Lots of blisteringly cold days. Snow that fell in large amounts and stuck around for most of the season. I love winter, so this was great for me.

In recent years, however, the winters have been milder and milder. When we do get snow, it's only around for a bit because days above freezing are now frequent enough that it's able to melt between snowfalls. Also, the snowfalls themselves are more intermittent. This year specifically we've actually had more rain than snow. I don't remember getting rain in January when I first moved here.

It irks me a bit because the shift has been so stark and noticeable in such a short period of time. There's a part of me that thinks that it's not a big deal and maybe my first years here were unnaturally cold and snowy for the area, so what I'm seeing now is simply the other side of the mean, but then there's another part of me that feels like that's simply a comforting lie I can tell myself in the face of the obvious effects of climate change.

Is there anyone else here that feels like they're missing their winters?

It's hard to find hopeful sci-fi these days. The zeitgeist is that things are bad and they will keep getting worse. That's a problem, because before you can build a better future, you must first imagine one. This is the first book I've found in a long time that does a credible job of that.

This post is about a pair of novels by Daniel Suarez. The first one is Delta-V, the physics term for a change in velocity; the second one is called Critical Mass. Together they're a heavily-researched look at asteroid mining, offworld economics, and space-based solar power.

The series takes place in the mid 2030s. By this point, the symptoms of climate change are becoming serious, creating what people call "the Long Emergency": famines, storms, and waves of climate refugees. There is real concern that the global economy will collapse under the strain. To avert financial apocalypse, an expedition is launched to mine the asteroid Ryugu; the first book covers the miners' training, their long journey through space, and the hazards of mining an asteroid in deep space. In the second book, they use those mined materials to build a space station in lunar orbit, to set up a railgun for launching materials from the moon's surface into its orbit, and to begin building the first space-based solar power satellites.

I was surprised to learn that space-based solar power is a real thing that the US, China, and several other countries and companies are actively pursuing. Basically, you have a bunch of solar panels in orbit, which beam power down to receiving antennas ("rectennas") on Earth. You lose a lot of efficiency converting the electricity to microwaves and back, but solar panels on orbit have access to ~7-10x more energy than those on the ground, since there's no atmosphere in the way and it's always solar noon. In exchange for a large initial investment, space-based solar power offers always-on, 100% renewable energy that can be switched from New York to California at a moment's notice.

That initial investment is a doozy, though. SpaceX is working on lowering launch costs, but launching material from Earth's surface into orbit is going to be very expensive for a very long time. So these books look at what might be possible if we could avoid those costs. What if we could create mining and manufacturing operations in space? What if we could use those to generate clean power in heretofore undreamt-of amounts?

I’m going to excerpt a conversation from the second book:

[At dinner,] chemist Sofia Boutros described the unfolding water crisis in the Nile watershed back on Earth—and the resulting regional conflict. This elicited from around the table a litany of other climate-change-related calamities back home, from wildfires, to floods, to famines, to extinctions.

The Russian observer, Colonel Voloshin, usually content to just listen, chimed in by saying, "Nations which have contributed least to carbon emissions suffering worst effects." He looked first to Lawler and then Colonel Fei. "Perhaps the biggest polluters should pay reparations."

Dr. Ohana looked down the table toward him. "It's my understanding that Russia has actually benefitted from warmer climate."

Yak replied instead. "Not overall. Soil in Siberia is poor. Wildfires and loss of permafrost also disruptive."

Lawler added. "You guys sell plenty of fossil fuels, too, Colonel."

The electrical engineer, Hoshiko Sato, said, "Complete decarbonization is the only way to solve climate change."

Most of the group groaned in response.

She looked around the table. "That might sound unrealistic, but there's no other choice if we want to save civilization."

Chindarkar said, "We've been saying the same thing for fifty years, Hoshiko. It's barely moved the needle."

"We’ve brought carbon emissions down considerably since 2020."

Boutros said, "You mean we slowed their growth."

Ohana said, "We should be planting more trees."

Monica Balter countered, "Trees require water and arable land. Climate change is causing deserts to spread, pitting food versus trees. Plus, whatever carbon a tree captures gets released when it dies—which could happen all at once in a wildfire."

Chindarkar looked down the table at her. "Nathan Joyce claimed we could use solar satellites to power direct carbon capture. Could that really be done at the scale necessary to reduce global CO2 levels?"

Colonel Voloshin let out a laugh. "That's not even in the realm of possibility. It wouldn't even make a dent."

Monica Balter said, "I respectfully disagree, Colonel." She looked to Boutros. "And Sofia, I understand we must do everything possible down on Earth to reduce carbon emissions: solar panels, wind turbines, geothermal—all of it. But that won't remove what's already in the atmosphere."

Voloshin shook his head. "We must adapt."

