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.