Lawler couldn't resist. "Easy for Russia to say."

Balter spoke to Voloshin. "Back in 1850, atmospheric carbon was at two hundred eighty parts per million. Now it's at four hundred fifty-seven parts per million. We put over a trillion tons of CO2 into Earth's atmosphere over that time. Humans caused the problem, and humans can solve it."

The colonel was unfazed. "Yes. All of humanity worked hard to cause this, and it still required almost two centuries to accomplish. It is naïve to think a few machines will correct it."

"Half of that excess carbon was emitted in the last forty years, and direct air carbon capture powered by solar satellites can actually work at a global scale. I can show you the numbers, if you like."

He scoffed. "Even billionaire Jack Macy says that solar power satellites are idiotic—that very little energy beamed from space reaches the terrestrial power grid due to transmission and conversion losses."

Balter nodded. "The number is 9 percent."

The crew around the table murmured.

He spread his hands. "I rest my case."

"But 9 percent of what? Jack Macy neglects to mention that a solar panel up in orbit is seven times more productive than one on the Earth's surface. The fact that he runs a rooftop solar company might have something to do with that.

Boutros asked, "A sevenfold difference just from being in space?"

Balter turned to her. "The best you can hope for on the Earth's equator at high noon is 1,000 watts of energy per square meter—and that's without factoring in nighttime, cloudy days, seasons, latitude. But a power sat in geosynchronous orbit would almost always be in 1,368 watts of sunlight per square meter. So you get a whole lot more energy from a solar panel in space even after transmission inefficiencies are factored in. Plus, a power sat won't be affected by unfolding chaos planetside."

Voloshin shrugged. "What if it is cloudy above your rectenna? You would not be able to beam down energy."

"Not true. We use microwaves in the 2.45-gigahertz range. The atmosphere is largely invisible at that frequency. We can beam the energy down regardless of weather—and directly to where it's needed. No need for long distance power lines."

"But to what purpose? It could not be done on a scale sufficient to impact Earth."

"Again, I could show you the numbers."

Chindarkar said, "I'd like to see them, Monica. Please."

Balter put down her fork and after searching through virtual UIs for a moment, put up a shared augmented-reality screen that appeared to float over the end of the table on the station's common layer. It displayed an array of numbers and labels. "Sorry for the spreadsheet."

Colonel Fei said, "We are quite interested in seeing it, Ms. Balter."

She looked to the faces around the table. "There are four reasons I got involved in space-based solar power... " She pealed them off on her fingers. "...electrification, desalination, food generation, and decarbonization. First: electricity. We all know the environmental, economic, and political havoc back on Earth from climate change. Blackouts make that chaos worse, but a 2-gigawatt solar power satellite in geosynchronous orbit could instantly transmit large amounts of energy anywhere it's needed in the hemisphere below it. Even several locations at once. All that's needed is a rectenna on the ground, and those are cheap and easy to construct."

Chindarkar nodded. "We saw one on Ascension Island."

Jin added, "J.T. and I are building sections of the lunar rectenna. It is fairly simple."

"Right. For example, space-based energy could be beamed to coastal desalination plants in regions suffering long-term drought-providing fresh water. It can also be used to remove CO2 directly from seawater, through what's known as single step carbon sequestration and storage, converting the CO2 into solid limestone and magnesite—essentially seashells. This would enable the oceans themselves to absorb more atmospheric CO2. Or we could power direct air capture plants that pull CO2 straight out of the atmosphere."

Voloshin interjected. "Again, a few satellites will not impact Earth's atmospheric concentrations, and where would you sequester all this CO2?"

"Just a few satellites wouldn't impact climate, no—but there's definitely a use for the CO2—in creating food. Droughts in equatorial zones are causing famine, but hydrogenotrophic bacteria can be used to make protein from electricity, hydrogen, and CO2. The hydrogen can be electrolyzed from seawater and CO2 from the air. All that's needed is clean energy." She glanced to Chindarkar. "NASA first experimented with this in the 1960s as a means for making food here in deep space."

"Really? Even back then."

"The bioreactor for it is like a small-batch brewery. You feed in what natural plants get from soil: phosphorus, sulfur, calcium, iron, potassium—all of which, incidentally, can be extracted from lunar regolith. But I digress..."

Colonel Fei's eyebrows raised. "That is indeed interesting."

"The bioreactor runs for a while, then the liquid is drained and the solids dried to a powder that contains 65 percent protein, 20 to 25 percent carbohydrates, and 5 percent fatty acids. This can be made into a natural food similar to soy or algae. So with energy, CO2, and seawater, we could provide life-saving nutrition just about anywhere on the planet via solar power satellites."

Voloshin was unimpressed. "Yet it would still not resolve climate change."

"At scale it could. Do the math ... " Balter brought up her spreadsheet. "We're emitting 40 billion tons of CO2 per year, 9 billion tons of which can't be sequestered by the natural carbon cycle and which results in an annual increase of roughly two parts per million atmospheric CO2—even after decades of conservation efforts."

She tapped a few screens and a virtual image of an industrial structure covered in fan housings appeared. "A direct air capture facility like this one could pull a million tons of CO2 out of the atmosphere each year at a cost of one hundred dollars a ton. All of the components are off-the-shelf and have existed for decades. Nothing fancy. But it needs 1.5 megawatts of constant clean energy to power it—and that's where solar power satellites come in."

Voloshin said, "But who would pay? Governments? Do not count on this."

Chindarkar asked, "Monica, seriously: How many carbon capture plants would it take to make a difference in the atmosphere of the entire Earth?"

Jin added, "And how many solar power satellites to power them?"

Balter brought her spreadsheet back up. "Merely to cancel out Earth's excess annual emissions—9 billion tons of CO2—we'd need nine thousand 1-megaton DAC plants worldwide, each requiring 150 to 300 acres."

The group groaned.

Tighe said, "That's a lot of hardware and a lot of real estate, Monica."

"It doesn't have to be on land. Just 2.7 million acres total—smaller than Connecticut. And that would be spread across the entire globe. More importantly, doing that stops the advance of climate change. If we reduce emissions, then it would actually help reverse climate change."

Chindarkar studied the numbers. "Powered by how many solar satellites?"

Balter highlighted the number. "It would take 1.6 terawatts of electricity—or 818 2-gigawatt SPS-Alphas. Each about 7,400 tons. But again: that halts the advance of climate change."

The group groaned again.

"Eight hundred eighteen satellites?" Jin shook his head. "That would take decades to build."

"Not with automation and sufficient materials here on orbit. You've seen the SPS-Alpha I'm building—it's made of simple, modular components."

"Yours is one-fortieth the size of these 7,400-ton monsters."

"But it's the same design. We just need the resources up here in space, and we could scale it rapidly with automation."

Voloshin picked up his fork. "As I said: it is a technological fantasy."

Chindarkar ignored him. "Monica, what would it require to not just halt climate change—but reverse it?"

Balter clicked through to another screen. "To return Earth to a safe level—say, three hundred fifty parts per million CO2-you'd need to pull three-quarters of a trillion tons out of the atmosphere." She made a few changes to her model. "So with forty thousand DAC plants, powered by thirty-six hundred 2-gigawatt satellites in geosynchronous orbit, you could accomplish that in eighteen years."

Fei asked, "At what cost?"

"Roughly seventy-two trillion dollars."

Again groans and an impressed whistle.

Voloshin shook his head. "I told you."

Balter added, "That's four trillion a year, over eighteen years. Spread across the entire population of Earth."

This was met with a different reaction.

Jin said, "That is actually less than I thought."

"And bear in mind the fossil fuel industry has been supported by half a trillion dollars in direct government subsidies worldwide every year for ages. Whereas this four trillion is for just a limited time and would permanently solve climate change, and we'd see significant climate benefits within a decade as CO2 levels came down. And once it was accomplished, all that clean energy could be put toward other productive uses, either on Earth or in space."

She studied the faces around her. "But to accomplish it, we'd need tens of millions of tons of mass in orbit. Launching all that mass up from Earth would never work because all those rockets would damage the atmosphere, too. However, with your lunar mass-driver—and the ones that follow it—we could make this work. This is why I'm here."

Those around the table pondered this. For the moment, even Voloshin was silent.

Boutros asked, "Is it not risky to tinker with the Earth's atmosphere?"

"That's what we're doing now, Sofia. This would just reverse what we've done and return Earth to the conditions we evolved in."

Chindarkar pointed to the virtual spreadsheet. "Does that seventy-two trillion dollars include the cost of the solar power satellites?"

"Yes. And doing nothing will cost us far more. Best estimates are that by the year 2100, continued climate change will reduce global GDP by 20 percent—which is about two thousand trillion dollars. Not to mention the cost of possibly losing civilization.

"But if, as your CEO Mr. Rochat says, we intend to prove the SPS concept at scale here in lunar orbit, well... then you will make this commercially feasible. In other words, you can make this future happen. Everyone else has talked it to death. The bean counters and decision makers back on Earth clearly won't do it, no matter how critical it is. And this needs to be started as soon as possible—before the situation on Earth gets truly untenable."

This book is not afraid to think big. That's what sci-fi is for, right? And it's extensively researched; there's a bibliography at the end of each book that I've used to start my own research journeys.

I like these books because they're ambitious. They never downplay the scale of the problems we face, but they maintain that these problems are solvable, and they expose me to new ideas I'd never heard of. I found them in my local library. Thanks for reading this wall of text!